Line data    Source code

       1             : // SPDX-License-Identifier: LGPL-2.1-or-later
       2             : /* Append a null-terminated string to another string, with length checking.
       3             :  * Copyright (C) 2016 Free Software Foundation, Inc.
       4             :  * This file is part of the GNU C Library.
       5             :  */
       6             : 
       7             : /* adapted for Quagga from glibc patch submission originally from
       8             :  * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
       9             : 
      10             : #ifdef HAVE_CONFIG_H
      11             : #include "config.h"
      12             : #endif
      13             : 
      14             : #include <stdint.h>
      15             : #include <string.h>
      16             : 
      17             : #ifndef HAVE_STRLCAT
      18             : #undef strlcat
      19             : 
      20             : size_t strlcat(char *__restrict dest,
      21             :                const char *__restrict src, size_t destsize);
      22             : 
      23          60 : size_t strlcat(char *__restrict dest,
      24             :                const char *__restrict src, size_t destsize)
      25             : {
      26          60 :         size_t src_length = strlen(src);
      27             : 
      28             :         /* Our implementation strlcat supports dest == NULL if size == 0
      29             :            (for consistency with snprintf and strlcpy), but strnlen does
      30             :            not, so we have to cover this case explicitly.  */
      31          60 :         if (destsize == 0)
      32             :                 return src_length;
      33             : 
      34          60 :         size_t dest_length = strnlen(dest, destsize);
      35          60 :         if (dest_length != destsize) {
      36             :                 /* Copy at most the remaining number of characters in the
      37             :                    destination buffer.  Leave for the NUL terminator.  */
      38          60 :                 size_t to_copy = destsize - dest_length - 1;
      39             :                 /* But not more than what is available in the source string.  */
      40          60 :                 if (to_copy > src_length)
      41             :                         to_copy = src_length;
      42             : 
      43          60 :                 char *target = dest + dest_length;
      44          60 :                 memcpy(target, src, to_copy);
      45          60 :                 target[to_copy] = '\0';
      46             :         }
      47             : 
      48             : /* If the sum wraps around, we have more than SIZE_MAX + 2 bytes in
      49             :    the two input strings (including both null terminators).  If each
      50             :    byte in the address space can be assigned a unique size_t value
      51             :    (which the static_assert checks), then by the pigeonhole
      52             :    principle, the two input strings must overlap, which is
      53             :    undefined.  */
      54          60 :         _Static_assert(sizeof(uintptr_t) == sizeof(size_t),
      55             :                        "theoretical maximum object size covers address space");
      56          60 :         return dest_length + src_length;
      57             : }
      58             : #endif /* HAVE_STRLCAT */