| /* Set the access and modification time of a file relative to directory fd. |
| Copyright (C) 2009-2020 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 Eric Blake */ |
| |
| #include <config.h> |
| |
| /* Specification. */ |
| #include <sys/stat.h> |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <stdlib.h> |
| |
| #include "stat-time.h" |
| #include "timespec.h" |
| #include "utimens.h" |
| |
| #if HAVE_UTIMENSAT |
| |
| # undef utimensat |
| |
| /* If we have a native utimensat, but are compiling this file, then |
| utimensat was defined to rpl_utimensat by our replacement |
| sys/stat.h. We assume the native version might fail with ENOSYS, |
| or succeed without properly affecting ctime (as is the case when |
| using newer glibc but older Linux kernel). In this scenario, |
| rpl_utimensat checks whether the native version is usable, and |
| local_utimensat provides the fallback manipulation. */ |
| |
| static int local_utimensat (int, char const *, struct timespec const[2], int); |
| # define AT_FUNC_NAME local_utimensat |
| |
| /* Like utimensat, but work around native bugs. */ |
| |
| int |
| rpl_utimensat (int fd, char const *file, struct timespec const times[2], |
| int flag) |
| { |
| # if defined __linux__ || defined __sun |
| struct timespec ts[2]; |
| # endif |
| |
| /* See comments in utimens.c for details. */ |
| static int utimensat_works_really; /* 0 = unknown, 1 = yes, -1 = no. */ |
| if (0 <= utimensat_works_really) |
| { |
| int result; |
| # if defined __linux__ || defined __sun |
| struct stat st; |
| /* As recently as Linux kernel 2.6.32 (Dec 2009), several file |
| systems (xfs, ntfs-3g) have bugs with a single UTIME_OMIT, |
| but work if both times are either explicitly specified or |
| UTIME_NOW. Work around it with a preparatory [l]stat prior |
| to calling utimensat; fortunately, there is not much timing |
| impact due to the extra syscall even on file systems where |
| UTIME_OMIT would have worked. |
| |
| The same bug occurs in Solaris 11.1 (Apr 2013). |
| |
| FIXME: Simplify this in 2024, when these file system bugs are |
| no longer common on Gnulib target platforms. */ |
| if (times && (times[0].tv_nsec == UTIME_OMIT |
| || times[1].tv_nsec == UTIME_OMIT)) |
| { |
| if (fstatat (fd, file, &st, flag)) |
| return -1; |
| if (times[0].tv_nsec == UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT) |
| return 0; |
| if (times[0].tv_nsec == UTIME_OMIT) |
| ts[0] = get_stat_atime (&st); |
| else |
| ts[0] = times[0]; |
| if (times[1].tv_nsec == UTIME_OMIT) |
| ts[1] = get_stat_mtime (&st); |
| else |
| ts[1] = times[1]; |
| times = ts; |
| } |
| # ifdef __hppa__ |
| /* Linux kernel 2.6.22.19 on hppa does not reject invalid tv_nsec |
| values. */ |
| else if (times |
| && ((times[0].tv_nsec != UTIME_NOW |
| && ! (0 <= times[0].tv_nsec |
| && times[0].tv_nsec < TIMESPEC_HZ)) |
| || (times[1].tv_nsec != UTIME_NOW |
| && ! (0 <= times[1].tv_nsec |
| && times[1].tv_nsec < TIMESPEC_HZ)))) |
| { |
| errno = EINVAL; |
| return -1; |
| } |
| # endif |
| # endif |
| result = utimensat (fd, file, times, flag); |
| /* Linux kernel 2.6.25 has a bug where it returns EINVAL for |
| UTIME_NOW or UTIME_OMIT with non-zero tv_sec, which |
| local_utimensat works around. Meanwhile, EINVAL for a bad |
| flag is indeterminate whether the native utimensat works, but |
| local_utimensat will also reject it. */ |
| if (result == -1 && errno == EINVAL && (flag & ~AT_SYMLINK_NOFOLLOW)) |
| return result; |
| if (result == 0 || (errno != ENOSYS && errno != EINVAL)) |
| { |
| utimensat_works_really = 1; |
| return result; |
| } |
| } |
| /* No point in trying openat/futimens, since on Linux, futimens is |
| implemented with the same syscall as utimensat. Only avoid the |
| native utimensat due to an ENOSYS failure; an EINVAL error was |
| data-dependent, and the next caller may pass valid data. */ |
| if (0 <= utimensat_works_really && errno == ENOSYS) |
| utimensat_works_really = -1; |
| return local_utimensat (fd, file, times, flag); |
| } |
| |
| #else /* !HAVE_UTIMENSAT */ |
| |
| # define AT_FUNC_NAME utimensat |
| |
| #endif /* !HAVE_UTIMENSAT */ |
| |
| /* Set the access and modification timestamps of FILE to be |
| TIMESPEC[0] and TIMESPEC[1], respectively; relative to directory |
| FD. If flag is AT_SYMLINK_NOFOLLOW, change the times of a symlink, |
| or fail with ENOSYS if not possible. If TIMESPEC is null, set the |
| timestamps to the current time. If possible, do it without |
| changing the working directory. Otherwise, resort to using |
| save_cwd/fchdir, then utimens/restore_cwd. If either the save_cwd |
| or the restore_cwd fails, then give a diagnostic and exit nonzero. |
| Return 0 on success, -1 (setting errno) on failure. */ |
| |
| /* AT_FUNC_NAME is now utimensat or local_utimensat. */ |
| #define AT_FUNC_F1 lutimens |
| #define AT_FUNC_F2 utimens |
| #define AT_FUNC_USE_F1_COND AT_SYMLINK_NOFOLLOW |
| #define AT_FUNC_POST_FILE_PARAM_DECLS , struct timespec const ts[2], int flag |
| #define AT_FUNC_POST_FILE_ARGS , ts |
| #include "at-func.c" |
| #undef AT_FUNC_NAME |
| #undef AT_FUNC_F1 |
| #undef AT_FUNC_F2 |
| #undef AT_FUNC_USE_F1_COND |
| #undef AT_FUNC_POST_FILE_PARAM_DECLS |
| #undef AT_FUNC_POST_FILE_ARGS |
