Fix data-loss with --batch.

* admin/merge-gnulib (GNULIB_MODULES): Add close-stream.
* lib/close-stream.c, lib/close-stream.h, lib/fpending.c
* lib/fpending.h, m4/close-stream.m4, m4/fpending.m4:
New files, from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* src/emacs.c: Include <close-stream.h>.
(close_output_streams): New function.
(main): Pass it to atexit, so that Emacs closes stdout and stderr
and handles errors appropriately.
(Fkill_emacs): Don't worry about flushing, as close_output_stream
does that now.

Fixes: debbugs:9574

2 files changed, 27 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 2f040accd9a..be10016fc33 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,13 @@
 2012-11-03  Paul Eggert  <eggert@cs.ucla.edu>
 
+        Fix data-loss with --batch (Bug#9574).
+        * emacs.c: Include <close-stream.h>.
+        (close_output_streams): New function.
+        (main): Pass it to atexit, so that Emacs closes stdout and stderr
+        and handles errors appropriately.
+        (Fkill_emacs): Don't worry about flushing, as close_output_stream
+        does that now.
+
         Fix a race condition that causes Emacs to mess up glib (Bug#8855).
         The symptom is a diagnostic "GLib-WARNING **: In call to
         g_spawn_sync(), exit status of a child process was requested but
diff --git a/src/emacs.c b/src/emacs.c
index 98e3f11f0cb..6588bcd78b1 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -27,6 +27,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <sys/file.h>
 #include <unistd.h>
 
+#include <close-stream.h>
 #include <ignore-value.h>
 
 #include "lisp.h"
@@ -675,6 +676,22 @@ void (*__malloc_initialize_hook) (void) EXTERNALLY_VISIBLE = malloc_initialize_h
 
 #endif /* DOUG_LEA_MALLOC */
 
+/* Close standard output and standard error, reporting any write
+   errors as best we can.  This is intended for use with atexit.  */
+static void
+close_output_streams (void)
+{
+  if (close_stream (stdout) != 0)
+    {
+      fprintf (stderr, "Write error to standard output: %s\n",
+               emacs_strerror (errno));
+      fflush (stderr);
+      _exit (EXIT_FAILURE);
+    }
+
+   if (close_stream (stderr) != 0)
+     _exit (EXIT_FAILURE);
+}
 
 /* ARGSUSED */
 int
@@ -890,6 +907,8 @@ main (int argc, char **argv)
   if (do_initial_setlocale)
     setlocale (LC_ALL, "");
 
+  atexit (close_output_streams);
+
   inhibit_window_system = 0;
 
   /* Handle the -t switch, which specifies filename to use as terminal.  */
@@ -1867,8 +1886,6 @@ all of which are called before Emacs is actually killed.  */)
     exit_code = (XINT (arg) < 0
                  ? XINT (arg) | INT_MIN
                  : XINT (arg) & INT_MAX);
-  else if (noninteractive && (fflush (stdout) || ferror (stdout)))
-    exit_code = EXIT_FAILURE;
   else
     exit_code = EXIT_SUCCESS;
   exit (exit_code);