Ignore write failures before stack overflow exit.

* m4/gnulib-cache.m4: Import ignore-value module.
* src/m4.c (fault_handler): Use it to avoid compiler warning.

Signed-off-by: Eric Blake <ebb9@byu.net>

3 files changed, 19 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index 5b4cc72a..19cf20d7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-11-26  Eric Blake  <ebb9@byu.net>
+
+	Ignore write failures before stack overflow exit.
+	* m4/gnulib-cache.m4: Import ignore-value module.
+	* src/m4.c (fault_handler): Use it to avoid compiler warning.
+
 2009-11-25  Eric Blake  <ebb9@byu.net>
 
 	Allow use of compiler warnings.
diff --git a/m4/gnulib-cache.m4 b/m4/gnulib-cache.m4
index 33aa0df0..2440df0a 100644
--- a/m4/gnulib-cache.m4
+++ b/m4/gnulib-cache.m4
@@ -15,7 +15,7 @@
 
 
 # Specification in the form of a command-line invocation:
-#   gnulib-tool --import --dir=. --local-dir=local --lib=libm4 --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --with-tests --avoid=lock-tests --avoid=tls-tests --makefile-name=gnulib.mk --no-libtool --macro-prefix=M4 announce-gen assert autobuild avltree-oset binary-io c-stack clean-temp cloexec close-stream closein config-h dirname error execute fdl-1.3 fflush filenamecat fopen fopen-safer fseeko gendocs getopt-gnu git-version-gen gnu-web-doc-update gnumakefile gnupload gpl-3.0 intprops maintainer-makefile manywarnings memchr2 mkstemp obstack pipe progname regex sigaction stdbool stdint stdlib-safer strsignal strstr strtod strtol unlocked-io update-copyright vc-list-files verror version-etc version-etc-fsf wait-process xalloc xprintf xvasprintf-posix
+#   gnulib-tool --import --dir=. --local-dir=local --lib=libm4 --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --with-tests --avoid=lock-tests --avoid=tls-tests --makefile-name=gnulib.mk --no-libtool --macro-prefix=M4 announce-gen assert autobuild avltree-oset binary-io c-stack clean-temp cloexec close-stream closein config-h dirname error execute fdl-1.3 fflush filenamecat fopen fopen-safer fseeko gendocs getopt-gnu git-version-gen gnu-web-doc-update gnumakefile gnupload gpl-3.0 ignore-value intprops maintainer-makefile manywarnings memchr2 mkstemp obstack pipe progname regex sigaction stdbool stdint stdlib-safer strsignal strstr strtod strtol unlocked-io update-copyright vc-list-files verror version-etc version-etc-fsf wait-process xalloc xprintf xvasprintf-posix
 
 # Specification in the form of a few gnulib-tool.m4 macro invocations:
 gl_LOCAL_DIR([local])
@@ -47,6 +47,7 @@ gl_MODULES([
   gnumakefile
   gnupload
   gpl-3.0
+  ignore-value
   intprops
   maintainer-makefile
   manywarnings
diff --git a/src/m4.c b/src/m4.c
index 685d022e..496b6e0d 100644
--- a/src/m4.c
+++ b/src/m4.c
@@ -26,6 +26,7 @@
 #include <signal.h>
 
 #include "c-stack.h"
+#include "ignore-value.h"
 #include "progname.h"
 #include "version-etc.h"
 
@@ -147,18 +148,21 @@ fault_handler (int signo)
 	 async-safe.  However, the static variables that we read are
 	 never modified once this handler is installed, so this
 	 particular usage is safe.  And it seems an oversight that
-	 POSIX claims strlen is not async-safe.	 */
-      write (STDERR_FILENO, program_name, strlen (program_name));
-      write (STDERR_FILENO, ": ", 2);
-      write (STDERR_FILENO, program_error_message,
+	 POSIX claims strlen is not async-safe.  Ignore write
+	 failures, since we will exit with non-zero status anyway.  */
+#define WRITE(f, b, l) ignore_value (write (f, b, l))
+      WRITE (STDERR_FILENO, program_name, strlen (program_name));
+      WRITE (STDERR_FILENO, ": ", 2);
+      WRITE (STDERR_FILENO, program_error_message,
 	     strlen (program_error_message));
       if (signal_message[signo])
 	{
-	  write (STDERR_FILENO, ": ", 2);
-	  write (STDERR_FILENO, signal_message[signo],
+	  WRITE (STDERR_FILENO, ": ", 2);
+	  WRITE (STDERR_FILENO, signal_message[signo],
 		 strlen (signal_message[signo]));
 	}
-      write (STDERR_FILENO, "\n", 1);
+      WRITE (STDERR_FILENO, "\n", 1);
+#undef WRITE
       _exit (EXIT_INTERNAL_ERROR);
     }
 }