1  /* Formatted output to strings.
       2     Copyright (C) 2004, 2006-2023 Free Software Foundation, Inc.
       3     Written by Simon Josefsson and Yoann Vandoorselaere <yoann@prelude-ids.org>.
       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  #ifdef HAVE_CONFIG_H
      19  # include <config.h>
      20  #endif
      21  
      22  /* Specification.  */
      23  #include <stdio.h>
      24  
      25  #include <errno.h>
      26  #include <limits.h>
      27  #include <stdarg.h>
      28  #include <stdlib.h>
      29  #include <string.h>
      30  
      31  #include "vasnprintf.h"
      32  
      33  /* Print formatted output to string STR.  Similar to vsprintf, but
      34     additional length SIZE limit how much is written into STR.  Returns
      35     string length of formatted string (which may be larger than SIZE).
      36     STR may be NULL, in which case nothing will be written.  On error,
      37     return a negative value.  */
      38  int
      39  vsnprintf (char *str, size_t size, const char *format, va_list args)
      40  {
      41    char *output;
      42    size_t len;
      43    size_t lenbuf = size;
      44  
      45    output = vasnprintf (str, &lenbuf, format, args);
      46    len = lenbuf;
      47  
      48    if (!output)
      49      return -1;
      50  
      51    if (output != str)
      52      {
      53        if (size)
      54          {
      55            size_t pruned_len = (len < size ? len : size - 1);
      56            memcpy (str, output, pruned_len);
      57            str[pruned_len] = '\0';
      58          }
      59  
      60        free (output);
      61      }
      62  
      63    if (len > INT_MAX)
      64      {
      65        errno = EOVERFLOW;
      66        return -1;
      67      }
      68  
      69    return len;
      70  }