futimens, utimensat: work around Linux bug

futimens is trivial - let fdutimens do the work.  utimensat
is tougher: we don't want to call into local_utimensat,
because that can cause unnecessary chdir.  So we have to
repeat the logic from utimens.c.

* m4/futimens.m4 (gl_FUNC_FUTIMENS): Detect ctime bug.
* m4/utimensat.m4 (gl_FUNC_UTIMENSAT): Likewise.
* lib/utimensat.c (rpl_utimensat): Work around it.
* lib/futimens.c (rpl_futimens): Adjust comment.

2 files changed, 45 insertions, 16 deletions

diff --git a/m4/futimens.m4 b/m4/futimens.m4
index 0547e7ad54..ba5d6b666f 100644
--- a/m4/futimens.m4
+++ b/m4/futimens.m4
@@ -1,4 +1,4 @@
-# serial 1
+# serial 2
 # See if we need to provide futimens replacement.
 
 dnl Copyright (C) 2009 Free Software Foundation, Inc.
@@ -22,17 +22,32 @@ AC_DEFUN([gl_FUNC_FUTIMENS],
       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <unistd.h>
+]], [[struct timespec ts[2] = { { 1, UTIME_OMIT }, { 1, UTIME_NOW } };
+      int fd = creat ("conftest.file", 0600);
+      struct stat st;
+      if (fd < 0) return 1;
+      if (futimens (AT_FDCWD, NULL)) return 2;
+      if (futimens (fd, ts)) return 3;
+      sleep (1);
+      ts[0].tv_nsec = UTIME_NOW;
+      ts[1].tv_nsec = UTIME_OMIT;
+      if (futimens (fd, ts)) return 4;
+      if (fstat (fd, &st)) return 5;
+      if (st.st_ctime < st.st_atime) return 6;
+      ]])],
+         [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #ifdef __linux__
-/* The Linux kernel added futimens in 2.6.22, but it had bugs until 2.6.26.
-   Always replace futimens to support older kernels.  */
+/* The Linux kernel added futimens in 2.6.22, but has bugs with UTIME_OMIT
+   in 2.6.32.  Always replace futimens to support older kernels.  */
 choke me
 #endif
-]], [[struct timespec ts[2] = { { 1, UTIME_OMIT }, { 1, UTIME_OMIT } };
-      if (futimens (AT_FDCWD, NULL)) return 1;
-      return futimens (open (".", O_RDONLY), ts);]])],
-         [gl_cv_func_futimens_works=yes],
-         [gl_cv_func_futimens_works="needs runtime check"],
-         [gl_cv_func_futimens_works="guessing no"])])
+      ]])],
+           [gl_cv_func_futimens_works=yes],
+           [gl_cv_func_futimens_works="needs runtime check"])],
+         [gl_cv_func_futimens_works=no],
+         [gl_cv_func_futimens_works="guessing no"])
+      rm -f conftest.file])
     if test "$gl_cv_func_futimens_works" != yes; then
       REPLACE_FUTIMENS=1
       AC_LIBOBJ([futimens])
diff --git a/m4/utimensat.m4 b/m4/utimensat.m4
index 2a6033f2c0..21e1ea526d 100644
--- a/m4/utimensat.m4
+++ b/m4/utimensat.m4
@@ -1,4 +1,4 @@
-# serial 1
+# serial 2
 # See if we need to provide utimensat replacement.
 
 dnl Copyright (C) 2009 Free Software Foundation, Inc.
@@ -22,15 +22,29 @@ AC_DEFUN([gl_FUNC_UTIMENSAT],
       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <unistd.h>
+]], [[struct timespec ts[2] = { { 1, UTIME_OMIT }, { 1, UTIME_NOW } };
+      struct stat st;
+      const char *f = "conftest.file";
+      if (close (creat (f, 0600))) return 1;
+      if (utimensat (AT_FDCWD, f, NULL, AT_SYMLINK_NOFOLLOW)) return 2;
+      if (utimensat (AT_FDCWD, f, ts, 0)) return 3;
+      sleep (1);
+      ts[0].tv_nsec = UTIME_NOW;
+      ts[1].tv_nsec = UTIME_OMIT;
+      if (utimensat (AT_FDCWD, f, ts, 0)) return 4;
+      if (stat (f, &st)) return 5;
+      if (st.st_ctime < st.st_atime) return 6;]])],
+         [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #ifdef __linux__
-/* The Linux kernel added utimensat in 2.6.22, but it had bugs until 2.6.26.
-   Always replace utimensat to support older kernels.  */
+/* The Linux kernel added utimensat in 2.6.22, but has bugs with UTIME_OMIT
+   in 2.6.32.  Always replace utimensat to support older kernels.  */
 choke me
 #endif
-]], [[struct timespec ts[2] = { { 1, UTIME_OMIT }, { 1, UTIME_OMIT } };
-      return utimensat (AT_FDCWD, ".", NULL, AT_SYMLINK_NOFOLLOW);]])],
-         [gl_cv_func_utimensat_works=yes],
-         [gl_cv_func_utimensat_works="needs runtime check"],
+      ]])],
+           [gl_cv_func_utimensat_works=yes],
+           [gl_cv_func_utimensat_works="needs runtime check"])],
+         [gl_cv_func_utimensat_works=no],
          [gl_cv_func_utimensat_works="guessing no"])])
     if test "$gl_cv_func_utimensat_works" != yes; then
       REPLACE_UTIMENSAT=1