X-Git-Url: https://git.cworth.org/git?p=tar;a=blobdiff_plain;f=gnu%2Futimensat.c;fp=gnu%2Futimensat.c;h=005214c52a3726c984eb82f6a097b623e6bc2b70;hp=0000000000000000000000000000000000000000;hb=de7372b23c3da92fbfaea2d1ac592f0b2ba87914;hpb=fbbfb9406a82e647ce27b6462b11a802fa48f31a

diff --git a/gnu/utimensat.c b/gnu/utimensat.c
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+/* -*- buffer-read-only: t -*- vi: set ro: */
+/* DO NOT EDIT! GENERATED AUTOMATICALLY! */
+/* Set the access and modification time of a file relative to directory fd.
+   Copyright (C) 2009, 2010 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 <http://www.gnu.org/licenses/>.  */
+
+/* written by Eric Blake */
+
+#include <config.h>
+
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.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)
+{
+  /* 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;
+# ifdef __linux__
+      struct stat st;
+      struct timespec ts[2];
+      /* 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.  FIXME: Simplify this in 2012,
+         when file system bugs are no longer common.  */
+      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;
+        }
+# endif /* __linux__ */
+      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 time stamps 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
+   time stamps 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