File synchronization fixes.

* admin/CPP-DEFINES (BSD_SYSTEM, HAVE_FSYNC): Remove.
* admin/merge-gnulib (GNULIB_MODULES): Add fsync, fdatasync.
* configure.ac (BSD_SYSTEM, BSD_SYSTEM_AHB): Remove; no longer needed.
(fsync): Remove check; now done by gnulib.
* lib/fdatasync.c, lib/fsync.c, m4/fdatasync.m4, m4/fsync.m4:
New files, from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib-src/Makefile.in (LIB_FDATASYNC): New macro.
(emacsclient${EXEEXT}): Use it.
* lib-src/emacsclient.c (main): Use fdatasync, not fsync, since we don't
care about metadata.  Keep trying if interrupted.
* lib-src/movemail.c (main, popmail): Don't worry about BSD_SYSTEM, since
fsync is available everywhere (or there is a substitute).  Don't
report an error if fsync returns EINVAL.
* nt/inc/ms-w32.h (fdatasync): New macro, suggested by Eli Zaretskii.
* src/Makefile.in (LIB_FDATASYNC): New macro.
(LIBES): Use it.
* src/conf_post.h (BSD_SYSTEM, BSD_SYSTEM_AHB): Remove; no longer needed.
* src/fileio.c (Fwrite_region, write_region_inhibit_fsync):
Don't worry about HAVE_FSYNC, since a substitute fsync is
available if the system lacks one.
(Fwrite_regin): Retry fsync if interrupted.

Fixes: debbugs:13944

6 files changed, 32 insertions, 25 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index ae6fe86f661..d328d0a74ca 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2013-03-13  Paul Eggert  <eggert@cs.ucla.edu>
+
+        File synchronization fixes (Bug#13944).
+        * Makefile.in (LIB_FDATASYNC): New macro.
+        (LIBES): Use it.
+        * conf_post.h (BSD_SYSTEM, BSD_SYSTEM_AHB): Remove; no longer needed.
+        * fileio.c (Fwrite_region, write_region_inhibit_fsync):
+        Don't worry about HAVE_FSYNC, since a substitute fsync is
+        available if the system lacks one.
+        (Fwrite_regin): Retry fsync if interrupted.
+
 2013-03-13  Eli Zaretskii  <eliz@gnu.org>
 
         * w32term.c (w32_read_socket): If we Emacs frame is being
diff --git a/src/Makefile.in b/src/Makefile.in
index b2034a3379d..31de9714c65 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -139,6 +139,7 @@ M17N_FLT_LIBS = @M17N_FLT_LIBS@
 
 LIB_CLOCK_GETTIME=@LIB_CLOCK_GETTIME@
 LIB_EACCESS=@LIB_EACCESS@
+LIB_FDATASYNC=@LIB_FDATASYNC@
 LIB_TIMER_TIME=@LIB_TIMER_TIME@
 
 DBUS_CFLAGS = @DBUS_CFLAGS@
@@ -391,7 +392,7 @@ ALLOBJS = $(VMLIMIT_OBJ) $(obj) $(otherobj)
 LIBES = $(LIBS) $(W32_LIBS) $(LIBS_GNUSTEP) $(LIBX_BASE) $(LIBIMAGE) \
    $(LIBX_OTHER) $(LIBSOUND) \
    $(RSVG_LIBS) $(IMAGEMAGICK_LIBS) $(LIB_CLOCK_GETTIME) \
-   $(LIB_EACCESS) $(LIB_TIMER_TIME) $(DBUS_LIBS) \
+   $(LIB_EACCESS) $(LIB_FDATASYNC) $(LIB_TIMER_TIME) $(DBUS_LIBS) \
    $(LIB_EXECINFO) \
    $(LIBXML2_LIBS) $(LIBGPM) $(LIBRESOLV) $(LIBS_SYSTEM) \
    $(LIBS_TERMCAP) $(GETLOADAVG_LIBS) $(SETTINGS_LIBS) $(LIBSELINUX_LIBS) \
diff --git a/src/conf_post.h b/src/conf_post.h
index 6c9747a436c..5cb385d9029 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -44,19 +44,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 # define __has_attribute(a) 0 /* non-clang */
 #endif
 
-/* This silences a few compilation warnings on FreeBSD.  */
-#ifdef BSD_SYSTEM_AHB
-#undef BSD_SYSTEM_AHB
-#undef BSD_SYSTEM
-#if __FreeBSD__ == 1
-#define BSD_SYSTEM 199103
-#elif __FreeBSD__ == 2
-#define BSD_SYSTEM 199306
-#elif __FreeBSD__ >= 3
-#define BSD_SYSTEM 199506
-#endif
-#endif
-
 #ifdef DARWIN_OS
 #ifdef emacs
 #define malloc unexec_malloc
diff --git a/src/fileio.c b/src/fileio.c
index 8937f7ca477..724250c8aaa 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4959,20 +4959,23 @@ This calls `write-region-annotate-functions' at the start, and
 
   immediate_quit = 0;
 
-#ifdef HAVE_FSYNC
   /* fsync appears to change the modtime on BSD4.2.
      Disk full in NFS may be reported here.  */
   /* mib says that closing the file will try to write as fast as NFS can do
      it, and that means the fsync here is not crucial for autosave files.  */
-  if (!auto_saving && !write_region_inhibit_fsync && fsync (desc) < 0)
+  if (!auto_saving && !write_region_inhibit_fsync)
     {
-      /* If fsync fails with EINTR, don't treat that as serious.  Also
+      /* Transfer data and metadata to disk, retrying if interrupted.  Also,
          ignore EINVAL which happens when fsync is not supported on this
          file.  */
-      if (errno != EINTR && errno != EINVAL)
-        ok = 0, save_errno = errno;
+      while (fsync (desc) != 0)
+        if (errno != EINTR)
+          {
+            if (errno != EINVAL)
+              ok = 0, save_errno = errno;
+            break;
+          }
     }
-#endif
 
   modtime = invalid_emacs_time ();
   if (visiting)
@@ -6046,13 +6049,11 @@ in the buffer; this is the default behavior, because the auto-save
 file is usually more useful if it contains the deleted text.  */);
   Vauto_save_include_big_deletions = Qnil;
 
-#ifdef HAVE_FSYNC
   DEFVAR_BOOL ("write-region-inhibit-fsync", write_region_inhibit_fsync,
                doc: /* Non-nil means don't call fsync in `write-region'.
 This variable affects calls to `write-region' as well as save commands.
 A non-nil value may result in data loss!  */);
   write_region_inhibit_fsync = 0;
-#endif
 
   DEFVAR_BOOL ("delete-by-moving-to-trash", delete_by_moving_to_trash,
                doc: /* Specifies whether to use the system's trash can.
diff --git a/src/filelock.c b/src/filelock.c
index 32992896c2b..f17d3182eab 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -437,6 +437,14 @@ create_lock_file (char *lfname, char *lock_info_str, bool force)
           if (emacs_write (fd, lock_info_str, lock_info_len) != lock_info_len
               || (need_fchmod && fchmod (fd, world_readable) != 0))
             err = errno;
+          else
+            while (fsync (fd) != 0)
+              if (errno != EINTR)
+                {
+                  if (errno != EINVAL)
+                    err = errno;
+                  break;
+                }
           if (emacs_close (fd) != 0)
             err = errno;
           if (!err && rename_lock_file (nonce, lfname, force) != 0)
diff --git a/src/sysdep.c b/src/sysdep.c
index b99f179210c..bff11fc9f75 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -1289,10 +1289,9 @@ reset_sys_modes (struct tty_display_info *tty_out)
   if (tty_out->terminal->reset_terminal_modes_hook)
     tty_out->terminal->reset_terminal_modes_hook (tty_out->terminal);
 
-#ifdef BSD_SYSTEM
   /* Avoid possible loss of output when changing terminal modes.  */
-  fsync (fileno (tty_out->output));
-#endif
+  while (fdatasync (fileno (tty_out->output)) != 0 && errno == EINTR)
+    continue;
 
 #ifndef DOS_NT
 #ifdef F_SETOWN