diff options
author | Markus Armbruster <armbru@redhat.com> | 2015-06-20 09:33:56 +0200 |
---|---|---|
committer | Markus Armbruster <armbru@redhat.com> | 2015-09-10 13:48:06 +0200 |
commit | 08e64640357cd9517aa30fd49840f05f0f2ee3a4 (patch) | |
tree | 1d4de3c1c8df39ca0d1d20d65eecdfa8a5d6dfd8 /qga | |
parent | e7cf59e84767e30b507b6bd7c1347072ec12b636 (diff) | |
download | qemu-08e64640357cd9517aa30fd49840f05f0f2ee3a4.zip qemu-08e64640357cd9517aa30fd49840f05f0f2ee3a4.tar.gz qemu-08e64640357cd9517aa30fd49840f05f0f2ee3a4.tar.bz2 |
qga/vss-win32: Document the DLL requires non-null errp
requester.cpp uses this pattern to receive an error and pass it on to
the caller (err_is_set() macro peeled off for clarity):
... code that may set errset->errp ...
if (errset->errp && *errset->errp) {
... handle error ...
}
This breaks when errset->errp is null. As far as I can tell, it
currently isn't, so this is merely fragile, not actually broken.
The robust way to do this is to receive the error in a local variable,
then propagate it up, like this:
Error *err = NULL;
... code that may set err ...
if (err)
... handle error ...
error_propagate(errset->errp, err);
}
See also commit 5e54769, 0f230bf, a903f40.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'qga')
-rw-r--r-- | qga/vss-win32.c | 1 | ||||
-rw-r--r-- | qga/vss-win32/requester.cpp | 3 | ||||
-rw-r--r-- | qga/vss-win32/requester.h | 2 |
3 files changed, 4 insertions, 2 deletions
diff --git a/qga/vss-win32.c b/qga/vss-win32.c index e1f5398..d75d7bb 100644 --- a/qga/vss-win32.c +++ b/qga/vss-win32.c @@ -154,6 +154,7 @@ void qga_vss_fsfreeze(int *nr_volume, Error **errp, bool freeze) .errp = errp, }; + g_assert(errp); /* requester.cpp requires it */ func = (QGAVSSRequesterFunc)GetProcAddress(provider_lib, func_name); if (!func) { error_setg_win32(errp, GetLastError(), "failed to load %s from %s", diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp index b130fee..aae0d5f 100644 --- a/qga/vss-win32/requester.cpp +++ b/qga/vss-win32/requester.cpp @@ -25,8 +25,9 @@ #define err_set(e, err, fmt, ...) \ ((e)->error_setg_win32((e)->errp, err, fmt, ## __VA_ARGS__)) +/* Bad idea, works only when (e)->errp != NULL: */ #define err_is_set(e) ((e)->errp && *(e)->errp) - +/* To lift this restriction, error_propagate(), like we do in QEMU code */ /* Handle to VSSAPI.DLL */ static HMODULE hLib; diff --git a/qga/vss-win32/requester.h b/qga/vss-win32/requester.h index 0a8d048..34be5c1 100644 --- a/qga/vss-win32/requester.h +++ b/qga/vss-win32/requester.h @@ -27,7 +27,7 @@ typedef void (*ErrorSetFunc)(struct Error **errp, int win32_err, const char *fmt, ...) GCC_FMT_ATTR(3, 4); typedef struct ErrorSet { ErrorSetFunc error_setg_win32; - struct Error **errp; + struct Error **errp; /* restriction: must not be null */ } ErrorSet; STDAPI requester_init(void); |