libssp/gets-chk.c

   1 /* Checking gets.
   2    Copyright (C) 2005-2017 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 }