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/* Copyright (C) 1991, 92, 94, 95, 96 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
struct memstream_info
{
char **buffer;
size_t *bufsize;
};
/* Enlarge STREAM's buffer. */
static void
enlarge_buffer (register FILE *stream, int c)
{
struct memstream_info *info = (struct memstream_info *) stream->__cookie;
size_t need;
if (stream->__put_limit != stream->__buffer)
/* Record how much has actually been written into the buffer. */
*info->bufsize = stream->__bufp - stream->__buffer;
if (stream->__target != -1
&& stream->__target > *info->bufsize)
/* Our target (where the buffer maps to) is always zero except when
the user just did a SEEK_END fseek. If he sought within the
buffer, we need do nothing and will zero the target below. If he
sought past the end of the object, grow and zero-fill the buffer
up to the target address. */
need = stream->__target;
else
need = *info->bufsize;
/* We always need an extra character in the buffer. Either we are
writing C, or we are flushing and need to write a NUL terminator. */
++need;
if (stream->__bufsize < need)
{
/* Enlarge the buffer. */
char *newbuf;
size_t newsize;
if (stream->__bufsize * 2 < need)
newsize = need;
else
newsize = stream->__bufsize * 2;
newbuf = (char *) realloc ((void *) stream->__buffer, newsize);
if (newbuf == NULL)
{
stream->__error = 1;
return;
}
*info->buffer = stream->__buffer = newbuf;
stream->__bufsize = newsize;
}
stream->__target = stream->__offset = 0;
stream->__get_limit = stream->__bufp = stream->__buffer + *info->bufsize;
stream->__put_limit = stream->__buffer + stream->__bufsize;
need -= stream->__bufp - stream->__buffer + 1;
if (need > 0)
{
/* We are extending the buffer after an fseek; zero-fill new space. */
memset (stream->__bufp, '\0', need);
stream->__bufp += need;
}
if (c != EOF)
*stream->__bufp++ = (unsigned char) c;
else
*stream->__bufp = '\0';
}
/* Seek function for memstreams.
There is no external state to munge. */
static int
seek (void *cookie, fpos_t *pos, int whence)
{
switch (whence)
{
case SEEK_SET:
case SEEK_CUR:
return 0;
case SEEK_END:
/* Return the position relative to the end of the object.
fseek has just flushed us, so the info is consistent. */
*pos += *((struct memstream_info *) cookie)->bufsize;
return 0;
default:
__libc_fatal ("memstream::seek called with bogus WHENCE\n");
return -1;
}
}
static int
free_info (void *cookie)
{
#if 0
struct memstream_info *info = (struct memstream_info *) cookie;
char *buf;
buf = (char *) realloc ((PTR) *info->buffer, *info->bufsize);
if (buf != NULL)
*info->buffer = buf;
#endif
free (cookie);
return 0;
}
/* Open a stream that writes into a malloc'd buffer that is expanded as
necessary. *BUFLOC and *SIZELOC are updated with the buffer's location
and the number of characters written on fflush or fclose. */
FILE *
open_memstream (bufloc, sizeloc)
char **bufloc;
size_t *sizeloc;
{
FILE *stream;
struct memstream_info *info;
if (bufloc == NULL || sizeloc == NULL)
{
__set_errno (EINVAL);
return NULL;
}
stream = fmemopen ((char *) NULL, BUFSIZ, "w+");
if (stream == NULL)
return NULL;
info = (struct memstream_info *) malloc (sizeof (struct memstream_info));
if (info == NULL)
{
int save = errno;
(void) fclose (stream);
__set_errno (save);
return NULL;
}
stream->__room_funcs.__output = enlarge_buffer;
stream->__io_funcs.__seek = seek;
stream->__io_funcs.__close = free_info;
stream->__cookie = (void *) info;
stream->__userbuf = 1;
info->buffer = bufloc;
info->bufsize = sizeloc;
*bufloc = stream->__buffer;
return stream;
}
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