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block: Fix -blockdev / blockdev-add for empty objects and arrays

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-blockdev and blockdev-add silently ignore empty objects and arrays in
their argument.  That's because qmp_blockdev_add() converts the
argument to a flat QDict, and qdict_flatten() eats empty QDict and
QList members.  For instance, we ignore an empty BlockdevOptions
member @cache.  No real harm, as absent means the same as empty there.

Thus, the flaw puts an artificial restriction on the QAPI schema: we
can't have potentially empty objects and arrays within
BlockdevOptions, except when they're optional and "empty" has the same
meaning as "absent".

Our QAPI schema satisfies this restriction (I checked), but it's a
trap for the unwary, and a temptation to employ awkward workarounds
for the wary.  Let's get rid of it.

Change qdict_flatten() and qdict_crumple() to treat empty dictionaries
and lists exactly like scalars.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Markus Armbruster 2018-06-14 21:14:41 +02:00 • committed by Kevin Wolf
parent bef96b1549
commit 2860b2b2cb
2 changed files with 63 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

54
qobject/block-qdict.c
View file

@ -56,6 +56,8 @@ static void qdict_flatten_qlist(QList *qlist, QDict *target, const char *prefix)
{
QObject *value;
const QListEntry *entry;
QDict *dict_val;
QList *list_val;
char *new_key;
int i;
@ -69,16 +71,18 @@ static void qdict_flatten_qlist(QList *qlist, QDict *target, const char *prefix)
for (i = 0; entry; entry = qlist_next(entry), i++) {
value = qlist_entry_obj(entry);
dict_val = qobject_to(QDict, value);
list_val = qobject_to(QList, value);
new_key = g_strdup_printf("%s.%i", prefix, i);
/*
* Flatten non-empty QDict and QList recursively into @target,
* copy other objects to @target
*/
if (qobject_type(value) == QTYPE_QDICT) {
qdict_flatten_qdict(qobject_to(QDict, value), target, new_key);
} else if (qobject_type(value) == QTYPE_QLIST) {
qdict_flatten_qlist(qobject_to(QList, value), target, new_key);
if (dict_val && qdict_size(dict_val)) {
qdict_flatten_qdict(dict_val, target, new_key);
} else if (list_val && !qlist_empty(list_val)) {
qdict_flatten_qlist(list_val, target, new_key);
} else {
qdict_put_obj(target, new_key, qobject_ref(value));
}
@ -91,6 +95,8 @@ static void qdict_flatten_qdict(QDict *qdict, QDict *target, const char *prefix)
{
QObject *value;
const QDictEntry *entry, *next;
QDict *dict_val;
QList *list_val;
char *new_key;
entry = qdict_first(qdict);
@ -98,6 +104,8 @@ static void qdict_flatten_qdict(QDict *qdict, QDict *target, const char *prefix)
while (entry != NULL) {
next = qdict_next(qdict, entry);
value = qdict_entry_value(entry);
dict_val = qobject_to(QDict, value);
list_val = qobject_to(QList, value);
new_key = NULL;
if (prefix) {
@ -108,12 +116,12 @@ static void qdict_flatten_qdict(QDict *qdict, QDict *target, const char *prefix)
* Flatten non-empty QDict and QList recursively into @target,
* copy other objects to @target
*/
if (qobject_type(value) == QTYPE_QDICT) {
qdict_flatten_qdict(qobject_to(QDict, value), target,
if (dict_val && qdict_size(dict_val)) {
qdict_flatten_qdict(dict_val, target,
new_key ? new_key : entry->key);
qdict_del(qdict, entry->key);
} else if (qobject_type(value) == QTYPE_QLIST) {
qdict_flatten_qlist(qobject_to(QList, value), target,
} else if (list_val && !qlist_empty(list_val)) {
qdict_flatten_qlist(list_val, target,
new_key ? new_key : entry->key);
qdict_del(qdict, entry->key);
} else if (target != qdict) {
@ -127,10 +135,11 @@ static void qdict_flatten_qdict(QDict *qdict, QDict *target, const char *prefix)
}
/**
* qdict_flatten(): For each nested QDict with key x, all fields with key y
* are moved to this QDict and their key is renamed to "x.y". For each nested
* QList with key x, the field at index y is moved to this QDict with the key
* "x.y" (i.e., the reverse of what qdict_array_split() does).
* qdict_flatten(): For each nested non-empty QDict with key x, all
* fields with key y are moved to this QDict and their key is renamed
* to "x.y". For each nested non-empty QList with key x, the field at
* index y is moved to this QDict with the key "x.y" (i.e., the
* reverse of what qdict_array_split() does).
* This operation is applied recursively for nested QDicts and QLists.
*/
void qdict_flatten(QDict *qdict)
@ -361,8 +370,8 @@ static int qdict_is_list(QDict *maybe_list, Error **errp)
* @src: the original flat dictionary (only scalar values) to crumple
*
* Takes a flat dictionary whose keys use '.' separator to indicate
* nesting, and values are scalars, and crumples it into a nested
* structure.
* nesting, and values are scalars, empty dictionaries or empty lists,
* and crumples it into a nested structure.
*
* To include a literal '.' in a key name, it must be escaped as '..'
*
@ -399,6 +408,8 @@ QObject *qdict_crumple(const QDict *src, Error **errp)
{
const QDictEntry *ent;
QDict *two_level, *multi_level = NULL, *child_dict;
QDict *dict_val;
QList *list_val;
QObject *dst = NULL, *child;
size_t i;
char *prefix = NULL;
@ -409,10 +420,11 @@ QObject *qdict_crumple(const QDict *src, Error **errp)
/* Step 1: split our totally flat dict into a two level dict */
for (ent = qdict_first(src); ent != NULL; ent = qdict_next(src, ent)) {
if (qobject_type(ent->value) == QTYPE_QDICT ||
qobject_type(ent->value) == QTYPE_QLIST) {
error_setg(errp, "Value %s is not a scalar",
ent->key);
dict_val = qobject_to(QDict, ent->value);
list_val = qobject_to(QList, ent->value);
if ((dict_val && qdict_size(dict_val))
|| (list_val && !qlist_empty(list_val))) {
error_setg(errp, "Value %s is not flat", ent->key);
goto error;
}
@ -451,9 +463,9 @@ QObject *qdict_crumple(const QDict *src, Error **errp)
multi_level = qdict_new();
for (ent = qdict_first(two_level); ent != NULL;
ent = qdict_next(two_level, ent)) {
QDict *dict = qobject_to(QDict, ent->value);
if (dict) {
child = qdict_crumple(dict, errp);
dict_val = qobject_to(QDict, ent->value);
if (dict_val && qdict_size(dict_val)) {
child = qdict_crumple(dict_val, errp);
if (!child) {
goto error;
}