debug/vsnprintf_chk.c

   1 /* Copyright (C) 1991-2023 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <libio/libioP.h>
  19
  20
  21 /* Write formatted output into S, according to the format
  22    string FORMAT, writing no more than MAXLEN characters.  */
  23 int
  24 ___vsnprintf_chk (char *s, size_t maxlen, int flag, size_t slen,
  25                   const char *format, va_list ap)
  26 {
  27   if (__glibc_unlikely (slen < maxlen))
  28     __chk_fail ();
  29
  30   /* For flag > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
  31      can only come from read-only format strings.  */
  32   unsigned int mode = (flag > 0) ? PRINTF_FORTIFY : 0;
  33
  34   return __vsnprintf_internal (s, maxlen, format, ap, mode);
  35 }
  36 ldbl_strong_alias (___vsnprintf_chk, __vsnprintf_chk)