1 /* Target directory operands for coreutils
2
3 Copyright 2004-2023 Free Software Foundation, Inc.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
9
10 This program 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
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19
20 #define TARGETDIR_INLINE _GL_EXTERN_INLINE
21 #include <targetdir.h>
22
23 #include <attribute.h>
24
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <sys/stat.h>
28 #include <unistd.h>
29
30 #ifdef O_PATH
31 enum { O_PATHSEARCH = O_PATH };
32 #else
33 enum { O_PATHSEARCH = O_SEARCH };
34 #endif
35
36 /* Must F designate the working directory? */
37
38 ATTRIBUTE_PURE static bool
must_be_working_directory(char const * f)39 must_be_working_directory (char const *f)
40 {
41 /* Return true for ".", "./.", ".///./", etc. */
42 while (*f++ == '.')
43 {
44 if (*f != '/')
45 return !*f;
46 while (*++f == '/')
47 continue;
48 if (!*f)
49 return true;
50 }
51 return false;
52 }
53
54 /* Return a file descriptor open to FILE, for use in openat.
55 As an optimization, return AT_FDCWD if FILE must be the working directory.
56 As a side effect, possibly set *ST to the file's status.
57 Fail and set errno if FILE is not a directory.
58 On failure return -2 if AT_FDCWD is -1, -1 otherwise. */
59
60 int
target_directory_operand(char const * file,struct stat * st)61 target_directory_operand (char const *file, struct stat *st)
62 {
63 if (must_be_working_directory (file))
64 return AT_FDCWD;
65
66 int fd = -1;
67 int try_to_open = 1;
68 int stat_result;
69
70 /* On old systems without O_DIRECTORY, like Solaris 10, check with
71 stat first lest we try to open a fifo for example and hang. */
72 if (!O_DIRECTORY)
73 {
74 stat_result = stat (file, st);
75 if (stat_result == 0)
76 {
77 try_to_open = S_ISDIR (st->st_mode);
78 errno = ENOTDIR;
79 }
80 else
81 {
82 /* On EOVERFLOW failure, give up on checking, as there is no
83 easy way to check. This should be rare. */
84 try_to_open = errno == EOVERFLOW;
85 }
86 }
87
88 if (try_to_open)
89 {
90 fd = open (file, O_PATHSEARCH | O_DIRECTORY);
91
92 /* On platforms lacking O_PATH, using O_SEARCH | O_DIRECTORY to
93 open an overly-protected non-directory can fail with either
94 EACCES or ENOTDIR. Prefer ENOTDIR as it makes for better
95 diagnostics. */
96 if (O_PATHSEARCH == O_SEARCH && fd < 0 && errno == EACCES)
97 errno = (((O_DIRECTORY ? stat (file, st) : stat_result) == 0
98 && !S_ISDIR (st->st_mode))
99 ? ENOTDIR : EACCES);
100 }
101
102 if (!O_DIRECTORY && 0 <= fd)
103 {
104 /* On old systems like Solaris 10 double check type,
105 to ensure we've opened a directory. */
106 int err;
107 if (fstat (fd, st) == 0
108 ? !S_ISDIR (st->st_mode) && (err = ENOTDIR, true)
109 : (err = errno) != EOVERFLOW)
110 {
111 close (fd);
112 errno = err;
113 fd = -1;
114 }
115 }
116
117 return fd - (AT_FDCWD == -1 && fd < 0);
118 }
119