1 /* Define an at-style functions like fstatat, unlinkat, fchownat, etc.
2 Copyright (C) 2006, 2009 Free Software Foundation, Inc.
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.
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.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* written by Jim Meyering */
19 #include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
21 #include "openat-priv.h"
24 #ifdef AT_FUNC_USE_F1_COND
25 # define CALL_FUNC(F) \
26 (flag == AT_FUNC_USE_F1_COND \
27 ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS) \
28 : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
29 # define VALIDATE_FLAG(F) \
30 if (flag & ~AT_FUNC_USE_F1_COND) \
36 # define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
37 # define VALIDATE_FLAG(F) /* empty */
41 # define FUNC_RESULT AT_FUNC_RESULT
43 # define FUNC_RESULT int
46 /* Call AT_FUNC_F1 to operate on FILE, which is in the directory
47 open on descriptor FD. If AT_FUNC_USE_F1_COND is defined to a value,
48 AT_FUNC_POST_FILE_PARAM_DECLS must inlude a parameter named flag;
49 call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
50 AT_FUNC_USE_F1_COND. If possible, do it without changing the
51 working directory. Otherwise, resort to using save_cwd/fchdir,
52 then AT_FUNC_F?/restore_cwd. If either the save_cwd or the restore_cwd
53 fails, then give a diagnostic and exit nonzero. */
55 AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
57 /* Be careful to choose names unlikely to conflict with
58 AT_FUNC_POST_FILE_PARAM_DECLS. */
59 struct saved_cwd saved_cwd;
65 if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
66 return CALL_FUNC (file);
69 char proc_buf[OPENAT_BUFFER_SIZE];
70 char *proc_file = openat_proc_name (proc_buf, fd, file);
73 FUNC_RESULT proc_result = CALL_FUNC (proc_file);
74 int proc_errno = errno;
75 if (proc_file != proc_buf)
77 /* If the syscall succeeds, or if it fails with an unexpected
78 errno value, then return right away. Otherwise, fall through
79 and resort to using save_cwd/restore_cwd. */
82 if (! EXPECTED_ERRNO (proc_errno))
90 if (save_cwd (&saved_cwd) != 0)
91 openat_save_fail (errno);
92 if (0 <= fd && fd == saved_cwd.desc)
94 /* If saving the working directory collides with the user's
95 requested fd, then the user's fd must have been closed to
97 free_cwd (&saved_cwd);
102 if (fchdir (fd) != 0)
105 free_cwd (&saved_cwd);
110 err = CALL_FUNC (file);
111 saved_errno = (err < 0 ? errno : 0);
113 if (restore_cwd (&saved_cwd) != 0)
114 openat_restore_fail (errno);
116 free_cwd (&saved_cwd);