/* Set file access and modification times.
- Copyright (C) 2003-2009 Free Software Foundation, Inc.
+ Copyright (C) 2003-2014 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
#include <config.h>
+#define _GL_UTIMENS_INLINE _GL_EXTERN_INLINE
#include "utimens.h"
#include <assert.h>
utimensat doesn't exist, or is in glibc but kernel 2.6.18 fails with ENOSYS
kernel 2.6.22 and earlier rejects AT_SYMLINK_NOFOLLOW
kernel 2.6.25 and earlier reject UTIME_NOW/UTIME_OMIT with non-zero tv_sec
- kernel 2.6.32 and earlier fail to bump ctime if mtime is UTIME_OMIT
+ kernel 2.6.32 used with xfs or ntfs-3g fail to honor UTIME_OMIT
utimensat completely works
For each cache variable: 0 = unknown, 1 = yes, -1 = no. */
static int utimensat_works_really;
static int lutimensat_works_really;
-static int utimensat_ctime_really;
-
-/* Determine whether the kernel has a ctime bug. ST1 and ST2
- correspond to stat data before and after a successful time change.
- TIMES contains the timestamps that were used during the time change
- (mtime will be UTIME_OMIT). Update the cache variable if there is
- conclusive evidence of the kernel working or being buggy. Return
- true if TIMES has been updated and another kernel call is needed,
- whether or not the kernel is known to have the bug. */
-static bool
-detect_ctime_bug (struct stat *st1, struct stat *st2, struct timespec times[2])
-{
- struct timespec now;
- if (st1->st_ctime != st2->st_ctime
- || get_stat_ctime_ns (st1) != get_stat_ctime_ns (st2))
- {
- utimensat_ctime_really = 1;
- return false;
- }
- /* The results are inconclusive if the ctime in st1 is within a file
- system quantization window of now. For FAT, this is 2 seconds,
- for systems with sub-second resolution, a typical resolution is
- 10 milliseconds; to be safe we declare an inconsistent result if
- ctime is within a 20 millisecond window. Avoid an extra gettime
- call if atime makes sense. It is unlikely that the original
- ctime is later than now, but rather than deal with the overflow,
- we treat that as consistent evidence of the bug. */
- if (times[0].tv_nsec == UTIME_NOW)
- now = get_stat_atime (st2);
- else
- gettime (&now);
- if (now.tv_sec < st2->st_ctime
- || 2 < now.tv_sec - st2->st_ctime
- || (get_stat_ctime_ns (st2)
- && now.tv_sec - st2->st_ctime < 2
- && (20000000 < (1000000000 * (now.tv_sec - st2->st_ctime)
- + now.tv_nsec - get_stat_ctime_ns (st2)))))
- utimensat_ctime_really = -1;
- times[1] = get_stat_mtime (st2);
- return true;
-}
#endif /* HAVE_UTIMENSAT || HAVE_FUTIMENS */
/* Validate the requested timestamps. Return 0 if the resulting
timespec can be used for utimensat (after possibly modifying it to
work around bugs in utimensat). Return a positive value if the
timespec needs further adjustment based on stat results: 1 if any
- adjustment is needed for utimes, and 2 if mtime was UTIME_OMIT and
- an adjustment is needed for utimensat. Return -1, with errno set
- to EINVAL, if timespec is out of range. */
+ adjustment is needed for utimes, and 2 if any adjustment is needed
+ for Linux utimensat. Return -1, with errno set to EINVAL, if
+ timespec is out of range. */
static int
validate_timespec (struct timespec timespec[2])
{
int result = 0;
+ int utime_omit_count = 0;
assert (timespec);
if ((timespec[0].tv_nsec != UTIME_NOW
&& timespec[0].tv_nsec != UTIME_OMIT
- && (timespec[0].tv_nsec < 0 || 1000000000 <= timespec[0].tv_nsec))
+ && ! (0 <= timespec[0].tv_nsec
+ && timespec[0].tv_nsec < TIMESPEC_RESOLUTION))
|| (timespec[1].tv_nsec != UTIME_NOW
&& timespec[1].tv_nsec != UTIME_OMIT
- && (timespec[1].tv_nsec < 0 || 1000000000 <= timespec[1].tv_nsec)))
+ && ! (0 <= timespec[1].tv_nsec
+ && timespec[1].tv_nsec < TIMESPEC_RESOLUTION)))
{
errno = EINVAL;
return -1;
{
timespec[0].tv_sec = 0;
result = 1;
+ if (timespec[0].tv_nsec == UTIME_OMIT)
+ utime_omit_count++;
}
- if (timespec[1].tv_nsec == UTIME_NOW)
+ if (timespec[1].tv_nsec == UTIME_NOW
+ || timespec[1].tv_nsec == UTIME_OMIT)
{
timespec[1].tv_sec = 0;
result = 1;
+ if (timespec[1].tv_nsec == UTIME_OMIT)
+ utime_omit_count++;
}
- else if (timespec[1].tv_nsec == UTIME_OMIT)
- {
- timespec[1].tv_sec = 0;
- result = 2;
- }
- return result;
+ return result + (utime_omit_count == 1);
}
/* Normalize any UTIME_NOW or UTIME_OMIT values in *TS, using stat
Return 0 on success, -1 (setting errno) on failure. */
int
-fdutimens (char const *file, int fd, struct timespec const timespec[2])
+fdutimens (int fd, char const *file, struct timespec const timespec[2])
{
struct timespec adjusted_timespec[2];
struct timespec *ts = timespec ? adjusted_timespec : NULL;
int adjustment_needed = 0;
+ struct stat st;
if (ts)
{
if (adjustment_needed < 0)
return -1;
- /* Require that at least one of FD or FILE are valid. Works around
+ /* Require that at least one of FD or FILE are potentially valid, to avoid
a Linux bug where futimens (AT_FDCWD, NULL) changes "." rather
than failing. */
- if (!file)
+ if (fd < 0 && !file)
{
- if (fd < 0)
- {
- errno = EBADF;
- return -1;
- }
- if (dup2 (fd, fd) != fd)
- return -1;
+ errno = EBADF;
+ return -1;
}
/* Some Linux-based NFS clients are buggy, and mishandle time stamps
if (0 <= utimensat_works_really)
{
int result;
- struct stat st1;
- struct stat st2;
- /* Linux kernel 2.6.32 has a bug where it fails to bump ctime if
- UTIME_OMIT was used for mtime. It costs time to do an extra
- [f]stat up front, so we cache whether the function works. */
- if (utimensat_ctime_really <= 0 && adjustment_needed == 2)
+# if __linux__ || __sun
+ /* 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 [f]stat prior
+ to calling futimens/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 for Linux in 2016 and for Solaris in
+ 2024, when file system bugs are no longer common. */
+ if (adjustment_needed == 2)
{
- if (fd < 0 ? stat (file, &st1) : fstat (fd, &st1))
+ if (fd < 0 ? stat (file, &st) : fstat (fd, &st))
return -1;
if (ts[0].tv_nsec == UTIME_OMIT)
- return 0;
- if (utimensat_ctime_really < 0)
- ts[1] = get_stat_mtime (&st1);
+ ts[0] = get_stat_atime (&st);
+ else if (ts[1].tv_nsec == UTIME_OMIT)
+ ts[1] = get_stat_mtime (&st);
+ /* Note that st is good, in case utimensat gives ENOSYS. */
+ adjustment_needed++;
}
+# endif
# if HAVE_UTIMENSAT
if (fd < 0)
{
if (result == 0 || errno != ENOSYS)
{
utimensat_works_really = 1;
- if (result == 0 && utimensat_ctime_really == 0
- && adjustment_needed == 2)
- {
- /* Perform a followup stat to see if the kernel has
- a ctime bug. */
- if (stat (file, &st2))
- return -1;
- if (detect_ctime_bug (&st1, &st2, ts))
- result = utimensat (AT_FDCWD, file, ts, 0);
- }
return result;
}
}
# endif /* HAVE_UTIMENSAT */
# if HAVE_FUTIMENS
- {
- result = futimens (fd, ts);
+ if (0 <= fd)
+ {
+ result = futimens (fd, ts);
# ifdef __linux__
- /* Work around the same bug as above. */
- if (0 < result)
- errno = ENOSYS;
+ /* Work around the same bug as above. */
+ if (0 < result)
+ errno = ENOSYS;
# endif /* __linux__ */
- if (result == 0 || errno != ENOSYS)
- {
- utimensat_works_really = 1;
- /* Work around the same bug as above. */
- if (result == 0 && utimensat_ctime_really == 0
- && adjustment_needed == 2)
- {
- if (fstat (fd, &st2))
- return -1;
- if (detect_ctime_bug (&st1, &st2, ts))
- result = futimens (fd, ts);
- }
- return result;
- }
- }
+ if (result == 0 || errno != ENOSYS)
+ {
+ utimensat_works_really = 1;
+ return result;
+ }
+ }
# endif /* HAVE_FUTIMENS */
}
utimensat_works_really = -1;
if (adjustment_needed || (REPLACE_FUNC_STAT_FILE && fd < 0))
{
- struct stat st;
- if (fd < 0 ? stat (file, &st) : fstat (fd, &st))
+ if (adjustment_needed != 3
+ && (fd < 0 ? stat (file, &st) : fstat (fd, &st)))
return -1;
if (ts && update_timespec (&st, &ts))
return 0;
{
#if HAVE_FUTIMESAT || HAVE_WORKING_UTIMES
struct timeval timeval[2];
- struct timeval const *t;
+ struct timeval *t;
if (ts)
{
timeval[0].tv_sec = ts[0].tv_sec;
worth optimizing, and who knows what other messed-up systems
are out there? So play it safe and fall back on the code
below. */
-# if HAVE_FUTIMESAT && !FUTIMESAT_NULL_BUG
- if (futimesat (fd, NULL, t) == 0)
- return 0;
-# elif HAVE_FUTIMES
+
+# if (HAVE_FUTIMESAT && !FUTIMESAT_NULL_BUG) || HAVE_FUTIMES
+# if HAVE_FUTIMESAT && !FUTIMESAT_NULL_BUG
+# undef futimes
+# define futimes(fd, t) futimesat (fd, NULL, t)
+# endif
if (futimes (fd, t) == 0)
- return 0;
+ {
+# if __linux__ && __GLIBC__
+ /* Work around a longstanding glibc bug, still present as
+ of 2010-12-27. On older Linux kernels that lack both
+ utimensat and utimes, glibc's futimes rounds instead of
+ truncating when falling back on utime. The same bug
+ occurs in futimesat with a null 2nd arg. */
+ if (t)
+ {
+ bool abig = 500000 <= t[0].tv_usec;
+ bool mbig = 500000 <= t[1].tv_usec;
+ if ((abig | mbig) && fstat (fd, &st) == 0)
+ {
+ /* If these two subtractions overflow, they'll
+ track the overflows inside the buggy glibc. */
+ time_t adiff = st.st_atime - t[0].tv_sec;
+ time_t mdiff = st.st_mtime - t[1].tv_sec;
+
+ struct timeval *tt = NULL;
+ struct timeval truncated_timeval[2];
+ truncated_timeval[0] = t[0];
+ truncated_timeval[1] = t[1];
+ if (abig && adiff == 1 && get_stat_atime_ns (&st) == 0)
+ {
+ tt = truncated_timeval;
+ tt[0].tv_usec = 0;
+ }
+ if (mbig && mdiff == 1 && get_stat_mtime_ns (&st) == 0)
+ {
+ tt = truncated_timeval;
+ tt[1].tv_usec = 0;
+ }
+ if (tt)
+ futimes (fd, tt);
+ }
+ }
+# endif
+
+ return 0;
+ }
# endif
}
#endif /* HAVE_FUTIMESAT || HAVE_WORKING_UTIMES */
}
}
-/* Set the access and modification time stamps of FD (a.k.a. FILE) to be
- TIMESPEC[0] and TIMESPEC[1], respectively.
- FD must be either negative -- in which case it is ignored --
- or a file descriptor that is open on FILE.
- If FD is nonnegative, then FILE can be NULL, which means
- use just futimes (or equivalent) instead of utimes (or equivalent),
- and fail if on an old system without futimes (or equivalent).
- If TIMESPEC is null, set the time stamps to the current time.
- Return 0 on success, -1 (setting errno) on failure. */
-
-int
-gl_futimens (int fd, char const *file, struct timespec const timespec[2])
-{
- return fdutimens (file, fd, timespec);
-}
-
/* Set the access and modification time stamps of FILE to be
TIMESPEC[0] and TIMESPEC[1], respectively. */
int
utimens (char const *file, struct timespec const timespec[2])
{
- return fdutimens (file, -1, timespec);
+ return fdutimens (-1, file, timespec);
}
/* Set the access and modification time stamps of FILE to be
/* The Linux kernel did not support symlink timestamps until
utimensat, in version 2.6.22, so we don't need to mimic
- gl_futimens' worry about buggy NFS clients. But we do have to
+ fdutimens' worry about buggy NFS clients. But we do have to
worry about bogus return values. */
#if HAVE_UTIMENSAT
if (0 <= lutimensat_works_really)
{
int result;
- struct stat st1;
- struct stat st2;
- /* Linux kernel 2.6.32 has a bug where it fails to bump ctime if
- UTIME_OMIT was used for mtime. It costs time to do an extra
- lstat up front, so we cache whether the function works. */
- if (utimensat_ctime_really <= 0 && adjustment_needed == 2)
+# if __linux__ || __sun
+ /* 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 lstat 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 for Linux in 2016 and for Solaris in
+ 2024, when file system bugs are no longer common. */
+ if (adjustment_needed == 2)
{
- if (lstat (file, &st1))
+ if (lstat (file, &st))
return -1;
if (ts[0].tv_nsec == UTIME_OMIT)
- return 0;
- if (utimensat_ctime_really < 0)
- ts[1] = get_stat_mtime (&st1);
+ ts[0] = get_stat_atime (&st);
+ else if (ts[1].tv_nsec == UTIME_OMIT)
+ ts[1] = get_stat_mtime (&st);
+ /* Note that st is good, in case utimensat gives ENOSYS. */
+ adjustment_needed++;
}
+# endif
result = utimensat (AT_FDCWD, file, ts, AT_SYMLINK_NOFOLLOW);
# ifdef __linux__
/* Work around a kernel bug:
{
utimensat_works_really = 1;
lutimensat_works_really = 1;
- if (result == 0 && utimensat_ctime_really == 0
- && adjustment_needed == 2)
- {
- /* Perform a followup stat to see if the kernel has a
- ctime bug. */
- if (lstat (file, &st2))
- return -1;
- if (detect_ctime_bug (&st1, &st2, ts))
- result = utimensat (AT_FDCWD, file, ts, AT_SYMLINK_NOFOLLOW);
- }
return result;
}
}
if (adjustment_needed || REPLACE_FUNC_STAT_FILE)
{
- if (lstat (file, &st))
+ if (adjustment_needed != 3 && lstat (file, &st))
return -1;
if (ts && update_timespec (&st, &ts))
return 0;
#if HAVE_LUTIMES && !HAVE_UTIMENSAT
{
struct timeval timeval[2];
- struct timeval const *t;
+ struct timeval *t;
int result;
if (ts)
{
if (!(adjustment_needed || REPLACE_FUNC_STAT_FILE) && lstat (file, &st))
return -1;
if (!S_ISLNK (st.st_mode))
- return fdutimens (file, -1, ts);
+ return fdutimens (-1, file, ts);
errno = ENOSYS;
return -1;
}
projects / gnulib.git / blobdiff