On Tue, May 21, 2013 at 06:56:07AM -0600, Eric Blake wrote: > On 05/21/2013 06:43 AM, Stefan Hajnoczi wrote: > > glibc wipes malloc(3) memory when the MALLOC_PERTURB_ environment > > variable is set. The value of the environment variable determines the > > bit pattern used to wipe memory. For more information, see > > http://udrepper.livejournal.com/11429.html. > > > > Set MALLOC_PERTURB_ for gtester and qemu-iotests. Note we pick a random > > value from 1 to 255 to expose more bugs. If you need to reproduce a > > crash use 'show environment' in gdb to extract the MALLOC_PERTURB_ > > value from a core dump. > > > > Both make check and qemu-iotests pass with MALLOC_PERTURB_ enabled. > > > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > > --- > > tests/Makefile | 5 ++++- > > tests/qemu-iotests/check | 3 ++- > > 2 files changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/tests/Makefile b/tests/Makefile > > index a307d5a..24880c6 100644 > > --- a/tests/Makefile > > +++ b/tests/Makefile > > @@ -171,6 +171,7 @@ GCOV_OPTIONS = -n $(if $(V),-f,) > > $(patsubst %, check-qtest-%, $(QTEST_TARGETS)): check-qtest-%: > > $(check-qtest-y) > > $(if $(CONFIG_GCOV),@rm -f *.gcda */*.gcda */*/*.gcda */*/*/*.gcda,) > > $(call quiet-command,QTEST_QEMU_BINARY=$*-softmmu/qemu-system-$* \ > > + MALLOC_PERTURB_=${MALLOC_PERTURB_:-$(($RANDOM % 255 + 1))} \ > > This is a Makefile; don't you need to use $$ instead of $ (three instances)? > > $RANDOM is a bash-ism. If make is run with SHELL as /bin/sh on a > platform where dash is the primary shell, it will fail: > > $ dash -c 'echo $(($RANDOM % 255))' > dash: 1: arithmetic expression: expecting primary: " % 255" > > HOWEVER: you can exploit the fact that inside $(()), you don't need $ to > use the value of a defined variable, and also the fact that unless set > -u is in effect, an undefined variable name silently evaluates as 0: > > $ dash -c 'echo $((RANDOM % 255))' > 0 > > then you could write the shell code: > > MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 + 1))} > > or the Makefile code: > > MALLOC_PERTURB_=$${MALLOC_PERTURB_:-$$((RANDOM % 255 + 1))} > > and things will at least work on /bin/sh as dash (even though there will > be no randomness and you are always testing with 1 in that case).
Silly me. I did test it but it silently "worked". Will resend. Stefan
