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Diffstat (limited to 'lib/utimensat.c')
| -rw-r--r-- | lib/utimensat.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/lib/utimensat.c b/lib/utimensat.c new file mode 100644 index 0000000..f81b0c7 --- /dev/null +++ b/lib/utimensat.c @@ -0,0 +1,217 @@ +/* Set the access and modification time of a file relative to directory fd. + Copyright (C) 2009-2022 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 <string.h> +#include <sys/stat.h> + +#include "stat-time.h" +#include "timespec.h" +#include "utimens.h" + +#if HAVE_NEARLY_WORKING_UTIMENSAT + +/* Use the original utimensat(), but correct the trailing slash handling. */ +int +rpl_utimensat (int fd, char const *file, struct timespec const times[2], + int flag) +# undef utimensat +{ + size_t len = strlen (file); + if (len && file[len - 1] == '/') + { + struct stat st; + if (fstatat (fd, file, &st, flag & AT_SYMLINK_NOFOLLOW) < 0) + return -1; + if (!S_ISDIR (st.st_mode)) + { + errno = ENOTDIR; + return -1; + } + } + + return utimensat (fd, file, times, flag); +} + +#else + +# if HAVE_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) +# undef utimensat +{ +# 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 +# if defined __APPLE__ && defined __MACH__ + /* macOS 10.13 does not reject invalid tv_nsec values either. */ + if (times + && ((times[0].tv_nsec != UTIME_OMIT + && times[0].tv_nsec != UTIME_NOW + && ! (0 <= times[0].tv_nsec + && times[0].tv_nsec < TIMESPEC_HZ)) + || (times[1].tv_nsec != UTIME_OMIT + && times[1].tv_nsec != UTIME_NOW + && ! (0 <= times[1].tv_nsec + && times[1].tv_nsec < TIMESPEC_HZ)))) + { + errno = EINVAL; + return -1; + } + size_t len = strlen (file); + if (len > 0 && file[len - 1] == '/') + { + struct stat statbuf; + if (fstatat (fd, file, &statbuf, 0) < 0) + return -1; + if (!S_ISDIR (statbuf.st_mode)) + { + errno = ENOTDIR; + return -1; + } + } +# 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 + +#endif /* !HAVE_NEARLY_WORKING_UTIMENSAT */ |