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68ab47e4b4
Returning a partial object on error is an invitation for a careless
caller to leak memory. We already fixed things in an earlier
patch to guarantee NULL if visit_start fails ("qapi: Guarantee
NULL obj on input visitor callback error"), but that does not
help the case where visit_start succeeds but some other failure
happens before visit_end, such that we leak a partially constructed
object outside visit_type_FOO(). As no one outside the testsuite
was actually relying on these semantics, it is cleaner to just
document and guarantee that ALL pointer-based visit_type_FOO()
functions always leave a safe value in *obj during an input visitor
(either the new object on success, or NULL if an error is
encountered), so callers can now unconditionally use
qapi_free_FOO() to clean up regardless of whether an error occurred.
The decision is done by adding visit_is_input(), then updating the
generated code to check if additional cleanup is needed based on
the type of visitor in use.
Note that we still leave *obj unchanged after a scalar-based
visit_type_FOO(); I did not feel like auditing all uses of
visit_type_Enum() to see if the callers would tolerate a specific
sentinel value (not to mention having to decide whether it would
be better to use 0 or ENUM__MAX as that sentinel).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1461879932-9020-25-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
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| .. | ||
| kvm | ||
| qemu-guest-agent | ||
| qemugdb | ||
| qmp | ||
| tracetool | ||
| analyse-9p-simpletrace.py | ||
| analyze-migration.py | ||
| check-qerror.sh | ||
| checkpatch.pl | ||
| clean-includes | ||
| cleanup-trace-events.pl | ||
| cocci-macro-file.h | ||
| coverity-model.c | ||
| create_config | ||
| disas-objdump.pl | ||
| dump-guest-memory.py | ||
| extract-vsssdk-headers | ||
| feature_to_c.sh | ||
| get_maintainer.pl | ||
| gtester-cat | ||
| hxtool | ||
| make_device_config.sh | ||
| make-release | ||
| ordereddict.py | ||
| qapi-commands.py | ||
| qapi-event.py | ||
| qapi-introspect.py | ||
| qapi-types.py | ||
| qapi-visit.py | ||
| qapi.py | ||
| qemu-binfmt-conf.sh | ||
| qemu-gdb.py | ||
| qtest.py | ||
| refresh-pxe-roms.sh | ||
| shaderinclude.pl | ||
| signrom.py | ||
| simpletrace.py | ||
| switch-timer-api | ||
| texi2pod.pl | ||
| tracetool.py | ||
| update-linux-headers.sh | ||
| vmstate-static-checker.py | ||