1 /* Set the access and modification time of a file relative to directory fd.
2 Copyright (C) 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 Eric Blake */
26 #include "stat-time.h"
34 /* If we have a native utimensat, but are compiling this file, then
35 utimensat was defined to rpl_utimensat by our replacement
36 sys/stat.h. We assume the native version might fail with ENOSYS,
37 or succeed without properly affecting ctime (as is the case when
38 using newer glibc but older Linux kernel). In this scenario,
39 rpl_utimensat checks whether the native version is usable, and
40 local_utimensat provides the fallback manipulation. */
42 static int local_utimensat (int, char const *, struct timespec const[2], int);
43 # define AT_FUNC_NAME local_utimensat
45 /* Like utimensat, but work around native bugs. */
48 rpl_utimensat (int fd, char const *file, struct timespec const times[2],
51 /* See comments in utimens.c for details. */
52 static int utimensat_works_really; /* 0 = unknown, 1 = yes, -1 = no. */
53 static int utimensat_ctime_really; /* 0 = unknown, 1 = yes, -1 = no. */
54 if (0 <= utimensat_works_really)
59 struct timespec ts[2];
60 /* Linux kernel 2.6.32 has a bug where mtime of UTIME_OMIT fails
62 if (utimensat_ctime_really <= 0 && times
63 && times[0].tv_nsec != UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT)
65 if (fstatat (fd, file, &st1, flag))
67 if (utimensat_ctime_really < 0)
70 ts[1] = get_stat_mtime (&st1);
74 result = utimensat (fd, file, times, flag);
75 /* Linux kernel 2.6.25 has a bug where it returns EINVAL for
76 UTIME_NOW or UTIME_OMIT with non-zero tv_sec, which
77 local_utimensat works around. Meanwhile, EINVAL for a bad
78 flag is indeterminate whether the native utimensat works, but
79 local_utimensat will also reject it. */
80 if (result == -1 && errno == EINVAL && (flag & ~AT_SYMLINK_NOFOLLOW))
82 if (result == 0 || (errno != ENOSYS && errno != EINVAL))
84 utimensat_works_really = 1;
85 if (result == 0 && utimensat_ctime_really == 0 && times
86 && times[0].tv_nsec != UTIME_OMIT
87 && times[1].tv_nsec == UTIME_OMIT)
89 /* Perform a followup [l]stat. See detect_ctime_bug in
90 utimens.c for more details. */
92 if (fstatat (fd, file, &st2, flag))
94 if (st1.st_ctime != st2.st_ctime
95 || get_stat_ctime_ns (&st1) != get_stat_ctime_ns (&st2))
97 utimensat_ctime_really = 1;
100 if (times[0].tv_nsec == UTIME_NOW)
101 now = get_stat_atime (&st2);
104 if (now.tv_sec < st2.st_ctime
105 || 2 < now.tv_sec - st2.st_ctime
106 || (get_stat_ctime_ns (&st2)
107 && now.tv_sec - st2.st_ctime < 2
108 && (20000000 < (1000000000 * (now.tv_sec - st2.st_ctime)
110 - get_stat_ctime_ns (&st2)))))
111 utimensat_ctime_really = -1;
113 ts[1] = get_stat_mtime (&st2);
114 result = utimensat (fd, file, ts, flag);
119 /* No point in trying openat/futimens, since on Linux, futimens is
120 implemented with the same syscall as utimensat. Only avoid the
121 native utimensat due to an ENOSYS failure; an EINVAL error was
122 data-dependent, and the next caller may pass valid data. */
123 if (0 <= utimensat_works_really && errno == ENOSYS)
124 utimensat_works_really = -1;
125 return local_utimensat (fd, file, times, flag);
128 #else /* !HAVE_UTIMENSAT */
130 # define AT_FUNC_NAME utimensat
132 #endif /* !HAVE_UTIMENSAT */
134 /* Set the access and modification time stamps of FILE to be
135 TIMESPEC[0] and TIMESPEC[1], respectively; relative to directory
136 FD. If flag is AT_SYMLINK_NOFOLLOW, change the times of a symlink,
137 or fail with ENOSYS if not possible. If TIMESPEC is null, set the
138 time stamps to the current time. If possible, do it without
139 changing the working directory. Otherwise, resort to using
140 save_cwd/fchdir, then utimens/restore_cwd. If either the save_cwd
141 or the restore_cwd fails, then give a diagnostic and exit nonzero.
142 Return 0 on success, -1 (setting errno) on failure. */
144 /* AT_FUNC_NAME is now utimensat or local_utimensat. */
145 #define AT_FUNC_F1 lutimens
146 #define AT_FUNC_F2 utimens
147 #define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW
148 #define AT_FUNC_POST_FILE_PARAM_DECLS , struct timespec const ts[2], int flag
149 #define AT_FUNC_POST_FILE_ARGS , ts
154 #undef AT_FUNC_USE_F1_COND
155 #undef AT_FUNC_POST_FILE_PARAM_DECLS
156 #undef AT_FUNC_POST_FILE_ARGS