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6ec2e0f5 | 1 | /* Define at-style functions like fstatat, unlinkat, fchownat, etc. |
7a6dbc2f | 2 | Copyright (C) 2006, 2009-2018 Free Software Foundation, Inc. |
6ec2e0f5 SDJ |
3 | |
4 | This program is free software: you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 3 of the License, or | |
7 | (at your option) any later version. | |
8 | ||
9 | This program 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 | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
7a6dbc2f | 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
6ec2e0f5 SDJ |
16 | |
17 | /* written by Jim Meyering */ | |
18 | ||
19 | #include "dosname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */ | |
20 | ||
21 | #ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD | |
22 | # include <errno.h> | |
23 | # ifndef ENOTSUP | |
24 | # define ENOTSUP EINVAL | |
25 | # endif | |
26 | #else | |
27 | # include "openat.h" | |
28 | # include "openat-priv.h" | |
29 | # include "save-cwd.h" | |
30 | #endif | |
31 | ||
32 | #ifdef AT_FUNC_USE_F1_COND | |
33 | # define CALL_FUNC(F) \ | |
34 | (flag == AT_FUNC_USE_F1_COND \ | |
35 | ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS) \ | |
36 | : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS)) | |
37 | # define VALIDATE_FLAG(F) \ | |
38 | if (flag & ~AT_FUNC_USE_F1_COND) \ | |
39 | { \ | |
40 | errno = EINVAL; \ | |
41 | return FUNC_FAIL; \ | |
42 | } | |
43 | #else | |
44 | # define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS)) | |
45 | # define VALIDATE_FLAG(F) /* empty */ | |
46 | #endif | |
47 | ||
48 | #ifdef AT_FUNC_RESULT | |
49 | # define FUNC_RESULT AT_FUNC_RESULT | |
50 | #else | |
51 | # define FUNC_RESULT int | |
52 | #endif | |
53 | ||
54 | #ifdef AT_FUNC_FAIL | |
55 | # define FUNC_FAIL AT_FUNC_FAIL | |
56 | #else | |
57 | # define FUNC_FAIL -1 | |
58 | #endif | |
59 | ||
60 | /* Call AT_FUNC_F1 to operate on FILE, which is in the directory | |
61 | open on descriptor FD. If AT_FUNC_USE_F1_COND is defined to a value, | |
62 | AT_FUNC_POST_FILE_PARAM_DECLS must include a parameter named flag; | |
63 | call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than | |
64 | AT_FUNC_USE_F1_COND. Return int and fail with -1 unless AT_FUNC_RESULT | |
65 | or AT_FUNC_FAIL are defined. If possible, do it without changing the | |
66 | working directory. Otherwise, resort to using save_cwd/fchdir, | |
67 | then AT_FUNC_F?/restore_cwd. If either the save_cwd or the restore_cwd | |
68 | fails, then give a diagnostic and exit nonzero. */ | |
69 | FUNC_RESULT | |
70 | AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS) | |
71 | { | |
72 | VALIDATE_FLAG (flag); | |
73 | ||
74 | if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file)) | |
75 | return CALL_FUNC (file); | |
76 | ||
77 | #ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD | |
78 | errno = ENOTSUP; | |
79 | return FUNC_FAIL; | |
80 | #else | |
81 | { | |
82 | /* Be careful to choose names unlikely to conflict with | |
83 | AT_FUNC_POST_FILE_PARAM_DECLS. */ | |
84 | struct saved_cwd saved_cwd; | |
85 | int saved_errno; | |
86 | FUNC_RESULT err; | |
87 | ||
88 | { | |
89 | char proc_buf[OPENAT_BUFFER_SIZE]; | |
90 | char *proc_file = openat_proc_name (proc_buf, fd, file); | |
91 | if (proc_file) | |
92 | { | |
93 | FUNC_RESULT proc_result = CALL_FUNC (proc_file); | |
94 | int proc_errno = errno; | |
95 | if (proc_file != proc_buf) | |
96 | free (proc_file); | |
97 | /* If the syscall succeeds, or if it fails with an unexpected | |
98 | errno value, then return right away. Otherwise, fall through | |
99 | and resort to using save_cwd/restore_cwd. */ | |
100 | if (FUNC_FAIL != proc_result) | |
101 | return proc_result; | |
102 | if (! EXPECTED_ERRNO (proc_errno)) | |
103 | { | |
104 | errno = proc_errno; | |
105 | return proc_result; | |
106 | } | |
107 | } | |
108 | } | |
109 | ||
110 | if (save_cwd (&saved_cwd) != 0) | |
111 | openat_save_fail (errno); | |
112 | if (0 <= fd && fd == saved_cwd.desc) | |
113 | { | |
114 | /* If saving the working directory collides with the user's | |
115 | requested fd, then the user's fd must have been closed to | |
116 | begin with. */ | |
117 | free_cwd (&saved_cwd); | |
118 | errno = EBADF; | |
119 | return FUNC_FAIL; | |
120 | } | |
121 | ||
122 | if (fchdir (fd) != 0) | |
123 | { | |
124 | saved_errno = errno; | |
125 | free_cwd (&saved_cwd); | |
126 | errno = saved_errno; | |
127 | return FUNC_FAIL; | |
128 | } | |
129 | ||
130 | err = CALL_FUNC (file); | |
131 | saved_errno = (err == FUNC_FAIL ? errno : 0); | |
132 | ||
133 | if (restore_cwd (&saved_cwd) != 0) | |
134 | openat_restore_fail (errno); | |
135 | ||
136 | free_cwd (&saved_cwd); | |
137 | ||
138 | if (saved_errno) | |
139 | errno = saved_errno; | |
140 | return err; | |
141 | } | |
142 | #endif | |
143 | } | |
144 | #undef CALL_FUNC | |
145 | #undef FUNC_RESULT | |
146 | #undef FUNC_FAIL |