stdio/vasprintf.c

   1 /* Copyright (C) 1991, 1992, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <stddef.h>
  20 #include <stdarg.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24
  25
  26
  27 /* Enlarge STREAM's buffer.  */
  28 static void
  29 enlarge_buffer (FILE *stream, int c)
  30 {
  31   ptrdiff_t bufp_offset = stream->__bufp - stream->__buffer;
  32   char *newbuf;
  33
  34   stream->__bufsize += 100;
  35   newbuf = (char *) realloc ((void *) stream->__buffer, stream->__bufsize);
  36   if (newbuf == NULL)
  37     {
  38       free ((void *) stream->__buffer);
  39       stream->__buffer = stream->__bufp
  40         = stream->__put_limit = stream->__get_limit = NULL;
  41       stream->__error = 1;
  42     }
  43   else
  44     {
  45       stream->__buffer = newbuf;
  46       stream->__bufp = stream->__buffer + bufp_offset;
  47       stream->__get_limit = stream->__put_limit;
  48       stream->__put_limit = stream->__buffer + stream->__bufsize;
  49       if (c != EOF)
  50         *stream->__bufp++ = (unsigned char) c;
  51     }
  52 }
  53
  54 /* Write formatted output from FORMAT to a string which is
  55    allocated with malloc and stored in *STRING_PTR.  */
  56 int
  57 vasprintf (char **string_ptr,
  58            const char *format,
  59            va_list args)
  60 {
  61   FILE f;
  62   int done;
  63
  64   memset ((void *) &f, 0, sizeof (f));
  65   f.__magic = _IOMAGIC;
  66   f.__bufsize = 100;
  67   f.__buffer = (char *) malloc (f.__bufsize);
  68   if (f.__buffer == NULL)
  69     return -1;
  70   f.__bufp = f.__buffer;
  71   f.__put_limit = f.__buffer + f.__bufsize;
  72   f.__mode.__write = 1;
  73   f.__room_funcs.__output = enlarge_buffer;
  74   f.__seen = 1;
  75
  76   done = vfprintf (&f, format, args);
  77   if (done < 0)
  78     return done;
  79
  80   *string_ptr = realloc (f.__buffer, (f.__bufp - f.__buffer) + 1);
  81   if (*string_ptr == NULL)
  82     *string_ptr = f.__buffer;
  83   (*string_ptr)[f.__bufp - f.__buffer] = '\0';
  84   return done;
  85 }