| 1 | /* Define an at-style functions like fstatat, unlinkat, fchownat, etc.
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| 2 | Copyright (C) 2006 Free Software Foundation, Inc.
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| 3 |
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| 4 | This program is free software; you can redistribute it and/or modify
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| 5 | it under the terms of the GNU General Public License as published by
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| 6 | the Free Software Foundation; either version 2, or (at your option)
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| 7 | any later version.
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| 8 |
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| 9 | This program is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU General Public License
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| 15 | along with this program; if not, write to the Free Software Foundation,
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| 16 | Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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| 17 |
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| 18 | /* written by Jim Meyering */
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| 19 |
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| 20 | #define CALL_FUNC(F) \
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| 21 | (AT_FUNC_USE_F1_COND \
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| 22 | ? AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS) \
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| 23 | : AT_FUNC_F2 (F AT_FUNC_POST_FILE_ARGS))
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| 24 |
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| 25 | /* Call AT_FUNC_F1 or AT_FUNC_F2 (testing AT_FUNC_USE_F1_COND to
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| 26 | determine which) to operate on FILE, which is in the directory
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| 27 | open on descriptor FD. If possible, do it without changing the
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| 28 | working directory. Otherwise, resort to using save_cwd/fchdir,
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| 29 | then AT_FUNC_F?/restore_cwd. If either the save_cwd or the restore_cwd
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| 30 | fails, then give a diagnostic and exit nonzero. */
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| 31 | int
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| 32 | AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
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| 33 | {
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| 34 | struct saved_cwd saved_cwd;
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| 35 | int saved_errno;
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| 36 | int err;
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| 37 |
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| 38 | if (fd == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file))
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| 39 | return CALL_FUNC (file);
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| 40 |
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| 41 | {
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| 42 | char buf[OPENAT_BUFFER_SIZE];
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| 43 | char *proc_file = openat_proc_name (buf, fd, file);
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| 44 | if (proc_file)
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| 45 | {
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| 46 | int proc_result = CALL_FUNC (proc_file);
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| 47 | int proc_errno = errno;
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| 48 | if (proc_file != buf)
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| 49 | free (proc_file);
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| 50 | /* If the syscall succeeds, or if it fails with an unexpected
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| 51 | errno value, then return right away. Otherwise, fall through
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| 52 | and resort to using save_cwd/restore_cwd. */
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| 53 | if (0 <= proc_result)
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| 54 | return proc_result;
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| 55 | if (! EXPECTED_ERRNO (proc_errno))
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| 56 | {
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| 57 | errno = proc_errno;
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| 58 | return proc_result;
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| 59 | }
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| 60 | }
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| 61 | }
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| 62 |
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| 63 | if (save_cwd (&saved_cwd) != 0)
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| 64 | openat_save_fail (errno);
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| 65 |
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| 66 | if (fchdir (fd) != 0)
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| 67 | {
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| 68 | saved_errno = errno;
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| 69 | free_cwd (&saved_cwd);
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| 70 | errno = saved_errno;
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| 71 | return -1;
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| 72 | }
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| 73 |
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| 74 | err = CALL_FUNC (file);
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| 75 | saved_errno = (err < 0 ? errno : 0);
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| 76 |
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| 77 | if (restore_cwd (&saved_cwd) != 0)
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| 78 | openat_restore_fail (errno);
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| 79 |
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| 80 | free_cwd (&saved_cwd);
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| 81 |
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| 82 | if (saved_errno)
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| 83 | errno = saved_errno;
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| 84 | return err;
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| 85 | }
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| 86 | #undef CALL_FUNC
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