glibc/debug/realpath_chk.c

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/* Copyright (C) 2005-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
char *
__realpath_chk (const char *buf, char *resolved, size_t resolvedlen)
{
#ifdef PATH_MAX
if (resolvedlen < PATH_MAX)
__chk_fail ();
return __realpath (buf, resolved);
#else
long int pathmax =__pathconf (buf, _PC_PATH_MAX);
if (pathmax != -1)
{
/* We do have a fixed limit. */
if (resolvedlen < pathmax)
__chk_fail ();
return __realpath (buf, resolved);
}
/* Since there is no fixed limit we check whether the size is large
enough. */
char *res = __realpath (buf, NULL);
if (res != NULL)
{
size_t actlen = strlen (res) + 1;
if (actlen > resolvedlen)
__chk_fail ();
memcpy (resolved, res, actlen);
free (res);
res = resolved;
}
return res;
#endif
}