1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/* Define at-style functions like fstatat, unlinkat, fchownat, etc.
Copyright (C) 2006, 2009-2024 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* written by Jim Meyering */
#include "filename.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
#ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD
# include <errno.h>
# ifndef ENOTSUP
# define ENOTSUP EINVAL
# endif
#else
# include "openat.h"
# include "openat-priv.h"
# include "save-cwd.h"
#endif
#ifdef AT_FUNC_USE_F1_COND
# define CALL_FUNC(F) \
(flag == AT_FUNC_USE_F1_COND \
? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS) \
: AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
# define VALIDATE_FLAG(F) \
if (flag & ~AT_FUNC_USE_F1_COND) \
{ \
errno = EINVAL; \
return FUNC_FAIL; \
}
#else
# define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
# define VALIDATE_FLAG(F) /* empty */
#endif
#ifdef AT_FUNC_RESULT
# define FUNC_RESULT AT_FUNC_RESULT
#else
# define FUNC_RESULT int
#endif
#ifdef AT_FUNC_FAIL
# define FUNC_FAIL AT_FUNC_FAIL
#else
# define FUNC_FAIL -1
#endif
/* Call AT_FUNC_F1 to operate on FILE, which is in the directory
open on descriptor FD. If AT_FUNC_USE_F1_COND is defined to a value,
AT_FUNC_POST_FILE_PARAM_DECLS must include a parameter named flag;
call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
AT_FUNC_USE_F1_COND. Return int and fail with -1 unless AT_FUNC_RESULT
or AT_FUNC_FAIL are defined. If possible, do it without changing the
working directory. Otherwise, resort to using save_cwd/fchdir,
then AT_FUNC_F?/restore_cwd. If either the save_cwd or the restore_cwd
fails, then give a diagnostic and exit nonzero. */
FUNC_RESULT
AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
{
VALIDATE_FLAG (flag);
if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
return CALL_FUNC (file);
#ifdef GNULIB_SUPPORT_ONLY_AT_FDCWD
errno = ENOTSUP;
return FUNC_FAIL;
#else
{
/* Be careful to choose names unlikely to conflict with
AT_FUNC_POST_FILE_PARAM_DECLS. */
struct saved_cwd saved_cwd;
int saved_errno;
FUNC_RESULT err;
{
char proc_buf[OPENAT_BUFFER_SIZE];
char *proc_file = openat_proc_name (proc_buf, fd, file);
if (proc_file)
{
FUNC_RESULT proc_result = CALL_FUNC (proc_file);
int proc_errno = errno;
if (proc_file != proc_buf)
free (proc_file);
/* If the syscall succeeds, or if it fails with an unexpected
errno value, then return right away. Otherwise, fall through
and resort to using save_cwd/restore_cwd. */
if (FUNC_FAIL != proc_result)
return proc_result;
if (! EXPECTED_ERRNO (proc_errno))
{
errno = proc_errno;
return proc_result;
}
}
}
if (save_cwd (&saved_cwd) != 0)
openat_save_fail (errno);
if (0 <= fd && fd == saved_cwd.desc)
{
/* If saving the working directory collides with the user's
requested fd, then the user's fd must have been closed to
begin with. */
free_cwd (&saved_cwd);
errno = EBADF;
return FUNC_FAIL;
}
if (fchdir (fd) != 0)
{
saved_errno = errno;
free_cwd (&saved_cwd);
errno = saved_errno;
return FUNC_FAIL;
}
err = CALL_FUNC (file);
saved_errno = (err == FUNC_FAIL ? errno : 0);
if (restore_cwd (&saved_cwd) != 0)
openat_restore_fail (errno);
free_cwd (&saved_cwd);
if (saved_errno)
errno = saved_errno;
return err;
}
#endif
}
#undef CALL_FUNC
#undef FUNC_RESULT
#undef FUNC_FAIL
|
