Fix testsuite bug when SIGPIPE is ignored.

* tests/builtins.at (divert): Consume all of m4's output, to avoid
spurious write failure.
* src/main.c (main): In batch mode, restore default handling of
SIGPIPE.
* doc/m4.texinfo (Operation modes): Document SIGPIPE behavior.
* THANKS: Update.
Reported by Bob Proulx, via his autobuilder.

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

5 files changed, 19 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index b4bdf140..1335a877 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2008-04-17  Eric Blake  <ebb9@byu.net>
+
+	Fix testsuite bug when SIGPIPE is ignored.
+	* tests/builtins.at (divert): Consume all of m4's output, to avoid
+	spurious write failure.
+	* src/main.c (main): In batch mode, restore default handling of
+	SIGPIPE.
+	* doc/m4.texinfo (Operation modes): Document SIGPIPE behavior.
+	* THANKS: Update.
+	Reported by Bob Proulx, via his autobuilder.
+
 2008-04-15  Eric Blake  <ebb9@byu.net>
 
 	Fix 'make installcheck' after './configure --prefix-progname'.
diff --git a/THANKS b/THANKS
index 6d476d32..0c655be4 100644
--- a/THANKS
+++ b/THANKS
@@ -25,6 +25,7 @@ Bernhard Daeubler	daeb@physik.uni-ulm.de
 Bill Bumgarner		bbum@thoughtport.com
 Bjorn R. Bjornsson	brb@falcon.is
 Bob Badour		bob@badour.net
+Bob Proulx		bob@proulx.com
 Brendan Kehoe		brendan@cygnus.com
 Brian J. Fox		bfox@datawave.net
 Brian D. Carlstrom	bdc@clark.lcs.mit.edu
diff --git a/doc/m4.texinfo b/doc/m4.texinfo
index d0bbfa47..280d633a 100644
--- a/doc/m4.texinfo
+++ b/doc/m4.texinfo
@@ -618,7 +618,8 @@ performing any other actions.
 @item -b
 @itemx --batch
 Makes this invocation of @code{m4} non-interactive.  This means that
-output will be buffered, and interrupts will halt execution.  If neither
+output will be buffered, and an interrupt or pipe write error will halt
+execution.  If neither
 @option{-b} nor @option{-i} are specified, this is activated by default
 when any input files are specified, or when either standard input or
 standard error is not a terminal.  Note that this means that @kbd{m4}
@@ -647,7 +648,8 @@ a warning is issued.  The introduction of behavior levels is new to M4
 @itemx --interactive
 @itemx -e
 Makes this invocation of @code{m4} interactive.  This means that all
-output will be unbuffered, and interrupts will be ignored.  If neither
+output will be unbuffered, interrupts will be ignored, and behavior on
+pipe write errors is inherited from the parent process.  If neither
 @option{-b} nor @option{-i} are specified, this is activated by default
 when no input files are specified, and when both standard input and
 standard error are terminals (similar to the way that /bin/sh determines
diff --git a/src/main.c b/src/main.c
index 86f21e76..7c3b9ccd 100644
--- a/src/main.c
+++ b/src/main.c
@@ -616,6 +616,8 @@ main (int argc, char *const *argv, char *const *envp)
       signal (SIGINT, SIG_IGN);
       setbuf (stdout, NULL);
     }
+  else
+    signal (SIGPIPE, SIG_DFL);
 
 
   /* Do the basic initializations.  */
diff --git a/tests/builtins.at b/tests/builtins.at
index 2030b14e..c63246bb 100644
--- a/tests/builtins.at
+++ b/tests/builtins.at
@@ -296,7 +296,7 @@ hello world
 
 dnl Test large diversions, which were broken in m4 1.4.8-1.4.10.
 AT_CHECK([echo 'divert(1)hi
-format(%1000000d, 1)' | $M4 | sed 1q], [0], [[hi
+format(%1000000d, 1)' | $M4 | sed -n 1p], [0], [[hi
 ]])
 
 AT_DATA([in.m4], [M4_ONE_MEG_DEFN[divert(`2')f`'dnl