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[gnulib.git] / lib / utimens.c

diff --git a/lib/utimens.c b/lib/utimens.c
index 4448f19..b33f883 100644 (file)
--- a/lib/utimens.c
+++ b/lib/utimens.c
@@ -1,8 +1,11 @@
-/* Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
+/* Set file access and modification times.

 
 

-   This program is free software; you can redistribute it and/or modify it
+   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 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
    under the terms of the GNU General Public License as published by the

-   Free Software Foundation; either version 2, or (at your option) any
+   Free Software Foundation; either version 3 of the License, or any

    later version.
 
    This program is distributed in the hope that it will be useful,
    later version.
 
    This program is distributed in the hope that it will be useful,


@@ -11,20 +14,26 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    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, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

 
 /* Written by Paul Eggert.  */
 
 /* derived from a function in touch.c */
 
 
 /* Written by Paul Eggert.  */
 
 /* derived from a function in touch.c */
 

-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>

 
 #include "utimens.h"
 
 
 #include "utimens.h"
 

+#include <assert.h>

 #include <errno.h>
 #include <errno.h>

+#include <fcntl.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+#include "stat-time.h"
+#include "timespec.h"

 
 #if HAVE_UTIME_H
 # include <utime.h>
 
 #if HAVE_UTIME_H
 # include <utime.h>


@@ -40,76 +49,294 @@ struct utimbuf
 };
 #endif
 
 };
 #endif
 

-#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8) || __STRICT_ANSI__
-# define __attribute__(x)
-#endif
+/* Avoid recursion with rpl_futimens or rpl_utimensat.  */
+#undef futimens
+#undef utimensat

 
 

-#ifndef ATTRIBUTE_UNUSED
-# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
-#endif
+#if HAVE_UTIMENSAT || HAVE_FUTIMENS
+/* Cache variable for whether syscall works; used to avoid calling the
+   syscall if we know it will just fail with ENOSYS.  0 = unknown, 1 =
+   yes, -1 = no.  */
+static int utimensat_works_really;
+#endif /* HAVE_UTIMENSAT || HAVE_UTIMENSAT */
+
+/* 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 1 if the timespec needs
+   further adjustment based on stat results for utimes or other less
+   powerful interfaces.  Return -1, with errno set to EINVAL, if
+   timespec is out of range.  */
+static int
+validate_timespec (struct timespec timespec[2])
+{
+  int result = 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))
+      || (timespec[1].tv_nsec != UTIME_NOW
+          && timespec[1].tv_nsec != UTIME_OMIT
+          && (timespec[1].tv_nsec < 0 || 1000000000 <= timespec[1].tv_nsec)))
+    {
+      errno = EINVAL;
+      return -1;
+    }
+  /* Work around Linux kernel 2.6.25 bug, where utimensat fails with
+     EINVAL if tv_sec is not 0 when using the flag values of
+     tv_nsec.  */
+  if (timespec[0].tv_nsec == UTIME_NOW
+      || timespec[0].tv_nsec == UTIME_OMIT)
+    {
+      timespec[0].tv_sec = 0;
+      result = 1;
+    }
+  if (timespec[1].tv_nsec == UTIME_NOW
+      || timespec[1].tv_nsec == UTIME_OMIT)
+    {
+      timespec[1].tv_sec = 0;
+      result = 1;
+    }
+  return result;
+}
+
+/* Normalize any UTIME_NOW or UTIME_OMIT values in *TS, using stat
+   buffer STATBUF to obtain the current timestamps of the file.  If
+   both times are UTIME_NOW, set *TS to NULL (as this can avoid some
+   permissions issues).  If both times are UTIME_OMIT, return true
+   (nothing further beyond the prior collection of STATBUF is
+   necessary); otherwise return false.  */
+static bool
+update_timespec (struct stat const *statbuf, struct timespec *ts[2])
+{
+  struct timespec *timespec = *ts;
+  if (timespec[0].tv_nsec == UTIME_OMIT
+      && timespec[1].tv_nsec == UTIME_OMIT)
+    return true;
+  if (timespec[0].tv_nsec == UTIME_NOW
+      && timespec[1].tv_nsec == UTIME_NOW)
+    {
+      *ts = NULL;
+      return false;
+    }
+
+  if (timespec[0].tv_nsec == UTIME_OMIT)
+    timespec[0] = get_stat_atime (statbuf);
+  else if (timespec[0].tv_nsec == UTIME_NOW)
+    gettime (&timespec[0]);
+
+  if (timespec[1].tv_nsec == UTIME_OMIT)
+    timespec[1] = get_stat_mtime (statbuf);
+  else if (timespec[1].tv_nsec == UTIME_NOW)
+    gettime (&timespec[1]);
+
+  return false;
+}

 
 /* 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.
 
 /* 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 TIMESPEC is null, set the time stamps to the current time.  */
+   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
 
 int

-futimens (int fd ATTRIBUTE_UNUSED,
-         char const *file, struct timespec const timespec[2])
+fdutimens (char const *file, int fd, struct timespec const timespec[2])

 {
 {

-  /* There's currently no interface to set file timestamps with
-     nanosecond resolution, so do the best we can, discarding any
-     fractional part of the timestamp.  */
-#if HAVE_WORKING_UTIMES
-  struct timeval timeval[2];
-  struct timeval const *t;
-  if (timespec)
+  struct timespec adjusted_timespec[2];
+  struct timespec *ts = timespec ? adjusted_timespec : NULL;
+  int adjustment_needed = 0;
+
+  if (ts)

     {
     {

-      timeval[0].tv_sec = timespec[0].tv_sec;
-      timeval[0].tv_usec = timespec[0].tv_nsec / 1000;
-      timeval[1].tv_sec = timespec[1].tv_sec;
-      timeval[1].tv_usec = timespec[1].tv_nsec / 1000;
-      t = timeval;
+      adjusted_timespec[0] = timespec[0];
+      adjusted_timespec[1] = timespec[1];
+      adjustment_needed = validate_timespec (ts);

     }
     }

+  if (adjustment_needed < 0)
+    return -1;
+
+  /* Require that at least one of FD or FILE are valid.  Works around
+     a Linux bug where futimens (AT_FDCWD, NULL) changes "." rather
+     than failing.  */
+  if (!file)
+    {
+      if (fd < 0)
+        {
+          errno = EBADF;
+          return -1;
+        }
+      if (dup2 (fd, fd) != fd)
+        return -1;
+    }
+
+  /* Some Linux-based NFS clients are buggy, and mishandle time stamps
+     of files in NFS file systems in some cases.  We have no
+     configure-time test for this, but please see
+     <http://bugs.gentoo.org/show_bug.cgi?id=132673> for references to
+     some of the problems with Linux 2.6.16.  If this affects you,
+     compile with -DHAVE_BUGGY_NFS_TIME_STAMPS; this is reported to
+     help in some cases, albeit at a cost in performance.  But you
+     really should upgrade your kernel to a fixed version, since the
+     problem affects many applications.  */
+
+#if HAVE_BUGGY_NFS_TIME_STAMPS
+  if (fd < 0)
+    sync ();

   else
   else

-    t = NULL;
-# if HAVE_FUTIMES
-  if (0 <= fd)
+    fsync (fd);
+#endif
+
+  /* POSIX 2008 added two interfaces to set file timestamps with
+     nanosecond resolution; newer Linux implements both functions via
+     a single syscall.  We provide a fallback for ENOSYS (for example,
+     compiling against Linux 2.6.25 kernel headers and glibc 2.7, but
+     running on Linux 2.6.18 kernel).  */
+#if HAVE_UTIMENSAT || HAVE_FUTIMENS
+  if (0 <= utimensat_works_really)

     {
     {

-      if (futimes (fd, t) == 0)
-       return 0;
-
-      /* On GNU/Linux without the futimes syscall and without /proc
-        mounted, glibc futimes fails with errno == ENOENT.  Fall back
-        on utimes if we get a weird error number like that.  */
-      switch (errno)
-       {
-       case EACCES:
-       case EIO:
-       case EPERM:
-       case EROFS:
-         return -1;
-       }
+# if HAVE_UTIMENSAT
+      if (fd < 0)
+        {
+          int result = utimensat (AT_FDCWD, file, ts, 0);
+#  ifdef __linux__
+          /* Work around a kernel bug:
+             http://bugzilla.redhat.com/442352
+             http://bugzilla.redhat.com/449910
+             It appears that utimensat can mistakenly return 280 rather
+             than -1 upon ENOSYS failure.
+             FIXME: remove in 2010 or whenever the offending kernels
+             are no longer in common use.  */
+          if (0 < result)
+            errno = ENOSYS;
+#  endif /* __linux__ */
+          if (result == 0 || errno != ENOSYS)
+            {
+              utimensat_works_really = 1;
+              return result;
+            }
+        }
+# endif /* HAVE_UTIMENSAT */
+# if HAVE_FUTIMENS
+      {
+        int result = futimens (fd, timespec);
+#  ifdef __linux__
+        /* Work around the same bug as above.  */
+        if (0 < result)
+          errno = ENOSYS;
+#  endif /* __linux__ */
+        if (result == 0 || errno != ENOSYS)
+          {
+            utimensat_works_really = 1;
+            return result;
+          }
+      }
+# endif /* HAVE_FUTIMENS */

     }
     }

-# endif
-  return utimes (file, t);
+  utimensat_works_really = -1;
+#endif /* HAVE_UTIMENSAT || HAVE_FUTIMENS */

 
 

-#else
+  /* The platform lacks an interface to set file timestamps with
+     nanosecond resolution, so do the best we can, discarding any
+     fractional part of the timestamp.  */

 
 

-  struct utimbuf utimbuf;
-  struct utimbuf const *t;
-  if (timespec)
+  if (adjustment_needed)

     {
     {

-      utimbuf.actime = timespec[0].tv_sec;
-      utimbuf.modtime = timespec[1].tv_sec;
-      t = &utimbuf;
+      struct stat st;
+      if (fd < 0 ? stat (file, &st) : fstat (fd, &st))
+        return -1;
+      if (update_timespec (&st, &ts))
+        return 0;

     }
     }

-  else
-    t = NULL;
-  return utime (file, t);

 
 

+  {
+#if HAVE_FUTIMESAT || HAVE_WORKING_UTIMES
+    struct timeval timeval[2];
+    struct timeval const *t;
+    if (ts)
+      {
+        timeval[0].tv_sec = ts[0].tv_sec;
+        timeval[0].tv_usec = ts[0].tv_nsec / 1000;
+        timeval[1].tv_sec = ts[1].tv_sec;
+        timeval[1].tv_usec = ts[1].tv_nsec / 1000;
+        t = timeval;
+      }
+    else
+      t = NULL;
+
+    if (fd < 0)
+      {
+# if HAVE_FUTIMESAT
+        return futimesat (AT_FDCWD, file, t);
+# endif
+      }
+    else
+      {
+        /* If futimesat or futimes fails here, don't try to speed things
+           up by returning right away.  glibc can incorrectly fail with
+           errno == ENOENT if /proc isn't mounted.  Also, Mandrake 10.0
+           in high security mode doesn't allow ordinary users to read
+           /proc/self, so glibc incorrectly fails with errno == EACCES.
+           If errno == EIO, EPERM, or EROFS, it's probably safe to fail
+           right away, but these cases are rare enough that they're not
+           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
+        if (futimesat (fd, NULL, t) == 0)
+          return 0;
+# elif HAVE_FUTIMES
+        if (futimes (fd, t) == 0)
+          return 0;
+# endif
+      }
+#endif /* HAVE_FUTIMESAT || HAVE_WORKING_UTIMES */
+
+    if (!file)
+      {
+#if ! (HAVE_FUTIMESAT || (HAVE_WORKING_UTIMES && HAVE_FUTIMES))
+        errno = ENOSYS;

 #endif
 #endif

+        return -1;
+      }
+
+#if HAVE_WORKING_UTIMES
+    return utimes (file, t);
+#else
+    {
+      struct utimbuf utimbuf;
+      struct utimbuf *ut;
+      if (ts)
+        {
+          utimbuf.actime = ts[0].tv_sec;
+          utimbuf.modtime = ts[1].tv_sec;
+          ut = &utimbuf;
+        }
+      else
+        ut = NULL;
+
+      return utime (file, ut);
+    }
+#endif /* !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
 }
 
 /* Set the access and modification time stamps of FILE to be


@@ -117,5 +344,95 @@ futimens (int fd ATTRIBUTE_UNUSED,
 int
 utimens (char const *file, struct timespec const timespec[2])
 {
 int
 utimens (char const *file, struct timespec const timespec[2])
 {

-  return futimens (-1, file, timespec);
+  return fdutimens (file, -1, timespec);
+}
+
+/* Set the access and modification time stamps of FILE to be
+   TIMESPEC[0] and TIMESPEC[1], respectively, without dereferencing
+   symlinks.  Fail with ENOSYS if the platform does not support
+   changing symlink timestamps, but FILE was a symlink.  */
+int
+lutimens (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)
+    {
+      adjusted_timespec[0] = timespec[0];
+      adjusted_timespec[1] = timespec[1];
+      adjustment_needed = validate_timespec (ts);
+    }
+  if (adjustment_needed < 0)
+    return -1;
+
+  /* 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
+     worry about bogus return values.  */
+
+#if HAVE_UTIMENSAT
+  if (0 <= utimensat_works_really)
+    {
+      int result = utimensat (AT_FDCWD, file, ts, AT_SYMLINK_NOFOLLOW);
+# ifdef __linux__
+      /* Work around a kernel bug:
+         http://bugzilla.redhat.com/442352
+         http://bugzilla.redhat.com/449910
+         It appears that utimensat can mistakenly return 280 rather
+         than -1 upon ENOSYS failure.
+         FIXME: remove in 2010 or whenever the offending kernels
+         are no longer in common use.  */
+      if (0 < result)
+        errno = ENOSYS;
+# endif
+      if (result == 0 || errno != ENOSYS)
+        {
+          utimensat_works_really = 1;
+          return result;
+        }
+    }
+  utimensat_works_really = -1;
+#endif /* HAVE_UTIMENSAT */
+
+  /* The platform lacks an interface to set file timestamps with
+     nanosecond resolution, so do the best we can, discarding any
+     fractional part of the timestamp.  */
+
+  if (adjustment_needed)
+    {
+      if (lstat (file, &st))
+        return -1;
+      if (update_timespec (&st, &ts))
+        return 0;
+    }
+
+#if HAVE_LUTIMES
+  {
+    struct timeval timeval[2];
+    struct timeval const *t;
+    if (ts)
+      {
+        timeval[0].tv_sec = ts[0].tv_sec;
+        timeval[0].tv_usec = ts[0].tv_nsec / 1000;
+        timeval[1].tv_sec = ts[1].tv_sec;
+        timeval[1].tv_usec = ts[1].tv_nsec / 1000;
+        t = timeval;
+      }
+    else
+      t = NULL;
+
+    return lutimes (file, t);
+  }
+#endif /* HAVE_LUTIMES */
+
+  /* Out of luck for symlinks, but we still handle regular files.  */
+  if (!adjustment_needed && lstat (file, &st))
+    return -1;
+  if (!S_ISLNK (st.st_mode))
+    return fdutimens (file, -1, ts);
+  errno = ENOSYS;
+  return -1;

 }
 }