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portability: fix several issues with M4 subprocess.

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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/local.mk (lib_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 22cc8d813e)

Conflicts:

	NEWS
	bootstrap.conf
	lib/.cvsignore
	lib/.gitignore
	lib/Makefile.am
	m4/.cvsignore
	m4/.gitignore
	src/output.c
This commit is contained in:
Joel E. Denny
2010-02-22 18:09:19 -05:00
parent e32050b0c7
commit f39ab2869c
19 changed files with 299 additions and 240 deletions
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12
src/scan-skel.l
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@@ -107,7 +107,7 @@ static void fail_for_invalid_at (char const *at);
"@@" { obstack_1grow (&obstack_for_string, '@'); }
"@{" { obstack_1grow (&obstack_for_string, '['); }
"@}" { obstack_1grow (&obstack_for_string, ']'); }
"@`" /* Emtpy. Useful for starting an argument
"@`" /* Empty. Useful for starting an argument
that begins with whitespace. */
@\n /* Empty. */
@@ -174,10 +174,10 @@ skel_scanner_free (void)
yylex_destroy ();
}
static
void at_directive_perform (int at_directive_argc,
char *at_directive_argv[],
char **outnamep, int *out_linenop)
static void
at_directive_perform (int at_directive_argc,
char *at_directive_argv[],
char **outnamep, int *out_linenop)
{
if (0 == strcmp (at_directive_argv[0], "@basename"))
{
@@ -276,7 +276,7 @@ void at_directive_perform (int at_directive_argc,
xfclose (yyout);
}
*outnamep = xstrdup (at_directive_argv[1]);
output_file_name_check (*outnamep);
output_file_name_check (outnamep);
yyout = xfopen (*outnamep, "w");
*out_linenop = 1;
}