lib/unistdio/u-vsnprintf.h

   1 /* Formatted output to strings.
   2    Copyright (C) 1999, 2002, 2006-2018 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify it
   5    under the terms of the GNU Lesser General Public License as published
   6    by the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 int
  18 VSNPRINTF (DCHAR_T *buf, size_t size, const FCHAR_T *format, va_list args)
  19 {
  20   size_t length;
  21   DCHAR_T *result;
  22
  23   if (size == 0)
  24     buf = NULL;
  25   else
  26     length = size;
  27   result = VASNPRINTF (buf, &length, format, args);
  28   if (result == NULL)
  29     return -1;
  30
  31   if (result != buf)
  32     {
  33       if (size != 0)
  34         {
  35           /* The result did not fit into the buffer.  Copy the initial segment
  36              into the buffer, truncating it if necessary.  */
  37           size_t n = (length < size ? length : size - 1);
  38           DCHAR_CPY (buf, result, n);
  39           buf[n] = '\0';
  40         }
  41       free (result);
  42     }
  43
  44   if (length > INT_MAX)
  45     {
  46       errno = EOVERFLOW;
  47       return -1;
  48     }
  49
  50   /* Return the number of resulting units, excluding the trailing NUL.  */
  51   return length;
  52 }