On Wed, Mar 27, 2019 at 01:02:07PM +0100, Andrea Bolognani wrote:
On Wed, 2019-03-27 at 10:50 +0100, Michal Privoznik wrote:
There is one specific caller (testInfoSetArgs() in qemuxml2argvtest.c) which expect the va_list argument to change
s/ / /
after returning from the virQEMUCapsSetVAList() function. However, since we are passing plain va_list this is not guaranteed. The man page of stdarg(3) says:
If ap is passed to a function that uses va_arg(ap,type), then the value of ap is undefined after the return of that function.
(ap is a variable of type va_list)
I've seen this in action in fact: on i686 the qemuxml2argvtest fails on the second test case because testInfoSetArgs() sees ARG_QEMU_CAPS and callse virQEMUCapsSetVAList to process the
s/callse/calls/
capabilities (in this case there's just one QEMU_CAPS_SECCOMP_BLACKLIST). But since the changes are not reflected in the caller, in the next iteration testInfoSetArgs() sees the qemu capability and not ARG_END.
s/qemu/QEMU/
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> ---
This passed successfully on x86_64 and i686 in my testing.
src/qemu/qemu_capabilities.c | 6 +++--- src/qemu/qemu_capabilities.h | 2 +- tests/qemuxml2argvtest.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-)
The changes look okay to me, so
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
however I'd like to hear Eric's opinion before this gets merged.
I'll trust Michal when he says it works, but it feels a bit odd to be passing a pointer to a va_list around. Personally I would have just inlined virQEMUCapsSetVAList() as it is only 2 lines of code. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|