portability: fix several issues with M4 subprocess.

M4's output pipe was not being drained upon fatal errors during
scan_skel.  As a result, broken-pipe messages from M4 were seen
on at least AIX, HP-UX, Solaris, and RHEL4, and this caused a
failure in the test suite.  The problem was that, on platforms
where the default disposition for SIGPIPE is ignore instead of
terminate, M4 sometimes saw fwrite fail with errno=EPIPE and
then reported it.  However, there's some sort of race condition,
because the new test group occasionally succeeded.
Reported by Albert Chin at
<http://lists.gnu.org/archive/html/bug-bison/2010-02/msg00004.html>.

There were also problems with the test suite livelocking on
Tru64 5.1b.  Reported by Didier Godefroy at
<http://lists.gnu.org/archive/html/bug-bison/2009-05/msg00005.html>.
Switching to create_pipe_bidi suggested by Akim Demaille.

To attempt to solve both of these problems, switch to gnulib's
create_pipe_bidi and register M4 process as a slave.  Along the
way, clean up file name conflict handling, which was affected by
the broken-pipe problem before the switch.
* NEWS (2.4.2): Document.
* THANKS (Didier Godefroy): Add.
* bootstrap.conf (gnulib_modules): Add pipe.
* gnulib: Update to latest to make sure we have all the latest
fixes.
* lib/Makefile.am (libbison_a_SOURCES): Remove subpipe.h and
subpipe.c.
* po/POTFILES.in (lib/subpipe.c): Remove.
* src/files.c (compute_output_file_names): Update invocations
of output_file_name_check.
(output_file_name_check): In the case that the grammar file
would be overwritten, use complain instead of fatal, but replace
the output file name with /dev/null.  Use the /dev/null solution
for the case of two conflicting output files as well because it
seems safer in case Bison one day tries to open both files at
the same time.
* src/files.h (output_file_name_check): Update prototype.
* src/output.c (output_skeleton): Use create_pipe_bidi and
wait_subprocess.  Assert that scan_skel completely drains the
pipe.
* src/scan-skel.l (at_directive_perform): Update
output_file_name_check invocation.
* tests/output.at (AT_CHECK_CONFLICTING_OUTPUT): Check that the
grammar file actually isn't overwritten.
(Conflicting output files: -o foo.y): Update expected output.
* tests/skeletons.at (Fatal errors but M4 continues producing
output): New test group.
(cherry picked from commit 22cc8d813ee57c9631e527a31010ab138f9b7e06)

Conflicts:

	NEWS
	bootstrap.conf
	lib/.cvsignore
	lib/.gitignore
	m4/.cvsignore
	m4/.gitignore
	src/output.c

5 files changed, 98 insertions, 206 deletions

diff --git a/lib/.cvsignore b/lib/.cvsignore
index 01087fd4..d3c20e87 100644
--- a/lib/.cvsignore
+++ b/lib/.cvsignore
@@ -8,6 +8,7 @@ argmatch.h
 asnprintf.c
 basename-lgpl.c
 basename.c
+binary-io.h
 bitrotate.h
 c-ctype.c
 c-ctype.h
@@ -15,6 +16,8 @@ c-strcase.h
 c-strcasecmp.c
 c-strncasecmp.c
 charset.alias
+cloexec.c
+cloexec.h
 config.charset
 config.h
 config.hin
@@ -22,6 +25,7 @@ configmake.h
 dirname-lgpl.c
 dirname.c
 dirname.h
+dup-safer-flag.c
 dup-safer.c
 dup2.c
 errno.h
@@ -30,9 +34,12 @@ error.c
 error.h
 exitfail.c
 exitfail.h
+fatal-signal.c
+fatal-signal.h
 fcntl.c
 fcntl.h
 fcntl.in.h
+fd-safer-flag.c
 fd-safer.c
 float+.h
 float.h
@@ -45,6 +52,7 @@ frexp.c
 frexpl.c
 fseterr.c
 fseterr.h
+getdtablesize.c
 getopt.c
 getopt.h
 getopt.in.h
@@ -80,7 +88,12 @@ memchr.c
 memchr.valgrind
 obstack.c
 obstack.h
+open.c
 pipe-safer.c
+pipe.c
+pipe.h
+pipe2-safer.c
+pipe2.c
 printf-args.c
 printf-args.h
 printf-frexp.c
@@ -94,18 +107,42 @@ quote.c
 quote.h
 quotearg.c
 quotearg.h
+rawmemchr.c
+rawmemchr.valgrind
 realloc.c
 ref-add.sed
 ref-add.sin
 ref-del.sed
 ref-del.sin
+sched.h
+sched.in.h
+sig-handler.h
+sigaction.c
+signal.h
+signal.in.h
 signbitd.c
 signbitf.c
 signbitl.c
+sigprocmask.c
 size_max.h
 snprintf.c
+spawn.h
+spawn.in.h
+spawn_faction_addclose.c
+spawn_faction_adddup2.c
+spawn_faction_addopen.c
+spawn_faction_destroy.c
+spawn_faction_init.c
+spawn_int.h
+spawnattr_destroy.c
+spawnattr_init.c
+spawnattr_setflags.c
+spawnattr_setsigmask.c
+spawni.c
+spawnp.c
 sprintf.c
 stamp-h1
+stat.c
 stdbool.h
 stdbool.in.h
 stdbool_.h
@@ -124,6 +161,8 @@ stdlib.h
 stdlib.in.h
 stdlib_.h
 stpcpy.c
+strchrnul.c
+strchrnul.valgrind
 streq.h
 strerror.c
 string.h
@@ -136,6 +175,13 @@ strtol.c
 strtoul.c
 strverscmp.c
 strverscmp.h
+sys
+sys_stat.h
+sys_stat.in.h
+sys_wait.h
+sys_wait.in.h
+time.h
+time.in.h
 unistd--.h
 unistd-safer.h
 unistd.h
@@ -152,6 +198,9 @@ verify.h
 vfprintf.c
 vsnprintf.c
 vsprintf.c
+w32spawn.h
+wait-process.c
+wait-process.h
 wchar.h
 wchar.in.h
 wchar_.h
diff --git a/lib/.gitignore b/lib/.gitignore
index 44d4102b..b2890169 100644
--- a/lib/.gitignore
+++ b/lib/.gitignore
@@ -11,6 +11,7 @@
 /asnprintf.c
 /basename-lgpl.c
 /basename.c
+/binary-io.h
 /bitrotate.h
 /c-ctype.c
 /c-ctype.h
@@ -18,6 +19,8 @@
 /c-strcasecmp.c
 /c-strncasecmp.c
 /charset.alias
+/cloexec.c
+/cloexec.h
 /config.charset
 /config.h
 /config.hin
@@ -25,6 +28,7 @@
 /dirname-lgpl.c
 /dirname.c
 /dirname.h
+/dup-safer-flag.c
 /dup-safer.c
 /dup2.c
 /errno.h
@@ -33,9 +37,12 @@
 /error.h
 /exitfail.c
 /exitfail.h
+/fatal-signal.c
+/fatal-signal.h
 /fcntl.c
 /fcntl.h
 /fcntl.in.h
+/fd-safer-flag.c
 /fd-safer.c
 /float+.h
 /float.h
@@ -48,6 +55,7 @@
 /frexpl.c
 /fseterr.c
 /fseterr.h
+/getdtablesize.c
 /getopt.c
 /getopt.h
 /getopt.in.h
@@ -83,7 +91,12 @@
 /memchr.valgrind
 /obstack.c
 /obstack.h
+/open.c
 /pipe-safer.c
+/pipe.c
+/pipe.h
+/pipe2-safer.c
+/pipe2.c
 /printf-args.c
 /printf-args.h
 /printf-frexp.c
@@ -97,18 +110,42 @@
 /quote.h
 /quotearg.c
 /quotearg.h
+/rawmemchr.c
+/rawmemchr.valgrind
 /realloc.c
 /ref-add.sed
 /ref-add.sin
 /ref-del.sed
 /ref-del.sin
+/sched.h
+/sched.in.h
+/sig-handler.h
+/sigaction.c
+/signal.h
+/signal.in.h
 /signbitd.c
 /signbitf.c
 /signbitl.c
+/sigprocmask.c
 /size_max.h
 /snprintf.c
+/spawn.h
+/spawn.in.h
+/spawn_faction_addclose.c
+/spawn_faction_adddup2.c
+/spawn_faction_addopen.c
+/spawn_faction_destroy.c
+/spawn_faction_init.c
+/spawn_int.h
+/spawnattr_destroy.c
+/spawnattr_init.c
+/spawnattr_setflags.c
+/spawnattr_setsigmask.c
+/spawni.c
+/spawnp.c
 /sprintf.c
 /stamp-h1
+/stat.c
 /stdbool.h
 /stdbool.in.h
 /stdbool_.h
@@ -127,6 +164,8 @@
 /stdlib.in.h
 /stdlib_.h
 /stpcpy.c
+/strchrnul.c
+/strchrnul.valgrind
 /streq.h
 /strerror.c
 /string.h
@@ -139,6 +178,13 @@
 /strtoul.c
 /strverscmp.c
 /strverscmp.h
+/sys
+/sys_stat.h
+/sys_stat.in.h
+/sys_wait.h
+/sys_wait.in.h
+/time.h
+/time.in.h
 /unistd--.h
 /unistd-safer.h
 /unistd.h
@@ -155,6 +201,9 @@
 /vfprintf.c
 /vsnprintf.c
 /vsprintf.c
+/w32spawn.h
+/wait-process.c
+/wait-process.h
 /wchar.h
 /wchar.in.h
 /wchar_.h
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 77ca6646..c2b4ec27 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -37,7 +37,6 @@ timevars_sources = \
 # Non-gnulib sources in Bison's internal library.
 libbison_a_SOURCES += \
   get-errno.h get-errno.c \
-  subpipe.h subpipe.c \
   $(bitsets_sources) $(additional_bitsets_sources) $(timevars_sources)
 
 # The Yacc compatibility library.
diff --git a/lib/subpipe.c b/lib/subpipe.c
deleted file mode 100644
index 1b7c36d8..00000000
--- a/lib/subpipe.c
+++ /dev/null
@@ -1,177 +0,0 @@
-/* Subprocesses with pipes.
-
-   Copyright (C) 2002, 2004-2006, 2009-2010 Free Software Foundation,
-   Inc.
-
-   This program is free software: you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation, either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-/* Written by Paul Eggert <eggert@twinsun.com>
-   and Florian Krohm <florian@edamail.fishkill.ibm.com>.  */
-
-#include <config.h>
-
-#include "subpipe.h"
-
-#include <errno.h>
-
-#include <signal.h>
-#if ! defined SIGCHLD && defined SIGCLD
-# define SIGCHLD SIGCLD
-#endif
-
-#include <stdlib.h>
-
-#include <unistd.h>
-#ifndef STDIN_FILENO
-# define STDIN_FILENO 0
-#endif
-#ifndef STDOUT_FILENO
-# define STDOUT_FILENO 1
-#endif
-#if ! HAVE_DUP2 && ! defined dup2
-# include <fcntl.h>
-# define dup2(f, t) (close (t), fcntl (f, F_DUPFD, t))
-#endif
-
-#if HAVE_SYS_WAIT_H
-# include <sys/wait.h>
-#endif
-#ifndef WEXITSTATUS
-# define WEXITSTATUS(stat_val) ((unsigned int) (stat_val) >> 8)
-#endif
-#ifndef WIFEXITED
-# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
-#endif
-
-#if HAVE_VFORK_H
-# include <vfork.h>
-#endif
-#if ! HAVE_WORKING_VFORK
-# define vfork fork
-#endif
-
-#include "error.h"
-#include "unistd-safer.h"
-
-#include "gettext.h"
-#define _(Msgid)  gettext (Msgid)
-
-#ifndef __attribute__
-/* This feature is available in gcc versions 2.5 and later.  */
-# if ! defined __GNUC__ || __GNUC__ < 2 || \
-(__GNUC__ == 2 && __GNUC_MINOR__ < 5) || __STRICT_ANSI__
-#  define __attribute__(Spec) /* empty */
-# endif
-#endif
-
-#ifndef ATTRIBUTE_UNUSED
-# define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
-#endif
-
-
-/* Initialize this module.  */
-
-void
-init_subpipe (void)
-{
-#ifdef SIGCHLD
-  /* System V fork+wait does not work if SIGCHLD is ignored.  */
-  signal (SIGCHLD, SIG_DFL);
-#endif
-}
-
-
-/* Create a subprocess that is run as a filter.  ARGV is the
-   NULL-terminated argument vector for the subprocess.  Store read and
-   write file descriptors for communication with the subprocess into
-   FD[0] and FD[1]: input meant for the process can be written into
-   FD[0], and output from the process can be read from FD[1].  Return
-   the subprocess id.
-
-   To avoid deadlock, the invoker must not let incoming data pile up
-   in FD[1] while writing data to FD[0].  */
-
-pid_t
-create_subpipe (char const * const *argv, int fd[2])
-{
-  int pipe_fd[2];
-  int child_fd[2];
-  pid_t pid;
-
-  if (pipe_safer (child_fd) != 0 || pipe_safer (pipe_fd) != 0)
-    error (EXIT_FAILURE, errno, "pipe");
-  fd[0] = child_fd[1];
-  fd[1] = pipe_fd[0];
-  child_fd[1] = pipe_fd[1];
-
-  pid = vfork ();
-  if (pid < 0)
-    error (EXIT_FAILURE, errno, "fork");
-
-  if (! pid)
-    {
-      /* Child.  */
-      close (fd[0]);
-      close (fd[1]);
-      dup2 (child_fd[0], STDIN_FILENO);
-      close (child_fd[0]);
-      dup2 (child_fd[1], STDOUT_FILENO);
-      close (child_fd[1]);
-
-      /* The cast to (char **) rather than (char * const *) is needed
-	 for portability to older hosts with a nonstandard prototype
-	 for execvp.  */
-      execvp (argv[0], (char **) argv);
-
-      _exit (errno == ENOENT ? 127 : 126);
-    }
-
-  /* Parent.  */
-  close (child_fd[0]);
-  close (child_fd[1]);
-  return pid;
-}
-
-
-/* Wait for the subprocess to exit.  */
-
-void
-reap_subpipe (pid_t pid, char const *program)
-{
-#if HAVE_WAITPID || defined waitpid
-  int wstatus;
-  if (waitpid (pid, &wstatus, 0) < 0)
-    error (EXIT_FAILURE, errno, "waitpid");
-  else
-    {
-      int status = WIFEXITED (wstatus) ? WEXITSTATUS (wstatus) : -1;
-      if (status)
-	error (EXIT_FAILURE, 0,
-	       _(status == 126
-		 ? "subsidiary program `%s' could not be invoked"
-		 : status == 127
-		 ? "subsidiary program `%s' not found"
-		 : status < 0
-		 ? "subsidiary program `%s' failed"
-		 : "subsidiary program `%s' failed (exit status %d)"),
-	       program, status);
-    }
-#endif
-}
-
-void
-end_of_output_subpipe (pid_t pid ATTRIBUTE_UNUSED,
-		       int fd[2] ATTRIBUTE_UNUSED)
-{
-}
diff --git a/lib/subpipe.h b/lib/subpipe.h
deleted file mode 100644
index ff791a81..00000000
--- a/lib/subpipe.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Subprocesses with pipes.
-   Copyright (C) 2002, 2004-2005, 2009-2010 Free Software Foundation,
-   Inc.
-
-   This program is free software: you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation, either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-/* Written by Paul Eggert <eggert@twinsun.com>
-   and Florian Krohm <florian@edamail.fishkill.ibm.com>.  */
-
-#if HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-
-void init_subpipe (void);
-pid_t create_subpipe (char const * const *, int[2]);
-void end_of_output_subpipe (pid_t, int[2]);
-void reap_subpipe (pid_t, char const *);