[Qemu-devel] [PATCH v2 3/4] block: qobject_is_equal() in bdrv_reopen_prepare()

[Max Reitz <mreitz@redhat.com>]

Currently, bdrv_reopen_prepare() assumes that all BDS options are
strings. However, this is not the case if the BDS has been created
through the json: pseudo-protocol or blockdev-add.

Note that the user-invokable reopen command is an HMP command, so you
can only specify strings there. Therefore, specifying a non-string
option with the "same" value as it was when originally created will now
return an error because the values are supposedly similar (and there is
no way for the user to circumvent this but to just not specify the
option again -- however, this is still strictly better than just
crashing).

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/block.c b/block.c
index fa1d06d..23424d5 100644
--- a/block.c
+++ b/block.c
@@ -2950,19 +2950,10 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
         const QDictEntry *entry = qdict_first(reopen_state->options);
 
         do {
-            QString *new_obj = qobject_to_qstring(entry->value);
-            const char *new = qstring_get_str(new_obj);
-            /*
-             * Caution: while qdict_get_try_str() is fine, getting
-             * non-string types would require more care.  When
-             * bs->options come from -blockdev or blockdev_add, its
-             * members are typed according to the QAPI schema, but
-             * when they come from -drive, they're all QString.
-             */
-            const char *old = qdict_get_try_str(reopen_state->bs->options,
-                                                entry->key);
+            QObject *new = entry->value;
+            QObject *old = qdict_get(reopen_state->bs->options, entry->key);
 
-            if (!old || strcmp(new, old)) {
+            if (!qobject_is_equal(new, old)) {
                 error_setg(errp, "Cannot change the option '%s'", entry->key);
                 ret = -EINVAL;
                 goto error;
-- 
2.9.4