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

[Fam Zheng]

On Tue, 05/13 13:30, Markus Armbruster wrote:
> Fam Zheng <address@hidden> writes:
> 
> > On Tue, 05/13 10:46, Markus Armbruster wrote:
> >> 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 <address@hidden>
> >> ---
> >>  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
> >
> > This works well.
> >
> > But when I try to put this in a function to avoid repeating:
> >
> >     function _no_dump_exec()
> >     {
> >         (ulimit -c 0; exec "$@")
> >     }
> >
> >     _no_dump_exec $QEMU_IO -c "write -P 0x5a 0 512" -c "abort" "$TEST_IMG") 
> > | _filter_qemu_io
> >
> > it doesn't work:
> >
> >     039 1s ... - output mismatch (see 039.out.bad)
> >     --- 039.out     2014-05-13 12:10:39.248866480 +0800
> >     +++ 039.out.bad 2014-05-13 17:19:46.161986618 +0800
> >     @@ -9,6 +9,7 @@
> >
> >      == Creating a dirty image file ==
> >      Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
> >     +./039: line 51: 10517 Aborted                 "$@"
> >      wrote 512/512 bytes at offset 0
> >      512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> >      incompatible_features     0x1
> >
> > Any idea what the difference is here?
> 
> Full patch of your version, please.

Here it goes:

diff --git a/tests/qemu-iotests/039 b/tests/qemu-iotests/039
index b9cbe99..27544f9 100755
--- a/tests/qemu-iotests/039
+++ b/tests/qemu-iotests/039
@@ -47,6 +47,13 @@ _supported_os Linux
 _default_cache_mode "writethrough"
 _supported_cache_modes "writethrough"

+function _no_dump_exec()
+{
+    (
+    ulimit -c 0
+    "$@")
+}
+
 size=128M

 echo
@@ -67,10 +74,7 @@ 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"
+_no_dump_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