libio/vasprintf.c

   1 /* Copyright (C) 1995, 1997, 1999, 2000 Free Software Foundation, Inc.
   2    This file is part of the GNU IO Library.
   3
   4    This library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU General Public License as
   6    published by the Free Software Foundation; either version 2, or (at
   7    your option) any later version.
   8
   9    This library 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 library; see the file COPYING.  If not, write to
  16    the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
  17    MA 02111-1307, USA.
  18
  19    As a special exception, if you link this library with files
  20    compiled with a GNU compiler to produce an executable, this does
  21    not cause the resulting executable to be covered by the GNU General
  22    Public License.  This exception does not however invalidate any
  23    other reasons why the executable file might be covered by the GNU
  24    General Public License.  */
  25
  26 #include <malloc.h>
  27 #include <string.h>
  28 #include "libioP.h"
  29 #include "stdio.h"
  30 #include "strfile.h"
  31
  32 int
  33 _IO_vasprintf (result_ptr, format, args)
  34      char **result_ptr;
  35      const char *format;
  36      _IO_va_list args;
  37 {
  38   /* Initial size of the buffer to be used.  Will be doubled each time an
  39      overflow occurs.  */
  40   const _IO_size_t init_string_size = 100;
  41   char *string;
  42   _IO_strfile sf;
  43 #ifdef _IO_MTSAFE_IO
  44   _IO_lock_t lock;
  45 #endif
  46   int ret;
  47   _IO_size_t needed;
  48   _IO_size_t allocated;
  49   string = (char *) malloc (init_string_size);
  50   if (string == NULL)
  51     return -1;
  52 #ifdef _IO_MTSAFE_IO
  53   sf._sbf._f._lock = &lock;
  54 #endif
  55   _IO_no_init ((_IO_FILE *) &sf._sbf, 0, -1, NULL, NULL);
  56   _IO_JUMPS ((struct _IO_FILE_plus *) &sf._sbf) = &_IO_str_jumps;
  57   _IO_str_init_static (&sf, string, init_string_size, string);
  58   sf._sbf._f._flags &= ~_IO_USER_BUF;
  59   sf._s._allocate_buffer = (_IO_alloc_type) malloc;
  60   sf._s._free_buffer = (_IO_free_type) free;
  61   ret = _IO_vfprintf ((_IO_FILE *) &sf, format, args);
  62   if (ret < 0)
  63     return ret;
  64   /* Only use realloc if the size we need is of the same order of
  65      magnitude then the memory we allocated.  */
  66   needed = sf._sbf._f._IO_write_ptr - sf._sbf._f._IO_write_base + 1;
  67   allocated = sf._sbf._f._IO_write_end - sf._sbf._f._IO_write_base;
  68   if ((allocated << 1) <= needed)
  69     *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed);
  70   else
  71     {
  72       *result_ptr = (char *) malloc (needed);
  73       if (*result_ptr != NULL)
  74         {
  75           memcpy (*result_ptr, sf._sbf._f._IO_buf_base, needed);
  76           free (sf._sbf._f._IO_buf_base);
  77         }
  78       else
  79         /* We have no choice, use the buffer we already have.  */
  80         *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed);
  81     }
  82   if (*result_ptr == NULL)
  83     *result_ptr = sf._sbf._f._IO_buf_base;
  84   (*result_ptr)[sf._sbf._f._IO_write_ptr-sf._sbf._f._IO_write_base] = '\0';
  85   return ret;
  86 }
  87
  88 #ifdef weak_alias
  89 weak_alias (_IO_vasprintf, vasprintf)
  90 #endif