stdio/vasprintf.c

   1 /* Copyright (C) 1991, 1992 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <stddef.h>
  21 #include <stdarg.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26
  27
  28 /* Enlarge STREAM's buffer.  */
  29 static void
  30 DEFUN(enlarge_buffer, (stream, c),
  31       register FILE *stream AND int c)
  32 {
  33   ptrdiff_t bufp_offset = stream->__bufp - stream->__buffer;
  34   char *newbuf;
  35
  36   stream->__bufsize += 100;
  37   newbuf = (char *) realloc ((PTR) stream->__buffer, stream->__bufsize);
  38   if (newbuf == NULL)
  39     {
  40       free ((PTR) stream->__buffer);
  41       stream->__buffer = stream->__bufp
  42         = stream->__put_limit = stream->__get_limit = NULL;
  43       stream->__error = 1;
  44     }
  45   else
  46     {
  47       stream->__buffer = newbuf;
  48       stream->__bufp = stream->__buffer + bufp_offset;
  49       stream->__get_limit = stream->__put_limit;
  50       stream->__put_limit = stream->__buffer + stream->__bufsize;
  51       if (c != EOF)
  52         *stream->__bufp++ = (unsigned char) c;
  53     }
  54 }
  55
  56 /* Write formatted output from FORMAT to a string which is
  57    allocated with malloc and stored in *STRING_PTR.  */
  58 int
  59 DEFUN(vasprintf, (string_ptr, format, args),
  60       char **string_ptr AND CONST char *format AND va_list args)
  61 {
  62   FILE f;
  63   int done;
  64
  65   memset ((PTR) &f, 0, sizeof (f));
  66   f.__magic = _IOMAGIC;
  67   f.__bufsize = 100;
  68   f.__buffer = (char *) malloc (f.__bufsize);
  69   if (f.__buffer == NULL)
  70     return -1;
  71   f.__bufp = f.__buffer;
  72   f.__put_limit = f.__buffer + f.__bufsize;
  73   f.__mode.__write = 1;
  74   f.__room_funcs.__output = enlarge_buffer;
  75   f.__seen = 1;
  76
  77   done = vfprintf (&f, format, args);
  78   if (done < 0)
  79     return done;
  80
  81   *string_ptr = realloc (f.__buffer, (f.__bufp - f.__buffer) + 1);
  82   if (*string_ptr == NULL)
  83     *string_ptr = f.__buffer;
  84   (*string_ptr)[f.__bufp - f.__buffer] = '\0';
  85   return done;
  86 }