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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/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.
This commit is contained in:
Joel E. Denny
2010-02-22 18:09:19 -05:00
parent 9398411bfc
commit 22cc8d813e
19 changed files with 306 additions and 242 deletions
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4
tests/output.at
View File

@@ -137,7 +137,9 @@ AT_DATA([$1],
foo: {};
]])
[cp ]$1[ expout]
AT_BISON_CHECK([$3 $1], $5, [], [$4])
AT_CHECK([[cat $1]], [[0]], [expout])
AT_CLEANUP
])
@@ -157,7 +159,7 @@ AT_CHECK_CONFLICTING_OUTPUT([foo.y],
])
AT_CHECK_CONFLICTING_OUTPUT([foo.y], [], [-o foo.y],
[foo.y: fatal error: refusing to overwrite the input file `foo.y'
[foo.y: refusing to overwrite the input file `foo.y'
], 1)

42
tests/skeletons.at
View File

@@ -288,3 +288,45 @@ foo.y:1.5-6: fatal error: M4 should exit immediately here
]])
AT_CLEANUP
## ------------------------------------------------ ##
## Fatal errors but M4 continues producing output. ##
## ------------------------------------------------ ##
# At one time, if Bison encountered a fatal error during M4 processing,
# Bison failed to drain M4's output pipe. The result was a SIGPIPE.
# On some platforms, the default disposition for SIGPIPE is terminate,
# which was fine. On others, it's ignore, which caused M4 to report
# the broken pipe to the user, but we don't want to bother the user with
# that.
# There is a race condition somewhere. That is, before the associated
# fix, running this test group many times in a row would occasionally
# produce a pass among all the failures.
AT_SETUP([[Fatal errors but M4 continues producing output]])
AT_DATA([[gen-skel.pl]],
[[use warnings;
use strict;
my $M4 = "m4";
my $DNL = "d"."nl";
print "${M4}_divert_push(0)$DNL\n";
print '@output(@,@)', "\n";
(print "garbage"x10, "\n") for (1..1000);
print "${M4}_divert_pop(0)\n";
]])
AT_CHECK([[perl gen-skel.pl > skel.c || exit 77]])
AT_DATA([[input.y]],
[[%skeleton "./skel.c"
%%
start: ;
]])
AT_BISON_CHECK([[input.y]], [[1]], [[]],
[[input.y: fatal error: too many arguments for @output directive in skeleton
]])
AT_CLEANUP