1  /* Checking gets.
       2     Copyright (C) 2005-2023 Free Software Foundation, Inc.
       3  
       4  This file is part of GCC.
       5  
       6  GCC is free software; you can redistribute it and/or modify it under
       7  the terms of the GNU General Public License as published by the Free
       8  Software Foundation; either version 3, or (at your option) any later
       9  version.
      10  
      11  In addition to the permissions in the GNU General Public License, the
      12  Free Software Foundation gives you unlimited permission to link the
      13  compiled version of this file into combinations with other programs,
      14  and to distribute those combinations without any restriction coming
      15  from the use of this file.  (The General Public License restrictions
      16  do apply in other respects; for example, they cover modification of
      17  the file, and distribution when not linked into a combine
      18  executable.)
      19  
      20  GCC is distributed in the hope that it will be useful, but WITHOUT ANY
      21  WARRANTY; without even the implied warranty of MERCHANTABILITY or
      22  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      23  for more details.
      24  
      25  Under Section 7 of GPL version 3, you are granted additional
      26  permissions described in the GCC Runtime Library Exception, version
      27  3.1, as published by the Free Software Foundation.
      28  
      29  You should have received a copy of the GNU General Public License and
      30  a copy of the GCC Runtime Library Exception along with this program;
      31  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      32  <http://www.gnu.org/licenses/>.  */
      33  
      34  
      35  #include "config.h"
      36  #include <ssp/ssp.h>
      37  #include <stdarg.h>
      38  #ifdef HAVE_STDLIB_H
      39  # include <stdlib.h>
      40  #endif
      41  #ifdef HAVE_ALLOCA_H
      42  # include <alloca.h>
      43  #endif
      44  #ifdef HAVE_LIMITS_H
      45  # include <limits.h>
      46  #endif
      47  #ifdef HAVE_STDIO_H
      48  # include <stdio.h>
      49  #endif
      50  #ifdef HAVE_STRING_H
      51  # include <string.h>
      52  #endif
      53  
      54  #if !(!defined __USE_ISOC11				\
      55        || (defined __cplusplus && __cplusplus <= 201103L))
      56  extern char *gets (char *);
      57  #endif
      58  
      59  extern void __chk_fail (void) __attribute__((__noreturn__));
      60  
      61  char *
      62  __gets_chk (char *s, size_t slen)
      63  {
      64    char *ret, *buf;
      65  
      66    if (slen >= (size_t) INT_MAX)
      67      return gets (s);
      68  
      69    if (slen <= 8192)
      70      buf = alloca (slen + 1);
      71    else
      72      buf = malloc (slen + 1);
      73    if (buf == NULL)
      74      return gets (s);
      75  
      76    ret = fgets (buf, (int) (slen + 1), stdin);
      77    if (ret != NULL)
      78      {
      79        size_t len = strlen (buf);
      80        if (len > 0 && buf[len - 1] == '\n')
      81          --len;
      82        if (len == slen)
      83          __chk_fail ();
      84        memcpy (s, buf, len);
      85        s[len] = '\0';
      86        ret = s;
      87      }
      88  
      89    if (slen > 8192)
      90      free (buf);
      91    return ret;
      92  }