Line data    Source code

       1             : /* Append a null-terminated string to another string, with length checking.
       2             :  * Copyright (C) 2016 Free Software Foundation, Inc.
       3             :  * This file is part of the GNU C Library.
       4             :  *
       5             :  * The GNU C Library is free software; you can redistribute it and/or
       6             :  * modify it under the terms of the GNU Lesser General Public
       7             :  * License as published by the Free Software Foundation; either
       8             :  * version 2.1 of the License, or (at your option) any later version.
       9             :  *
      10             :  * The GNU C Library is distributed in the hope that it will be useful,
      11             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      12             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13             :  * Lesser General Public License for more details.
      14             :  *
      15             :  * You should have received a copy of the GNU Lesser General Public
      16             :  * License along with the GNU C Library; if not, see
      17             :  * <http://www.gnu.org/licenses/>.
      18             :  */
      19             : 
      20             : /* adapted for Quagga from glibc patch submission originally from
      21             :  * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
      22             : 
      23             : #ifdef HAVE_CONFIG_H
      24             : #include "config.h"
      25             : #endif
      26             : 
      27             : #include <stdint.h>
      28             : #include <string.h>
      29             : 
      30             : #ifndef HAVE_STRLCAT
      31             : #undef strlcat
      32             : 
      33             : size_t strlcat(char *__restrict dest,
      34             :                const char *__restrict src, size_t destsize);
      35             : 
      36        4860 : size_t strlcat(char *__restrict dest,
      37             :                const char *__restrict src, size_t destsize)
      38             : {
      39        4860 :         size_t src_length = strlen(src);
      40             : 
      41             :         /* Our implementation strlcat supports dest == NULL if size == 0
      42             :            (for consistency with snprintf and strlcpy), but strnlen does
      43             :            not, so we have to cover this case explicitly.  */
      44        4860 :         if (destsize == 0)
      45             :                 return src_length;
      46             : 
      47        4860 :         size_t dest_length = strnlen(dest, destsize);
      48        4860 :         if (dest_length != destsize) {
      49             :                 /* Copy at most the remaining number of characters in the
      50             :                    destination buffer.  Leave for the NUL terminator.  */
      51        4860 :                 size_t to_copy = destsize - dest_length - 1;
      52             :                 /* But not more than what is available in the source string.  */
      53        4860 :                 if (to_copy > src_length)
      54             :                         to_copy = src_length;
      55             : 
      56        4860 :                 char *target = dest + dest_length;
      57        4860 :                 memcpy(target, src, to_copy);
      58        4860 :                 target[to_copy] = '\0';
      59             :         }
      60             : 
      61             : /* If the sum wraps around, we have more than SIZE_MAX + 2 bytes in
      62             :    the two input strings (including both null terminators).  If each
      63             :    byte in the address space can be assigned a unique size_t value
      64             :    (which the static_assert checks), then by the pigeonhole
      65             :    principle, the two input strings must overlap, which is
      66             :    undefined.  */
      67        4860 :         _Static_assert(sizeof(uintptr_t) == sizeof(size_t),
      68             :                        "theoretical maximum object size covers address space");
      69        4860 :         return dest_length + src_length;
      70             : }
      71             : #endif /* HAVE_STRLCAT */