Re: [PATCH for-9.2 1/9] tests/qtest/migration-test: Fix bootfile cleanup handling

[Fabiano Rosas <farosas@suse.de>]

Peter Maydell <peter.maydell@linaro.org> writes:

> If you invoke the migration-test binary in such a way that it doesn't run
> any tests, then we never call bootfile_create(), and at the end of
> main() bootfile_delete() will try to unlink(NULL), which is not valid.
> This can happen if for instance you tell the test binary to run a
> subset of tests that turns out to be empty, like this:
>
>  (cd build/asan && QTEST_QEMU_BINARY=./qemu-system-x86_64 ./tests/qtest/migration-test --tap -k -p bang)
>  # random seed: R02S6501b289ff8ced4231ba452c3a87bc6f
>  # Skipping test: userfaultfd not available
>  1..0
>  ../../tests/qtest/migration-test.c:182:12: runtime error: null pointer passed as argument 1, which is declared to never be null
>  /usr/include/unistd.h:858:48: note: nonnull attribute specified here
>
> Conversely, because we call bootfile_create() once per test
> but only call bootfile_delete() at the end of the whole test
> run, we will leak the memory we used for bootpath when we
> overwrite it.
>
> Handle these by:
>  * making bootfile_delete() handle not needing to do anything
>    because bootfile_create() was never called
>  * making bootfile_create() call bootfile_delete() first to
>    tidy up any previous bootfile before it creates a fresh one
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Fabiano Rosas <farosas@suse.de>