lib/snzprintf.c

   1 /* Formatted output to strings.
   2    Copyright (C) 2004, 2006-2024 Free Software Foundation, Inc.
   3    Written by Simon Josefsson and Paul Eggert.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <stdio.h>
  22
  23 #include <errno.h>
  24 #include <stdarg.h>
  25 #include <stdint.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 #include "vasnprintf.h"
  30
  31 ptrdiff_t
  32 snzprintf (char *str, size_t size, const char *format, ...)
  33 {
  34   char *output;
  35   size_t len;
  36   size_t lenbuf = size;
  37   va_list args;
  38
  39   va_start (args, format);
  40   output = vasnprintf (str, &lenbuf, format, args);
  41   len = lenbuf;
  42   va_end (args);
  43
  44   if (!output)
  45     return -1;
  46
  47   if (output != str)
  48     {
  49       if (size)
  50         {
  51           size_t pruned_len = (len < size ? len : size - 1);
  52           memcpy (str, output, pruned_len);
  53           str[pruned_len] = '\0';
  54         }
  55
  56       free (output);
  57     }
  58
  59   if (len > PTRDIFF_MAX)
  60     {
  61       errno = ENOMEM;
  62       return -1;
  63     }
  64
  65   return len;
  66 }