newlib-2.4.0

git-svn-id: svn://kolibrios.org@6536 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/newlib/libc/stdio/fmemopen.c

@@ -0,0 +1,371 @@
+/* Copyright (C) 2007 Eric Blake
+ * Permission to use, copy, modify, and distribute this software
+ * is freely granted, provided that this notice is preserved.
+ */
+
+/*
+FUNCTION
+<<fmemopen>>---open a stream around a fixed-length string
+
+INDEX
+	fmemopen
+
+ANSI_SYNOPSIS
+	#include <stdio.h>
+	FILE *fmemopen(void *restrict <[buf]>, size_t <[size]>,
+		       const char *restrict <[mode]>);
+
+DESCRIPTION
+<<fmemopen>> creates a seekable <<FILE>> stream that wraps a
+fixed-length buffer of <[size]> bytes starting at <[buf]>.  The stream
+is opened with <[mode]> treated as in <<fopen>>, where append mode
+starts writing at the first NUL byte.  If <[buf]> is NULL, then
+<[size]> bytes are automatically provided as if by <<malloc>>, with
+the initial size of 0, and <[mode]> must contain <<+>> so that data
+can be read after it is written.
+
+The stream maintains a current position, which moves according to
+bytes read or written, and which can be one past the end of the array.
+The stream also maintains a current file size, which is never greater
+than <[size]>.  If <[mode]> starts with <<r>>, the position starts at
+<<0>>, and file size starts at <[size]> if <[buf]> was provided.  If
+<[mode]> starts with <<w>>, the position and file size start at <<0>>,
+and if <[buf]> was provided, the first byte is set to NUL.  If
+<[mode]> starts with <<a>>, the position and file size start at the
+location of the first NUL byte, or else <[size]> if <[buf]> was
+provided.
+
+When reading, NUL bytes have no significance, and reads cannot exceed
+the current file size.  When writing, the file size can increase up to
+<[size]> as needed, and NUL bytes may be embedded in the stream (see
+<<open_memstream>> for an alternative that automatically enlarges the
+buffer).  When the stream is flushed or closed after a write that
+changed the file size, a NUL byte is written at the current position
+if there is still room; if the stream is not also open for reading, a
+NUL byte is additionally written at the last byte of <[buf]> when the
+stream has exceeded <[size]>, so that a write-only <[buf]> is always
+NUL-terminated when the stream is flushed or closed (and the initial
+<[size]> should take this into account).  It is not possible to seek
+outside the bounds of <[size]>.  A NUL byte written during a flush is
+restored to its previous value when seeking elsewhere in the string.
+
+RETURNS
+The return value is an open FILE pointer on success.  On error,
+<<NULL>> is returned, and <<errno>> will be set to EINVAL if <[size]>
+is zero or <[mode]> is invalid, ENOMEM if <[buf]> was NULL and memory
+could not be allocated, or EMFILE if too many streams are already
+open.
+
+PORTABILITY
+This function is being added to POSIX 200x, but is not in POSIX 2001.
+
+Supporting OS subroutines required: <<sbrk>>.
+*/
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/lock.h>
+#include "local.h"
+
+/* Describe details of an open memstream.  */
+typedef struct fmemcookie {
+  void *storage; /* storage to free on close */
+  char *buf; /* buffer start */
+  size_t pos; /* current position */
+  size_t eof; /* current file size */
+  size_t max; /* maximum file size */
+  char append; /* nonzero if appending */
+  char writeonly; /* 1 if write-only */
+  char saved; /* saved character that lived at pos before write-only NUL */
+} fmemcookie;
+
+/* Read up to non-zero N bytes into BUF from stream described by
+   COOKIE; return number of bytes read (0 on EOF).  */
+static _READ_WRITE_RETURN_TYPE
+_DEFUN(fmemreader, (ptr, cookie, buf, n),
+       struct _reent *ptr _AND
+       void *cookie _AND
+       char *buf _AND
+       _READ_WRITE_BUFSIZE_TYPE n)
+{
+  fmemcookie *c = (fmemcookie *) cookie;
+  /* Can't read beyond current size, but EOF condition is not an error.  */
+  if (c->pos > c->eof)
+    return 0;
+  if (n >= c->eof - c->pos)
+    n = c->eof - c->pos;
+  memcpy (buf, c->buf + c->pos, n);
+  c->pos += n;
+  return n;
+}
+
+/* Write up to non-zero N bytes of BUF into the stream described by COOKIE,
+   returning the number of bytes written or EOF on failure.  */
+static _READ_WRITE_RETURN_TYPE
+_DEFUN(fmemwriter, (ptr, cookie, buf, n),
+       struct _reent *ptr _AND
+       void *cookie _AND
+       const char *buf _AND
+       _READ_WRITE_BUFSIZE_TYPE n)
+{
+  fmemcookie *c = (fmemcookie *) cookie;
+  int adjust = 0; /* true if at EOF, but still need to write NUL.  */
+
+  /* Append always seeks to eof; otherwise, if we have previously done
+     a seek beyond eof, ensure all intermediate bytes are NUL.  */
+  if (c->append)
+    c->pos = c->eof;
+  else if (c->pos > c->eof)
+    memset (c->buf + c->eof, '\0', c->pos - c->eof);
+  /* Do not write beyond EOF; saving room for NUL on write-only stream.  */
+  if (c->pos + n > c->max - c->writeonly)
+    {
+      adjust = c->writeonly;
+      n = c->max - c->pos;
+    }
+  /* Now n is the number of bytes being modified, and adjust is 1 if
+     the last byte is NUL instead of from buf.  Write a NUL if
+     write-only; or if read-write, eof changed, and there is still
+     room.  When we are within the file contents, remember what we
+     overwrite so we can restore it if we seek elsewhere later.  */
+  if (c->pos + n > c->eof)
+    {
+      c->eof = c->pos + n;
+      if (c->eof - adjust < c->max)
+	c->saved = c->buf[c->eof - adjust] = '\0';
+    }
+  else if (c->writeonly)
+    {
+      if (n)
+	{
+	  c->saved = c->buf[c->pos + n - adjust];
+	  c->buf[c->pos + n - adjust] = '\0';
+	}
+      else
+	adjust = 0;
+    }
+  c->pos += n;
+  if (n - adjust)
+    memcpy (c->buf + c->pos - n, buf, n - adjust);
+  else
+    {
+      ptr->_errno = ENOSPC;
+      return EOF;
+    }
+  return n;
+}
+
+/* Seek to position POS relative to WHENCE within stream described by
+   COOKIE; return resulting position or fail with EOF.  */
+static _fpos_t
+_DEFUN(fmemseeker, (ptr, cookie, pos, whence),
+       struct _reent *ptr _AND
+       void *cookie _AND
+       _fpos_t pos _AND
+       int whence)
+{
+  fmemcookie *c = (fmemcookie *) cookie;
+#ifndef __LARGE64_FILES
+  off_t offset = (off_t) pos;
+#else /* __LARGE64_FILES */
+  _off64_t offset = (_off64_t) pos;
+#endif /* __LARGE64_FILES */
+
+  if (whence == SEEK_CUR)
+    offset += c->pos;
+  else if (whence == SEEK_END)
+    offset += c->eof;
+  if (offset < 0)
+    {
+      ptr->_errno = EINVAL;
+      offset = -1;
+    }
+  else if (offset > c->max)
+    {
+      ptr->_errno = ENOSPC;
+      offset = -1;
+    }
+#ifdef __LARGE64_FILES
+  else if ((_fpos_t) offset != offset)
+    {
+      ptr->_errno = EOVERFLOW;
+      offset = -1;
+    }
+#endif /* __LARGE64_FILES */
+  else
+    {
+      if (c->writeonly && c->pos < c->eof)
+	{
+	  c->buf[c->pos] = c->saved;
+	  c->saved = '\0';
+	}
+      c->pos = offset;
+      if (c->writeonly && c->pos < c->eof)
+	{
+	  c->saved = c->buf[c->pos];
+	  c->buf[c->pos] = '\0';
+	}
+    }
+  return (_fpos_t) offset;
+}
+
+/* Seek to position POS relative to WHENCE within stream described by
+   COOKIE; return resulting position or fail with EOF.  */
+#ifdef __LARGE64_FILES
+static _fpos64_t
+_DEFUN(fmemseeker64, (ptr, cookie, pos, whence),
+       struct _reent *ptr _AND
+       void *cookie _AND
+       _fpos64_t pos _AND
+       int whence)
+{
+  _off64_t offset = (_off64_t) pos;
+  fmemcookie *c = (fmemcookie *) cookie;
+  if (whence == SEEK_CUR)
+    offset += c->pos;
+  else if (whence == SEEK_END)
+    offset += c->eof;
+  if (offset < 0)
+    {
+      ptr->_errno = EINVAL;
+      offset = -1;
+    }
+  else if (offset > c->max)
+    {
+      ptr->_errno = ENOSPC;
+      offset = -1;
+    }
+  else
+    {
+      if (c->writeonly && c->pos < c->eof)
+	{
+	  c->buf[c->pos] = c->saved;
+	  c->saved = '\0';
+	}
+      c->pos = offset;
+      if (c->writeonly && c->pos < c->eof)
+	{
+	  c->saved = c->buf[c->pos];
+	  c->buf[c->pos] = '\0';
+	}
+    }
+  return (_fpos64_t) offset;
+}
+#endif /* __LARGE64_FILES */
+
+/* Reclaim resources used by stream described by COOKIE.  */
+static int
+_DEFUN(fmemcloser, (ptr, cookie),
+       struct _reent *ptr _AND
+       void *cookie)
+{
+  fmemcookie *c = (fmemcookie *) cookie;
+  _free_r (ptr, c->storage);
+  return 0;
+}
+
+/* Open a memstream around buffer BUF of SIZE bytes, using MODE.
+   Return the new stream, or fail with NULL.  */
+FILE *
+_DEFUN(_fmemopen_r, (ptr, buf, size, mode),
+       struct _reent *ptr _AND
+       void *__restrict buf _AND
+       size_t size _AND
+       const char *__restrict mode)
+{
+  FILE *fp;
+  fmemcookie *c;
+  int flags;
+  int dummy;
+
+  if ((flags = __sflags (ptr, mode, &dummy)) == 0)
+    return NULL;
+  if (!size || !(buf || flags & __SRW))
+    {
+      ptr->_errno = EINVAL;
+      return NULL;
+    }
+  if ((fp = __sfp (ptr)) == NULL)
+    return NULL;
+  if ((c = (fmemcookie *) _malloc_r (ptr, sizeof *c + (buf ? 0 : size)))
+      == NULL)
+    {
+      _newlib_sfp_lock_start ();
+      fp->_flags = 0;		/* release */
+#ifndef __SINGLE_THREAD__
+      __lock_close_recursive (fp->_lock);
+#endif
+      _newlib_sfp_lock_end ();
+      return NULL;
+    }
+
+  c->storage = c;
+  c->max = size;
+  /* 9 modes to worry about.  */
+  /* w/a, buf or no buf: Guarantee a NUL after any file writes.  */
+  c->writeonly = (flags & __SWR) != 0;
+  c->saved = '\0';
+  if (!buf)
+    {
+      /* r+/w+/a+, and no buf: file starts empty.  */
+      c->buf = (char *) (c + 1);
+      c->buf[0] = '\0';
+      c->pos = c->eof = 0;
+      c->append = (flags & __SAPP) != 0;
+    }
+  else
+    {
+      c->buf = (char *) buf;
+      switch (*mode)
+	{
+	case 'a':
+	  /* a/a+ and buf: position and size at first NUL.  */
+	  buf = memchr (c->buf, '\0', size);
+	  c->eof = c->pos = buf ? (char *) buf - c->buf : size;
+	  if (!buf && c->writeonly)
+	    /* a: guarantee a NUL within size even if no writes.  */
+	    c->buf[size - 1] = '\0';
+	  c->append = 1;
+	  break;
+	case 'r':
+	  /* r/r+ and buf: read at beginning, full size available.  */
+	  c->pos = c->append = 0;
+	  c->eof = size;
+	  break;
+	case 'w':
+	  /* w/w+ and buf: write at beginning, truncate to empty.  */
+	  c->pos = c->append = c->eof = 0;
+	  *c->buf = '\0';
+	  break;
+	default:
+	  abort ();
+	}
+    }
+
+  _newlib_flockfile_start (fp);
+  fp->_file = -1;
+  fp->_flags = flags;
+  fp->_cookie = c;
+  fp->_read = flags & (__SRD | __SRW) ? fmemreader : NULL;
+  fp->_write = flags & (__SWR | __SRW) ? fmemwriter : NULL;
+  fp->_seek = fmemseeker;
+#ifdef __LARGE64_FILES
+  fp->_seek64 = fmemseeker64;
+  fp->_flags |= __SL64;
+#endif
+  fp->_close = fmemcloser;
+  _newlib_flockfile_end (fp);
+  return fp;
+}
+
+#ifndef _REENT_ONLY
+FILE *
+_DEFUN(fmemopen, (buf, size, mode),
+       void *__restrict buf _AND
+       size_t size _AND
+       const char *__restrict mode)
+{
+  return _fmemopen_r (_REENT, buf, size, mode);
+}
+#endif /* !_REENT_ONLY */