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glibc  2.9
realpath_chk.c
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00001 /* Copyright (C) 2005 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <limits.h>
00020 #include <stdlib.h>
00021 #include <string.h>
00022 #include <unistd.h>
00023 
00024 
00025 char *
00026 __realpath_chk (const char *buf, char *resolved, size_t resolvedlen)
00027 {
00028 #ifdef PATH_MAX
00029   if (resolvedlen < PATH_MAX)
00030     __chk_fail ();
00031 
00032   return __realpath (buf, resolved);
00033 #else
00034   long int pathmax =__pathconf (buf, _PC_PATH_MAX);
00035   if (pathmax != -1)
00036     {
00037       /* We do have a fixed limit.  */
00038       if (resolvedlen < pathmax)
00039        __chk_fail ();
00040 
00041       return __realpath (buf, resolved);
00042     }
00043 
00044   /* Since there is no fixed limit we check whether the size is large
00045      enough.  */
00046   char *res = __realpath (buf, NULL);
00047   if (res != NULL)
00048     {
00049       size_t actlen = strlen (res) + 1;
00050       if (actlen > resolvedlen)
00051        __chk_fail ();
00052 
00053       memcpy (resolved, res, actlen);
00054       free (res);
00055       res = resolved;
00056     }
00057 
00058   return res;
00059 #endif
00060 }