Regression introduced in commit e6b68d7 (Nov 2010).
Prior to that point, handlesAlloc was always a multiple of
EVENT_ALLOC_EXTENT (10), and was an int (so even if the subtraction
had been able to wrap, a negative value would be less than the count
not try to free the handles array). But after that point,
VIR_RESIZE_N made handlesAlloc grow geometrically (with a pattern of
10, 20, 30, 45 for the handles array) but still freed in multiples of
EVENT_ALLOC_EXTENT; and the count changed to size_t. Which means that
after 31 handles have been created, then 30 handles destroyed,
handlesAlloc is 5 while handlesCount is 1, and since (size_t)(1 - 5)
is indeed greater than 1, this then tried to free 10 elements, which
had the awful effect of nuking the handles array while there were
still live handles.
Nuking live handles puts libvirtd in an inconsistent state, and was
easily reproducible by starting and then stopping 60 faqemu guests.
* daemon/event.c (virEventCleanupTimeouts, virEventCleanupHandles):
Avoid integer wrap-around causing us to delete the entire array
while entries are still active.
* tests/eventtest.c (mymain): Expose the bug.
Only print out '.' for each test case, full test output can be
re-enabled with VIR_TEST_VERBOSE=1, or VIR_TEST_DEBUG=XXXX
Sample output now looks like
TEST: statstest
........................................ 40
................................... 75 OK
PASS: statstest
TEST: qparamtest
................................ 32 OK
PASS: qparamtest
TEST:
............ 12 OK
If a file descriptor with events=0 was added to the libvirtd
event loop, it would still be added to the poll() fds' array.
While it wouldn't see any POLLIN/OUT events, it'd still get
triggered for HANGUP/ERROR events which was not in compliance
with the libvirt events API contract.
* qemud/event.c: Don't poll on FDs with events=0
* tests/eventtest.c: Add test case to validate fix to event.c
* src/logging.c src/logging.h src/libvirt_private.syms:
define new functions virLogSetFromEnv and virLogParseDefaultPriority
* qemud/qemud.c src/libvirt.c tests/eventtest.c: cleanup to use the
unified functions
