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kolibrios-gitea/kernel/trunk/blkdev/disk.inc
Ivan Baravy 02da1fd4f3 Fix for GPT partitions scan. 
GPT partition entry array (GPEA) has 128 entries by default, unused ones
must be zeroed. Due to memory corruption GPEA contained non-zero data of
first sectors of partitions. This led to fake partitions detected which
were mostly filtered out by their start:length and thus didn't show up.
Pass ebx=three-sector-sized buffer to disk_add_partition as expected.

git-svn-id: svn://kolibrios.org@7270 a494cfbc-eb01-0410-851d-a64ba20cac60
2018-05-05 13:50:04 +00:00

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ;;
;; Copyright (C) KolibriOS team 2011-2015. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License ;;
;; ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
$Revision$
; =============================================================================
; ================================= Constants =================================
; =============================================================================
; Error codes for callback functions.
DISK_STATUS_OK = 0 ; success
DISK_STATUS_GENERAL_ERROR = -1; if no other code is suitable
DISK_STATUS_INVALID_CALL = 1 ; invalid input parameters
DISK_STATUS_NO_MEDIA = 2 ; no media present
DISK_STATUS_END_OF_MEDIA = 3 ; end of media while reading/writing data
DISK_STATUS_NO_MEMORY = 4 ; insufficient memory for driver operation
; Driver flags. Represent bits in DISK.DriverFlags.
DISK_NO_INSERT_NOTIFICATION = 1
; Media flags. Represent bits in DISKMEDIAINFO.Flags.
DISK_MEDIA_READONLY = 1
; If too many partitions are detected,there is probably an error on the disk.
; 256 partitions should be enough for any reasonable use.
; Also, the same number is limiting the number of MBRs to process; if
; too many MBRs are visible,there probably is a loop in the MBR structure.
MAX_NUM_PARTITIONS = 256
; =============================================================================
; ================================ Structures =================================
; =============================================================================
; This structure defines all callback functions for working with the physical
; device. They are implemented by a driver. Objects with this structure reside
; in a driver.
struct DISKFUNC
strucsize dd ?
; Size of the structure. This field is intended for possible extensions of
; this structure. If a new function is added to this structure and a driver
; implements an old version, the caller can detect this by checking .strucsize,
; so the driver remains compatible.
close dd ?
; The pointer to the function which frees all driver-specific resources for
; the disk.
; Optional, may be NULL.
; void close(void* userdata);
closemedia dd ?
; The pointer to the function which informs the driver that the kernel has
; finished all processing with the current media. If media is removed, the
; driver should decline all requests to that media with DISK_STATUS_NO_MEDIA,
; even if new media is inserted, until this function is called. If media is
; removed, a new call to 'disk_media_changed' is not allowed until this
; function is called.
; Optional, may be NULL (if media is not removable).
; void closemedia(void* userdata);
querymedia dd ?
; The pointer to the function which determines capabilities of the media.
; int querymedia(void* userdata, DISKMEDIAINFO* info);
; Return value: one of DISK_STATUS_*
read dd ?
; The pointer to the function which reads data from the device.
; int read(void* userdata, void* buffer, __int64 startsector, int* numsectors);
; input: *numsectors = number of sectors to read
; output: *numsectors = number of sectors which were successfully read
; Return value: one of DISK_STATUS_*
write dd ?
; The pointer to the function which writes data to the device.
; Optional, may be NULL.
; int write(void* userdata, void* buffer, __int64 startsector, int* numsectors);
; input: *numsectors = number of sectors to write
; output: *numsectors = number of sectors which were successfully written
; Return value: one of DISK_STATUS_*
flush dd ?
; The pointer to the function which flushes the internal device cache.
; Optional, may be NULL.
; int flush(void* userdata);
; Return value: one of DISK_STATUS_*
; Note that read/write are called by the cache manager, so a driver should not
; create a software cache. This function is implemented for flushing a hardware
; cache, if it exists.
adjust_cache_size dd ?
; The pointer to the function which returns the cache size for this device.
; Optional, may be NULL.
; unsigned int adjust_cache_size(unsigned int suggested_size);
; Return value: 0 = disable cache, otherwise = used cache size in bytes.
ends
; This structure holds information on a medium.
; Objects with this structure are allocated by the kernel as a part of the DISK
; structure and are filled by a driver in the 'querymedia' callback.
struct DISKMEDIAINFO
Flags dd ?
; Combination of DISK_MEDIA_* bits.
SectorSize dd ?
; Size of the sector.
Capacity dq ?
; Size of the media in sectors.
ends
; This structure represents the disk cache. To follow the old implementation,
; there are two distinct caches for a disk, one for "system" data,and the other
; for "application" data.
struct DISKCACHE
; The following fields are inherited from data32.inc:cache_ideX.
pointer dd ?
data_size dd ? ; unused
data dd ?
sad_size dd ?
search_start dd ?
sector_size_log dd ?
ends
; This structure represents a disk device and its media for the kernel.
; This structure is allocated by the kernel in the 'disk_add' function,
; freed in the 'disk_dereference' function.
struct DISK
; Fields of disk object
Next dd ?
Prev dd ?
; All disk devices are linked in one list with these two fields.
; Head of the list is the 'disk_list' variable.
Functions dd ?
; Pointer to the 'DISKFUNC' structure with driver functions.
Name dd ?
; Pointer to the string used for accesses through the global filesystem.
UserData dd ?
; This field is passed to all callback functions so a driver can decide which
; physical device is addressed.
DriverFlags dd ?
; Bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit is defined.
; If it is set, the driver will never issue 'disk_media_changed' notification
; with argument set to true, so the kernel must try to detect media during
; requests from the file system.
RefCount dd ?
; Count of active references to this structure. One reference is kept during
; the lifetime of the structure between 'disk_add' and 'disk_del'.
; Another reference is taken during any filesystem operation for this disk.
; One reference is added if media is inserted.
; The structure is destroyed when the reference count decrements to zero:
; this usually occurs in 'disk_del', but can be delayed to the end of last
; filesystem operation, if one is active.
MediaLock MUTEX
; Lock to protect the MEDIA structure. See the description after
; 'disk_list_mutex' for the locking strategy.
; Fields of media object
MediaInserted db ?
; 0 if media is not inserted, nonzero otherwise.
MediaUsed db ?
; 0 if media fields are not used, nonzero otherwise. If .MediaRefCount is
; nonzero, this field is nonzero too; however, when .MediaRefCount goes
; to zero, there is some time interval during which media object is still used.
dw ? ; padding
; The following fields are not valid unless either .MediaInserted is nonzero
; or they are accessed from a code which has obtained the reference when
; .MediaInserted was nonzero.
MediaRefCount dd ?
; Count of active references to the media object. One reference is kept during
; the lifetime of the media between two calls to 'disk_media_changed'.
; Another reference is taken during any filesystem operation for this media.
; The callback 'closemedia' is called when the reference count decrements to
; zero: this usually occurs in 'disk_media_changed', but can be delayed to the
; end of the last filesystem operation, if one is active.
MediaInfo DISKMEDIAINFO
; This field keeps information on the current media.
NumPartitions dd ?
; Number of partitions on this media.
Partitions dd ?
; Pointer to array of .NumPartitions pointers to PARTITION structures.
cache_size dd ?
; inherited from cache_ideX_size
CacheLock MUTEX
; Lock to protect both caches.
SysCache DISKCACHE
AppCache DISKCACHE
; Two caches for the disk.
ends
; This structure represents one partition for the kernel. This is a base
; template, the actual contents after common fields is determined by the
; file system code for this partition.
struct PARTITION
FirstSector dq ?
; First sector of the partition.
Length dq ?
; Length of the partition in sectors.
Disk dd ?
; Pointer to parent DISK structure.
FSUserFunctions dd ?
; Handlers for the sysfunction 70h. This field is a pointer to the following
; array. The first dword is pointer to disconnect handler.
; The first dword is a number of supported subfunctions, other dwords
; point to handlers of corresponding subfunctions.
; ...fs-specific data may follow...
ends
; This is an external structure, it represents an entry in the partition table.
struct PARTITION_TABLE_ENTRY
Bootable db ?
; 80h = bootable partition, 0 = non-bootable partition, other values = invalid
FirstHead db ?
FirstSector db ?
FirstTrack db ?
; Coordinates of first sector in CHS.
Type db ?
; Partition type, one of predefined constants. 0 = empty, several types denote
; extended partition (see process_partition_table_entry), we are not interested
; in other values.
LastHead db ?
LastSector db ?
LastTrack db ?
; Coordinates of last sector in CHS.
FirstAbsSector dd ?
; Coordinate of first sector in LBA.
Length dd ?
; Length of the partition in sectors.
ends
; GUID Partition Table Header, UEFI 2.6, Table 18
struct GPTH
Signature rb 8
; 'EFI PART'
Revision dd ?
; 0x00010000
HeaderSize dd ?
; Size of this header in bytes, must fit to one sector.
HeaderCRC32 dd ?
; Set this field to zero, compute CRC32 via 0xEDB88320, compare.
Reserved dd ?
; Must be zero.
MyLBA dq ?
; LBA of the sector containing this GPT header.
AlternateLBA dq ?
; LBA of the sector containing the other GPT header.
; AlternateLBA of Primary GPTH points to Backup one and vice versa.
FirstUsableLBA dq ?
; Only sectors between first and last UsableLBA may form partitions
LastUsableLBA dq ?
DiskGUID rb 16
; Globally Unique IDentifier
PartitionEntryLBA dq ?
; First LBA of Partition Entry Array.
; Length in bytes is computed as a product of two following fields.
NumberOfPartitionEntries dd ?
; Actual number of partitions depends on the contents of Partition Entry Array.
; A partition entry is unused if zeroed.
SizeOfPartitionEntry dd ? ; in bytes
PartitionEntryArrayCRC32 dd ?
; Same CRC as for GPT header.
ends
; GPT Partition Entry, UEFI 2.6, Table 19
struct GPE
PartitionTypeGUID rb 16
UniquePartitionGUID rb 16
StartingLBA dq ?
EndingLBA dq ?
; Length in sectors is EndingLBA - StartingLBA + 1.
Attributes dq ?
PartitionName rb 72
ends
; =============================================================================
; ================================ Global data ================================
; =============================================================================
iglobal
; The pseudo-item for the list of all DISK structures.
; Initialized to the empty list.
disk_list:
dd disk_list
dd disk_list
endg
uglobal
; This mutex guards all operations with the global list of DISK structures.
disk_list_mutex MUTEX
; * There are two dependent objects, a disk and a media. In the simplest case,
; disk and media are both non-removable. However, in the general case both
; can be removed at any time, simultaneously or only media,and this makes things
; complicated.
; * For efficiency, both disk and media objects are located in the one
; structure named DISK. However, logically they are different.
; * The following operations use data of disk object: adding (disk_add);
; deleting (disk_del); filesystem (fs_lfn which eventually calls
; dyndisk_handler or dyndisk_enum_root).
; * The following operations use data of media object: adding/removing
; (disk_media_changed); filesystem (fs_lfn which eventually calls
; dyndisk_handler; dyndisk_enum_root doesn't work with media).
; * Notifications disk_add, disk_media_changed, disk_del are synchronized
; between themselves, this is a requirement for the driver. However, file
; system operations are asynchronous, can be issued at any time by any
; thread.
; * We must prevent a situation when a filesystem operation thinks that the
; object is still valid but in fact the notification has destroyed the
; object. So we keep a reference counter for both disk and media and destroy
; the object when this counter goes to zero.
; * The driver must know when it is safe to free driver-allocated resources.
; The object can be alive even after death notification has completed.
; We use special callbacks to satisfy both assertions: 'close' for the disk
; and 'closemedia' for the media. The destruction of the object includes
; calling the corresponding callback.
; * Each filesystem operation keeps one reference for the disk and one
; reference for the media. Notification disk_del forces notification on the
; media death, so the reference counter for the disk is always not less than
; the reference counter for the media.
; * Two operations "get the object" and "increment the reference counter" can
; not be done simultaneously. We use a mutex to guard the consistency here.
; It must be a part of the container for the object, so that this mutex can
; be acquired as a part of getting the object from the container. The
; container for disk object is the global list, and this list is guarded by
; 'disk_list_mutex'. The container for media object is the disk object, and
; the corresponding mutex is DISK.MediaLock.
; * Notifications do not change the data of objects, they can only remove
; objects. Thus we don't need another synchronization at this level. If two
; filesystem operations are referencing the same filesystem data, this is
; better resolved at the level of the filesystem.
endg
iglobal
; The function 'disk_scan_partitions' needs three sector-sized buffers for
; MBR, bootsector and fs-temporary sector data. It can not use the static
; buffers always, since it can be called for two or more disks in parallel.
; However, this case is not typical. We reserve three static 512-byte buffers
; and a flag that these buffers are currently used. If 'disk_scan_partitions'
; detects that the buffers are currently used, it allocates buffers from the
; heap. Also, the heap is used when sector size is other than 512.
; The flag is implemented as a global dword variable. When the static buffers
; are not used, the value is -1. When the static buffers are used, the value
; is normally 0 and temporarily can become greater. The function increments
; this value. If the resulting value is zero, it uses the buffers and
; decrements the value when the job is done. Otherwise, it immediately
; decrements the value and uses buffers from the heap, allocated in the
; beginning and freed in the end.
partition_buffer_users dd -1
endg
uglobal
; The static buffers for MBR, bootsector and fs-temporary sector data.
align 16
mbr_buffer rb 512
bootsect_buffer rb 512
fs_tmp_buffer rb 512
endg
iglobal
; This is the array of default implementations of driver callbacks.
; Same as DRIVERFUNC structure except for the first field; all functions must
; have the default implementations.
align 4
disk_default_callbacks:
dd disk_default_close
dd disk_default_closemedia
dd disk_default_querymedia
dd disk_default_read
dd disk_default_write
dd disk_default_flush
dd disk_default_adjust_cache_size
endg
; =============================================================================
; ================================= Functions =================================
; =============================================================================
; This function registers a disk device.
; This includes:
; - allocating an internal structure describing this device;
; - registering this structure in the global filesystem.
; The function initializes the disk as if there is no media. If a media is
; present, the function 'disk_media_changed' should be called after this
; function succeeds.
; Parameters:
; [esp+4] = pointer to DISKFUNC structure with the callbacks
; [esp+8] = pointer to name (ASCIIZ string)
; [esp+12] = userdata to be passed to the callbacks as is.
; [esp+16] = flags, bitfield. Currently only DISK_NO_INSERT_NOTIFICATION bit
; is defined.
; Return value:
; NULL = operation has failed
; non-NULL = handle of the disk. This handle can be used
; in the operations with other Disk* functions.
; The handle is the pointer to the internal structure DISK.
disk_add:
push ebx esi ; save used registers to be stdcall
; 1. Allocate the DISK structure.
; 1a. Call the heap manager.
movi eax, sizeof.DISK
call malloc
; 1b. Check the result. If allocation failed, return (go to 9) with eax = 0.
test eax, eax
jz .nothing
; 2. Copy the disk name to the DISK structure.
; 2a. Get length of the name, including the terminating zero.
mov ebx, [esp+8+8] ; ebx = pointer to name
push eax ; save allocated pointer to DISK
xor eax, eax ; the argument of malloc() is in eax
@@:
inc eax
cmp byte [ebx+eax-1], 0
jnz @b
; 2b. Call the heap manager.
call malloc
; 2c. Check the result. If allocation failed, go to 7.
pop esi ; restore allocated pointer to DISK
test eax, eax
jz .free
; 2d. Store the allocated pointer to the DISK structure.
mov [esi+DISK.Name], eax
; 2e. Copy the name.
@@:
mov dl, [ebx]
mov [eax], dl
inc ebx
inc eax
test dl, dl
jnz @b
; 3. Copy other arguments of the function to the DISK structure.
mov eax, [esp+4+8]
mov [esi+DISK.Functions], eax
mov eax, [esp+12+8]
mov [esi+DISK.UserData], eax
mov eax, [esp+16+8]
mov [esi+DISK.DriverFlags], eax
; 4. Initialize other fields of the DISK structure.
; Media is not inserted, reference counter is 1.
lea ecx, [esi+DISK.MediaLock]
call mutex_init
xor eax, eax
mov dword [esi+DISK.MediaInserted], eax
mov [esi+DISK.MediaRefCount], eax
inc eax
mov [esi+DISK.RefCount], eax
; The DISK structure is initialized.
; 5. Insert the new structure to the global list.
; 5a. Acquire the mutex.
mov ecx, disk_list_mutex
call mutex_lock
; 5b. Insert item to the tail of double-linked list.
mov edx, disk_list
list_add_tail esi, edx ;esi= new edx= list head
; 5c. Release the mutex.
call mutex_unlock
; 6. Return with eax = pointer to DISK.
xchg eax, esi
jmp .nothing
.free:
; Memory allocation for DISK structure succeeded, but for disk name failed.
; 7. Free the DISK structure.
xchg eax, esi
call free
; 8. Return with eax = 0.
xor eax, eax
.nothing:
; 9. Return.
pop esi ebx ; restore used registers to be stdcall
ret 16 ; purge 4 dword arguments to be stdcall
; This function deletes a disk device from the global filesystem.
; This includes:
; - removing a media including all partitions;
; - deleting this structure from the global filesystem;
; - dereferencing the DISK structure and possibly destroying it.
; Parameters:
; [esp+4] = handle of the disk, i.e. the pointer to the DISK structure.
; Return value: none.
disk_del:
push esi ; save used registers to be stdcall
; 1. Force media to be removed. If the media is already removed, the
; call does nothing.
mov esi, [esp+4+4] ; esi = handle of the disk
stdcall disk_media_changed, esi, 0
; 2. Delete the structure from the global list.
; 2a. Acquire the mutex.
mov ecx, disk_list_mutex
call mutex_lock
; 2b. Delete item from double-linked list.
mov eax, [esi+DISK.Next]
mov edx, [esi+DISK.Prev]
mov [eax+DISK.Prev], edx
mov [edx+DISK.Next], eax
; 2c. Release the mutex.
call mutex_unlock
; 3. The structure still has one reference created in disk_add. Remove this
; reference. If there are no other references, disk_dereference will free the
; structure.
call disk_dereference
; 4. Return.
pop esi ; restore used registers to be stdcall
ret 4 ; purge 1 dword argument to be stdcall
; This is an internal function which removes a previously obtained reference
; to the disk. If this is the last reference, this function lets the driver
; finalize all associated data, and afterwards frees the DISK structure.
; esi = pointer to DISK structure
disk_dereference:
; 1. Decrement reference counter. Use atomic operation to correctly handle
; possible simultaneous calls.
lock dec [esi+DISK.RefCount]
; 2. If the result is nonzero, there are other references, so nothing to do.
; In this case, return (go to 4).
jnz .nothing
; 3. If we are here, we just removed the last reference and must destroy the
; disk object.
; 3a. Call the driver.
mov al, DISKFUNC.close
stdcall disk_call_driver
; 3b. Free the structure.
xchg eax, esi
push ebx
call free
pop ebx
; 4. Return.
.nothing:
ret
; This is an internal function which removes a previously obtained reference
; to the media. If this is the last reference, this function calls 'closemedia'
; callback to signal the driver that the processing has finished and it is safe
; to inform about a new media.
; esi = pointer to DISK structure
disk_media_dereference:
; 1. Decrement reference counter. Use atomic operation to correctly handle
; possible simultaneous calls.
lock dec [esi+DISK.MediaRefCount]
; 2. If the result is nonzero, there are other references, so nothing to do.
; In this case, return (go to 4).
jnz .nothing
; 3. If we are here, we just removed the last reference and must destroy the
; media object.
; Note that the same place inside the DISK structure is reused for all media
; objects, so we must guarantee that reusing does not happen while freeing.
; Reusing is only possible when someone processes a new media. There are two
; mutually exclusive variants:
; * driver issues media insert notifications (DISK_NO_INSERT_NOTIFICATION bit
; in DISK.DriverFlags is not set). In this case, we require from the driver
; that such notification (except for the first one) can occur only after a
; call to 'closemedia' callback.
; * driver does not issue media insert notifications. In this case, the kernel
; itself must sometimes check whether media is inserted. We have the flag
; DISK.MediaUsed, visible to the kernel. This flag signals to the other parts
; of kernel that the way is free.
; In the first case other parts of the kernel do not use DISK.MediaUsed, so it
; does not matter when this flag is cleared. In the second case this flag must
; be cleared after all other actions, including call to 'closemedia'.
; 3a. Free all partitions.
push esi edi
mov edi, [esi+DISK.NumPartitions]
mov esi, [esi+DISK.Partitions]
test edi, edi
jz .nofree
.freeloop:
lodsd
mov ecx, [eax+PARTITION.FSUserFunctions]
call dword [ecx]
dec edi
jnz .freeloop
.nofree:
pop edi esi
; 3b. Free the cache.
call disk_free_cache
; 3c. Call the driver.
mov al, DISKFUNC.closemedia
stdcall disk_call_driver
; 3d. Clear the flag.
mov [esi+DISK.MediaUsed], 0
.nothing:
ret
; This function is called by the driver and informs the kernel that the media
; has changed. If the media is non-removable, it is called exactly once
; immediately after 'disk_add' and once from 'disk_del'.
; Parameters:
; [esp+4] = handle of the disk, i.e. the pointer to the DISK structure.
; [esp+8] = new status of the media: zero = no media, nonzero = media inserted.
disk_media_changed:
push ebx esi edi ; save used registers to be stdcall
; 1. Remove the existing media, if it is present.
mov esi, [esp+4+12] ; esi = pointer to DISK
; 1a. Check whether it is present. Since DISK.MediaInserted is changed only
; in this function and calls to this function are synchronized, no lock is
; required for checking.
cmp [esi+DISK.MediaInserted], 0
jz .noremove
; We really need to remove the media.
; 1b. Acquire mutex.
lea ecx, [esi+DISK.MediaLock]
call mutex_lock
; 1c. Clear the flag.
mov [esi+DISK.MediaInserted], 0
; 1d. Release mutex.
call mutex_unlock
; 1e. Remove the "lifetime" reference and possibly destroy the structure.
call disk_media_dereference
.noremove:
; 2. Test whether there is new media.
cmp dword [esp+8+12], 0
jz .noinsert
; Yep, there is.
; 3. Process the new media. We assume that all media fields are available to
; use, see comments in 'disk_media_dereference' (this covers using by previous
; media referencers) and note that calls to this function are synchronized
; (this covers using by new media referencers).
; 3a. Call the 'querymedia' callback.
; .Flags are set to zero for possible future extensions.
lea edx, [esi+DISK.MediaInfo]
and [edx+DISKMEDIAINFO.Flags], 0
mov al, DISKFUNC.querymedia
stdcall disk_call_driver, edx
; 3b. Check the result of the callback. Abort if it failed.
test eax, eax
jnz .noinsert
; 3c. Allocate the cache unless disabled by the driver. Abort if failed.
call disk_init_cache
test al, al
jz .noinsert
; 3d. Acquire the lifetime reference for the media object.
inc [esi+DISK.MediaRefCount]
; 3e. Scan for partitions. Ignore result; the list of partitions is valid even
; on errors.
call disk_scan_partitions
; 3f. Media is inserted and available for use.
inc [esi+DISK.MediaInserted]
.noinsert:
; 4. Return.
pop edi esi ebx ; restore used registers to be stdcall
ret 8 ; purge 2 dword arguments to be stdcall
; This function is a thunk for all functions of a disk driver.
; It checks whether the referenced function is implemented in the driver.
; If so, this function jumps to the function in the driver.
; Otherwise, it jumps to the default implementation.
; al = offset of function in the DISKFUNC structure;
; esi = pointer to the DISK structure;
; stack is the same as for the corresponding function except that the
; first parameter (void* userdata) is prepended automatically.
disk_call_driver:
movzx eax, al ; eax = offset of function in the DISKFUNC structure
; 1. Prepend the first argument to the stack.
pop ecx ; ecx = return address
push [esi+DISK.UserData] ; add argument
push ecx ; save return address
; 2. Check that the required function is inside the table. If not, go to 5.
mov ecx, [esi+DISK.Functions]
cmp eax, [ecx+DISKFUNC.strucsize]
jae .default
; 3. Check that the required function is implemented. If not, go to 5.
mov ecx, [ecx+eax]
test ecx, ecx
jz .default
; 4. Jump to the required function.
jmp ecx
.default:
; 5. Driver does not implement the required function; use default implementation.
jmp dword [disk_default_callbacks+eax-4]
; The default implementation of DISKFUNC.querymedia.
disk_default_querymedia:
movi eax, DISK_STATUS_INVALID_CALL
ret 8
; The default implementation of DISKFUNC.read and DISKFUNC.write.
disk_default_read:
disk_default_write:
movi eax, DISK_STATUS_INVALID_CALL
ret 20
; The default implementation of DISKFUNC.close, DISKFUNC.closemedia and
; DISKFUNC.flush.
disk_default_close:
disk_default_closemedia:
disk_default_flush:
xor eax, eax
ret 4
; The default implementation of DISKFUNC.adjust_cache_size.
disk_default_adjust_cache_size:
mov eax, [esp+8]
ret 8
; This is an internal function called from 'disk_media_changed' when a new media
; is detected. It creates the list of partitions for the media.
; If media is not partitioned, then the list consists of one partition which
; covers all the media.
; esi = pointer to the DISK structure.
disk_scan_partitions:
; 1. Initialize .NumPartitions and .Partitions fields as zeros: empty list.
and [esi+DISK.NumPartitions], 0
and [esi+DISK.Partitions], 0
; 2. Acquire the buffer for MBR and bootsector tests. See the comment before
; the 'partition_buffer_users' variable.
mov eax, [esi+DISK.MediaInfo.SectorSize]
cmp eax, 512
jnz @f
mov ebx, mbr_buffer ; assume the global buffer is free
lock inc [partition_buffer_users]
jz .buffer_acquired ; yes, it is free
lock dec [partition_buffer_users] ; no, we must allocate
@@:
lea eax, [eax*3]
stdcall kernel_alloc, eax
test eax, eax
jz .nothing
xchg eax, ebx
.buffer_acquired:
; MBR/EBRs are organized in the chain. We use a loop over MBR/EBRs, but no
; more than MAX_NUM_PARTITION times.
; 3. Prepare things for the loop.
; ebp will hold the sector number for current MBR/EBR.
; [esp] will hold the sector number for current extended partition, if there
; is one.
; [esp+4] will hold the counter that prevents long loops.
push ebp ; save ebp
push MAX_NUM_PARTITIONS ; the counter of max MBRs to process
xor ebp, ebp ; start from sector zero
push ebp ; no extended partition yet
; 4. MBR is 512 bytes long. If sector size is less than 512 bytes,
; assume no MBR, no partitions and go to 11.
cmp [esi+DISK.MediaInfo.SectorSize], 512
jb .notmbr
.new_mbr:
; 5. Read the current sector.
; Note that 'read' callback operates with 64-bit sector numbers, so we must
; push additional zero as a high dword of sector number.
mov al, DISKFUNC.read
push 1
stdcall disk_call_driver, ebx, ebp, 0, esp
pop ecx
; 6. If the read has failed, abort the loop.
dec ecx
jnz .mbr_failed
; 7. Check the MBR/EBR signature. If it is wrong, abort the loop.
; Soon we will access the partition table which starts at ebx+0x1BE,
; so we can fill its address right now. If we do it now, then the addressing
; [ecx+0x40] is shorter than [ebx+0x1fe]: one-byte offset vs 4-bytes offset.
lea ecx, [ebx+0x1be] ; ecx -> partition table
cmp word [ecx+0x40], 0xaa55
jnz .mbr_failed
; 8. The MBR is treated differently from EBRs. For MBR we additionally need to
; execute step 10 and possibly step 11.
test ebp, ebp
jnz .mbr
; 9. Handle GUID Partition Table
; 9a. Check if MBR is protective
call is_protective_mbr
jnz .no_gpt
; 9b. If so, try to scan GPT headers
call disk_scan_gpt
; 9c. If any GPT header is valid, ignore MBR
jz .done
; Otherwise process legacy/protective MBR
.no_gpt:
; The partition table can be present or not present. In the first case, we just
; read the MBR. In the second case, we just read the bootsector for a
; filesystem.
; The following algorithm is used to distinguish between these cases.
; A. If at least one entry of the partition table is invalid, this is
; a bootsector. See the description of 'is_partition_table_entry' for
; definition of validity.
; B. If all entries are empty (filesystem type field is zero) and the first
; byte is jmp opcode (0EBh or 0E9h), this is a bootsector which happens to
; have zeros in the place of partition table.
; C. Otherwise, this is an MBR.
; 10. Test for MBR vs bootsector.
; 10a. Check entries. If any is invalid, go to 11 (rule A).
call is_partition_table_entry
jc .notmbr
add ecx, 10h
call is_partition_table_entry
jc .notmbr
add ecx, 10h
call is_partition_table_entry
jc .notmbr
add ecx, 10h
call is_partition_table_entry
jc .notmbr
; 10b. Check types of the entries. If at least one is nonzero, go to 12 (rule C).
mov al, [ecx-30h+PARTITION_TABLE_ENTRY.Type]
or al, [ecx-20h+PARTITION_TABLE_ENTRY.Type]
or al, [ecx-10h+PARTITION_TABLE_ENTRY.Type]
or al, [ecx+PARTITION_TABLE_ENTRY.Type]
jnz .mbr
; 10c. Empty partition table or bootsector with many zeroes? (rule B)
cmp byte [ebx], 0EBh
jz .notmbr
cmp byte [ebx], 0E9h
jnz .mbr
.notmbr:
; 11. This is not an MBR. The media is not partitioned. Create one partition
; which covers all the media and abort the loop.
stdcall disk_add_partition, 0, 0, \
dword [esi+DISK.MediaInfo.Capacity], dword [esi+DISK.MediaInfo.Capacity+4], esi
jmp .done
.mbr:
; 12. Process all entries of the new MBR/EBR
lea ecx, [ebx+0x1be] ; ecx -> partition table
push 0 ; assume no extended partition
call process_partition_table_entry
add ecx, 10h
call process_partition_table_entry
add ecx, 10h
call process_partition_table_entry
add ecx, 10h
call process_partition_table_entry
pop ebp
; 13. Test whether we found a new EBR and should continue the loop.
; 13a. If there was no next EBR, return.
test ebp, ebp
jz .done
; Ok, we have EBR.
; 13b. EBRs addresses are relative to the start of extended partition.
; For simplicity, just abort if an 32-bit overflow occurs; large disks
; are most likely partitioned with GPT, not MBR scheme, since the precise
; calculation here would increase limit just twice at the price of big
; compatibility problems.
pop eax ; load extended partition
add ebp, eax
jc .mbr_failed
; 13c. If extended partition has not yet started, start it.
test eax, eax
jnz @f
mov eax, ebp
@@:
; 13d. If the limit is not exceeded, continue the loop.
dec dword [esp]
push eax ; store extended partition
jnz .new_mbr
.mbr_failed:
.done:
; 14. Cleanup after the loop.
pop eax ; not important anymore
pop eax ; not important anymore
pop ebp ; restore ebp
; 15. Release the buffer.
; 15a. Test whether it is the global buffer or we have allocated it.
cmp ebx, mbr_buffer
jz .release_partition_buffer
; 15b. If we have allocated it, free it.
xchg eax, ebx
call free
jmp .nothing
; 15c. Otherwise, release reference.
.release_partition_buffer:
lock dec [partition_buffer_users]
.nothing:
; 16. Return.
ret
; This function is called from disk_scan_partitions to validate and parse
; primary and backup GPTs.
proc disk_scan_gpt
push ecx
; Scan primary GPT (second sector)
stdcall scan_gpt, 1, 0
test eax, eax
; There is no code to restore backup GPT if it's corrupt.
; Therefore just exit if Primary GPT has been parsed successfully.
jz .exit
DEBUGF 1, 'K : Primary GPT is corrupt, trying backup one\n'
mov eax, dword[esi+DISK.MediaInfo.Capacity+0]
mov edx, dword[esi+DISK.MediaInfo.Capacity+4]
sub eax, 1
sbb edx, 0
; Scan backup GPT (last sector)
stdcall scan_gpt, eax, edx
test eax, eax
jz .exit
DEBUGF 1, 'K : Backup GPT is also corrupt, fallback to legacy MBR\n'
.exit:
; Return value is ZF
pop ecx
ret
endp
; This function is called from disk_scan_gpt to process a single GPT.
proc scan_gpt _mylba:qword
locals
GPEA_len dd ? ; Length of GPT Partition Entry Array in bytes
endl
push ebx edi
; Allocalte memory for GPT header
mov eax, [esi+DISK.MediaInfo.SectorSize]
stdcall kernel_alloc, eax
test eax, eax
jz .fail
; Save pointer to stack, just in case
push eax
mov ebx, eax
; Read GPT header
mov al, DISKFUNC.read
push 1
stdcall disk_call_driver, ebx, dword[_mylba+0], dword[_mylba+4], esp
pop ecx
test eax, eax
jnz .fail_free_gpt
; Check signature
cmp dword[ebx+GPTH.Signature+0], 'EFI '
jnz .fail_free_gpt
cmp dword[ebx+GPTH.Signature+4], 'PART'
jnz .fail_free_gpt
; Check Revision
cmp [ebx+GPTH.Revision], 0x00010000
jnz .fail_free_gpt
; Compute and check CRC32
xor edx, edx
xchg edx, [ebx+GPTH.HeaderCRC32]
mov eax, -1
stdcall crc_32, 0xEDB88320, ebx, [ebx+GPTH.HeaderSize]
xor eax, -1
cmp eax, edx
jnz .fail_free_gpt
; Reserved must be zero
cmp [ebx+GPTH.Reserved], 0
jnz .fail_free_gpt
; MyLBA of GPT header at LBA X must equal X
mov eax, dword[ebx+GPTH.MyLBA+0]
mov edx, dword[ebx+GPTH.MyLBA+4]
cmp eax, dword[_mylba+0]
jnz .fail_free_gpt
cmp edx, dword[_mylba+4]
jnz .fail_free_gpt
; Capacity - MyLBA = AlternateLBA
mov eax, dword[esi+DISK.MediaInfo.Capacity+0]
mov edx, dword[esi+DISK.MediaInfo.Capacity+4]
sub eax, dword[_mylba+0]
sbb edx, dword[_mylba+4]
cmp eax, dword[ebx+GPTH.AlternateLBA+0]
jnz .fail_free_gpt
cmp edx, dword[ebx+GPTH.AlternateLBA+4]
jnz .fail_free_gpt
; Compute GPT Partition Entry Array (GPEA) length in bytes
mov eax, [ebx+GPTH.NumberOfPartitionEntries]
mul [ebx+GPTH.SizeOfPartitionEntry]
test edx, edx ; far too big
jnz .fail_free_gpt
; Round up to sector boundary
mov ecx, [esi+DISK.MediaInfo.SectorSize] ; power of two
dec ecx
add eax, ecx
jc .fail_free_gpt ; too big
not ecx
and eax, ecx
; We will need this length to compute CRC32 of GPEA
mov [GPEA_len], eax
; Allocate memory for GPEA
stdcall kernel_alloc, eax
test eax, eax
jz .fail_free_gpt
; Save to not juggle with registers
push eax
mov edi, eax
mov eax, [GPEA_len]
xor edx, edx
; Get the number of sectors GPEA fits into
div [esi+DISK.MediaInfo.SectorSize]
push eax ; esp = pointer to the number of sectors
mov al, DISKFUNC.read
stdcall disk_call_driver, edi, dword[ebx+GPTH.PartitionEntryLBA+0], \
dword[ebx+GPTH.PartitionEntryLBA+4], esp
test eax, eax
pop eax
jnz .fail_free_gpea_gpt
; Compute and check CRC32 of GPEA
mov eax, -1
stdcall crc_32, 0xEDB88320, edi, [GPEA_len]
xor eax, -1
cmp eax, [ebx+GPTH.PartitionEntryArrayCRC32]
jnz .fail_free_gpea_gpt
; Process partitions, skip zeroed ones.
.next_gpe:
xor eax, eax
mov ecx, [ebx+GPTH.SizeOfPartitionEntry]
repz scasb
jz .skip
add edi, ecx
sub edi, [ebx+GPTH.SizeOfPartitionEntry]
; Length of a partition in sectors is EndingLBA - StartingLBA + 1
mov eax, dword[edi+GPE.EndingLBA+0]
mov edx, dword[edi+GPE.EndingLBA+4]
sub eax, dword[edi+GPE.StartingLBA+0]
sbb edx, dword[edi+GPE.StartingLBA+4]
add eax, 1
adc edx, 0
push ebx
mov ebx, [ebp-8] ; three-sectors-sized buffer
stdcall disk_add_partition, dword[edi+GPE.StartingLBA+0], \
dword[edi+GPE.StartingLBA+4], eax, edx, esi
pop ebx
add edi, [ebx+GPTH.SizeOfPartitionEntry]
.skip:
dec [ebx+GPTH.NumberOfPartitionEntries]
jnz .next_gpe
; Pointers to GPT header and GPEA are on the stack
stdcall kernel_free
stdcall kernel_free
pop edi ebx
xor eax, eax
ret
.fail_free_gpea_gpt:
stdcall kernel_free
.fail_free_gpt:
stdcall kernel_free
.fail:
pop edi ebx
xor eax, eax
inc eax
ret
endp
; ecx = pointer to partition records array (MBR + 446)
is_protective_mbr:
push ecx edi
xor eax, eax
; cmp [ecx-6], eax
; jnz .exit
cmp [ecx-2], ax
jnz .exit
; Partition record 0 has specific fields
cmp [ecx+0], al
jnz .exit
cmp byte[ecx+4], 0xEE
jnz .exit
cmp dword[ecx+8], 1
jnz .exit
cmp dword[esi+DISK.MediaInfo.Capacity+4], eax
mov edi, 0xFFFFFFFF
jnz @f
mov edi, dword[esi+DISK.MediaInfo.Capacity+0]
dec edi
@@:
cmp dword[ecx+12], edi
jnz .exit
; Check that partition records 1-3 are filled with zero
lea edi, [ecx+16]
mov ecx, 16*3/2 ; 3 partitions
repz scasw
.exit:
pop edi ecx
; Return value is ZF
ret
; This is an internal function called from disk_scan_partitions. It checks
; whether the entry pointed to by ecx is a valid entry of partition table.
; The entry is valid if the first byte is 0 or 80h, the first sector plus the
; length is less than twice the size of media. Multiplication by two is
; required since the size mentioned in the partition table can be slightly
; greater than the real size.
is_partition_table_entry:
; 1. Check .Bootable field.
mov al, [ecx+PARTITION_TABLE_ENTRY.Bootable]
and al, 7Fh
jnz .invalid
; 3. Calculate first sector + length. Note that .FirstAbsSector is relative
; to the MBR/EBR, so the real sum is ebp + .FirstAbsSector + .Length.
mov eax, ebp
xor edx, edx
add eax, [ecx+PARTITION_TABLE_ENTRY.FirstAbsSector]
adc edx, 0
add eax, [ecx+PARTITION_TABLE_ENTRY.Length]
adc edx, 0
; 4. Divide by two.
shr edx, 1
rcr eax, 1
; 5. Compare with capacity. If the subtraction (edx:eax) - .Capacity does not
; overflow, this is bad.
sub eax, dword [esi+DISK.MediaInfo.Capacity]
sbb edx, dword [esi+DISK.MediaInfo.Capacity+4]
jnc .invalid
.valid:
; 5. Return success: CF is cleared.
clc
ret
.invalid:
; 6. Return fail: CF is set.
stc
ret
; This is an internal function called from disk_scan_partitions. It processes
; the entry pointed to by ecx.
; * If the entry is invalid, just ignore this entry.
; * If the type is zero, just ignore this entry.
; * If the type is one of types for extended partition, store the address
; of this partition as the new MBR in [esp+4].
; * Otherwise, add the partition to the list of partitions for this disk.
; We don't use the type from the entry to identify the file system;
; fs-specific checks do this more reliably.
process_partition_table_entry:
; 1. Check for valid entry. If invalid, return (go to 5).
call is_partition_table_entry
jc .nothing
; 2. Check for empty entry. If invalid, return (go to 5).
mov al, [ecx+PARTITION_TABLE_ENTRY.Type]
test al, al
jz .nothing
; 3. Check for extended partition. If extended, go to 6.
irp type,\
0x05,\ ; DOS: extended partition
0x0f,\ ; WIN95: extended partition, LBA-mapped
0xc5,\ ; DRDOS/secured: extended partition
0xd5 ; Old Multiuser DOS secured: extended partition
{
cmp al, type
jz .extended
}
; 4. If we are here, that is a normal partition. Add it to the list.
; Note that the first sector is relative to MBR/EBR.
mov eax, ebp
xor edx, edx
add eax, [ecx+PARTITION_TABLE_ENTRY.FirstAbsSector]
adc edx, 0
push ecx
stdcall disk_add_partition, eax, edx, \
[ecx+PARTITION_TABLE_ENTRY.Length], 0, esi
pop ecx
.nothing:
; 5. Return.
ret
.extended:
; 6. If we are here, that is an extended partition. Store the address.
mov eax, [ecx+PARTITION_TABLE_ENTRY.FirstAbsSector]
mov [esp+4], eax
ret
; This is an internal function called from disk_scan_partitions and
; process_partition_table_entry. It adds one partition to the list of
; partitions for the media.
; Important note: start, length, disk MUST be present and
; MUST be in the same order as in PARTITION structure.
; esi duplicates [disk].
proc disk_add_partition stdcall uses ebx edi, start:qword, length:qword, disk:dword
; 1. Check that this partition will not exceed the limit on total number.
cmp [esi+DISK.NumPartitions], MAX_NUM_PARTITIONS
jae .nothing
; 2. Check that this partition does not overlap with any already registered
; partition. Since any file system assumes that the disk data will not change
; outside of its control, such overlap could be destructive.
; Since the number of partitions is usually very small and is guaranteed not
; to be large, the simple linear search is sufficient.
; 2a. Prepare the loop: edi will point to the current item of .Partitions
; array, ecx will be the current item, ebx will hold number of items left.
mov edi, [esi+DISK.Partitions]
mov ebx, [esi+DISK.NumPartitions]
test ebx, ebx
jz .partitionok
.scan_existing:
; 2b. Get the next partition.
mov ecx, [edi]
add edi, 4
; The range [.FirstSector, .FirstSector+.Length) must be either entirely to
; the left of [start, start+length) or entirely to the right.
; 2c. Subtract .FirstSector - start. The possible overflow distinguish between
; cases "to the left" (2e) and "to the right" (2d).
mov eax, dword [ecx+PARTITION.FirstSector]
mov edx, dword [ecx+PARTITION.FirstSector+4]
sub eax, dword [start]
sbb edx, dword [start+4]
jb .less
; 2d. .FirstSector is greater than or equal to start. Check that .FirstSector
; is greater than or equal to start+length; the subtraction
; (.FirstSector-start) - length must not cause overflow. Go to 2g if life is
; good or to 2f in the other case.
sub eax, dword [length]
sbb edx, dword [length+4]
jb .overlap
jmp .next_existing
.less:
; 2e. .FirstSector is less than start. Check that .FirstSector+.Length is less
; than or equal to start. If the addition (.FirstSector-start) + .Length does
; not cause overflow, then .FirstSector + .Length is strictly less than start;
; since the equality is also valid, use decrement preliminarily. Go to 2g or
; 2f depending on the overflow.
sub eax, 1
sbb edx, 0
add eax, dword [ecx+PARTITION.Length]
adc edx, dword [ecx+PARTITION.Length+4]
jnc .next_existing
.overlap:
; 2f. The partition overlaps with previously registered partition. Say warning
; and return with nothing done.
dbgstr 'two partitions overlap, ignoring the last one'
jmp .nothing
.next_existing:
; 2g. The partition does not overlap with the current partition. Continue the
; loop.
dec ebx
jnz .scan_existing
.partitionok:
; 3. The partition has passed tests. Reallocate the partitions array for a new
; entry.
; 3a. Call the allocator.
mov eax, [esi+DISK.NumPartitions]
inc eax ; one more entry
shl eax, 2 ; each entry is dword
call malloc
; 3b. Test the result. If failed, return with nothing done.
test eax, eax
jz .nothing
; 3c. Copy the old array to the new array.
mov edi, eax
push esi
mov ecx, [esi+DISK.NumPartitions]
mov esi, [esi+DISK.Partitions]
rep movsd
pop esi
; 3d. Set the field in the DISK structure to the new array.
xchg [esi+DISK.Partitions], eax
; 3e. Free the old array.
call free
; 4. Recognize the file system.
; 4a. Call the filesystem recognizer. It will allocate the PARTITION structure
; with possible filesystem-specific fields.
call disk_detect_partition
; 4b. Check return value. If zero, return with list not changed; so far only
; the array was reallocated, this is ok for other code.
test eax, eax
jz .nothing
; 5. Insert the new partition to the list.
stosd
inc [esi+DISK.NumPartitions]
; 6. Return.
.nothing:
ret
endp
; This is an internal function called from disk_add_partition.
; It tries to recognize the file system on the partition and allocates the
; corresponding PARTITION structure with filesystem-specific fields.
disk_detect_partition:
; This function inherits the stack frame from disk_add_partition. In stdcall
; with ebp-based frame arguments start from ebp+8, since [ebp]=saved ebp
; and [ebp+4]=return address.
virtual at ebp+8
.start dq ?
.length dq ?
.disk dd ?
end virtual
; 1. Read the bootsector to the buffer.
; When disk_add_partition is called, ebx contains a pointer to
; a three-sectors-sized buffer. This function saves ebx in the stack
; immediately before ebp.
mov ebx, [ebp-4] ; get buffer
add ebx, [esi+DISK.MediaInfo.SectorSize] ; advance over MBR data to bootsector data
add ebp, 8 ; ebp points to part of PARTITION structure
xor eax, eax ; first sector of the partition
call fs_read32_sys
push eax
; 2. Run tests for all supported filesystems. If at least one test succeeded,
; go to 4.
; For tests:
; ebp -> first three fields of PARTITION structure, .start, .length, .disk;
; [esp] = error code after bootsector read: 0 = ok, otherwise = failed,
; ebx points to the buffer for bootsector,
; ebx+[esi+DISK.MediaInfo.SectorSize] points to sector-sized buffer that can be used for anything.
call fat_create_partition
test eax, eax
jnz .success
call ntfs_create_partition
test eax, eax
jnz .success
call ext2_create_partition
test eax, eax
jnz .success
call xfs_create_partition
test eax, eax
jnz .success
; 3. No file system has recognized the volume, so just allocate the PARTITION
; structure without extra fields.
movi eax, sizeof.PARTITION
call malloc
test eax, eax
jz .nothing
mov edx, dword [ebp+PARTITION.FirstSector]
mov dword [eax+PARTITION.FirstSector], edx
mov edx, dword [ebp+PARTITION.FirstSector+4]
mov dword [eax+PARTITION.FirstSector+4], edx
mov edx, dword [ebp+PARTITION.Length]
mov dword [eax+PARTITION.Length], edx
mov edx, dword [ebp+PARTITION.Length+4]
mov dword [eax+PARTITION.Length+4], edx
mov [eax+PARTITION.Disk], esi
mov [eax+PARTITION.FSUserFunctions], default_fs_functions
.success:
.nothing:
sub ebp, 8 ; restore ebp
; 4. Return with eax = pointer to PARTITION or NULL.
pop ecx
ret
iglobal
align 4
default_fs_functions:
dd free
dd 0 ; no user functions
endg
; This function is called from file_system_lfn.
; This handler gets the control each time when fn 70 is called
; with unknown item of root subdirectory.
; in: esi = ebp -> path string
; out: if the handler processes path, it must not return in file_system_lfn,
; but instead pop return address and return directly to the caller
; otherwise simply return
dyndisk_handler:
push ebx edi ; save registers used in file_system_lfn
; 1. Acquire the mutex.
mov ecx, disk_list_mutex
call mutex_lock
; 2. Loop over the list of DISK structures.
; 2a. Initialize.
mov ebx, disk_list
.scan:
; 2b. Get the next item.
mov ebx, [ebx+DISK.Next]
; 2c. Check whether the list is done. If so, go to 3.
cmp ebx, disk_list
jz .notfound
; 2d. Compare names. If names match, go to 5.
mov edi, [ebx+DISK.Name]
push esi
@@:
; esi points to the name from fs operation; it is terminated by zero or slash.
lodsb
test al, al
jz .eoin_dec
cmp al, '/'
jz .eoin
; edi points to the disk name.
inc edi
; edi points to lowercase name, this is a requirement for the driver.
; Characters at esi can have any register. Lowercase the current character.
; This lowercasing works for latin letters and digits; since the disk name
; should not contain other symbols, this is ok.
or al, 20h
cmp al, [edi-1]
jz @b
.wrongname:
; 2f. Names don't match. Continue the loop.
pop esi
jmp .scan
.notfound:
; The loop is done and no name matches.
; 3. Release the mutex.
call mutex_unlock
; 4. Return normally.
pop edi ebx ; restore registers used in file_system_lfn
ret
; part of 2d: the name matches partially, but we must check that this is full
; equality.
.eoin_dec:
dec esi
.eoin:
cmp byte [edi], 0
jnz .wrongname
; We found the addressed DISK structure.
; 5. Reference the disk.
lock inc [ebx+DISK.RefCount]
; 6. Now we are sure that the DISK structure is not going to die at least
; while we are working with it, so release the global mutex.
call mutex_unlock
pop ecx ; pop from the stack saved value of esi
; 7. Acquire the mutex for media object.
pop edi ; restore edi
lea ecx, [ebx+DISK.MediaLock]
call mutex_lock
; 8. Get the media object. If it is not NULL, reference it.
xor edx, edx
cmp [ebx+DISK.MediaInserted], dl
jz @f
mov edx, ebx
inc [ebx+DISK.MediaRefCount]
@@:
; 9. Now we are sure that the media object, if it exists, is not going to die
; at least while we are working with it, so release the mutex for media object.
call mutex_unlock
mov ecx, ebx
pop ebx eax ; restore ebx, pop return address
; 10. Check whether the fs operation wants to enumerate partitions (go to 11)
; or work with some concrete partition (go to 12).
cmp byte [esi], 0
jnz .haspartition
; 11. The fs operation wants to enumerate partitions.
; Check whether the media is inserted.
mov esi, fs_dyndisk_next_nomedia
test edx, edx
jz @f
mov esi, fs_dyndisk_next
@@: ; Let the procedure from fs_lfn.inc do the job.
jmp file_system_lfn.maindir_noesi
.root:
pop ecx edx
xor eax, eax
cmp byte [ebx], 9
jz .cleanup_ecx
.access_denied:
movi eax, ERROR_ACCESS_DENIED
.cleanup_ecx:
mov [esp+32], eax
mov esi, ecx ; disk*dereference assume that esi points to DISK
test edx, edx ; if there are no media, we didn't reference it
jz @f
call disk_media_dereference
@@:
call disk_dereference
stdcall kernel_free, ebp
ret
.dyndisk_cleanup:
pop ecx edx
movi eax, ERROR_FILE_NOT_FOUND
jmp .cleanup_ecx
.haspartition:
; 12. The fs operation has specified some partition.
push edx ecx
xor eax, eax
lodsb
sub eax, '0'
jz .dyndisk_cleanup
cmp eax, 10
jnc .dyndisk_cleanup
mov ecx, eax
lodsb
cmp eax, '/'
jz @f
test eax, eax
jnz .dyndisk_cleanup
dec esi
@@:
cmp byte [esi], 0
jnz @f
cmp byte [ebx], 1
jz @f
cmp byte [ebx], 5
jnz .root
@@:
dec ecx ; convert to zero-based partition index
pop edx ; edx = pointer to DISK, dword [esp] = NULL or edx
; If the driver does not support insert notifications and we are the only fs
; operation with this disk, ask the driver whether the media
; was inserted/removed/changed. Otherwise, assume that media status is valid.
test byte [edx+DISK.DriverFlags], DISK_NO_INSERT_NOTIFICATION
jz .media_accurate
push ecx esi
mov esi, edx
cmp dword [esp+8], 0
jz .test_no_media
cmp [esi+DISK.MediaRefCount], 2
jnz .media_accurate_pop
lea edx, [esi+DISK.MediaInfo]
and [edx+DISKMEDIAINFO.Flags], 0
mov al, DISKFUNC.querymedia
stdcall disk_call_driver, edx
test eax, eax
jz .media_accurate_pop
stdcall disk_media_dereference ; drop our reference so that disk_media_changed could close the media
stdcall disk_media_changed, esi, 0
and dword [esp+8], 0 ; no media
.test_no_media:
stdcall disk_media_changed, esi, 1 ; issue fake notification
; if querymedia() inside disk_media_changed returns error, the notification is ignored
cmp [esi+DISK.MediaInserted], 0
jz .media_accurate_pop
lock inc [esi+DISK.MediaRefCount]
mov dword [esp+8], esi
.media_accurate_pop:
mov edx, esi
pop esi ecx
.media_accurate:
pop eax
test eax, eax
jz .nomedia
cmp ecx, [edx+DISK.NumPartitions]
jae .notfound2
mov eax, [edx+DISK.Partitions]
mov eax, [eax+ecx*4]
mov edi, [eax+PARTITION.FSUserFunctions]
mov ecx, [ebx]
cmp [edi+4], ecx
jbe .unsupported
pushd edx ebp eax [edi+8+ecx*4]
cmp ecx, 10
jnz .callFS
or ecx, -1
mov edi, esi
xor eax, eax
repnz scasb
mov edx, edi
dec edi
mov al, '/'
std
repnz scasb
cld
inc edi
mov [edi], ah
mov ebp, [current_slot]
add ebp, APPDATA.cur_dir
pushd ebx esi edx [ebp] ebp edi
sub esi, 2
mov [ebp], esi
mov edi, edx
mov esi, [ebx+16]
mov eax, [ebx+20]
cmp eax, 4
jc @f
xor eax, eax
@@:
call getFullPath
pop edi ebp
mov byte [edi], '/'
popd [ebp] edi esi ebx
add edi, 2
test eax, eax
jz .errorRename
cmp byte [edi], 0
jz .errorRename
.callFS:
pop eax ebp
call eax
pop ebp edx
mov dword [esp+20], ebx
.cleanup:
mov dword [esp+32], eax
mov esi, edx
call disk_media_dereference
@@:
call disk_dereference
stdcall kernel_free, ebp
ret
.unsupported:
movi eax, ERROR_UNKNOWN_FS
cmp edi, default_fs_functions
jz .cleanup
movi eax, ERROR_UNSUPPORTED_FS
jmp .cleanup
.errorRename:
pop eax eax ebp edx
.notfound2:
movi eax, ERROR_FILE_NOT_FOUND
jmp .cleanup
.nomedia:
test ecx, ecx
jnz .notfound2
mov dword [esp+32], ERROR_DEVICE
mov esi, edx
jmp @b
; This is a callback for enumerating partitions called from
; file_system_lfn.maindir in the case of inserted media.
; It just increments eax until DISK.NumPartitions reached and then
; cleans up.
fs_dyndisk_next:
mov ecx, [esp+8]
cmp eax, [ecx+DISK.NumPartitions]
jae .nomore
inc eax
clc
ret
.nomore:
pusha
mov esi, ecx
call disk_media_dereference
call disk_dereference
popa
stc
ret
; This is a callback for enumerating partitions called from
; file_system_lfn.maindir in the case of missing media.
; In this case we create one pseudo-partition.
fs_dyndisk_next_nomedia:
cmp eax, 1
jae .nomore
inc eax
clc
ret
.nomore:
mov ecx, [esp+8]
pusha
mov esi, ecx
call disk_dereference
popa
stc
ret
; This function is called from file_system_lfn.
; This handler is called when virtual root is enumerated
; and must return all items which can be handled by this.
; It is called several times, first time with eax=0
; in: eax = 0 for first call, previously returned value for subsequent calls
; out: eax = 0 => no more items
; eax != 0 => buffer pointed to by edi contains name of item
dyndisk_enum_root:
push edx ; save register used in file_system_lfn
mov ecx, disk_list_mutex ; it will be useful
; 1. If this is the first call, acquire the mutex and initialize.
test eax, eax
jnz .notfirst
call mutex_lock
mov eax, disk_list
.notfirst:
; 2. Get next item.
mov eax, [eax+DISK.Next]
; 3. If there are no more items, go to 6.
cmp eax, disk_list
jz .last
; 4. Copy name from the DISK structure to edi.
push eax esi
mov esi, [eax+DISK.Name]
@@:
lodsb
stosb
test al, al
jnz @b
pop esi eax
; 5. Return with eax = item.
pop edx ; restore register used in file_system_lfn
ret
.last:
; 6. Release the mutex and return with eax = 0.
call mutex_unlock
xor eax, eax
pop edx ; restore register used in file_system_lfn
ret
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