| 1 | /* Define at-style functions like fstatat, unlinkat, fchownat, etc. |
| 2 | Copyright (C) 2006, 2009-2016 Free Software Foundation, Inc. |
| 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 |
| 15 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 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 |