089: fix error caused by weird stdout buffer handling

(v2: Get rid of the diff mambo-jambo in the commit description)

We have hit the error while running 089.

FSTYP -- ext3
PLATFORM -- Linux/x86_64 localhost 2.6.32-109.el6.x86_64

...
...
completed 50 iterations
completed 50 iterations
completed 50 iterations
-completed 50 iterations
completed 10000 iterations
directory entries:
t_mtab
Ran: 089
Failures: 089
Failed 1 of 1 tests

This is not very easily reproducible, however one can hit it eventually when running 089 in the loop. The problem is apparently, that the output might get lost, probably due to some stdio buffer weirdness.

This commit workaround the issue by adding an optional argument to the t_mtab to specify output file. The t_mtab output is then appended to a file which content is then printed to the stdout as it would if no output file is used.

With this commit applied the problem is no longer reproducible.

Signed-off-by Lukas Czerner <[email protected]>

---
 089          |    9 ++++++---
 src/t_mtab.c |    8 +++++++-
 2 files changed, 13 insertions(+), 4 deletions(-)

089 +6 -3

index e28e099..1714bec 100755
@@ -28,6 +28,7 @@ [email protected]
 seq=`basename $0`
 echo "QA output created by $seq"
 
+mtab_output=$TEST_DIR/mtab_output
 here=`pwd`
 tmp=/tmp/$$
 status=1	# failure is the default!

@@ -62,10 +63,12 @@ mount > t_mtab
 
 mtab()
 {
-	$here/src/t_mtab 50 &
-	$here/src/t_mtab 50 &
-	$here/src/t_mtab 50 &
+	rm -f $mtab_output
+	$here/src/t_mtab 50 $mtab_output &
+	$here/src/t_mtab 50 $mtab_output &
+	$here/src/t_mtab 50 $mtab_output &
 	wait
+	cat $mtab_output
 
 	$here/src/t_mtab 10000
 

src/t_mtab.c +7 -1

index 2931887..9bca954 100644
@@ -263,6 +263,7 @@ update_mtab (void)
 int main(int argc, char **argv)
 {
 	int i, stop = 100000;
+	FILE *fout = NULL;
 
 	if (argc > 1)
 		stop = atoi(argv[1]);

@@ -270,6 +271,11 @@ int main(int argc, char **argv)
 	for (i = 0; i < stop; i++) {
 		update_mtab();
 	}
-	printf("completed %d iterations\n", stop);
+
+	if (argc > 2)
+		fout = fopen(argv[2],"a");
+	if (!fout)
+		fout = stdout;
+	fprintf(fout, "completed %d iterations\n", stop);
 	return 0;
 }