glibc/debug/sprintf_chk.c

/* Copyright (C) 1991-2024 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <stdarg.h>
#include <libio/libioP.h>


/* Write formatted output into S, according to the format string FORMAT.  */
int
___sprintf_chk (char *s, int flag, size_t slen, const char *format, ...)
{
  /* For flag > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
     can only come from read-only format strings.  */
  unsigned int mode = (flag > 0) ? PRINTF_FORTIFY : 0;
  va_list ap;
  int ret;

  /* Regardless of the value of flag, let __vsprintf_internal know that
     this is a call from *printf_chk.  */
  mode |= PRINTF_CHK;

  if (slen == 0)
    __chk_fail ();

  va_start (ap, format);
  ret = __vsprintf_internal (s, slen, format, ap, mode);
  va_end (ap);

  return ret;
}
ldbl_hidden_def (___sprintf_chk, __sprintf_chk)
ldbl_strong_alias (___sprintf_chk, __sprintf_chk)