/* Set the access and modification time of a file relative to directory fd. Copyright (C) 2009-2019 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 . */ /* written by Eric Blake */ #include #include #include #include #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