[Qemu-devel] [PATCH] qemu-iotests: Fix core dump suppression in test 039

[Markus Armbruster <armbru@redhat.com>]

The shell script attempts to suppress core dumps like this:

    old_ulimit=$(ulimit -c)
    ulimit -c 0
    $QEMU_IO arg...
    ulimit -c "$old_ulimit"

This breaks the test hard unless the limit was zero to begin with!
ulimit sets both hard and soft limit by default, and (re-)raising the
hard limit requires privileges.  Broken since it was added in commit
dc68afe.

Could be fixed by adding -S to set only the soft limit, but I'm not
sure how portable that is in practice.  Simply do it in a subshell
instead, like this:

    (ulimit -c 0; exec $QEMU_IO arg...)

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 tests/qemu-iotests/039 | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/tests/qemu-iotests/039 b/tests/qemu-iotests/039
index b9cbe99..182b0f0 100755
--- a/tests/qemu-iotests/039
+++ b/tests/qemu-iotests/039
@@ -67,10 +67,8 @@ echo "== Creating a dirty image file =="
 IMGOPTS="compat=1.1,lazy_refcounts=on"
 _make_test_img $size
 
-old_ulimit=$(ulimit -c)
-ulimit -c 0 # do not produce a core dump on abort(3)
-$QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG" | _filter_qemu_io
-ulimit -c "$old_ulimit"
+(ulimit -c 0 # do not produce a core dump on abort(3)
+exec $QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG") | _filter_qemu_io
 
 # The dirty bit must be set
 ./qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
@@ -103,10 +101,8 @@ echo "== Opening a dirty image read/write should repair it =="
 IMGOPTS="compat=1.1,lazy_refcounts=on"
 _make_test_img $size
 
-old_ulimit=$(ulimit -c)
-ulimit -c 0 # do not produce a core dump on abort(3)
-$QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG" | _filter_qemu_io
-ulimit -c "$old_ulimit"
+(ulimit -c 0 # do not produce a core dump on abort(3)
+exec $QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG") | _filter_qemu_io
 
 # The dirty bit must be set
 ./qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
@@ -122,10 +118,8 @@ echo "== Creating an image file with lazy_refcounts=off =="
 IMGOPTS="compat=1.1,lazy_refcounts=off"
 _make_test_img $size
 
-old_ulimit=$(ulimit -c)
-ulimit -c 0 # do not produce a core dump on abort(3)
-$QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG" | _filter_qemu_io
-ulimit -c "$old_ulimit"
+(ulimit -c 0 # do not produce a core dump on abort(3)
+exec $QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG") | _filter_qemu_io
 
 # The dirty bit must not be set since lazy_refcounts=off
 ./qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
-- 
1.8.1.4