2.3.2/src/common/open_memstream.c

   1 /*
   2  * Copyright (C) 2005 Richard Kettlewell
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  17  * USA
  18  */
  19
  20 #include <stdio.h>
  21 #include <errno.h>
  22 #include <string.h>
  23 #include <stdlib.h>
  24 #include <assert.h>
  25
  26 #include <config.h>
  27 #include <vde.h>
  28 #include <vdecommon.h>
  29
  30 /* BSD-compatible implementation of open_memstream */
  31
  32 #if HAVE_FUNOPEN
  33 struct memstream {
  34   char *buffer;
  35   size_t size, space;
  36
  37   char **ptr;
  38   size_t *sizeloc;
  39 };
  40
  41 static int memstream_writefn(void *u, const char *buffer, int bytes) {
  42   struct memstream *m = u;
  43   size_t needed = m->size + bytes + 1;
  44   size_t newspace;
  45   char *newbuffer;
  46
  47   assert(bytes >= 0);
  48   if(needed > m->space) {
  49     newspace = m->space ? m->space : 32;
  50     while(newspace && newspace < needed)
  51       newspace *= 2;
  52     if(!newspace) {
  53       errno = ENOMEM;
  54       return -1;
  55     }
  56     if(!(newbuffer = realloc(m->buffer, newspace)))
  57       return -1;
  58     m->buffer = newbuffer;
  59     m->space = newspace;
  60   }
  61   memcpy(m->buffer + m->size, buffer, bytes);
  62   m->size += bytes;
  63   m->buffer[m->size] = 0;
  64
  65   *m->ptr = m->buffer;
  66   *m->sizeloc = m->size;
  67   return bytes;
  68 }
  69
  70 FILE *open_memstream(char **ptr, size_t *sizeloc) {
  71   struct memstream *m;
  72
  73   if(!(m = malloc(sizeof *m))) return 0;
  74   m->buffer = 0;
  75   m->size = 0;
  76   m->space = 0;
  77   m->ptr = ptr;
  78   m->sizeloc = sizeloc;
  79   *ptr = 0;
  80   *sizeloc = 0;
  81   return funopen(m,
  82                  0,                     /* read */
  83                  memstream_writefn,
  84                  0,                     /* seek */
  85                  0);                    /* close */
  86 }
  87 #endif
  88