vde-2/compat/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 <config.h>
  21
  22 #include <stdio.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <assert.h>
  27
  28 /* BSD-compatible implementation of open_memstream */
  29
  30 #if HAVE_FUNOPEN
  31 struct memstream {
  32   char *buffer;
  33   size_t size, space;
  34
  35   char **ptr;
  36   size_t *sizeloc;
  37 };
  38
  39 static int memstream_writefn(void *u, const char *buffer, int bytes) {
  40   struct memstream *m = u;
  41   size_t needed = m->size + bytes + 1;
  42   size_t newspace;
  43   char *newbuffer;
  44
  45   assert(bytes >= 0);
  46   if(needed > m->space) {
  47     newspace = m->space ? m->space : 32;
  48     while(newspace && newspace < needed)
  49       newspace *= 2;
  50     if(!newspace) {
  51       errno = ENOMEM;
  52       return -1;
  53     }
  54     if(!(newbuffer = realloc(m->buffer, newspace)))
  55       return -1;
  56     m->buffer = newbuffer;
  57     m->space = newspace;
  58   }
  59   memcpy(m->buffer + m->size, buffer, bytes);
  60   m->size += bytes;
  61   m->buffer[m->size] = 0;
  62
  63   *m->ptr = m->buffer;
  64   *m->sizeloc = m->size;
  65   return bytes;
  66 }
  67
  68 FILE *open_memstream(char **ptr, size_t *sizeloc) {
  69   struct memstream *m;
  70
  71   if(!(m = malloc(sizeof *m))) return 0;
  72   m->buffer = 0;
  73   m->size = 0;
  74   m->space = 0;
  75   m->ptr = ptr;
  76   m->sizeloc = sizeloc;
  77   *ptr = 0;
  78   *sizeloc = 0;
  79   return funopen(m,
  80                  0,                     /* read */
  81                  memstream_writefn,
  82                  0,                     /* seek */
  83                  0);                    /* close */
  84 }
  85 #endif
  86