1/* Copyright (C) 2005-2024 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <limits.h>
19#include <stdlib.h>
20#include <string.h>
21#include <unistd.h>
22#include <errno.h>
23
24
25char *
26__realpath_chk (const char *buf, char *resolved, size_t resolvedlen)
27{
28#ifdef PATH_MAX
29 if (resolvedlen < PATH_MAX)
30 __chk_fail ();
31
32 return __realpath (buf, resolved);
33#else
34 long int pathmax;
35
36 if (buf == NULL)
37 {
38 __set_errno (EINVAL);
39 return NULL;
40 }
41
42 pathmax = __pathconf (buf, _PC_PATH_MAX);
43 if (pathmax != -1)
44 {
45 /* We do have a fixed limit. */
46 if (resolvedlen < pathmax)
47 __chk_fail ();
48
49 return __realpath (buf, resolved);
50 }
51
52 /* Since there is no fixed limit we check whether the size is large
53 enough. */
54 char *res = __realpath (buf, NULL);
55 if (res != NULL)
56 {
57 size_t actlen = strlen (res) + 1;
58 if (actlen > resolvedlen)
59 __chk_fail ();
60
61 memcpy (resolved, res, actlen);
62 free (res);
63 res = resolved;
64 }
65
66 return res;
67#endif
68}
69

source code of glibc/debug/realpath_chk.c