3368 lines
129 KiB
C
3368 lines
129 KiB
C
/*
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This is a version (aka dlmalloc) of malloc/free/realloc written by
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Doug Lea and released to the public domain, as explained at
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http://creativecommons.org/publicdomain/zero/1.0/ Send questions,
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comments, complaints, performance data, etc to dl@cs.oswego.edu
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* Version 2.8.6 Wed Aug 29 06:57:58 2012 Doug Lea
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Note: There may be an updated version of this malloc obtainable at
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ftp://gee.cs.oswego.edu/pub/misc/malloc.c
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Check before installing!
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* Quickstart
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This library is all in one file to simplify the most common usage:
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ftp it, compile it (-O3), and link it into another program. All of
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the compile-time options default to reasonable values for use on
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most platforms. You might later want to step through various
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compile-time and dynamic tuning options.
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For convenience, an include file for code using this malloc is at:
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ftp://gee.cs.oswego.edu/pub/misc/malloc-2.8.6.h
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You don't really need this .h file unless you call functions not
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defined in your system include files. The .h file contains only the
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excerpts from this file needed for using this malloc on ANSI C/C++
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systems, so long as you haven't changed compile-time options about
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naming and tuning parameters. If you do, then you can create your
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own malloc.h that does include all settings by cutting at the point
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indicated below. Note that you may already by default be using a C
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library containing a malloc that is based on some version of this
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malloc (for example in linux). You might still want to use the one
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in this file to customize settings or to avoid overheads associated
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with library versions.
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* Vital statistics:
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Supported pointer/size_t representation: 4 or 8 bytes
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size_t MUST be an unsigned type of the same width as
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pointers. (If you are using an ancient system that declares
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size_t as a signed type, or need it to be a different width
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than pointers, you can use a previous release of this malloc
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(e.g. 2.7.2) supporting these.)
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Alignment: 8 bytes (minimum)
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This suffices for nearly all current machines and C compilers.
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However, you can define MALLOC_ALIGNMENT to be wider than this
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if necessary (up to 128bytes), at the expense of using more space.
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Minimum overhead per allocated chunk: 4 or 8 bytes (if 4byte sizes)
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8 or 16 bytes (if 8byte sizes)
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Each malloced chunk has a hidden word of overhead holding size
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and status information, and additional cross-check word
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if FOOTERS is defined.
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Minimum allocated size: 4-byte ptrs: 16 bytes (including overhead)
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8-byte ptrs: 32 bytes (including overhead)
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Even a request for zero bytes (i.e., malloc(0)) returns a
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pointer to something of the minimum allocatable size.
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The maximum overhead wastage (i.e., number of extra bytes
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allocated than were requested in malloc) is less than or equal
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to the minimum size, except for requests >= mmap_threshold that
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are serviced via mmap(), where the worst case wastage is about
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32 bytes plus the remainder from a system page (the minimal
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mmap unit); typically 4096 or 8192 bytes.
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Security: static-safe; optionally more or less
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The "security" of malloc refers to the ability of malicious
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code to accentuate the effects of errors (for example, freeing
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space that is not currently malloc'ed or overwriting past the
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ends of chunks) in code that calls malloc. This malloc
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guarantees not to modify any memory locations below the base of
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heap, i.e., static variables, even in the presence of usage
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errors. The routines additionally detect most improper frees
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and reallocs. All this holds as long as the static bookkeeping
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for malloc itself is not corrupted by some other means. This
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is only one aspect of security -- these checks do not, and
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cannot, detect all possible programming errors.
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If FOOTERS is defined nonzero, then each allocated chunk
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carries an additional check word to verify that it was malloced
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from its space. These check words are the same within each
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execution of a program using malloc, but differ across
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executions, so externally crafted fake chunks cannot be
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freed. This improves security by rejecting frees/reallocs that
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could corrupt heap memory, in addition to the checks preventing
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writes to statics that are always on. This may further improve
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security at the expense of time and space overhead. (Note that
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FOOTERS may also be worth using with MSPACES.)
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By default detected errors cause the program to abort (calling
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"abort()"). You can override this to instead proceed past
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errors by defining PROCEED_ON_ERROR. In this case, a bad free
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has no effect, and a malloc that encounters a bad address
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caused by user overwrites will ignore the bad address by
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dropping pointers and indices to all known memory. This may
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be appropriate for programs that should continue if at all
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possible in the face of programming errors, although they may
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run out of memory because dropped memory is never reclaimed.
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If you don't like either of these options, you can define
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CORRUPTION_ERROR_ACTION and USAGE_ERROR_ACTION to do anything
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else. And if if you are sure that your program using malloc has
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no errors or vulnerabilities, you can define INSECURE to 1,
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which might (or might not) provide a small performance improvement.
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It is also possible to limit the maximum total allocatable
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space, using malloc_set_footprint_limit. This is not
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designed as a security feature in itself (calls to set limits
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are not screened or privileged), but may be useful as one
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aspect of a secure implementation.
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Thread-safety: NOT thread-safe unless USE_LOCKS defined non-zero
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When USE_LOCKS is defined, each public call to malloc, free,
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etc is surrounded with a lock. By default, this uses a plain
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pthread mutex, win32 critical section, or a spin-lock if if
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available for the platform and not disabled by setting
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USE_SPIN_LOCKS=0. However, if USE_RECURSIVE_LOCKS is defined,
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recursive versions are used instead (which are not required for
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base functionality but may be needed in layered extensions).
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Using a global lock is not especially fast, and can be a major
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bottleneck. It is designed only to provide minimal protection
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in concurrent environments, and to provide a basis for
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extensions. If you are using malloc in a concurrent program,
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consider instead using nedmalloc
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(http://www.nedprod.com/programs/portable/nedmalloc/) or
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ptmalloc (See http://www.malloc.de), which are derived from
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versions of this malloc.
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System requirements: Any combination of MORECORE and/or MMAP/MUNMAP
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This malloc can use unix sbrk or any emulation (invoked using
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the CALL_MORECORE macro) and/or mmap/munmap or any emulation
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(invoked using CALL_MMAP/CALL_MUNMAP) to get and release system
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memory. On most unix systems, it tends to work best if both
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MORECORE and MMAP are enabled. On Win32, it uses emulations
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based on VirtualAlloc. It also uses common C library functions
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like memset.
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Compliance: I believe it is compliant with the Single Unix Specification
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(See http://www.unix.org). Also SVID/XPG, ANSI C, and probably
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others as well.
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* Overview of algorithms
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This is not the fastest, most space-conserving, most portable, or
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most tunable malloc ever written. However it is among the fastest
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while also being among the most space-conserving, portable and
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tunable. Consistent balance across these factors results in a good
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general-purpose allocator for malloc-intensive programs.
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In most ways, this malloc is a best-fit allocator. Generally, it
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chooses the best-fitting existing chunk for a request, with ties
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broken in approximately least-recently-used order. (This strategy
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normally maintains low fragmentation.) However, for requests less
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than 256bytes, it deviates from best-fit when there is not an
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exactly fitting available chunk by preferring to use space adjacent
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to that used for the previous small request, as well as by breaking
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ties in approximately most-recently-used order. (These enhance
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locality of series of small allocations.) And for very large requests
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(>= 256Kb by default), it relies on system memory mapping
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facilities, if supported. (This helps avoid carrying around and
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possibly fragmenting memory used only for large chunks.)
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All operations (except malloc_stats and mallinfo) have execution
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times that are bounded by a constant factor of the number of bits in
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a size_t, not counting any clearing in calloc or copying in realloc,
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or actions surrounding MORECORE and MMAP that have times
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proportional to the number of non-contiguous regions returned by
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system allocation routines, which is often just 1. In real-time
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applications, you can optionally suppress segment traversals using
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NO_SEGMENT_TRAVERSAL, which assures bounded execution even when
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system allocators return non-contiguous spaces, at the typical
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expense of carrying around more memory and increased fragmentation.
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The implementation is not very modular and seriously overuses
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macros. Perhaps someday all C compilers will do as good a job
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inlining modular code as can now be done by brute-force expansion,
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but now, enough of them seem not to.
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Some compilers issue a lot of warnings about code that is
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dead/unreachable only on some platforms, and also about intentional
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uses of negation on unsigned types. All known cases of each can be
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ignored.
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For a longer but out of date high-level description, see
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http://gee.cs.oswego.edu/dl/html/malloc.html
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* MSPACES
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If MSPACES is defined, then in addition to malloc, free, etc.,
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this file also defines mspace_malloc, mspace_free, etc. These
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are versions of malloc routines that take an "mspace" argument
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obtained using create_mspace, to control all internal bookkeeping.
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If ONLY_MSPACES is defined, only these versions are compiled.
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So if you would like to use this allocator for only some allocations,
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and your system malloc for others, you can compile with
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ONLY_MSPACES and then do something like...
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static mspace mymspace = create_mspace(0,0); // for example
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#define mymalloc(bytes) mspace_malloc(mymspace, bytes)
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(Note: If you only need one instance of an mspace, you can instead
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use "USE_DL_PREFIX" to relabel the global malloc.)
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You can similarly create thread-local allocators by storing
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mspaces as thread-locals. For example:
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static __thread mspace tlms = 0;
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void* tlmalloc(size_t bytes) {
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if (tlms == 0) tlms = create_mspace(0, 0);
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return mspace_malloc(tlms, bytes);
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}
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void tlfree(void* mem) { mspace_free(tlms, mem); }
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Unless FOOTERS is defined, each mspace is completely independent.
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You cannot allocate from one and free to another (although
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conformance is only weakly checked, so usage errors are not always
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caught). If FOOTERS is defined, then each chunk carries around a tag
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indicating its originating mspace, and frees are directed to their
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originating spaces. Normally, this requires use of locks.
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------------------------- Compile-time options ---------------------------
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Be careful in setting #define values for numerical constants of type
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size_t. On some systems, literal values are not automatically extended
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to size_t precision unless they are explicitly casted. You can also
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use the symbolic values MAX_SIZE_T, SIZE_T_ONE, etc below.
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WIN32 default: defined if _WIN32 defined
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Defining WIN32 sets up defaults for MS environment and compilers.
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Otherwise defaults are for unix. Beware that there seem to be some
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cases where this malloc might not be a pure drop-in replacement for
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Win32 malloc: Random-looking failures from Win32 GDI API's (eg;
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SetDIBits()) may be due to bugs in some video driver implementations
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when pixel buffers are malloc()ed, and the region spans more than
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one VirtualAlloc()ed region. Because dlmalloc uses a small (64Kb)
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default granularity, pixel buffers may straddle virtual allocation
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regions more often than when using the Microsoft allocator. You can
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avoid this by using VirtualAlloc() and VirtualFree() for all pixel
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buffers rather than using malloc(). If this is not possible,
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recompile this malloc with a larger DEFAULT_GRANULARITY. Note:
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in cases where MSC and gcc (cygwin) are known to differ on WIN32,
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conditions use _MSC_VER to distinguish them.
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DLMALLOC_EXPORT default: extern
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Defines how public APIs are declared. If you want to export via a
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Windows DLL, you might define this as
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#define DLMALLOC_EXPORT extern __declspec(dllexport)
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If you want a POSIX ELF shared object, you might use
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#define DLMALLOC_EXPORT extern __attribute__((visibility("default")))
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MALLOC_ALIGNMENT default: (size_t)(2 * sizeof(void *))
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Controls the minimum alignment for malloc'ed chunks. It must be a
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power of two and at least 8, even on machines for which smaller
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alignments would suffice. It may be defined as larger than this
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though. Note however that code and data structures are optimized for
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the case of 8-byte alignment.
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MSPACES default: 0 (false)
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If true, compile in support for independent allocation spaces.
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This is only supported if HAVE_MMAP is true.
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ONLY_MSPACES default: 0 (false)
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If true, only compile in mspace versions, not regular versions.
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USE_LOCKS default: 0 (false)
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Causes each call to each public routine to be surrounded with
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pthread or WIN32 mutex lock/unlock. (If set true, this can be
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overridden on a per-mspace basis for mspace versions.) If set to a
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non-zero value other than 1, locks are used, but their
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implementation is left out, so lock functions must be supplied manually,
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as described below.
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USE_SPIN_LOCKS default: 1 iff USE_LOCKS and spin locks available
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If true, uses custom spin locks for locking. This is currently
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supported only gcc >= 4.1, older gccs on x86 platforms, and recent
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MS compilers. Otherwise, posix locks or win32 critical sections are
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used.
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USE_RECURSIVE_LOCKS default: not defined
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If defined nonzero, uses recursive (aka reentrant) locks, otherwise
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uses plain mutexes. This is not required for malloc proper, but may
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be needed for layered allocators such as nedmalloc.
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LOCK_AT_FORK default: not defined
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If defined nonzero, performs pthread_atfork upon initialization
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to initialize child lock while holding parent lock. The implementation
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assumes that pthread locks (not custom locks) are being used. In other
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cases, you may need to customize the implementation.
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FOOTERS default: 0
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If true, provide extra checking and dispatching by placing
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information in the footers of allocated chunks. This adds
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space and time overhead.
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INSECURE default: 0
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If true, omit checks for usage errors and heap space overwrites.
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USE_DL_PREFIX default: NOT defined
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Causes compiler to prefix all public routines with the string 'dl'.
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This can be useful when you only want to use this malloc in one part
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of a program, using your regular system malloc elsewhere.
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MALLOC_INSPECT_ALL default: NOT defined
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If defined, compiles malloc_inspect_all and mspace_inspect_all, that
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perform traversal of all heap space. Unless access to these
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functions is otherwise restricted, you probably do not want to
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include them in secure implementations.
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ABORT default: defined as abort()
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Defines how to abort on failed checks. On most systems, a failed
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check cannot die with an "assert" or even print an informative
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message, because the underlying print routines in turn call malloc,
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which will fail again. Generally, the best policy is to simply call
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abort(). It's not very useful to do more than this because many
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errors due to overwriting will show up as address faults (null, odd
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addresses etc) rather than malloc-triggered checks, so will also
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abort. Also, most compilers know that abort() does not return, so
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can better optimize code conditionally calling it.
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PROCEED_ON_ERROR default: defined as 0 (false)
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Controls whether detected bad addresses cause them to bypassed
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rather than aborting. If set, detected bad arguments to free and
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realloc are ignored. And all bookkeeping information is zeroed out
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upon a detected overwrite of freed heap space, thus losing the
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ability to ever return it from malloc again, but enabling the
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application to proceed. If PROCEED_ON_ERROR is defined, the
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static variable malloc_corruption_error_count is compiled in
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and can be examined to see if errors have occurred. This option
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generates slower code than the default abort policy.
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DEBUG default: NOT defined
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The DEBUG setting is mainly intended for people trying to modify
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this code or diagnose problems when porting to new platforms.
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However, it may also be able to better isolate user errors than just
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using runtime checks. The assertions in the check routines spell
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out in more detail the assumptions and invariants underlying the
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algorithms. The checking is fairly extensive, and will slow down
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execution noticeably. Calling malloc_stats or mallinfo with DEBUG
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set will attempt to check every non-mmapped allocated and free chunk
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in the course of computing the summaries.
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ABORT_ON_ASSERT_FAILURE default: defined as 1 (true)
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Debugging assertion failures can be nearly impossible if your
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version of the assert macro causes malloc to be called, which will
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lead to a cascade of further failures, blowing the runtime stack.
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ABORT_ON_ASSERT_FAILURE cause assertions failures to call abort(),
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which will usually make debugging easier.
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MALLOC_FAILURE_ACTION default: sets errno to ENOMEM, or no-op on win32
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The action to take before "return 0" when malloc fails to be able to
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return memory because there is none available.
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HAVE_MORECORE default: 1 (true) unless win32 or ONLY_MSPACES
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True if this system supports sbrk or an emulation of it.
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MORECORE default: sbrk
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The name of the sbrk-style system routine to call to obtain more
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memory. See below for guidance on writing custom MORECORE
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functions. The type of the argument to sbrk/MORECORE varies across
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systems. It cannot be size_t, because it supports negative
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arguments, so it is normally the signed type of the same width as
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size_t (sometimes declared as "intptr_t"). It doesn't much matter
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though. Internally, we only call it with arguments less than half
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the max value of a size_t, which should work across all reasonable
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possibilities, although sometimes generating compiler warnings.
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MORECORE_CONTIGUOUS default: 1 (true) if HAVE_MORECORE
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If true, take advantage of fact that consecutive calls to MORECORE
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with positive arguments always return contiguous increasing
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addresses. This is true of unix sbrk. It does not hurt too much to
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set it true anyway, since malloc copes with non-contiguities.
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Setting it false when definitely non-contiguous saves time
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and possibly wasted space it would take to discover this though.
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MORECORE_CANNOT_TRIM default: NOT defined
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True if MORECORE cannot release space back to the system when given
|
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negative arguments. This is generally necessary only if you are
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using a hand-crafted MORECORE function that cannot handle negative
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arguments.
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NO_SEGMENT_TRAVERSAL default: 0
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If non-zero, suppresses traversals of memory segments
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returned by either MORECORE or CALL_MMAP. This disables
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merging of segments that are contiguous, and selectively
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releasing them to the OS if unused, but bounds execution times.
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HAVE_MMAP default: 1 (true)
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True if this system supports mmap or an emulation of it. If so, and
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HAVE_MORECORE is not true, MMAP is used for all system
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allocation. If set and HAVE_MORECORE is true as well, MMAP is
|
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primarily used to directly allocate very large blocks. It is also
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used as a backup strategy in cases where MORECORE fails to provide
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space from system. Note: A single call to MUNMAP is assumed to be
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able to unmap memory that may have be allocated using multiple calls
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to MMAP, so long as they are adjacent.
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HAVE_MREMAP default: 1 on linux, else 0
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If true realloc() uses mremap() to re-allocate large blocks and
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extend or shrink allocation spaces.
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MMAP_CLEARS default: 1 except on WINCE.
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True if mmap clears memory so calloc doesn't need to. This is true
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for standard unix mmap using /dev/zero and on WIN32 except for WINCE.
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USE_BUILTIN_FFS default: 0 (i.e., not used)
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Causes malloc to use the builtin ffs() function to compute indices.
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Some compilers may recognize and intrinsify ffs to be faster than the
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supplied C version. Also, the case of x86 using gcc is special-cased
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to an asm instruction, so is already as fast as it can be, and so
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this setting has no effect. Similarly for Win32 under recent MS compilers.
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(On most x86s, the asm version is only slightly faster than the C version.)
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malloc_getpagesize default: derive from system includes, or 4096.
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The system page size. To the extent possible, this malloc manages
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memory from the system in page-size units. This may be (and
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usually is) a function rather than a constant. This is ignored
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if WIN32, where page size is determined using getSystemInfo during
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initialization.
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USE_DEV_RANDOM default: 0 (i.e., not used)
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Causes malloc to use /dev/random to initialize secure magic seed for
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stamping footers. Otherwise, the current time is used.
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NO_MALLINFO default: 0
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If defined, don't compile "mallinfo". This can be a simple way
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of dealing with mismatches between system declarations and
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those in this file.
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MALLINFO_FIELD_TYPE default: size_t
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The type of the fields in the mallinfo struct. This was originally
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defined as "int" in SVID etc, but is more usefully defined as
|
|
size_t. The value is used only if HAVE_USR_INCLUDE_MALLOC_H is not set
|
|
|
|
NO_MALLOC_STATS default: 0
|
|
If defined, don't compile "malloc_stats". This avoids calls to
|
|
fprintf and bringing in stdio dependencies you might not want.
|
|
|
|
REALLOC_ZERO_BYTES_FREES default: not defined
|
|
This should be set if a call to realloc with zero bytes should
|
|
be the same as a call to free. Some people think it should. Otherwise,
|
|
since this malloc returns a unique pointer for malloc(0), so does
|
|
realloc(p, 0).
|
|
|
|
LACKS_UNISTD_H, LACKS_FCNTL_H, LACKS_SYS_PARAM_H, LACKS_SYS_MMAN_H
|
|
LACKS_STRINGS_H, LACKS_STRING_H, LACKS_SYS_TYPES_H, LACKS_ERRNO_H
|
|
LACKS_STDLIB_H LACKS_SCHED_H LACKS_TIME_H default: NOT defined unless on WIN32
|
|
Define these if your system does not have these header files.
|
|
You might need to manually insert some of the declarations they provide.
|
|
|
|
DEFAULT_GRANULARITY default: page size if MORECORE_CONTIGUOUS,
|
|
system_info.dwAllocationGranularity in WIN32,
|
|
otherwise 64K.
|
|
Also settable using mallopt(M_GRANULARITY, x)
|
|
The unit for allocating and deallocating memory from the system. On
|
|
most systems with contiguous MORECORE, there is no reason to
|
|
make this more than a page. However, systems with MMAP tend to
|
|
either require or encourage larger granularities. You can increase
|
|
this value to prevent system allocation functions to be called so
|
|
often, especially if they are slow. The value must be at least one
|
|
page and must be a power of two. Setting to 0 causes initialization
|
|
to either page size or win32 region size. (Note: In previous
|
|
versions of malloc, the equivalent of this option was called
|
|
"TOP_PAD")
|
|
|
|
DEFAULT_TRIM_THRESHOLD default: 2MB
|
|
Also settable using mallopt(M_TRIM_THRESHOLD, x)
|
|
The maximum amount of unused top-most memory to keep before
|
|
releasing via malloc_trim in free(). Automatic trimming is mainly
|
|
useful in long-lived programs using contiguous MORECORE. Because
|
|
trimming via sbrk can be slow on some systems, and can sometimes be
|
|
wasteful (in cases where programs immediately afterward allocate
|
|
more large chunks) the value should be high enough so that your
|
|
overall system performance would improve by releasing this much
|
|
memory. As a rough guide, you might set to a value close to the
|
|
average size of a process (program) running on your system.
|
|
Releasing this much memory would allow such a process to run in
|
|
memory. Generally, it is worth tuning trim thresholds when a
|
|
program undergoes phases where several large chunks are allocated
|
|
and released in ways that can reuse each other's storage, perhaps
|
|
mixed with phases where there are no such chunks at all. The trim
|
|
value must be greater than page size to have any useful effect. To
|
|
disable trimming completely, you can set to MAX_SIZE_T. Note that the trick
|
|
some people use of mallocing a huge space and then freeing it at
|
|
program startup, in an attempt to reserve system memory, doesn't
|
|
have the intended effect under automatic trimming, since that memory
|
|
will immediately be returned to the system.
|
|
|
|
DEFAULT_MMAP_THRESHOLD default: 256K
|
|
Also settable using mallopt(M_MMAP_THRESHOLD, x)
|
|
The request size threshold for using MMAP to directly service a
|
|
request. Requests of at least this size that cannot be allocated
|
|
using already-existing space will be serviced via mmap. (If enough
|
|
normal freed space already exists it is used instead.) Using mmap
|
|
segregates relatively large chunks of memory so that they can be
|
|
individually obtained and released from the host system. A request
|
|
serviced through mmap is never reused by any other request (at least
|
|
not directly; the system may just so happen to remap successive
|
|
requests to the same locations). Segregating space in this way has
|
|
the benefits that: Mmapped space can always be individually released
|
|
back to the system, which helps keep the system level memory demands
|
|
of a long-lived program low. Also, mapped memory doesn't become
|
|
`locked' between other chunks, as can happen with normally allocated
|
|
chunks, which means that even trimming via malloc_trim would not
|
|
release them. However, it has the disadvantage that the space
|
|
cannot be reclaimed, consolidated, and then used to service later
|
|
requests, as happens with normal chunks. The advantages of mmap
|
|
nearly always outweigh disadvantages for "large" chunks, but the
|
|
value of "large" may vary across systems. The default is an
|
|
empirically derived value that works well in most systems. You can
|
|
disable mmap by setting to MAX_SIZE_T.
|
|
|
|
MAX_RELEASE_CHECK_RATE default: 4095 unless not HAVE_MMAP
|
|
The number of consolidated frees between checks to release
|
|
unused segments when freeing. When using non-contiguous segments,
|
|
especially with multiple mspaces, checking only for topmost space
|
|
doesn't always suffice to trigger trimming. To compensate for this,
|
|
free() will, with a period of MAX_RELEASE_CHECK_RATE (or the
|
|
current number of segments, if greater) try to release unused
|
|
segments to the OS when freeing chunks that result in
|
|
consolidation. The best value for this parameter is a compromise
|
|
between slowing down frees with relatively costly checks that
|
|
rarely trigger versus holding on to unused memory. To effectively
|
|
disable, set to MAX_SIZE_T. This may lead to a very slight speed
|
|
improvement at the expense of carrying around more memory.
|
|
*/
|
|
|
|
#include <ddk.h>
|
|
#include <linux/mutex.h>
|
|
#include <syscall.h>
|
|
|
|
/* Version identifier to allow people to support multiple versions */
|
|
#ifndef DLMALLOC_VERSION
|
|
#define DLMALLOC_VERSION 20806
|
|
#endif /* DLMALLOC_VERSION */
|
|
|
|
|
|
/*
|
|
malloc(size_t n)
|
|
Returns a pointer to a newly allocated chunk of at least n bytes, or
|
|
null if no space is available, in which case errno is set to ENOMEM
|
|
on ANSI C systems.
|
|
|
|
If n is zero, malloc returns a minimum-sized chunk. (The minimum
|
|
size is 16 bytes on most 32bit systems, and 32 bytes on 64bit
|
|
systems.) Note that size_t is an unsigned type, so calls with
|
|
arguments that would be negative if signed are interpreted as
|
|
requests for huge amounts of space, which will often fail. The
|
|
maximum supported value of n differs across systems, but is in all
|
|
cases less than the maximum representable value of a size_t.
|
|
*/
|
|
|
|
/*
|
|
free(void* p)
|
|
Releases the chunk of memory pointed to by p, that had been previously
|
|
allocated using malloc or a related routine such as realloc.
|
|
It has no effect if p is null. If p was not malloced or already
|
|
freed, free(p) will by default cause the current program to abort.
|
|
*/
|
|
|
|
/*
|
|
calloc(size_t n_elements, size_t element_size);
|
|
Returns a pointer to n_elements * element_size bytes, with all locations
|
|
set to zero.
|
|
*/
|
|
|
|
/*
|
|
realloc(void* p, size_t n)
|
|
Returns a pointer to a chunk of size n that contains the same data
|
|
as does chunk p up to the minimum of (n, p's size) bytes, or null
|
|
if no space is available.
|
|
|
|
The returned pointer may or may not be the same as p. The algorithm
|
|
prefers extending p in most cases when possible, otherwise it
|
|
employs the equivalent of a malloc-copy-free sequence.
|
|
|
|
If p is null, realloc is equivalent to malloc.
|
|
|
|
If space is not available, realloc returns null, errno is set (if on
|
|
ANSI) and p is NOT freed.
|
|
|
|
if n is for fewer bytes than already held by p, the newly unused
|
|
space is lopped off and freed if possible. realloc with a size
|
|
argument of zero (re)allocates a minimum-sized chunk.
|
|
|
|
The old unix realloc convention of allowing the last-free'd chunk
|
|
to be used as an argument to realloc is not supported.
|
|
*/
|
|
/*
|
|
memalign(size_t alignment, size_t n);
|
|
Returns a pointer to a newly allocated chunk of n bytes, aligned
|
|
in accord with the alignment argument.
|
|
|
|
The alignment argument should be a power of two. If the argument is
|
|
not a power of two, the nearest greater power is used.
|
|
8-byte alignment is guaranteed by normal malloc calls, so don't
|
|
bother calling memalign with an argument of 8 or less.
|
|
|
|
Overreliance on memalign is a sure way to fragment space.
|
|
*/
|
|
|
|
|
|
#define DEBUG 1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
#define assert(x)
|
|
|
|
#define MAX_SIZE_T (~(size_t)0)
|
|
|
|
#define CALL_DIRECT_MMAP(s) MMAP_DEFAULT(s)
|
|
|
|
/* ------------------- size_t and alignment properties -------------------- */
|
|
|
|
/* The byte and bit size of a size_t */
|
|
#define SIZE_T_SIZE (sizeof(size_t))
|
|
#define SIZE_T_BITSIZE (sizeof(size_t) << 3)
|
|
|
|
/* Some constants coerced to size_t */
|
|
/* Annoying but necessary to avoid errors on some platforms */
|
|
#define SIZE_T_ZERO ((size_t)0)
|
|
#define SIZE_T_ONE ((size_t)1)
|
|
#define SIZE_T_TWO ((size_t)2)
|
|
#define SIZE_T_FOUR ((size_t)4)
|
|
#define TWO_SIZE_T_SIZES (SIZE_T_SIZE<<1)
|
|
#define FOUR_SIZE_T_SIZES (SIZE_T_SIZE<<2)
|
|
#define SIX_SIZE_T_SIZES (FOUR_SIZE_T_SIZES+TWO_SIZE_T_SIZES)
|
|
#define HALF_MAX_SIZE_T (MAX_SIZE_T / 2U)
|
|
|
|
#define USE_LOCK_BIT (2U)
|
|
#define USE_MMAP_BIT (SIZE_T_ONE)
|
|
#define USE_NONCONTIGUOUS_BIT (4U)
|
|
|
|
/* segment bit set in create_mspace_with_base */
|
|
#define EXTERN_BIT (8U)
|
|
|
|
#define HAVE_MMAP 1
|
|
#define HAVE_MORECORE 0
|
|
#define MORECORE_CANNOT_TRIM 1
|
|
#define CALL_MMAP(s) MMAP_DEFAULT(s)
|
|
#define CALL_MUNMAP(a, s) MUNMAP_DEFAULT((a), (s))
|
|
#define CALL_MREMAP(addr, osz, nsz, mv) MFAIL
|
|
#define MAX_RELEASE_CHECK_RATE 4095
|
|
#define NO_SEGMENT_TRAVERSAL 1
|
|
#define MALLOC_ALIGNMENT ((size_t)8U)
|
|
#define CHUNK_OVERHEAD (SIZE_T_SIZE)
|
|
#define DEFAULT_GRANULARITY ((size_t)128U * (size_t)1024U)
|
|
#define DEFAULT_MMAP_THRESHOLD ((size_t)512U * (size_t)1024U)
|
|
#define DEFAULT_TRIM_THRESHOLD ((size_t)1024U * (size_t)1024U)
|
|
|
|
/* The bit mask value corresponding to MALLOC_ALIGNMENT */
|
|
#define CHUNK_ALIGN_MASK (MALLOC_ALIGNMENT - SIZE_T_ONE)
|
|
|
|
/* True if address a has acceptable alignment */
|
|
#define is_aligned(A) (((size_t)((A)) & (CHUNK_ALIGN_MASK)) == 0)
|
|
|
|
/* the number of bytes to offset an address to align it */
|
|
#define align_offset(A)\
|
|
((((size_t)(A) & CHUNK_ALIGN_MASK) == 0)? 0 :\
|
|
((MALLOC_ALIGNMENT - ((size_t)(A) & CHUNK_ALIGN_MASK)) & CHUNK_ALIGN_MASK))
|
|
|
|
/* -------------------------- MMAP preliminaries ------------------------- */
|
|
|
|
/*
|
|
If HAVE_MORECORE or HAVE_MMAP are false, we just define calls and
|
|
checks to fail so compiler optimizer can delete code rather than
|
|
using so many "#if"s.
|
|
*/
|
|
|
|
|
|
/* MORECORE and MMAP must return MFAIL on failure */
|
|
#define MFAIL ((void*)(MAX_SIZE_T))
|
|
#define CMFAIL ((char*)(MFAIL)) /* defined for convenience */
|
|
|
|
#define should_trim(M,s) (0)
|
|
|
|
|
|
|
|
/* --------------------------- Lock preliminaries ------------------------ */
|
|
|
|
/*
|
|
When locks are defined, there is one global lock, plus
|
|
one per-mspace lock.
|
|
|
|
The global lock_ensures that mparams.magic and other unique
|
|
mparams values are initialized only once. It also protects
|
|
sequences of calls to MORECORE. In many cases sys_alloc requires
|
|
two calls, that should not be interleaved with calls by other
|
|
threads. This does not protect against direct calls to MORECORE
|
|
by other threads not using this lock, so there is still code to
|
|
cope the best we can on interference.
|
|
|
|
Per-mspace locks surround calls to malloc, free, etc.
|
|
By default, locks are simple non-reentrant mutexes.
|
|
|
|
Because lock-protected regions generally have bounded times, it is
|
|
OK to use the supplied simple spinlocks. Spinlocks are likely to
|
|
improve performance for lightly contended applications, but worsen
|
|
performance under heavy contention.
|
|
|
|
If USE_LOCKS is > 1, the definitions of lock routines here are
|
|
bypassed, in which case you will need to define the type MLOCK_T,
|
|
and at least INITIAL_LOCK, DESTROY_LOCK, ACQUIRE_LOCK, RELEASE_LOCK
|
|
and TRY_LOCK. You must also declare a
|
|
static MLOCK_T malloc_global_mutex = { initialization values };.
|
|
|
|
*/
|
|
|
|
static DEFINE_MUTEX(malloc_global_mutex);
|
|
|
|
#define ACQUIRE_MALLOC_GLOBAL_LOCK() MutexLock(&malloc_global_mutex);
|
|
#define RELEASE_MALLOC_GLOBAL_LOCK() MutexUnlock(&malloc_global_mutex);
|
|
|
|
|
|
/* ----------------------- Chunk representations ------------------------ */
|
|
|
|
/*
|
|
(The following includes lightly edited explanations by Colin Plumb.)
|
|
|
|
The malloc_chunk declaration below is misleading (but accurate and
|
|
necessary). It declares a "view" into memory allowing access to
|
|
necessary fields at known offsets from a given base.
|
|
|
|
Chunks of memory are maintained using a `boundary tag' method as
|
|
originally described by Knuth. (See the paper by Paul Wilson
|
|
ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a survey of such
|
|
techniques.) Sizes of free chunks are stored both in the front of
|
|
each chunk and at the end. This makes consolidating fragmented
|
|
chunks into bigger chunks fast. The head fields also hold bits
|
|
representing whether chunks are free or in use.
|
|
|
|
Here are some pictures to make it clearer. They are "exploded" to
|
|
show that the state of a chunk can be thought of as extending from
|
|
the high 31 bits of the head field of its header through the
|
|
prev_foot and PINUSE_BIT bit of the following chunk header.
|
|
|
|
A chunk that's in use looks like:
|
|
|
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Size of previous chunk (if P = 0) |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
|
|
| Size of this chunk 1| +-+
|
|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| |
|
|
+- -+
|
|
| |
|
|
+- -+
|
|
| :
|
|
+- size - sizeof(size_t) available payload bytes -+
|
|
: |
|
|
chunk-> +- -+
|
|
| |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|
|
|
| Size of next chunk (may or may not be in use) | +-+
|
|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
|
|
And if it's free, it looks like this:
|
|
|
|
chunk-> +- -+
|
|
| User payload (must be in use, or we would have merged!) |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
|
|
| Size of this chunk 0| +-+
|
|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Next pointer |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Prev pointer |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| :
|
|
+- size - sizeof(struct chunk) unused bytes -+
|
|
: |
|
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Size of this chunk |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|
|
|
| Size of next chunk (must be in use, or we would have merged)| +-+
|
|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| :
|
|
+- User payload -+
|
|
: |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
|0|
|
|
+-+
|
|
Note that since we always merge adjacent free chunks, the chunks
|
|
adjacent to a free chunk must be in use.
|
|
|
|
Given a pointer to a chunk (which can be derived trivially from the
|
|
payload pointer) we can, in O(1) time, find out whether the adjacent
|
|
chunks are free, and if so, unlink them from the lists that they
|
|
are on and merge them with the current chunk.
|
|
|
|
Chunks always begin on even word boundaries, so the mem portion
|
|
(which is returned to the user) is also on an even word boundary, and
|
|
thus at least double-word aligned.
|
|
|
|
The P (PINUSE_BIT) bit, stored in the unused low-order bit of the
|
|
chunk size (which is always a multiple of two words), is an in-use
|
|
bit for the *previous* chunk. If that bit is *clear*, then the
|
|
word before the current chunk size contains the previous chunk
|
|
size, and can be used to find the front of the previous chunk.
|
|
The very first chunk allocated always has this bit set, preventing
|
|
access to non-existent (or non-owned) memory. If pinuse is set for
|
|
any given chunk, then you CANNOT determine the size of the
|
|
previous chunk, and might even get a memory addressing fault when
|
|
trying to do so.
|
|
|
|
The C (CINUSE_BIT) bit, stored in the unused second-lowest bit of
|
|
the chunk size redundantly records whether the current chunk is
|
|
inuse (unless the chunk is mmapped). This redundancy enables usage
|
|
checks within free and realloc, and reduces indirection when freeing
|
|
and consolidating chunks.
|
|
|
|
Each freshly allocated chunk must have both cinuse and pinuse set.
|
|
That is, each allocated chunk borders either a previously allocated
|
|
and still in-use chunk, or the base of its memory arena. This is
|
|
ensured by making all allocations from the `lowest' part of any
|
|
found chunk. Further, no free chunk physically borders another one,
|
|
so each free chunk is known to be preceded and followed by either
|
|
inuse chunks or the ends of memory.
|
|
|
|
Note that the `foot' of the current chunk is actually represented
|
|
as the prev_foot of the NEXT chunk. This makes it easier to
|
|
deal with alignments etc but can be very confusing when trying
|
|
to extend or adapt this code.
|
|
|
|
The exceptions to all this are
|
|
|
|
1. The special chunk `top' is the top-most available chunk (i.e.,
|
|
the one bordering the end of available memory). It is treated
|
|
specially. Top is never included in any bin, is used only if
|
|
no other chunk is available, and is released back to the
|
|
system if it is very large (see M_TRIM_THRESHOLD). In effect,
|
|
the top chunk is treated as larger (and thus less well
|
|
fitting) than any other available chunk. The top chunk
|
|
doesn't update its trailing size field since there is no next
|
|
contiguous chunk that would have to index off it. However,
|
|
space is still allocated for it (TOP_FOOT_SIZE) to enable
|
|
separation or merging when space is extended.
|
|
|
|
3. Chunks allocated via mmap, have both cinuse and pinuse bits
|
|
cleared in their head fields. Because they are allocated
|
|
one-by-one, each must carry its own prev_foot field, which is
|
|
also used to hold the offset this chunk has within its mmapped
|
|
region, which is needed to preserve alignment. Each mmapped
|
|
chunk is trailed by the first two fields of a fake next-chunk
|
|
for sake of usage checks.
|
|
|
|
*/
|
|
|
|
struct malloc_chunk {
|
|
size_t prev_foot; /* Size of previous chunk (if free). */
|
|
size_t head; /* Size and inuse bits. */
|
|
struct malloc_chunk* fd; /* double links -- used only if free. */
|
|
struct malloc_chunk* bk;
|
|
};
|
|
|
|
typedef struct malloc_chunk mchunk;
|
|
typedef struct malloc_chunk* mchunkptr;
|
|
typedef struct malloc_chunk* sbinptr; /* The type of bins of chunks */
|
|
typedef unsigned int bindex_t; /* Described below */
|
|
typedef unsigned int binmap_t; /* Described below */
|
|
typedef unsigned int flag_t; /* The type of various bit flag sets */
|
|
|
|
/* ------------------- Chunks sizes and alignments ----------------------- */
|
|
|
|
#define MCHUNK_SIZE (sizeof(mchunk))
|
|
|
|
#if FOOTERS
|
|
#define CHUNK_OVERHEAD (TWO_SIZE_T_SIZES)
|
|
#else /* FOOTERS */
|
|
#define CHUNK_OVERHEAD (SIZE_T_SIZE)
|
|
#endif /* FOOTERS */
|
|
|
|
/* MMapped chunks need a second word of overhead ... */
|
|
#define MMAP_CHUNK_OVERHEAD (TWO_SIZE_T_SIZES)
|
|
/* ... and additional padding for fake next-chunk at foot */
|
|
#define MMAP_FOOT_PAD (FOUR_SIZE_T_SIZES)
|
|
|
|
/* The smallest size we can malloc is an aligned minimal chunk */
|
|
#define MIN_CHUNK_SIZE\
|
|
((MCHUNK_SIZE + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK)
|
|
|
|
/* conversion from malloc headers to user pointers, and back */
|
|
#define chunk2mem(p) ((void*)((char*)(p) + TWO_SIZE_T_SIZES))
|
|
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - TWO_SIZE_T_SIZES))
|
|
/* chunk associated with aligned address A */
|
|
#define align_as_chunk(A) (mchunkptr)((A) + align_offset(chunk2mem(A)))
|
|
|
|
/* Bounds on request (not chunk) sizes. */
|
|
#define MAX_REQUEST ((-MIN_CHUNK_SIZE) << 2)
|
|
#define MIN_REQUEST (MIN_CHUNK_SIZE - CHUNK_OVERHEAD - SIZE_T_ONE)
|
|
|
|
/* pad request bytes into a usable size */
|
|
#define pad_request(req) \
|
|
(((req) + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK)
|
|
|
|
/* pad request, checking for minimum (but not maximum) */
|
|
#define request2size(req) \
|
|
(((req) < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(req))
|
|
|
|
|
|
/* ------------------ Operations on head and foot fields ----------------- */
|
|
|
|
/*
|
|
The head field of a chunk is or'ed with PINUSE_BIT when previous
|
|
adjacent chunk in use, and or'ed with CINUSE_BIT if this chunk is in
|
|
use, unless mmapped, in which case both bits are cleared.
|
|
|
|
FLAG4_BIT is not used by this malloc, but might be useful in extensions.
|
|
*/
|
|
|
|
#define PINUSE_BIT (SIZE_T_ONE)
|
|
#define CINUSE_BIT (SIZE_T_TWO)
|
|
#define FLAG4_BIT (SIZE_T_FOUR)
|
|
#define INUSE_BITS (PINUSE_BIT|CINUSE_BIT)
|
|
#define FLAG_BITS (PINUSE_BIT|CINUSE_BIT|FLAG4_BIT)
|
|
|
|
/* Head value for fenceposts */
|
|
#define FENCEPOST_HEAD (INUSE_BITS|SIZE_T_SIZE)
|
|
|
|
/* extraction of fields from head words */
|
|
#define cinuse(p) ((p)->head & CINUSE_BIT)
|
|
#define pinuse(p) ((p)->head & PINUSE_BIT)
|
|
#define flag4inuse(p) ((p)->head & FLAG4_BIT)
|
|
#define is_inuse(p) (((p)->head & INUSE_BITS) != PINUSE_BIT)
|
|
#define is_mmapped(p) (((p)->head & INUSE_BITS) == 0)
|
|
|
|
#define chunksize(p) ((p)->head & ~(FLAG_BITS))
|
|
|
|
#define clear_pinuse(p) ((p)->head &= ~PINUSE_BIT)
|
|
#define set_flag4(p) ((p)->head |= FLAG4_BIT)
|
|
#define clear_flag4(p) ((p)->head &= ~FLAG4_BIT)
|
|
|
|
/* Treat space at ptr +/- offset as a chunk */
|
|
#define chunk_plus_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
|
|
#define chunk_minus_offset(p, s) ((mchunkptr)(((char*)(p)) - (s)))
|
|
|
|
/* Ptr to next or previous physical malloc_chunk. */
|
|
#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->head & ~FLAG_BITS)))
|
|
#define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_foot) ))
|
|
|
|
/* extract next chunk's pinuse bit */
|
|
#define next_pinuse(p) ((next_chunk(p)->head) & PINUSE_BIT)
|
|
|
|
/* Get/set size at footer */
|
|
#define get_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_foot)
|
|
#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_foot = (s))
|
|
|
|
/* Set size, pinuse bit, and foot */
|
|
#define set_size_and_pinuse_of_free_chunk(p, s)\
|
|
((p)->head = (s|PINUSE_BIT), set_foot(p, s))
|
|
|
|
/* Set size, pinuse bit, foot, and clear next pinuse */
|
|
#define set_free_with_pinuse(p, s, n)\
|
|
(clear_pinuse(n), set_size_and_pinuse_of_free_chunk(p, s))
|
|
|
|
/* Get the internal overhead associated with chunk p */
|
|
#define overhead_for(p)\
|
|
(is_mmapped(p)? MMAP_CHUNK_OVERHEAD : CHUNK_OVERHEAD)
|
|
|
|
/* Return true if malloced space is not necessarily cleared */
|
|
#if MMAP_CLEARS
|
|
#define calloc_must_clear(p) (!is_mmapped(p))
|
|
#else /* MMAP_CLEARS */
|
|
#define calloc_must_clear(p) (1)
|
|
#endif /* MMAP_CLEARS */
|
|
|
|
/* ---------------------- Overlaid data structures ----------------------- */
|
|
|
|
/*
|
|
When chunks are not in use, they are treated as nodes of either
|
|
lists or trees.
|
|
|
|
"Small" chunks are stored in circular doubly-linked lists, and look
|
|
like this:
|
|
|
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Size of previous chunk |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
`head:' | Size of chunk, in bytes |P|
|
|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Forward pointer to next chunk in list |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Back pointer to previous chunk in list |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Unused space (may be 0 bytes long) .
|
|
. .
|
|
. |
|
|
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
`foot:' | Size of chunk, in bytes |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
|
|
Larger chunks are kept in a form of bitwise digital trees (aka
|
|
tries) keyed on chunksizes. Because malloc_tree_chunks are only for
|
|
free chunks greater than 256 bytes, their size doesn't impose any
|
|
constraints on user chunk sizes. Each node looks like:
|
|
|
|
chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Size of previous chunk |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
`head:' | Size of chunk, in bytes |P|
|
|
mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Forward pointer to next chunk of same size |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Back pointer to previous chunk of same size |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Pointer to left child (child[0]) |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Pointer to right child (child[1]) |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Pointer to parent |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| bin index of this chunk |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
| Unused space .
|
|
. |
|
|
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
`foot:' | Size of chunk, in bytes |
|
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
|
|
|
Each tree holding treenodes is a tree of unique chunk sizes. Chunks
|
|
of the same size are arranged in a circularly-linked list, with only
|
|
the oldest chunk (the next to be used, in our FIFO ordering)
|
|
actually in the tree. (Tree members are distinguished by a non-null
|
|
parent pointer.) If a chunk with the same size an an existing node
|
|
is inserted, it is linked off the existing node using pointers that
|
|
work in the same way as fd/bk pointers of small chunks.
|
|
|
|
Each tree contains a power of 2 sized range of chunk sizes (the
|
|
smallest is 0x100 <= x < 0x180), which is is divided in half at each
|
|
tree level, with the chunks in the smaller half of the range (0x100
|
|
<= x < 0x140 for the top nose) in the left subtree and the larger
|
|
half (0x140 <= x < 0x180) in the right subtree. This is, of course,
|
|
done by inspecting individual bits.
|
|
|
|
Using these rules, each node's left subtree contains all smaller
|
|
sizes than its right subtree. However, the node at the root of each
|
|
subtree has no particular ordering relationship to either. (The
|
|
dividing line between the subtree sizes is based on trie relation.)
|
|
If we remove the last chunk of a given size from the interior of the
|
|
tree, we need to replace it with a leaf node. The tree ordering
|
|
rules permit a node to be replaced by any leaf below it.
|
|
|
|
The smallest chunk in a tree (a common operation in a best-fit
|
|
allocator) can be found by walking a path to the leftmost leaf in
|
|
the tree. Unlike a usual binary tree, where we follow left child
|
|
pointers until we reach a null, here we follow the right child
|
|
pointer any time the left one is null, until we reach a leaf with
|
|
both child pointers null. The smallest chunk in the tree will be
|
|
somewhere along that path.
|
|
|
|
The worst case number of steps to add, find, or remove a node is
|
|
bounded by the number of bits differentiating chunks within
|
|
bins. Under current bin calculations, this ranges from 6 up to 21
|
|
(for 32 bit sizes) or up to 53 (for 64 bit sizes). The typical case
|
|
is of course much better.
|
|
*/
|
|
|
|
struct malloc_tree_chunk {
|
|
/* The first four fields must be compatible with malloc_chunk */
|
|
size_t prev_foot;
|
|
size_t head;
|
|
struct malloc_tree_chunk* fd;
|
|
struct malloc_tree_chunk* bk;
|
|
|
|
struct malloc_tree_chunk* child[2];
|
|
struct malloc_tree_chunk* parent;
|
|
bindex_t index;
|
|
};
|
|
|
|
typedef struct malloc_tree_chunk tchunk;
|
|
typedef struct malloc_tree_chunk* tchunkptr;
|
|
typedef struct malloc_tree_chunk* tbinptr; /* The type of bins of trees */
|
|
|
|
/* A little helper macro for trees */
|
|
#define leftmost_child(t) ((t)->child[0] != 0? (t)->child[0] : (t)->child[1])
|
|
|
|
/* ----------------------------- Segments -------------------------------- */
|
|
|
|
/*
|
|
Each malloc space may include non-contiguous segments, held in a
|
|
list headed by an embedded malloc_segment record representing the
|
|
top-most space. Segments also include flags holding properties of
|
|
the space. Large chunks that are directly allocated by mmap are not
|
|
included in this list. They are instead independently created and
|
|
destroyed without otherwise keeping track of them.
|
|
|
|
Segment management mainly comes into play for spaces allocated by
|
|
MMAP. Any call to MMAP might or might not return memory that is
|
|
adjacent to an existing segment. MORECORE normally contiguously
|
|
extends the current space, so this space is almost always adjacent,
|
|
which is simpler and faster to deal with. (This is why MORECORE is
|
|
used preferentially to MMAP when both are available -- see
|
|
sys_alloc.) When allocating using MMAP, we don't use any of the
|
|
hinting mechanisms (inconsistently) supported in various
|
|
implementations of unix mmap, or distinguish reserving from
|
|
committing memory. Instead, we just ask for space, and exploit
|
|
contiguity when we get it. It is probably possible to do
|
|
better than this on some systems, but no general scheme seems
|
|
to be significantly better.
|
|
|
|
Management entails a simpler variant of the consolidation scheme
|
|
used for chunks to reduce fragmentation -- new adjacent memory is
|
|
normally prepended or appended to an existing segment. However,
|
|
there are limitations compared to chunk consolidation that mostly
|
|
reflect the fact that segment processing is relatively infrequent
|
|
(occurring only when getting memory from system) and that we
|
|
don't expect to have huge numbers of segments:
|
|
|
|
* Segments are not indexed, so traversal requires linear scans. (It
|
|
would be possible to index these, but is not worth the extra
|
|
overhead and complexity for most programs on most platforms.)
|
|
* New segments are only appended to old ones when holding top-most
|
|
memory; if they cannot be prepended to others, they are held in
|
|
different segments.
|
|
|
|
Except for the top-most segment of an mstate, each segment record
|
|
is kept at the tail of its segment. Segments are added by pushing
|
|
segment records onto the list headed by &mstate.seg for the
|
|
containing mstate.
|
|
|
|
Segment flags control allocation/merge/deallocation policies:
|
|
* If EXTERN_BIT set, then we did not allocate this segment,
|
|
and so should not try to deallocate or merge with others.
|
|
(This currently holds only for the initial segment passed
|
|
into create_mspace_with_base.)
|
|
* If USE_MMAP_BIT set, the segment may be merged with
|
|
other surrounding mmapped segments and trimmed/de-allocated
|
|
using munmap.
|
|
* If neither bit is set, then the segment was obtained using
|
|
MORECORE so can be merged with surrounding MORECORE'd segments
|
|
and deallocated/trimmed using MORECORE with negative arguments.
|
|
*/
|
|
|
|
struct malloc_segment {
|
|
char* base; /* base address */
|
|
size_t size; /* allocated size */
|
|
struct malloc_segment* next; /* ptr to next segment */
|
|
flag_t sflags; /* mmap and extern flag */
|
|
};
|
|
|
|
#define is_mmapped_segment(S) ((S)->sflags & USE_MMAP_BIT)
|
|
#define is_extern_segment(S) ((S)->sflags & EXTERN_BIT)
|
|
|
|
typedef struct malloc_segment msegment;
|
|
typedef struct malloc_segment* msegmentptr;
|
|
|
|
/* ---------------------------- malloc_state ----------------------------- */
|
|
|
|
/*
|
|
A malloc_state holds all of the bookkeeping for a space.
|
|
The main fields are:
|
|
|
|
Top
|
|
The topmost chunk of the currently active segment. Its size is
|
|
cached in topsize. The actual size of topmost space is
|
|
topsize+TOP_FOOT_SIZE, which includes space reserved for adding
|
|
fenceposts and segment records if necessary when getting more
|
|
space from the system. The size at which to autotrim top is
|
|
cached from mparams in trim_check, except that it is disabled if
|
|
an autotrim fails.
|
|
|
|
Designated victim (dv)
|
|
This is the preferred chunk for servicing small requests that
|
|
don't have exact fits. It is normally the chunk split off most
|
|
recently to service another small request. Its size is cached in
|
|
dvsize. The link fields of this chunk are not maintained since it
|
|
is not kept in a bin.
|
|
|
|
SmallBins
|
|
An array of bin headers for free chunks. These bins hold chunks
|
|
with sizes less than MIN_LARGE_SIZE bytes. Each bin contains
|
|
chunks of all the same size, spaced 8 bytes apart. To simplify
|
|
use in double-linked lists, each bin header acts as a malloc_chunk
|
|
pointing to the real first node, if it exists (else pointing to
|
|
itself). This avoids special-casing for headers. But to avoid
|
|
waste, we allocate only the fd/bk pointers of bins, and then use
|
|
repositioning tricks to treat these as the fields of a chunk.
|
|
|
|
TreeBins
|
|
Treebins are pointers to the roots of trees holding a range of
|
|
sizes. There are 2 equally spaced treebins for each power of two
|
|
from TREE_SHIFT to TREE_SHIFT+16. The last bin holds anything
|
|
larger.
|
|
|
|
Bin maps
|
|
There is one bit map for small bins ("smallmap") and one for
|
|
treebins ("treemap). Each bin sets its bit when non-empty, and
|
|
clears the bit when empty. Bit operations are then used to avoid
|
|
bin-by-bin searching -- nearly all "search" is done without ever
|
|
looking at bins that won't be selected. The bit maps
|
|
conservatively use 32 bits per map word, even if on 64bit system.
|
|
For a good description of some of the bit-based techniques used
|
|
here, see Henry S. Warren Jr's book "Hacker's Delight" (and
|
|
supplement at http://hackersdelight.org/). Many of these are
|
|
intended to reduce the branchiness of paths through malloc etc, as
|
|
well as to reduce the number of memory locations read or written.
|
|
|
|
Segments
|
|
A list of segments headed by an embedded malloc_segment record
|
|
representing the initial space.
|
|
|
|
Address check support
|
|
The least_addr field is the least address ever obtained from
|
|
MORECORE or MMAP. Attempted frees and reallocs of any address less
|
|
than this are trapped (unless INSECURE is defined).
|
|
|
|
Magic tag
|
|
A cross-check field that should always hold same value as mparams.magic.
|
|
|
|
Max allowed footprint
|
|
The maximum allowed bytes to allocate from system (zero means no limit)
|
|
|
|
Flags
|
|
Bits recording whether to use MMAP, locks, or contiguous MORECORE
|
|
|
|
Statistics
|
|
Each space keeps track of current and maximum system memory
|
|
obtained via MORECORE or MMAP.
|
|
|
|
Trim support
|
|
Fields holding the amount of unused topmost memory that should trigger
|
|
trimming, and a counter to force periodic scanning to release unused
|
|
non-topmost segments.
|
|
|
|
Locking
|
|
If USE_LOCKS is defined, the "mutex" lock is acquired and released
|
|
around every public call using this mspace.
|
|
|
|
Extension support
|
|
A void* pointer and a size_t field that can be used to help implement
|
|
extensions to this malloc.
|
|
*/
|
|
|
|
/* Bin types, widths and sizes */
|
|
#define NSMALLBINS (32U)
|
|
#define NTREEBINS (32U)
|
|
#define SMALLBIN_SHIFT (3U)
|
|
#define SMALLBIN_WIDTH (SIZE_T_ONE << SMALLBIN_SHIFT)
|
|
#define TREEBIN_SHIFT (8U)
|
|
#define MIN_LARGE_SIZE (SIZE_T_ONE << TREEBIN_SHIFT)
|
|
#define MAX_SMALL_SIZE (MIN_LARGE_SIZE - SIZE_T_ONE)
|
|
#define MAX_SMALL_REQUEST (MAX_SMALL_SIZE - CHUNK_ALIGN_MASK - CHUNK_OVERHEAD)
|
|
|
|
struct malloc_state {
|
|
binmap_t smallmap;
|
|
binmap_t treemap;
|
|
size_t dvsize;
|
|
size_t topsize;
|
|
char* least_addr;
|
|
mchunkptr dv;
|
|
mchunkptr top;
|
|
size_t trim_check;
|
|
size_t release_checks;
|
|
size_t magic;
|
|
mchunkptr smallbins[(NSMALLBINS+1)*2];
|
|
tbinptr treebins[NTREEBINS];
|
|
size_t footprint;
|
|
size_t max_footprint;
|
|
size_t footprint_limit; /* zero means no limit */
|
|
flag_t mflags;
|
|
struct mutex lock; /* locate lock among fields that rarely change */
|
|
msegment seg;
|
|
void* extp; /* Unused but available for extensions */
|
|
size_t exts;
|
|
};
|
|
|
|
typedef struct malloc_state* mstate;
|
|
|
|
/* ------------- Global malloc_state and malloc_params ------------------- */
|
|
|
|
/*
|
|
malloc_params holds global properties, including those that can be
|
|
dynamically set using mallopt. There is a single instance, mparams,
|
|
initialized in init_mparams. Note that the non-zeroness of "magic"
|
|
also serves as an initialization flag.
|
|
*/
|
|
|
|
struct malloc_params {
|
|
size_t magic;
|
|
size_t page_size;
|
|
size_t granularity;
|
|
size_t mmap_threshold;
|
|
size_t trim_threshold;
|
|
flag_t default_mflags;
|
|
};
|
|
|
|
static struct malloc_params mparams;
|
|
|
|
/* Ensure mparams initialized */
|
|
#define ensure_initialization() (void)(mparams.magic != 0 || init_mparams())
|
|
|
|
static struct malloc_state _gm_;
|
|
#define gm (&_gm_)
|
|
#define is_global(M) ((M) == &_gm_)
|
|
|
|
#define is_initialized(M) ((M)->top != 0)
|
|
|
|
/* -------------------------- system alloc setup ------------------------- */
|
|
|
|
/* Operations on mflags */
|
|
|
|
#define use_lock(M) ((M)->mflags & USE_LOCK_BIT)
|
|
#define enable_lock(M) ((M)->mflags |= USE_LOCK_BIT)
|
|
#if USE_LOCKS
|
|
#define disable_lock(M) ((M)->mflags &= ~USE_LOCK_BIT)
|
|
#else
|
|
#define disable_lock(M)
|
|
#endif
|
|
|
|
#define use_mmap(M) ((M)->mflags & USE_MMAP_BIT)
|
|
#define enable_mmap(M) ((M)->mflags |= USE_MMAP_BIT)
|
|
#if HAVE_MMAP
|
|
#define disable_mmap(M) ((M)->mflags &= ~USE_MMAP_BIT)
|
|
#else
|
|
#define disable_mmap(M)
|
|
#endif
|
|
|
|
#define use_noncontiguous(M) ((M)->mflags & USE_NONCONTIGUOUS_BIT)
|
|
#define disable_contiguous(M) ((M)->mflags |= USE_NONCONTIGUOUS_BIT)
|
|
|
|
#define set_lock(M,L)\
|
|
((M)->mflags = (L)?\
|
|
((M)->mflags | USE_LOCK_BIT) :\
|
|
((M)->mflags & ~USE_LOCK_BIT))
|
|
|
|
/* page-align a size */
|
|
#define page_align(S)\
|
|
(((S) + (mparams.page_size - SIZE_T_ONE)) & ~(mparams.page_size - SIZE_T_ONE))
|
|
|
|
/* granularity-align a size */
|
|
#define granularity_align(S)\
|
|
(((S) + (mparams.granularity - SIZE_T_ONE))\
|
|
& ~(mparams.granularity - SIZE_T_ONE))
|
|
|
|
|
|
/* For mmap, use granularity alignment on windows, else page-align */
|
|
#ifdef WIN32
|
|
#define mmap_align(S) granularity_align(S)
|
|
#else
|
|
#define mmap_align(S) page_align(S)
|
|
#endif
|
|
|
|
/* For sys_alloc, enough padding to ensure can malloc request on success */
|
|
#define SYS_ALLOC_PADDING (TOP_FOOT_SIZE + MALLOC_ALIGNMENT)
|
|
|
|
#define is_page_aligned(S)\
|
|
(((size_t)(S) & (mparams.page_size - SIZE_T_ONE)) == 0)
|
|
#define is_granularity_aligned(S)\
|
|
(((size_t)(S) & (mparams.granularity - SIZE_T_ONE)) == 0)
|
|
|
|
/* True if segment S holds address A */
|
|
#define segment_holds(S, A)\
|
|
((char*)(A) >= S->base && (char*)(A) < S->base + S->size)
|
|
|
|
/* Return segment holding given address */
|
|
static msegmentptr segment_holding(mstate m, char* addr) {
|
|
msegmentptr sp = &m->seg;
|
|
for (;;) {
|
|
if (addr >= sp->base && addr < sp->base + sp->size)
|
|
return sp;
|
|
if ((sp = sp->next) == 0)
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* Return true if segment contains a segment link */
|
|
static int has_segment_link(mstate m, msegmentptr ss) {
|
|
msegmentptr sp = &m->seg;
|
|
for (;;) {
|
|
if ((char*)sp >= ss->base && (char*)sp < ss->base + ss->size)
|
|
return 1;
|
|
if ((sp = sp->next) == 0)
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
TOP_FOOT_SIZE is padding at the end of a segment, including space
|
|
that may be needed to place segment records and fenceposts when new
|
|
noncontiguous segments are added.
|
|
*/
|
|
#define TOP_FOOT_SIZE\
|
|
(align_offset(chunk2mem(0))+pad_request(sizeof(struct malloc_segment))+MIN_CHUNK_SIZE)
|
|
|
|
|
|
/* ------------------------------- Hooks -------------------------------- */
|
|
|
|
/*
|
|
PREACTION should be defined to return 0 on success, and nonzero on
|
|
failure. If you are not using locking, you can redefine these to do
|
|
anything you like.
|
|
*/
|
|
|
|
#define PREACTION(M) ( MutexLock(&(M)->lock))
|
|
#define POSTACTION(M) { MutexUnlock(&(M)->lock); }
|
|
|
|
/* -------------------------- Debugging setup ---------------------------- */
|
|
|
|
#if ! DEBUG
|
|
|
|
#define check_free_chunk(M,P)
|
|
#define check_inuse_chunk(M,P)
|
|
#define check_malloced_chunk(M,P,N)
|
|
#define check_mmapped_chunk(M,P)
|
|
#define check_malloc_state(M)
|
|
#define check_top_chunk(M,P)
|
|
|
|
#else /* DEBUG */
|
|
#define check_free_chunk(M,P) do_check_free_chunk(M,P)
|
|
#define check_inuse_chunk(M,P) do_check_inuse_chunk(M,P)
|
|
#define check_top_chunk(M,P) do_check_top_chunk(M,P)
|
|
#define check_malloced_chunk(M,P,N) do_check_malloced_chunk(M,P,N)
|
|
#define check_mmapped_chunk(M,P) do_check_mmapped_chunk(M,P)
|
|
#define check_malloc_state(M) do_check_malloc_state(M)
|
|
|
|
static void do_check_any_chunk(mstate m, mchunkptr p);
|
|
static void do_check_top_chunk(mstate m, mchunkptr p);
|
|
static void do_check_mmapped_chunk(mstate m, mchunkptr p);
|
|
static void do_check_inuse_chunk(mstate m, mchunkptr p);
|
|
static void do_check_free_chunk(mstate m, mchunkptr p);
|
|
static void do_check_malloced_chunk(mstate m, void* mem, size_t s);
|
|
static void do_check_tree(mstate m, tchunkptr t);
|
|
static void do_check_treebin(mstate m, bindex_t i);
|
|
static void do_check_smallbin(mstate m, bindex_t i);
|
|
static void do_check_malloc_state(mstate m);
|
|
static int bin_find(mstate m, mchunkptr x);
|
|
static size_t traverse_and_check(mstate m);
|
|
#endif /* DEBUG */
|
|
|
|
/* ---------------------------- Indexing Bins ---------------------------- */
|
|
|
|
#define is_small(s) (((s) >> SMALLBIN_SHIFT) < NSMALLBINS)
|
|
#define small_index(s) (bindex_t)((s) >> SMALLBIN_SHIFT)
|
|
#define small_index2size(i) ((i) << SMALLBIN_SHIFT)
|
|
#define MIN_SMALL_INDEX (small_index(MIN_CHUNK_SIZE))
|
|
|
|
/* addressing by index. See above about smallbin repositioning */
|
|
#define smallbin_at(M, i) ((sbinptr)((char*)&((M)->smallbins[(i)<<1])))
|
|
#define treebin_at(M,i) (&((M)->treebins[i]))
|
|
|
|
#define compute_tree_index(S, I)\
|
|
{\
|
|
unsigned int X = S >> TREEBIN_SHIFT;\
|
|
if (X == 0)\
|
|
I = 0;\
|
|
else if (X > 0xFFFF)\
|
|
I = NTREEBINS-1;\
|
|
else {\
|
|
unsigned int K = (unsigned) sizeof(X)*__CHAR_BIT__ - 1 - (unsigned) __builtin_clz(X); \
|
|
I = (bindex_t)((K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1)));\
|
|
}\
|
|
}
|
|
|
|
|
|
|
|
/* Bit representing maximum resolved size in a treebin at i */
|
|
#define bit_for_tree_index(i) \
|
|
(i == NTREEBINS-1)? (SIZE_T_BITSIZE-1) : (((i) >> 1) + TREEBIN_SHIFT - 2)
|
|
|
|
/* Shift placing maximum resolved bit in a treebin at i as sign bit */
|
|
#define leftshift_for_tree_index(i) \
|
|
((i == NTREEBINS-1)? 0 : \
|
|
((SIZE_T_BITSIZE-SIZE_T_ONE) - (((i) >> 1) + TREEBIN_SHIFT - 2)))
|
|
|
|
/* The size of the smallest chunk held in bin with index i */
|
|
#define minsize_for_tree_index(i) \
|
|
((SIZE_T_ONE << (((i) >> 1) + TREEBIN_SHIFT)) | \
|
|
(((size_t)((i) & SIZE_T_ONE)) << (((i) >> 1) + TREEBIN_SHIFT - 1)))
|
|
|
|
|
|
/* ------------------------ Operations on bin maps ----------------------- */
|
|
|
|
/* bit corresponding to given index */
|
|
#define idx2bit(i) ((binmap_t)(1) << (i))
|
|
|
|
/* Mark/Clear bits with given index */
|
|
#define mark_smallmap(M,i) ((M)->smallmap |= idx2bit(i))
|
|
#define clear_smallmap(M,i) ((M)->smallmap &= ~idx2bit(i))
|
|
#define smallmap_is_marked(M,i) ((M)->smallmap & idx2bit(i))
|
|
|
|
#define mark_treemap(M,i) ((M)->treemap |= idx2bit(i))
|
|
#define clear_treemap(M,i) ((M)->treemap &= ~idx2bit(i))
|
|
#define treemap_is_marked(M,i) ((M)->treemap & idx2bit(i))
|
|
|
|
/* isolate the least set bit of a bitmap */
|
|
#define least_bit(x) ((x) & -(x))
|
|
|
|
/* mask with all bits to left of least bit of x on */
|
|
#define left_bits(x) ((x<<1) | -(x<<1))
|
|
|
|
/* mask with all bits to left of or equal to least bit of x on */
|
|
#define same_or_left_bits(x) ((x) | -(x))
|
|
|
|
#define compute_bit2idx(X, I)\
|
|
{\
|
|
unsigned int J;\
|
|
J = __builtin_ctz(X); \
|
|
I = (bindex_t)J;\
|
|
}
|
|
|
|
/* ----------------------- Runtime Check Support ------------------------- */
|
|
|
|
/*
|
|
For security, the main invariant is that malloc/free/etc never
|
|
writes to a static address other than malloc_state, unless static
|
|
malloc_state itself has been corrupted, which cannot occur via
|
|
malloc (because of these checks). In essence this means that we
|
|
believe all pointers, sizes, maps etc held in malloc_state, but
|
|
check all of those linked or offsetted from other embedded data
|
|
structures. These checks are interspersed with main code in a way
|
|
that tends to minimize their run-time cost.
|
|
|
|
When FOOTERS is defined, in addition to range checking, we also
|
|
verify footer fields of inuse chunks, which can be used guarantee
|
|
that the mstate controlling malloc/free is intact. This is a
|
|
streamlined version of the approach described by William Robertson
|
|
et al in "Run-time Detection of Heap-based Overflows" LISA'03
|
|
http://www.usenix.org/events/lisa03/tech/robertson.html The footer
|
|
of an inuse chunk holds the xor of its mstate and a random seed,
|
|
that is checked upon calls to free() and realloc(). This is
|
|
(probabalistically) unguessable from outside the program, but can be
|
|
computed by any code successfully malloc'ing any chunk, so does not
|
|
itself provide protection against code that has already broken
|
|
security through some other means. Unlike Robertson et al, we
|
|
always dynamically check addresses of all offset chunks (previous,
|
|
next, etc). This turns out to be cheaper than relying on hashes.
|
|
*/
|
|
|
|
#if !INSECURE
|
|
/* Check if address a is at least as high as any from MORECORE or MMAP */
|
|
#define ok_address(M, a) ((char*)(a) >= (M)->least_addr)
|
|
/* Check if address of next chunk n is higher than base chunk p */
|
|
#define ok_next(p, n) ((char*)(p) < (char*)(n))
|
|
/* Check if p has inuse status */
|
|
#define ok_inuse(p) is_inuse(p)
|
|
/* Check if p has its pinuse bit on */
|
|
#define ok_pinuse(p) pinuse(p)
|
|
|
|
#else /* !INSECURE */
|
|
#define ok_address(M, a) (1)
|
|
#define ok_next(b, n) (1)
|
|
#define ok_inuse(p) (1)
|
|
#define ok_pinuse(p) (1)
|
|
#endif /* !INSECURE */
|
|
|
|
#if (FOOTERS && !INSECURE)
|
|
/* Check if (alleged) mstate m has expected magic field */
|
|
#define ok_magic(M) ((M)->magic == mparams.magic)
|
|
#else /* (FOOTERS && !INSECURE) */
|
|
#define ok_magic(M) (1)
|
|
#endif /* (FOOTERS && !INSECURE) */
|
|
|
|
/* In gcc, use __builtin_expect to minimize impact of checks */
|
|
#if !INSECURE
|
|
#if defined(__GNUC__) && __GNUC__ >= 3
|
|
#define RTCHECK(e) __builtin_expect(e, 1)
|
|
#else /* GNUC */
|
|
#define RTCHECK(e) (e)
|
|
#endif /* GNUC */
|
|
#else /* !INSECURE */
|
|
#define RTCHECK(e) (1)
|
|
#endif /* !INSECURE */
|
|
|
|
/* macros to set up inuse chunks with or without footers */
|
|
|
|
#if !FOOTERS
|
|
|
|
#define mark_inuse_foot(M,p,s)
|
|
|
|
/* Macros for setting head/foot of non-mmapped chunks */
|
|
|
|
/* Set cinuse bit and pinuse bit of next chunk */
|
|
#define set_inuse(M,p,s)\
|
|
((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\
|
|
((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT)
|
|
|
|
/* Set cinuse and pinuse of this chunk and pinuse of next chunk */
|
|
#define set_inuse_and_pinuse(M,p,s)\
|
|
((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
|
|
((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT)
|
|
|
|
/* Set size, cinuse and pinuse bit of this chunk */
|
|
#define set_size_and_pinuse_of_inuse_chunk(M, p, s)\
|
|
((p)->head = (s|PINUSE_BIT|CINUSE_BIT))
|
|
|
|
#else /* FOOTERS */
|
|
|
|
/* Set foot of inuse chunk to be xor of mstate and seed */
|
|
#define mark_inuse_foot(M,p,s)\
|
|
(((mchunkptr)((char*)(p) + (s)))->prev_foot = ((size_t)(M) ^ mparams.magic))
|
|
|
|
#define get_mstate_for(p)\
|
|
((mstate)(((mchunkptr)((char*)(p) +\
|
|
(chunksize(p))))->prev_foot ^ mparams.magic))
|
|
|
|
#define set_inuse(M,p,s)\
|
|
((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\
|
|
(((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT), \
|
|
mark_inuse_foot(M,p,s))
|
|
|
|
#define set_inuse_and_pinuse(M,p,s)\
|
|
((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
|
|
(((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT),\
|
|
mark_inuse_foot(M,p,s))
|
|
|
|
#define set_size_and_pinuse_of_inuse_chunk(M, p, s)\
|
|
((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
|
|
mark_inuse_foot(M, p, s))
|
|
|
|
#endif /* !FOOTERS */
|
|
|
|
/* ---------------------------- setting mparams -------------------------- */
|
|
|
|
#if LOCK_AT_FORK
|
|
static void pre_fork(void) { ACQUIRE_LOCK(&(gm)->mutex); }
|
|
static void post_fork_parent(void) { RELEASE_LOCK(&(gm)->mutex); }
|
|
static void post_fork_child(void) { INITIAL_LOCK(&(gm)->mutex); }
|
|
#endif /* LOCK_AT_FORK */
|
|
|
|
/* Initialize mparams */
|
|
static int init_mparams(void) {
|
|
|
|
ACQUIRE_MALLOC_GLOBAL_LOCK();
|
|
if (mparams.magic == 0) {
|
|
size_t magic;
|
|
size_t psize;
|
|
size_t gsize;
|
|
|
|
psize = 4096;
|
|
gsize = ((DEFAULT_GRANULARITY != 0)? DEFAULT_GRANULARITY : psize);
|
|
|
|
mparams.granularity = gsize;
|
|
mparams.page_size = psize;
|
|
mparams.mmap_threshold = DEFAULT_MMAP_THRESHOLD;
|
|
mparams.trim_threshold = DEFAULT_TRIM_THRESHOLD;
|
|
mparams.default_mflags = USE_LOCK_BIT|USE_MMAP_BIT|USE_NONCONTIGUOUS_BIT;
|
|
|
|
/* Set up lock for main malloc area */
|
|
gm->mflags = mparams.default_mflags;
|
|
MutexInit(&gm->lock);
|
|
|
|
{
|
|
magic = (size_t)&magic ^ (size_t)0x55555555U;
|
|
magic |= (size_t)8U; /* ensure nonzero */
|
|
magic &= ~(size_t)7U; /* improve chances of fault for bad values */
|
|
/* Until memory modes commonly available, use volatile-write */
|
|
(*(volatile size_t *)(&(mparams.magic))) = magic;
|
|
}
|
|
}
|
|
|
|
RELEASE_MALLOC_GLOBAL_LOCK();
|
|
return 1;
|
|
}
|
|
|
|
|
|
#if DEBUG
|
|
/* ------------------------- Debugging Support --------------------------- */
|
|
|
|
/* Check properties of any chunk, whether free, inuse, mmapped etc */
|
|
static void do_check_any_chunk(mstate m, mchunkptr p) {
|
|
assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
|
|
assert(ok_address(m, p));
|
|
}
|
|
|
|
/* Check properties of top chunk */
|
|
static void do_check_top_chunk(mstate m, mchunkptr p) {
|
|
msegmentptr sp = segment_holding(m, (char*)p);
|
|
size_t sz = p->head & ~INUSE_BITS; /* third-lowest bit can be set! */
|
|
assert(sp != 0);
|
|
assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
|
|
assert(ok_address(m, p));
|
|
assert(sz == m->topsize);
|
|
assert(sz > 0);
|
|
assert(sz == ((sp->base + sp->size) - (char*)p) - TOP_FOOT_SIZE);
|
|
assert(pinuse(p));
|
|
assert(!pinuse(chunk_plus_offset(p, sz)));
|
|
}
|
|
|
|
/* Check properties of (inuse) mmapped chunks */
|
|
static void do_check_mmapped_chunk(mstate m, mchunkptr p) {
|
|
size_t sz = chunksize(p);
|
|
size_t len = (sz + (p->prev_foot) + MMAP_FOOT_PAD);
|
|
assert(is_mmapped(p));
|
|
assert(use_mmap(m));
|
|
assert((is_aligned(chunk2mem(p))) || (p->head == FENCEPOST_HEAD));
|
|
assert(ok_address(m, p));
|
|
assert(!is_small(sz));
|
|
assert((len & (mparams.page_size-SIZE_T_ONE)) == 0);
|
|
assert(chunk_plus_offset(p, sz)->head == FENCEPOST_HEAD);
|
|
assert(chunk_plus_offset(p, sz+SIZE_T_SIZE)->head == 0);
|
|
}
|
|
|
|
/* Check properties of inuse chunks */
|
|
static void do_check_inuse_chunk(mstate m, mchunkptr p) {
|
|
do_check_any_chunk(m, p);
|
|
assert(is_inuse(p));
|
|
assert(next_pinuse(p));
|
|
/* If not pinuse and not mmapped, previous chunk has OK offset */
|
|
assert(is_mmapped(p) || pinuse(p) || next_chunk(prev_chunk(p)) == p);
|
|
if (is_mmapped(p))
|
|
do_check_mmapped_chunk(m, p);
|
|
}
|
|
|
|
/* Check properties of free chunks */
|
|
static void do_check_free_chunk(mstate m, mchunkptr p) {
|
|
size_t sz = chunksize(p);
|
|
mchunkptr next = chunk_plus_offset(p, sz);
|
|
do_check_any_chunk(m, p);
|
|
assert(!is_inuse(p));
|
|
assert(!next_pinuse(p));
|
|
assert (!is_mmapped(p));
|
|
if (p != m->dv && p != m->top) {
|
|
if (sz >= MIN_CHUNK_SIZE) {
|
|
assert((sz & CHUNK_ALIGN_MASK) == 0);
|
|
assert(is_aligned(chunk2mem(p)));
|
|
assert(next->prev_foot == sz);
|
|
assert(pinuse(p));
|
|
assert (next == m->top || is_inuse(next));
|
|
assert(p->fd->bk == p);
|
|
assert(p->bk->fd == p);
|
|
}
|
|
else /* markers are always of size SIZE_T_SIZE */
|
|
assert(sz == SIZE_T_SIZE);
|
|
}
|
|
}
|
|
|
|
/* Check properties of malloced chunks at the point they are malloced */
|
|
static void do_check_malloced_chunk(mstate m, void* mem, size_t s) {
|
|
if (mem != 0) {
|
|
mchunkptr p = mem2chunk(mem);
|
|
size_t sz = p->head & ~INUSE_BITS;
|
|
do_check_inuse_chunk(m, p);
|
|
assert((sz & CHUNK_ALIGN_MASK) == 0);
|
|
assert(sz >= MIN_CHUNK_SIZE);
|
|
assert(sz >= s);
|
|
/* unless mmapped, size is less than MIN_CHUNK_SIZE more than request */
|
|
assert(is_mmapped(p) || sz < (s + MIN_CHUNK_SIZE));
|
|
}
|
|
}
|
|
|
|
/* Check a tree and its subtrees. */
|
|
static void do_check_tree(mstate m, tchunkptr t) {
|
|
tchunkptr head = 0;
|
|
tchunkptr u = t;
|
|
bindex_t tindex = t->index;
|
|
size_t tsize = chunksize(t);
|
|
bindex_t idx;
|
|
compute_tree_index(tsize, idx);
|
|
assert(tindex == idx);
|
|
assert(tsize >= MIN_LARGE_SIZE);
|
|
assert(tsize >= minsize_for_tree_index(idx));
|
|
assert((idx == NTREEBINS-1) || (tsize < minsize_for_tree_index((idx+1))));
|
|
|
|
do { /* traverse through chain of same-sized nodes */
|
|
do_check_any_chunk(m, ((mchunkptr)u));
|
|
assert(u->index == tindex);
|
|
assert(chunksize(u) == tsize);
|
|
assert(!is_inuse(u));
|
|
assert(!next_pinuse(u));
|
|
assert(u->fd->bk == u);
|
|
assert(u->bk->fd == u);
|
|
if (u->parent == 0) {
|
|
assert(u->child[0] == 0);
|
|
assert(u->child[1] == 0);
|
|
}
|
|
else {
|
|
assert(head == 0); /* only one node on chain has parent */
|
|
head = u;
|
|
assert(u->parent != u);
|
|
assert (u->parent->child[0] == u ||
|
|
u->parent->child[1] == u ||
|
|
*((tbinptr*)(u->parent)) == u);
|
|
if (u->child[0] != 0) {
|
|
assert(u->child[0]->parent == u);
|
|
assert(u->child[0] != u);
|
|
do_check_tree(m, u->child[0]);
|
|
}
|
|
if (u->child[1] != 0) {
|
|
assert(u->child[1]->parent == u);
|
|
assert(u->child[1] != u);
|
|
do_check_tree(m, u->child[1]);
|
|
}
|
|
if (u->child[0] != 0 && u->child[1] != 0) {
|
|
assert(chunksize(u->child[0]) < chunksize(u->child[1]));
|
|
}
|
|
}
|
|
u = u->fd;
|
|
} while (u != t);
|
|
assert(head != 0);
|
|
}
|
|
|
|
/* Check all the chunks in a treebin. */
|
|
static void do_check_treebin(mstate m, bindex_t i) {
|
|
tbinptr* tb = treebin_at(m, i);
|
|
tchunkptr t = *tb;
|
|
int empty = (m->treemap & (1U << i)) == 0;
|
|
if (t == 0)
|
|
assert(empty);
|
|
if (!empty)
|
|
do_check_tree(m, t);
|
|
}
|
|
|
|
/* Check all the chunks in a smallbin. */
|
|
static void do_check_smallbin(mstate m, bindex_t i) {
|
|
sbinptr b = smallbin_at(m, i);
|
|
mchunkptr p = b->bk;
|
|
unsigned int empty = (m->smallmap & (1U << i)) == 0;
|
|
if (p == b)
|
|
assert(empty);
|
|
if (!empty) {
|
|
for (; p != b; p = p->bk) {
|
|
size_t size = chunksize(p);
|
|
mchunkptr q;
|
|
/* each chunk claims to be free */
|
|
do_check_free_chunk(m, p);
|
|
/* chunk belongs in bin */
|
|
assert(small_index(size) == i);
|
|
assert(p->bk == b || chunksize(p->bk) == chunksize(p));
|
|
/* chunk is followed by an inuse chunk */
|
|
q = next_chunk(p);
|
|
if (q->head != FENCEPOST_HEAD)
|
|
do_check_inuse_chunk(m, q);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Find x in a bin. Used in other check functions. */
|
|
static int bin_find(mstate m, mchunkptr x) {
|
|
size_t size = chunksize(x);
|
|
if (is_small(size)) {
|
|
bindex_t sidx = small_index(size);
|
|
sbinptr b = smallbin_at(m, sidx);
|
|
if (smallmap_is_marked(m, sidx)) {
|
|
mchunkptr p = b;
|
|
do {
|
|
if (p == x)
|
|
return 1;
|
|
} while ((p = p->fd) != b);
|
|
}
|
|
}
|
|
else {
|
|
bindex_t tidx;
|
|
compute_tree_index(size, tidx);
|
|
if (treemap_is_marked(m, tidx)) {
|
|
tchunkptr t = *treebin_at(m, tidx);
|
|
size_t sizebits = size << leftshift_for_tree_index(tidx);
|
|
while (t != 0 && chunksize(t) != size) {
|
|
t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1];
|
|
sizebits <<= 1;
|
|
}
|
|
if (t != 0) {
|
|
tchunkptr u = t;
|
|
do {
|
|
if (u == (tchunkptr)x)
|
|
return 1;
|
|
} while ((u = u->fd) != t);
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Traverse each chunk and check it; return total */
|
|
static size_t traverse_and_check(mstate m) {
|
|
size_t sum = 0;
|
|
if (is_initialized(m)) {
|
|
msegmentptr s = &m->seg;
|
|
sum += m->topsize + TOP_FOOT_SIZE;
|
|
while (s != 0) {
|
|
mchunkptr q = align_as_chunk(s->base);
|
|
mchunkptr lastq = 0;
|
|
assert(pinuse(q));
|
|
while (segment_holds(s, q) &&
|
|
q != m->top && q->head != FENCEPOST_HEAD) {
|
|
sum += chunksize(q);
|
|
if (is_inuse(q)) {
|
|
assert(!bin_find(m, q));
|
|
do_check_inuse_chunk(m, q);
|
|
}
|
|
else {
|
|
assert(q == m->dv || bin_find(m, q));
|
|
assert(lastq == 0 || is_inuse(lastq)); /* Not 2 consecutive free */
|
|
do_check_free_chunk(m, q);
|
|
}
|
|
lastq = q;
|
|
q = next_chunk(q);
|
|
}
|
|
s = s->next;
|
|
}
|
|
}
|
|
return sum;
|
|
}
|
|
|
|
|
|
/* Check all properties of malloc_state. */
|
|
static void do_check_malloc_state(mstate m) {
|
|
bindex_t i;
|
|
size_t total;
|
|
/* check bins */
|
|
for (i = 0; i < NSMALLBINS; ++i)
|
|
do_check_smallbin(m, i);
|
|
for (i = 0; i < NTREEBINS; ++i)
|
|
do_check_treebin(m, i);
|
|
|
|
if (m->dvsize != 0) { /* check dv chunk */
|
|
do_check_any_chunk(m, m->dv);
|
|
assert(m->dvsize == chunksize(m->dv));
|
|
assert(m->dvsize >= MIN_CHUNK_SIZE);
|
|
assert(bin_find(m, m->dv) == 0);
|
|
}
|
|
|
|
if (m->top != 0) { /* check top chunk */
|
|
do_check_top_chunk(m, m->top);
|
|
/*assert(m->topsize == chunksize(m->top)); redundant */
|
|
assert(m->topsize > 0);
|
|
assert(bin_find(m, m->top) == 0);
|
|
}
|
|
|
|
total = traverse_and_check(m);
|
|
assert(total <= m->footprint);
|
|
assert(m->footprint <= m->max_footprint);
|
|
}
|
|
#endif /* DEBUG */
|
|
|
|
#define CORRUPTION_ERROR_ACTION(m) \
|
|
do { \
|
|
printf("%s malloc heap corrupted\n",__FUNCTION__); \
|
|
while(1) \
|
|
{ \
|
|
delay(100); \
|
|
} \
|
|
}while(0) \
|
|
|
|
|
|
#define USAGE_ERROR_ACTION(m, p) \
|
|
do { \
|
|
printf("%s malloc heap corrupted\n",__FUNCTION__); \
|
|
while(1) \
|
|
{ \
|
|
delay(100); \
|
|
} \
|
|
}while(0) \
|
|
|
|
/* ----------------------- Operations on smallbins ----------------------- */
|
|
|
|
/*
|
|
Various forms of linking and unlinking are defined as macros. Even
|
|
the ones for trees, which are very long but have very short typical
|
|
paths. This is ugly but reduces reliance on inlining support of
|
|
compilers.
|
|
*/
|
|
|
|
/* Link a free chunk into a smallbin */
|
|
#define insert_small_chunk(M, P, S) {\
|
|
bindex_t I = small_index(S);\
|
|
mchunkptr B = smallbin_at(M, I);\
|
|
mchunkptr F = B;\
|
|
assert(S >= MIN_CHUNK_SIZE);\
|
|
if (!smallmap_is_marked(M, I))\
|
|
mark_smallmap(M, I);\
|
|
else if (RTCHECK(ok_address(M, B->fd)))\
|
|
F = B->fd;\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
B->fd = P;\
|
|
F->bk = P;\
|
|
P->fd = F;\
|
|
P->bk = B;\
|
|
}
|
|
/* ----------------------- Operations on smallbins ----------------------- */
|
|
|
|
/*
|
|
Various forms of linking and unlinking are defined as macros. Even
|
|
the ones for trees, which are very long but have very short typical
|
|
paths. This is ugly but reduces reliance on inlining support of
|
|
compilers.
|
|
*/
|
|
|
|
/* Link a free chunk into a smallbin */
|
|
#define insert_small_chunk(M, P, S) {\
|
|
bindex_t I = small_index(S);\
|
|
mchunkptr B = smallbin_at(M, I);\
|
|
mchunkptr F = B;\
|
|
assert(S >= MIN_CHUNK_SIZE);\
|
|
if (!smallmap_is_marked(M, I))\
|
|
mark_smallmap(M, I);\
|
|
else if (RTCHECK(ok_address(M, B->fd)))\
|
|
F = B->fd;\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
B->fd = P;\
|
|
F->bk = P;\
|
|
P->fd = F;\
|
|
P->bk = B;\
|
|
}
|
|
|
|
/* Unlink a chunk from a smallbin */
|
|
#define unlink_small_chunk(M, P, S) {\
|
|
mchunkptr F = P->fd;\
|
|
mchunkptr B = P->bk;\
|
|
bindex_t I = small_index(S);\
|
|
assert(P != B);\
|
|
assert(P != F);\
|
|
assert(chunksize(P) == small_index2size(I));\
|
|
if (RTCHECK(F == smallbin_at(M,I) || (ok_address(M, F) && F->bk == P))) { \
|
|
if (B == F) {\
|
|
clear_smallmap(M, I);\
|
|
}\
|
|
else if (RTCHECK(B == smallbin_at(M,I) ||\
|
|
(ok_address(M, B) && B->fd == P))) {\
|
|
F->bk = B;\
|
|
B->fd = F;\
|
|
}\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}
|
|
|
|
/* Unlink the first chunk from a smallbin */
|
|
#define unlink_first_small_chunk(M, B, P, I) {\
|
|
mchunkptr F = P->fd;\
|
|
assert(P != B);\
|
|
assert(P != F);\
|
|
assert(chunksize(P) == small_index2size(I));\
|
|
if (B == F) {\
|
|
clear_smallmap(M, I);\
|
|
}\
|
|
else if (RTCHECK(ok_address(M, F) && F->bk == P)) {\
|
|
F->bk = B;\
|
|
B->fd = F;\
|
|
}\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}
|
|
|
|
/* Replace dv node, binning the old one */
|
|
/* Used only when dvsize known to be small */
|
|
#define replace_dv(M, P, S) {\
|
|
size_t DVS = M->dvsize;\
|
|
assert(is_small(DVS));\
|
|
if (DVS != 0) {\
|
|
mchunkptr DV = M->dv;\
|
|
insert_small_chunk(M, DV, DVS);\
|
|
}\
|
|
M->dvsize = S;\
|
|
M->dv = P;\
|
|
}
|
|
|
|
/* ------------------------- Operations on trees ------------------------- */
|
|
|
|
/* Insert chunk into tree */
|
|
#define insert_large_chunk(M, X, S) {\
|
|
tbinptr* H;\
|
|
bindex_t I;\
|
|
compute_tree_index(S, I);\
|
|
H = treebin_at(M, I);\
|
|
X->index = I;\
|
|
X->child[0] = X->child[1] = 0;\
|
|
if (!treemap_is_marked(M, I)) {\
|
|
mark_treemap(M, I);\
|
|
*H = X;\
|
|
X->parent = (tchunkptr)H;\
|
|
X->fd = X->bk = X;\
|
|
}\
|
|
else {\
|
|
tchunkptr T = *H;\
|
|
size_t K = S << leftshift_for_tree_index(I);\
|
|
for (;;) {\
|
|
if (chunksize(T) != S) {\
|
|
tchunkptr* C = &(T->child[(K >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]);\
|
|
K <<= 1;\
|
|
if (*C != 0)\
|
|
T = *C;\
|
|
else if (RTCHECK(ok_address(M, C))) {\
|
|
*C = X;\
|
|
X->parent = T;\
|
|
X->fd = X->bk = X;\
|
|
break;\
|
|
}\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
break;\
|
|
}\
|
|
}\
|
|
else {\
|
|
tchunkptr F = T->fd;\
|
|
if (RTCHECK(ok_address(M, T) && ok_address(M, F))) {\
|
|
T->fd = F->bk = X;\
|
|
X->fd = F;\
|
|
X->bk = T;\
|
|
X->parent = 0;\
|
|
break;\
|
|
}\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
break;\
|
|
}\
|
|
}\
|
|
}\
|
|
}\
|
|
}
|
|
|
|
/*
|
|
Unlink steps:
|
|
|
|
1. If x is a chained node, unlink it from its same-sized fd/bk links
|
|
and choose its bk node as its replacement.
|
|
2. If x was the last node of its size, but not a leaf node, it must
|
|
be replaced with a leaf node (not merely one with an open left or
|
|
right), to make sure that lefts and rights of descendents
|
|
correspond properly to bit masks. We use the rightmost descendent
|
|
of x. We could use any other leaf, but this is easy to locate and
|
|
tends to counteract removal of leftmosts elsewhere, and so keeps
|
|
paths shorter than minimally guaranteed. This doesn't loop much
|
|
because on average a node in a tree is near the bottom.
|
|
3. If x is the base of a chain (i.e., has parent links) relink
|
|
x's parent and children to x's replacement (or null if none).
|
|
*/
|
|
|
|
#define unlink_large_chunk(M, X) {\
|
|
tchunkptr XP = X->parent;\
|
|
tchunkptr R;\
|
|
if (X->bk != X) {\
|
|
tchunkptr F = X->fd;\
|
|
R = X->bk;\
|
|
if (RTCHECK(ok_address(M, F) && F->bk == X && R->fd == X)) {\
|
|
F->bk = R;\
|
|
R->fd = F;\
|
|
}\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}\
|
|
else {\
|
|
tchunkptr* RP;\
|
|
if (((R = *(RP = &(X->child[1]))) != 0) ||\
|
|
((R = *(RP = &(X->child[0]))) != 0)) {\
|
|
tchunkptr* CP;\
|
|
while ((*(CP = &(R->child[1])) != 0) ||\
|
|
(*(CP = &(R->child[0])) != 0)) {\
|
|
R = *(RP = CP);\
|
|
}\
|
|
if (RTCHECK(ok_address(M, RP)))\
|
|
*RP = 0;\
|
|
else {\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}\
|
|
}\
|
|
if (XP != 0) {\
|
|
tbinptr* H = treebin_at(M, X->index);\
|
|
if (X == *H) {\
|
|
if ((*H = R) == 0) \
|
|
clear_treemap(M, X->index);\
|
|
}\
|
|
else if (RTCHECK(ok_address(M, XP))) {\
|
|
if (XP->child[0] == X) \
|
|
XP->child[0] = R;\
|
|
else \
|
|
XP->child[1] = R;\
|
|
}\
|
|
else\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
if (R != 0) {\
|
|
if (RTCHECK(ok_address(M, R))) {\
|
|
tchunkptr C0, C1;\
|
|
R->parent = XP;\
|
|
if ((C0 = X->child[0]) != 0) {\
|
|
if (RTCHECK(ok_address(M, C0))) {\
|
|
R->child[0] = C0;\
|
|
C0->parent = R;\
|
|
}\
|
|
else\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
if ((C1 = X->child[1]) != 0) {\
|
|
if (RTCHECK(ok_address(M, C1))) {\
|
|
R->child[1] = C1;\
|
|
C1->parent = R;\
|
|
}\
|
|
else\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}\
|
|
else\
|
|
CORRUPTION_ERROR_ACTION(M);\
|
|
}\
|
|
}\
|
|
}
|
|
|
|
/* Relays to large vs small bin operations */
|
|
|
|
#define insert_chunk(M, P, S)\
|
|
if (is_small(S)) insert_small_chunk(M, P, S)\
|
|
else { tchunkptr TP = (tchunkptr)(P); insert_large_chunk(M, TP, S); }
|
|
|
|
#define unlink_chunk(M, P, S)\
|
|
if (is_small(S)) unlink_small_chunk(M, P, S)\
|
|
else { tchunkptr TP = (tchunkptr)(P); unlink_large_chunk(M, TP); }
|
|
|
|
|
|
/* Relays to internal calls to malloc/free from realloc, memalign etc */
|
|
|
|
#if ONLY_MSPACES
|
|
#define internal_malloc(m, b) mspace_malloc(m, b)
|
|
#define internal_free(m, mem) mspace_free(m,mem);
|
|
#else /* ONLY_MSPACES */
|
|
#if MSPACES
|
|
#define internal_malloc(m, b)\
|
|
((m == gm)? dlmalloc(b) : mspace_malloc(m, b))
|
|
#define internal_free(m, mem)\
|
|
if (m == gm) dlfree(mem); else mspace_free(m,mem);
|
|
#else /* MSPACES */
|
|
#define internal_malloc(m, b) malloc(b)
|
|
#define internal_free(m, mem) free(mem)
|
|
#endif /* MSPACES */
|
|
#endif /* ONLY_MSPACES */
|
|
|
|
|
|
static inline void* os_mmap(size_t size)
|
|
{
|
|
void* ptr = KernelAlloc(size);
|
|
printf("%s %x %d bytes\n",__FUNCTION__, ptr, size);
|
|
return (ptr != 0)? ptr: MFAIL;
|
|
}
|
|
|
|
static inline int os_munmap(void* ptr, size_t size)
|
|
{
|
|
return (KernelFree(ptr) != 0) ? 0 : -1;
|
|
}
|
|
|
|
|
|
#define MMAP_DEFAULT(s) os_mmap(s)
|
|
#define MUNMAP_DEFAULT(a, s) os_munmap((a), (s))
|
|
#define DIRECT_MMAP_DEFAULT(s) os_mmap(s)
|
|
|
|
|
|
/* ----------------------- Direct-mmapping chunks ----------------------- */
|
|
|
|
/*
|
|
Directly mmapped chunks are set up with an offset to the start of
|
|
the mmapped region stored in the prev_foot field of the chunk. This
|
|
allows reconstruction of the required argument to MUNMAP when freed,
|
|
and also allows adjustment of the returned chunk to meet alignment
|
|
requirements (especially in memalign).
|
|
*/
|
|
|
|
/* Malloc using mmap */
|
|
static void* mmap_alloc(mstate m, size_t nb) {
|
|
size_t mmsize = mmap_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
|
|
if (m->footprint_limit != 0) {
|
|
size_t fp = m->footprint + mmsize;
|
|
if (fp <= m->footprint || fp > m->footprint_limit)
|
|
return 0;
|
|
}
|
|
if (mmsize > nb) { /* Check for wrap around 0 */
|
|
char* mm = (char*)(CALL_DIRECT_MMAP(mmsize));
|
|
if (mm != CMFAIL) {
|
|
size_t offset = align_offset(chunk2mem(mm));
|
|
size_t psize = mmsize - offset - MMAP_FOOT_PAD;
|
|
mchunkptr p = (mchunkptr)(mm + offset);
|
|
p->prev_foot = offset;
|
|
p->head = psize;
|
|
mark_inuse_foot(m, p, psize);
|
|
chunk_plus_offset(p, psize)->head = FENCEPOST_HEAD;
|
|
chunk_plus_offset(p, psize+SIZE_T_SIZE)->head = 0;
|
|
|
|
if (m->least_addr == 0 || mm < m->least_addr)
|
|
m->least_addr = mm;
|
|
if ((m->footprint += mmsize) > m->max_footprint)
|
|
m->max_footprint = m->footprint;
|
|
assert(is_aligned(chunk2mem(p)));
|
|
check_mmapped_chunk(m, p);
|
|
return chunk2mem(p);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Realloc using mmap */
|
|
static mchunkptr mmap_resize(mstate m, mchunkptr oldp, size_t nb, int flags) {
|
|
size_t oldsize = chunksize(oldp);
|
|
(void)flags; /* placate people compiling -Wunused */
|
|
if (is_small(nb)) /* Can't shrink mmap regions below small size */
|
|
return 0;
|
|
/* Keep old chunk if big enough but not too big */
|
|
if (oldsize >= nb + SIZE_T_SIZE &&
|
|
(oldsize - nb) <= (mparams.granularity << 1))
|
|
return oldp;
|
|
else {
|
|
size_t offset = oldp->prev_foot;
|
|
size_t oldmmsize = oldsize + offset + MMAP_FOOT_PAD;
|
|
size_t newmmsize = mmap_align(nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
|
|
char* cp = (char*)CALL_MREMAP((char*)oldp - offset,
|
|
oldmmsize, newmmsize, flags);
|
|
if (cp != CMFAIL) {
|
|
mchunkptr newp = (mchunkptr)(cp + offset);
|
|
size_t psize = newmmsize - offset - MMAP_FOOT_PAD;
|
|
newp->head = psize;
|
|
mark_inuse_foot(m, newp, psize);
|
|
chunk_plus_offset(newp, psize)->head = FENCEPOST_HEAD;
|
|
chunk_plus_offset(newp, psize+SIZE_T_SIZE)->head = 0;
|
|
|
|
if (cp < m->least_addr)
|
|
m->least_addr = cp;
|
|
if ((m->footprint += newmmsize - oldmmsize) > m->max_footprint)
|
|
m->max_footprint = m->footprint;
|
|
check_mmapped_chunk(m, newp);
|
|
return newp;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/* -------------------------- mspace management -------------------------- */
|
|
|
|
/* Initialize top chunk and its size */
|
|
static void init_top(mstate m, mchunkptr p, size_t psize) {
|
|
/* Ensure alignment */
|
|
size_t offset = align_offset(chunk2mem(p));
|
|
p = (mchunkptr)((char*)p + offset);
|
|
psize -= offset;
|
|
|
|
m->top = p;
|
|
m->topsize = psize;
|
|
p->head = psize | PINUSE_BIT;
|
|
/* set size of fake trailing chunk holding overhead space only once */
|
|
chunk_plus_offset(p, psize)->head = TOP_FOOT_SIZE;
|
|
m->trim_check = mparams.trim_threshold; /* reset on each update */
|
|
}
|
|
|
|
/* Initialize bins for a new mstate that is otherwise zeroed out */
|
|
static void init_bins(mstate m) {
|
|
/* Establish circular links for smallbins */
|
|
bindex_t i;
|
|
for (i = 0; i < NSMALLBINS; ++i) {
|
|
sbinptr bin = smallbin_at(m,i);
|
|
bin->fd = bin->bk = bin;
|
|
}
|
|
}
|
|
|
|
/* Allocate chunk and prepend remainder with chunk in successor base. */
|
|
static void* prepend_alloc(mstate m, char* newbase, char* oldbase,
|
|
size_t nb) {
|
|
mchunkptr p = align_as_chunk(newbase);
|
|
mchunkptr oldfirst = align_as_chunk(oldbase);
|
|
size_t psize = (char*)oldfirst - (char*)p;
|
|
mchunkptr q = chunk_plus_offset(p, nb);
|
|
size_t qsize = psize - nb;
|
|
set_size_and_pinuse_of_inuse_chunk(m, p, nb);
|
|
|
|
assert((char*)oldfirst > (char*)q);
|
|
assert(pinuse(oldfirst));
|
|
assert(qsize >= MIN_CHUNK_SIZE);
|
|
|
|
/* consolidate remainder with first chunk of old base */
|
|
if (oldfirst == m->top) {
|
|
size_t tsize = m->topsize += qsize;
|
|
m->top = q;
|
|
q->head = tsize | PINUSE_BIT;
|
|
check_top_chunk(m, q);
|
|
}
|
|
else if (oldfirst == m->dv) {
|
|
size_t dsize = m->dvsize += qsize;
|
|
m->dv = q;
|
|
set_size_and_pinuse_of_free_chunk(q, dsize);
|
|
}
|
|
else {
|
|
if (!is_inuse(oldfirst)) {
|
|
size_t nsize = chunksize(oldfirst);
|
|
unlink_chunk(m, oldfirst, nsize);
|
|
oldfirst = chunk_plus_offset(oldfirst, nsize);
|
|
qsize += nsize;
|
|
}
|
|
set_free_with_pinuse(q, qsize, oldfirst);
|
|
insert_chunk(m, q, qsize);
|
|
check_free_chunk(m, q);
|
|
}
|
|
|
|
check_malloced_chunk(m, chunk2mem(p), nb);
|
|
return chunk2mem(p);
|
|
}
|
|
|
|
/* Add a segment to hold a new noncontiguous region */
|
|
static void add_segment(mstate m, char* tbase, size_t tsize, flag_t mmapped) {
|
|
/* Determine locations and sizes of segment, fenceposts, old top */
|
|
char* old_top = (char*)m->top;
|
|
msegmentptr oldsp = segment_holding(m, old_top);
|
|
char* old_end = oldsp->base + oldsp->size;
|
|
size_t ssize = pad_request(sizeof(struct malloc_segment));
|
|
char* rawsp = old_end - (ssize + FOUR_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
|
|
size_t offset = align_offset(chunk2mem(rawsp));
|
|
char* asp = rawsp + offset;
|
|
char* csp = (asp < (old_top + MIN_CHUNK_SIZE))? old_top : asp;
|
|
mchunkptr sp = (mchunkptr)csp;
|
|
msegmentptr ss = (msegmentptr)(chunk2mem(sp));
|
|
mchunkptr tnext = chunk_plus_offset(sp, ssize);
|
|
mchunkptr p = tnext;
|
|
int nfences = 0;
|
|
|
|
/* reset top to new space */
|
|
init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
|
|
|
|
/* Set up segment record */
|
|
assert(is_aligned(ss));
|
|
set_size_and_pinuse_of_inuse_chunk(m, sp, ssize);
|
|
*ss = m->seg; /* Push current record */
|
|
m->seg.base = tbase;
|
|
m->seg.size = tsize;
|
|
m->seg.sflags = mmapped;
|
|
m->seg.next = ss;
|
|
|
|
/* Insert trailing fenceposts */
|
|
for (;;) {
|
|
mchunkptr nextp = chunk_plus_offset(p, SIZE_T_SIZE);
|
|
p->head = FENCEPOST_HEAD;
|
|
++nfences;
|
|
if ((char*)(&(nextp->head)) < old_end)
|
|
p = nextp;
|
|
else
|
|
break;
|
|
}
|
|
assert(nfences >= 2);
|
|
|
|
/* Insert the rest of old top into a bin as an ordinary free chunk */
|
|
if (csp != old_top) {
|
|
mchunkptr q = (mchunkptr)old_top;
|
|
size_t psize = csp - old_top;
|
|
mchunkptr tn = chunk_plus_offset(q, psize);
|
|
set_free_with_pinuse(q, psize, tn);
|
|
insert_chunk(m, q, psize);
|
|
}
|
|
|
|
check_top_chunk(m, m->top);
|
|
}
|
|
|
|
/* -------------------------- System allocation -------------------------- */
|
|
|
|
/* Get memory from system using MORECORE or MMAP */
|
|
static void* sys_alloc(mstate m, size_t nb) {
|
|
char* tbase = CMFAIL;
|
|
size_t tsize = 0;
|
|
flag_t mmap_flag = 0;
|
|
size_t asize; /* allocation size */
|
|
|
|
ensure_initialization();
|
|
|
|
printf("%s %d bytes\n", __FUNCTION__, nb);
|
|
|
|
/* Directly map large chunks, but only if already initialized */
|
|
if (use_mmap(m) && nb >= mparams.mmap_threshold && m->topsize != 0) {
|
|
void* mem = mmap_alloc(m, nb);
|
|
if (mem != 0)
|
|
return mem;
|
|
}
|
|
|
|
asize = granularity_align(nb + SYS_ALLOC_PADDING);
|
|
if (asize <= nb)
|
|
return 0; /* wraparound */
|
|
if (m->footprint_limit != 0) {
|
|
size_t fp = m->footprint + asize;
|
|
if (fp <= m->footprint || fp > m->footprint_limit)
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
Try getting memory in any of three ways (in most-preferred to
|
|
least-preferred order):
|
|
1. A call to MORECORE that can normally contiguously extend memory.
|
|
(disabled if not MORECORE_CONTIGUOUS or not HAVE_MORECORE or
|
|
or main space is mmapped or a previous contiguous call failed)
|
|
2. A call to MMAP new space (disabled if not HAVE_MMAP).
|
|
Note that under the default settings, if MORECORE is unable to
|
|
fulfill a request, and HAVE_MMAP is true, then mmap is
|
|
used as a noncontiguous system allocator. This is a useful backup
|
|
strategy for systems with holes in address spaces -- in this case
|
|
sbrk cannot contiguously expand the heap, but mmap may be able to
|
|
find space.
|
|
3. A call to MORECORE that cannot usually contiguously extend memory.
|
|
(disabled if not HAVE_MORECORE)
|
|
|
|
In all cases, we need to request enough bytes from system to ensure
|
|
we can malloc nb bytes upon success, so pad with enough space for
|
|
top_foot, plus alignment-pad to make sure we don't lose bytes if
|
|
not on boundary, and round this up to a granularity unit.
|
|
*/
|
|
|
|
#if 0
|
|
if (MORECORE_CONTIGUOUS && !use_noncontiguous(m)) {
|
|
char* br = CMFAIL;
|
|
size_t ssize = asize; /* sbrk call size */
|
|
msegmentptr ss = (m->top == 0)? 0 : segment_holding(m, (char*)m->top);
|
|
ACQUIRE_MALLOC_GLOBAL_LOCK();
|
|
|
|
if (ss == 0) { /* First time through or recovery */
|
|
char* base = (char*)CALL_MORECORE(0);
|
|
if (base != CMFAIL) {
|
|
size_t fp;
|
|
/* Adjust to end on a page boundary */
|
|
if (!is_page_aligned(base))
|
|
ssize += (page_align((size_t)base) - (size_t)base);
|
|
fp = m->footprint + ssize; /* recheck limits */
|
|
if (ssize > nb && ssize < HALF_MAX_SIZE_T &&
|
|
(m->footprint_limit == 0 ||
|
|
(fp > m->footprint && fp <= m->footprint_limit)) &&
|
|
(br = (char*)(CALL_MORECORE(ssize))) == base) {
|
|
tbase = base;
|
|
tsize = ssize;
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
/* Subtract out existing available top space from MORECORE request. */
|
|
ssize = granularity_align(nb - m->topsize + SYS_ALLOC_PADDING);
|
|
/* Use mem here only if it did continuously extend old space */
|
|
if (ssize < HALF_MAX_SIZE_T &&
|
|
(br = (char*)(CALL_MORECORE(ssize))) == ss->base+ss->size) {
|
|
tbase = br;
|
|
tsize = ssize;
|
|
}
|
|
}
|
|
|
|
if (tbase == CMFAIL) { /* Cope with partial failure */
|
|
if (br != CMFAIL) { /* Try to use/extend the space we did get */
|
|
if (ssize < HALF_MAX_SIZE_T &&
|
|
ssize < nb + SYS_ALLOC_PADDING) {
|
|
size_t esize = granularity_align(nb + SYS_ALLOC_PADDING - ssize);
|
|
if (esize < HALF_MAX_SIZE_T) {
|
|
char* end = (char*)CALL_MORECORE(esize);
|
|
if (end != CMFAIL)
|
|
ssize += esize;
|
|
else { /* Can't use; try to release */
|
|
(void) CALL_MORECORE(-ssize);
|
|
br = CMFAIL;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (br != CMFAIL) { /* Use the space we did get */
|
|
tbase = br;
|
|
tsize = ssize;
|
|
}
|
|
else
|
|
disable_contiguous(m); /* Don't try contiguous path in the future */
|
|
}
|
|
|
|
RELEASE_MALLOC_GLOBAL_LOCK();
|
|
}
|
|
#endif
|
|
|
|
if (HAVE_MMAP && tbase == CMFAIL) { /* Try MMAP */
|
|
char* mp = (char*)(CALL_MMAP(asize));
|
|
if (mp != CMFAIL) {
|
|
tbase = mp;
|
|
tsize = asize;
|
|
mmap_flag = USE_MMAP_BIT;
|
|
}
|
|
}
|
|
|
|
#if 0
|
|
if (HAVE_MORECORE && tbase == CMFAIL) { /* Try noncontiguous MORECORE */
|
|
if (asize < HALF_MAX_SIZE_T) {
|
|
char* br = CMFAIL;
|
|
char* end = CMFAIL;
|
|
ACQUIRE_MALLOC_GLOBAL_LOCK();
|
|
br = (char*)(CALL_MORECORE(asize));
|
|
end = (char*)(CALL_MORECORE(0));
|
|
RELEASE_MALLOC_GLOBAL_LOCK();
|
|
if (br != CMFAIL && end != CMFAIL && br < end) {
|
|
size_t ssize = end - br;
|
|
if (ssize > nb + TOP_FOOT_SIZE) {
|
|
tbase = br;
|
|
tsize = ssize;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
if (tbase != CMFAIL) {
|
|
|
|
if ((m->footprint += tsize) > m->max_footprint)
|
|
m->max_footprint = m->footprint;
|
|
|
|
if (!is_initialized(m)) { /* first-time initialization */
|
|
if (m->least_addr == 0 || tbase < m->least_addr)
|
|
m->least_addr = tbase;
|
|
m->seg.base = tbase;
|
|
m->seg.size = tsize;
|
|
m->seg.sflags = mmap_flag;
|
|
m->magic = mparams.magic;
|
|
m->release_checks = MAX_RELEASE_CHECK_RATE;
|
|
init_bins(m);
|
|
|
|
if (is_global(m))
|
|
init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
|
|
else
|
|
{
|
|
/* Offset top by embedded malloc_state */
|
|
mchunkptr mn = next_chunk(mem2chunk(m));
|
|
init_top(m, mn, (size_t)((tbase + tsize) - (char*)mn) -TOP_FOOT_SIZE);
|
|
}
|
|
}
|
|
|
|
else {
|
|
/* Try to merge with an existing segment */
|
|
msegmentptr sp = &m->seg;
|
|
/* Only consider most recent segment if traversal suppressed */
|
|
while (sp != 0 && tbase != sp->base + sp->size)
|
|
sp = (NO_SEGMENT_TRAVERSAL) ? 0 : sp->next;
|
|
if (sp != 0 &&
|
|
!is_extern_segment(sp) &&
|
|
(sp->sflags & USE_MMAP_BIT) == mmap_flag &&
|
|
segment_holds(sp, m->top)) { /* append */
|
|
sp->size += tsize;
|
|
init_top(m, m->top, m->topsize + tsize);
|
|
}
|
|
else {
|
|
if (tbase < m->least_addr)
|
|
m->least_addr = tbase;
|
|
sp = &m->seg;
|
|
while (sp != 0 && sp->base != tbase + tsize)
|
|
sp = (NO_SEGMENT_TRAVERSAL) ? 0 : sp->next;
|
|
if (sp != 0 &&
|
|
!is_extern_segment(sp) &&
|
|
(sp->sflags & USE_MMAP_BIT) == mmap_flag) {
|
|
char* oldbase = sp->base;
|
|
sp->base = tbase;
|
|
sp->size += tsize;
|
|
return prepend_alloc(m, tbase, oldbase, nb);
|
|
}
|
|
else
|
|
add_segment(m, tbase, tsize, mmap_flag);
|
|
}
|
|
}
|
|
|
|
if (nb < m->topsize) { /* Allocate from new or extended top space */
|
|
size_t rsize = m->topsize -= nb;
|
|
mchunkptr p = m->top;
|
|
mchunkptr r = m->top = chunk_plus_offset(p, nb);
|
|
r->head = rsize | PINUSE_BIT;
|
|
set_size_and_pinuse_of_inuse_chunk(m, p, nb);
|
|
check_top_chunk(m, m->top);
|
|
check_malloced_chunk(m, chunk2mem(p), nb);
|
|
return chunk2mem(p);
|
|
}
|
|
}
|
|
|
|
// MALLOC_FAILURE_ACTION;
|
|
return 0;
|
|
}
|
|
|
|
/* ----------------------- system deallocation -------------------------- */
|
|
|
|
/* Unmap and unlink any mmapped segments that don't contain used chunks */
|
|
static size_t release_unused_segments(mstate m) {
|
|
size_t released = 0;
|
|
int nsegs = 0;
|
|
msegmentptr pred = &m->seg;
|
|
msegmentptr sp = pred->next;
|
|
while (sp != 0) {
|
|
char* base = sp->base;
|
|
size_t size = sp->size;
|
|
msegmentptr next = sp->next;
|
|
++nsegs;
|
|
if (is_mmapped_segment(sp) && !is_extern_segment(sp)) {
|
|
mchunkptr p = align_as_chunk(base);
|
|
size_t psize = chunksize(p);
|
|
/* Can unmap if first chunk holds entire segment and not pinned */
|
|
if (!is_inuse(p) && (char*)p + psize >= base + size - TOP_FOOT_SIZE) {
|
|
tchunkptr tp = (tchunkptr)p;
|
|
assert(segment_holds(sp, (char*)sp));
|
|
if (p == m->dv) {
|
|
m->dv = 0;
|
|
m->dvsize = 0;
|
|
}
|
|
else {
|
|
unlink_large_chunk(m, tp);
|
|
}
|
|
if (CALL_MUNMAP(base, size) == 0) {
|
|
released += size;
|
|
m->footprint -= size;
|
|
/* unlink obsoleted record */
|
|
sp = pred;
|
|
sp->next = next;
|
|
}
|
|
else { /* back out if cannot unmap */
|
|
insert_large_chunk(m, tp, psize);
|
|
}
|
|
}
|
|
}
|
|
if (NO_SEGMENT_TRAVERSAL) /* scan only first segment */
|
|
break;
|
|
pred = sp;
|
|
sp = next;
|
|
}
|
|
/* Reset check counter */
|
|
m->release_checks = (((size_t) nsegs > (size_t) MAX_RELEASE_CHECK_RATE)?
|
|
(size_t) nsegs : (size_t) MAX_RELEASE_CHECK_RATE);
|
|
return released;
|
|
}
|
|
|
|
static int sys_trim(mstate m, size_t pad) {
|
|
size_t released = 0;
|
|
ensure_initialization();
|
|
if (pad < MAX_REQUEST && is_initialized(m)) {
|
|
pad += TOP_FOOT_SIZE; /* ensure enough room for segment overhead */
|
|
|
|
if (m->topsize > pad) {
|
|
/* Shrink top space in granularity-size units, keeping at least one */
|
|
size_t unit = mparams.granularity;
|
|
size_t extra = ((m->topsize - pad + (unit - SIZE_T_ONE)) / unit -
|
|
SIZE_T_ONE) * unit;
|
|
msegmentptr sp = segment_holding(m, (char*)m->top);
|
|
|
|
if (!is_extern_segment(sp)) {
|
|
if (is_mmapped_segment(sp)) {
|
|
if (HAVE_MMAP &&
|
|
sp->size >= extra &&
|
|
!has_segment_link(m, sp)) { /* can't shrink if pinned */
|
|
size_t newsize = sp->size - extra;
|
|
(void)newsize; /* placate people compiling -Wunused-variable */
|
|
/* Prefer mremap, fall back to munmap */
|
|
if ((CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL) ||
|
|
(CALL_MUNMAP(sp->base + newsize, extra) == 0)) {
|
|
released = extra;
|
|
}
|
|
}
|
|
}
|
|
else if (HAVE_MORECORE) {
|
|
if (extra >= HALF_MAX_SIZE_T) /* Avoid wrapping negative */
|
|
extra = (HALF_MAX_SIZE_T) + SIZE_T_ONE - unit;
|
|
ACQUIRE_MALLOC_GLOBAL_LOCK();
|
|
{
|
|
/* Make sure end of memory is where we last set it. */
|
|
char* old_br = (char*)(CALL_MORECORE(0));
|
|
if (old_br == sp->base + sp->size) {
|
|
char* rel_br = (char*)(CALL_MORECORE(-extra));
|
|
char* new_br = (char*)(CALL_MORECORE(0));
|
|
if (rel_br != CMFAIL && new_br < old_br)
|
|
released = old_br - new_br;
|
|
}
|
|
}
|
|
RELEASE_MALLOC_GLOBAL_LOCK();
|
|
}
|
|
}
|
|
|
|
if (released != 0) {
|
|
sp->size -= released;
|
|
m->footprint -= released;
|
|
init_top(m, m->top, m->topsize - released);
|
|
check_top_chunk(m, m->top);
|
|
}
|
|
}
|
|
|
|
/* Unmap any unused mmapped segments */
|
|
if (HAVE_MMAP)
|
|
released += release_unused_segments(m);
|
|
|
|
/* On failure, disable autotrim to avoid repeated failed future calls */
|
|
if (released == 0 && m->topsize > m->trim_check)
|
|
m->trim_check = MAX_SIZE_T;
|
|
}
|
|
|
|
return (released != 0)? 1 : 0;
|
|
}
|
|
|
|
/* Consolidate and bin a chunk. Differs from exported versions
|
|
of free mainly in that the chunk need not be marked as inuse.
|
|
*/
|
|
static void dispose_chunk(mstate m, mchunkptr p, size_t psize) {
|
|
mchunkptr next = chunk_plus_offset(p, psize);
|
|
if (!pinuse(p)) {
|
|
mchunkptr prev;
|
|
size_t prevsize = p->prev_foot;
|
|
if (is_mmapped(p)) {
|
|
psize += prevsize + MMAP_FOOT_PAD;
|
|
if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
|
|
m->footprint -= psize;
|
|
return;
|
|
}
|
|
prev = chunk_minus_offset(p, prevsize);
|
|
psize += prevsize;
|
|
p = prev;
|
|
if (RTCHECK(ok_address(m, prev))) { /* consolidate backward */
|
|
if (p != m->dv) {
|
|
unlink_chunk(m, p, prevsize);
|
|
}
|
|
else if ((next->head & INUSE_BITS) == INUSE_BITS) {
|
|
m->dvsize = psize;
|
|
set_free_with_pinuse(p, psize, next);
|
|
return;
|
|
}
|
|
}
|
|
else {
|
|
CORRUPTION_ERROR_ACTION(m);
|
|
return;
|
|
}
|
|
}
|
|
if (RTCHECK(ok_address(m, next))) {
|
|
if (!cinuse(next)) { /* consolidate forward */
|
|
if (next == m->top) {
|
|
size_t tsize = m->topsize += psize;
|
|
m->top = p;
|
|
p->head = tsize | PINUSE_BIT;
|
|
if (p == m->dv) {
|
|
m->dv = 0;
|
|
m->dvsize = 0;
|
|
}
|
|
return;
|
|
}
|
|
else if (next == m->dv) {
|
|
size_t dsize = m->dvsize += psize;
|
|
m->dv = p;
|
|
set_size_and_pinuse_of_free_chunk(p, dsize);
|
|
return;
|
|
}
|
|
else {
|
|
size_t nsize = chunksize(next);
|
|
psize += nsize;
|
|
unlink_chunk(m, next, nsize);
|
|
set_size_and_pinuse_of_free_chunk(p, psize);
|
|
if (p == m->dv) {
|
|
m->dvsize = psize;
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
set_free_with_pinuse(p, psize, next);
|
|
}
|
|
insert_chunk(m, p, psize);
|
|
}
|
|
else {
|
|
CORRUPTION_ERROR_ACTION(m);
|
|
}
|
|
}
|
|
|
|
/* ---------------------------- malloc --------------------------- */
|
|
|
|
/* allocate a large request from the best fitting chunk in a treebin */
|
|
static void* tmalloc_large(mstate m, size_t nb) {
|
|
tchunkptr v = 0;
|
|
size_t rsize = -nb; /* Unsigned negation */
|
|
tchunkptr t;
|
|
bindex_t idx;
|
|
compute_tree_index(nb, idx);
|
|
if ((t = *treebin_at(m, idx)) != 0) {
|
|
/* Traverse tree for this bin looking for node with size == nb */
|
|
size_t sizebits = nb << leftshift_for_tree_index(idx);
|
|
tchunkptr rst = 0; /* The deepest untaken right subtree */
|
|
for (;;) {
|
|
tchunkptr rt;
|
|
size_t trem = chunksize(t) - nb;
|
|
if (trem < rsize) {
|
|
v = t;
|
|
if ((rsize = trem) == 0)
|
|
break;
|
|
}
|
|
rt = t->child[1];
|
|
t = t->child[(sizebits >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1];
|
|
if (rt != 0 && rt != t)
|
|
rst = rt;
|
|
if (t == 0) {
|
|
t = rst; /* set t to least subtree holding sizes > nb */
|
|
break;
|
|
}
|
|
sizebits <<= 1;
|
|
}
|
|
}
|
|
if (t == 0 && v == 0) { /* set t to root of next non-empty treebin */
|
|
binmap_t leftbits = left_bits(idx2bit(idx)) & m->treemap;
|
|
if (leftbits != 0) {
|
|
bindex_t i;
|
|
binmap_t leastbit = least_bit(leftbits);
|
|
compute_bit2idx(leastbit, i);
|
|
t = *treebin_at(m, i);
|
|
}
|
|
}
|
|
|
|
while (t != 0) { /* find smallest of tree or subtree */
|
|
size_t trem = chunksize(t) - nb;
|
|
if (trem < rsize) {
|
|
rsize = trem;
|
|
v = t;
|
|
}
|
|
t = leftmost_child(t);
|
|
}
|
|
|
|
/* If dv is a better fit, return 0 so malloc will use it */
|
|
if (v != 0 && rsize < (size_t)(m->dvsize - nb)) {
|
|
if (RTCHECK(ok_address(m, v))) { /* split */
|
|
mchunkptr r = chunk_plus_offset(v, nb);
|
|
assert(chunksize(v) == rsize + nb);
|
|
if (RTCHECK(ok_next(v, r))) {
|
|
unlink_large_chunk(m, v);
|
|
if (rsize < MIN_CHUNK_SIZE)
|
|
set_inuse_and_pinuse(m, v, (rsize + nb));
|
|
else {
|
|
set_size_and_pinuse_of_inuse_chunk(m, v, nb);
|
|
set_size_and_pinuse_of_free_chunk(r, rsize);
|
|
insert_chunk(m, r, rsize);
|
|
}
|
|
return chunk2mem(v);
|
|
}
|
|
}
|
|
CORRUPTION_ERROR_ACTION(m);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* allocate a small request from the best fitting chunk in a treebin */
|
|
static void* tmalloc_small(mstate m, size_t nb) {
|
|
tchunkptr t, v;
|
|
size_t rsize;
|
|
bindex_t i;
|
|
binmap_t leastbit = least_bit(m->treemap);
|
|
compute_bit2idx(leastbit, i);
|
|
v = t = *treebin_at(m, i);
|
|
rsize = chunksize(t) - nb;
|
|
|
|
while ((t = leftmost_child(t)) != 0) {
|
|
size_t trem = chunksize(t) - nb;
|
|
if (trem < rsize) {
|
|
rsize = trem;
|
|
v = t;
|
|
}
|
|
}
|
|
|
|
if (RTCHECK(ok_address(m, v))) {
|
|
mchunkptr r = chunk_plus_offset(v, nb);
|
|
assert(chunksize(v) == rsize + nb);
|
|
if (RTCHECK(ok_next(v, r))) {
|
|
unlink_large_chunk(m, v);
|
|
if (rsize < MIN_CHUNK_SIZE)
|
|
set_inuse_and_pinuse(m, v, (rsize + nb));
|
|
else {
|
|
set_size_and_pinuse_of_inuse_chunk(m, v, nb);
|
|
set_size_and_pinuse_of_free_chunk(r, rsize);
|
|
replace_dv(m, r, rsize);
|
|
}
|
|
return chunk2mem(v);
|
|
}
|
|
}
|
|
|
|
CORRUPTION_ERROR_ACTION(m);
|
|
return 0;
|
|
}
|
|
|
|
|
|
void* malloc(size_t bytes)
|
|
{
|
|
/*
|
|
Basic algorithm:
|
|
If a small request (< 256 bytes minus per-chunk overhead):
|
|
1. If one exists, use a remainderless chunk in associated smallbin.
|
|
(Remainderless means that there are too few excess bytes to
|
|
represent as a chunk.)
|
|
2. If it is big enough, use the dv chunk, which is normally the
|
|
chunk adjacent to the one used for the most recent small request.
|
|
3. If one exists, split the smallest available chunk in a bin,
|
|
saving remainder in dv.
|
|
4. If it is big enough, use the top chunk.
|
|
5. If available, get memory from system and use it
|
|
Otherwise, for a large request:
|
|
1. Find the smallest available binned chunk that fits, and use it
|
|
if it is better fitting than dv chunk, splitting if necessary.
|
|
2. If better fitting than any binned chunk, use the dv chunk.
|
|
3. If it is big enough, use the top chunk.
|
|
4. If request size >= mmap threshold, try to directly mmap this chunk.
|
|
5. If available, get memory from system and use it
|
|
|
|
The ugly goto's here ensure that postaction occurs along all paths.
|
|
*/
|
|
|
|
ensure_initialization(); /* initialize in sys_alloc if not using locks */
|
|
|
|
PREACTION(gm);
|
|
{
|
|
void* mem;
|
|
size_t nb;
|
|
if (bytes <= MAX_SMALL_REQUEST) {
|
|
bindex_t idx;
|
|
binmap_t smallbits;
|
|
nb = (bytes < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(bytes);
|
|
idx = small_index(nb);
|
|
smallbits = gm->smallmap >> idx;
|
|
|
|
if ((smallbits & 0x3U) != 0) { /* Remainderless fit to a smallbin. */
|
|
mchunkptr b, p;
|
|
idx += ~smallbits & 1; /* Uses next bin if idx empty */
|
|
b = smallbin_at(gm, idx);
|
|
p = b->fd;
|
|
assert(chunksize(p) == small_index2size(idx));
|
|
unlink_first_small_chunk(gm, b, p, idx);
|
|
set_inuse_and_pinuse(gm, p, small_index2size(idx));
|
|
mem = chunk2mem(p);
|
|
check_malloced_chunk(gm, mem, nb);
|
|
goto postaction;
|
|
}
|
|
|
|
else if (nb > gm->dvsize) {
|
|
if (smallbits != 0) { /* Use chunk in next nonempty smallbin */
|
|
mchunkptr b, p, r;
|
|
size_t rsize;
|
|
bindex_t i;
|
|
binmap_t leftbits = (smallbits << idx) & left_bits(idx2bit(idx));
|
|
binmap_t leastbit = least_bit(leftbits);
|
|
compute_bit2idx(leastbit, i);
|
|
b = smallbin_at(gm, i);
|
|
p = b->fd;
|
|
assert(chunksize(p) == small_index2size(i));
|
|
unlink_first_small_chunk(gm, b, p, i);
|
|
rsize = small_index2size(i) - nb;
|
|
/* Fit here cannot be remainderless if 4byte sizes */
|
|
if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
|
|
set_inuse_and_pinuse(gm, p, small_index2size(i));
|
|
else {
|
|
set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
|
|
r = chunk_plus_offset(p, nb);
|
|
set_size_and_pinuse_of_free_chunk(r, rsize);
|
|
replace_dv(gm, r, rsize);
|
|
}
|
|
mem = chunk2mem(p);
|
|
check_malloced_chunk(gm, mem, nb);
|
|
goto postaction;
|
|
}
|
|
|
|
else if (gm->treemap != 0 && (mem = tmalloc_small(gm, nb)) != 0) {
|
|
check_malloced_chunk(gm, mem, nb);
|
|
goto postaction;
|
|
}
|
|
}
|
|
}
|
|
else if (bytes >= MAX_REQUEST)
|
|
nb = MAX_SIZE_T; /* Too big to allocate. Force failure (in sys alloc) */
|
|
else {
|
|
nb = pad_request(bytes);
|
|
if (gm->treemap != 0 && (mem = tmalloc_large(gm, nb)) != 0) {
|
|
check_malloced_chunk(gm, mem, nb);
|
|
goto postaction;
|
|
}
|
|
}
|
|
|
|
if (nb <= gm->dvsize) {
|
|
size_t rsize = gm->dvsize - nb;
|
|
mchunkptr p = gm->dv;
|
|
if (rsize >= MIN_CHUNK_SIZE) { /* split dv */
|
|
mchunkptr r = gm->dv = chunk_plus_offset(p, nb);
|
|
gm->dvsize = rsize;
|
|
set_size_and_pinuse_of_free_chunk(r, rsize);
|
|
set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
|
|
}
|
|
else { /* exhaust dv */
|
|
size_t dvs = gm->dvsize;
|
|
gm->dvsize = 0;
|
|
gm->dv = 0;
|
|
set_inuse_and_pinuse(gm, p, dvs);
|
|
}
|
|
mem = chunk2mem(p);
|
|
check_malloced_chunk(gm, mem, nb);
|
|
goto postaction;
|
|
}
|
|
|
|
else if (nb < gm->topsize) { /* Split top */
|
|
size_t rsize = gm->topsize -= nb;
|
|
mchunkptr p = gm->top;
|
|
mchunkptr r = gm->top = chunk_plus_offset(p, nb);
|
|
r->head = rsize | PINUSE_BIT;
|
|
set_size_and_pinuse_of_inuse_chunk(gm, p, nb);
|
|
mem = chunk2mem(p);
|
|
check_top_chunk(gm, gm->top);
|
|
check_malloced_chunk(gm, mem, nb);
|
|
goto postaction;
|
|
}
|
|
|
|
mem = sys_alloc(gm, nb);
|
|
|
|
postaction:
|
|
POSTACTION(gm);
|
|
// printf("%s %p %d\n", __FUNCTION__, mem, bytes);
|
|
return mem;
|
|
}
|
|
// FAIL();
|
|
return 0;
|
|
}
|
|
|
|
/* ---------------------------- free --------------------------- */
|
|
|
|
void free(void* mem){
|
|
/*
|
|
Consolidate freed chunks with preceeding or succeeding bordering
|
|
free chunks, if they exist, and then place in a bin. Intermixed
|
|
with special cases for top, dv, mmapped chunks, and usage errors.
|
|
*/
|
|
|
|
// dbgprintf("%s %p\n", __FUNCTION__, mem);
|
|
|
|
if (mem != 0) {
|
|
mchunkptr p = mem2chunk(mem);
|
|
#if FOOTERS
|
|
mstate fm = get_mstate_for(p);
|
|
if (!ok_magic(fm)) {
|
|
USAGE_ERROR_ACTION(fm, p);
|
|
return;
|
|
}
|
|
#else /* FOOTERS */
|
|
#define fm gm
|
|
#endif /* FOOTERS */
|
|
PREACTION(fm);
|
|
{
|
|
check_inuse_chunk(fm, p);
|
|
if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {
|
|
size_t psize = chunksize(p);
|
|
mchunkptr next = chunk_plus_offset(p, psize);
|
|
if (!pinuse(p)) {
|
|
size_t prevsize = p->prev_foot;
|
|
if (is_mmapped(p)) {
|
|
psize += prevsize + MMAP_FOOT_PAD;
|
|
if (CALL_MUNMAP((char*)p - prevsize, psize) == 0)
|
|
fm->footprint -= psize;
|
|
goto postaction;
|
|
}
|
|
else {
|
|
mchunkptr prev = chunk_minus_offset(p, prevsize);
|
|
psize += prevsize;
|
|
p = prev;
|
|
if (RTCHECK(ok_address(fm, prev))) { /* consolidate backward */
|
|
if (p != fm->dv) {
|
|
unlink_chunk(fm, p, prevsize);
|
|
}
|
|
else if ((next->head & INUSE_BITS) == INUSE_BITS) {
|
|
fm->dvsize = psize;
|
|
set_free_with_pinuse(p, psize, next);
|
|
goto postaction;
|
|
}
|
|
}
|
|
else
|
|
goto erroraction;
|
|
}
|
|
}
|
|
|
|
if (RTCHECK(ok_next(p, next) && ok_pinuse(next))) {
|
|
if (!cinuse(next)) { /* consolidate forward */
|
|
if (next == fm->top) {
|
|
size_t tsize = fm->topsize += psize;
|
|
fm->top = p;
|
|
p->head = tsize | PINUSE_BIT;
|
|
if (p == fm->dv) {
|
|
fm->dv = 0;
|
|
fm->dvsize = 0;
|
|
}
|
|
if (should_trim(fm, tsize))
|
|
sys_trim(fm, 0);
|
|
goto postaction;
|
|
}
|
|
else if (next == fm->dv) {
|
|
size_t dsize = fm->dvsize += psize;
|
|
fm->dv = p;
|
|
set_size_and_pinuse_of_free_chunk(p, dsize);
|
|
goto postaction;
|
|
}
|
|
else {
|
|
size_t nsize = chunksize(next);
|
|
psize += nsize;
|
|
unlink_chunk(fm, next, nsize);
|
|
set_size_and_pinuse_of_free_chunk(p, psize);
|
|
if (p == fm->dv) {
|
|
fm->dvsize = psize;
|
|
goto postaction;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
set_free_with_pinuse(p, psize, next);
|
|
|
|
if (is_small(psize)) {
|
|
insert_small_chunk(fm, p, psize);
|
|
check_free_chunk(fm, p);
|
|
}
|
|
else {
|
|
tchunkptr tp = (tchunkptr)p;
|
|
insert_large_chunk(fm, tp, psize);
|
|
check_free_chunk(fm, p);
|
|
if (--fm->release_checks == 0)
|
|
release_unused_segments(fm);
|
|
}
|
|
goto postaction;
|
|
}
|
|
}
|
|
erroraction:
|
|
USAGE_ERROR_ACTION(fm, p);
|
|
postaction:
|
|
POSTACTION(fm);
|
|
}
|
|
}
|
|
|
|
// LEAVE();
|
|
|
|
#if !FOOTERS
|
|
#undef fm
|
|
#endif /* FOOTERS */
|
|
}
|
|
|
|
void* calloc(size_t n_elements, size_t elem_size) {
|
|
void* mem;
|
|
size_t req = 0;
|
|
if (n_elements != 0) {
|
|
req = n_elements * elem_size;
|
|
if (((n_elements | elem_size) & ~(size_t)0xffff) &&
|
|
(req / n_elements != elem_size))
|
|
req = MAX_SIZE_T; /* force downstream failure on overflow */
|
|
}
|
|
mem = malloc(req);
|
|
if (mem != 0 && calloc_must_clear(mem2chunk(mem)))
|
|
memset(mem, 0, req);
|
|
return mem;
|
|
}
|
|
|
|
/* ------------ Internal support for realloc, memalign, etc -------------- */
|
|
|
|
/* Try to realloc; only in-place unless can_move true */
|
|
static mchunkptr try_realloc_chunk(mstate m, mchunkptr p, size_t nb,
|
|
int can_move) {
|
|
mchunkptr newp = 0;
|
|
size_t oldsize = chunksize(p);
|
|
mchunkptr next = chunk_plus_offset(p, oldsize);
|
|
if (RTCHECK(ok_address(m, p) && ok_inuse(p) &&
|
|
ok_next(p, next) && ok_pinuse(next))) {
|
|
if (is_mmapped(p)) {
|
|
newp = mmap_resize(m, p, nb, can_move);
|
|
}
|
|
else if (oldsize >= nb) { /* already big enough */
|
|
size_t rsize = oldsize - nb;
|
|
if (rsize >= MIN_CHUNK_SIZE) { /* split off remainder */
|
|
mchunkptr r = chunk_plus_offset(p, nb);
|
|
set_inuse(m, p, nb);
|
|
set_inuse(m, r, rsize);
|
|
dispose_chunk(m, r, rsize);
|
|
}
|
|
newp = p;
|
|
}
|
|
else if (next == m->top) { /* extend into top */
|
|
if (oldsize + m->topsize > nb) {
|
|
size_t newsize = oldsize + m->topsize;
|
|
size_t newtopsize = newsize - nb;
|
|
mchunkptr newtop = chunk_plus_offset(p, nb);
|
|
set_inuse(m, p, nb);
|
|
newtop->head = newtopsize |PINUSE_BIT;
|
|
m->top = newtop;
|
|
m->topsize = newtopsize;
|
|
newp = p;
|
|
}
|
|
}
|
|
else if (next == m->dv) { /* extend into dv */
|
|
size_t dvs = m->dvsize;
|
|
if (oldsize + dvs >= nb) {
|
|
size_t dsize = oldsize + dvs - nb;
|
|
if (dsize >= MIN_CHUNK_SIZE) {
|
|
mchunkptr r = chunk_plus_offset(p, nb);
|
|
mchunkptr n = chunk_plus_offset(r, dsize);
|
|
set_inuse(m, p, nb);
|
|
set_size_and_pinuse_of_free_chunk(r, dsize);
|
|
clear_pinuse(n);
|
|
m->dvsize = dsize;
|
|
m->dv = r;
|
|
}
|
|
else { /* exhaust dv */
|
|
size_t newsize = oldsize + dvs;
|
|
set_inuse(m, p, newsize);
|
|
m->dvsize = 0;
|
|
m->dv = 0;
|
|
}
|
|
newp = p;
|
|
}
|
|
}
|
|
else if (!cinuse(next)) { /* extend into next free chunk */
|
|
size_t nextsize = chunksize(next);
|
|
if (oldsize + nextsize >= nb) {
|
|
size_t rsize = oldsize + nextsize - nb;
|
|
unlink_chunk(m, next, nextsize);
|
|
if (rsize < MIN_CHUNK_SIZE) {
|
|
size_t newsize = oldsize + nextsize;
|
|
set_inuse(m, p, newsize);
|
|
}
|
|
else {
|
|
mchunkptr r = chunk_plus_offset(p, nb);
|
|
set_inuse(m, p, nb);
|
|
set_inuse(m, r, rsize);
|
|
dispose_chunk(m, r, rsize);
|
|
}
|
|
newp = p;
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
USAGE_ERROR_ACTION(m, chunk2mem(p));
|
|
}
|
|
return newp;
|
|
}
|
|
|
|
|
|
void* realloc(void* oldmem, size_t bytes) {
|
|
void* mem = 0;
|
|
if (oldmem == 0) {
|
|
mem = malloc(bytes);
|
|
}
|
|
else if (bytes >= MAX_REQUEST) {
|
|
// MALLOC_FAILURE_ACTION;
|
|
}
|
|
#ifdef REALLOC_ZERO_BYTES_FREES
|
|
else if (bytes == 0) {
|
|
free(oldmem);
|
|
}
|
|
#endif /* REALLOC_ZERO_BYTES_FREES */
|
|
else {
|
|
size_t nb = request2size(bytes);
|
|
mchunkptr oldp = mem2chunk(oldmem);
|
|
#if ! FOOTERS
|
|
mstate m = gm;
|
|
#else /* FOOTERS */
|
|
mstate m = get_mstate_for(oldp);
|
|
if (!ok_magic(m)) {
|
|
USAGE_ERROR_ACTION(m, oldmem);
|
|
return 0;
|
|
}
|
|
#endif /* FOOTERS */
|
|
PREACTION(m); {
|
|
mchunkptr newp = try_realloc_chunk(m, oldp, nb, 1);
|
|
POSTACTION(m);
|
|
if (newp != 0) {
|
|
check_inuse_chunk(m, newp);
|
|
mem = chunk2mem(newp);
|
|
}
|
|
else {
|
|
mem = internal_malloc(m, bytes);
|
|
if (mem != 0) {
|
|
size_t oc = chunksize(oldp) - overhead_for(oldp);
|
|
memcpy(mem, oldmem, (oc < bytes)? oc : bytes);
|
|
internal_free(m, oldmem);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return mem;
|
|
}
|
|
|
|
|
|
|
|
|