qom: Drop parameter @errp of object_property_add() & friends

The only way object_property_add() can fail is when a property with
the same name already exists.  Since our property names are all
hardcoded, failure is a programming error, and the appropriate way to
handle it is passing &error_abort.

Same for its variants, except for object_property_add_child(), which
additionally fails when the child already has a parent.  Parentage is
also under program control, so this is a programming error, too.

We have a bit over 500 callers.  Almost half of them pass
&error_abort, slightly fewer ignore errors, one test case handles
errors, and the remaining few callers pass them to their own callers.

The previous few commits demonstrated once again that ignoring
programming errors is a bad idea.

Of the few ones that pass on errors, several violate the Error API.
The Error ** argument must be NULL, &error_abort, &error_fatal, or a
pointer to a variable containing NULL.  Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.  ich9_pm_add_properties(), sparc32_ledma_realize(),
sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize()
are wrong that way.

When the one appropriate choice of argument is &error_abort, letting
users pick the argument is a bad idea.

Drop parameter @errp and assert the preconditions instead.

There's one exception to "duplicate property name is a programming
error": the way object_property_add() implements the magic (and
undocumented) "automatic arrayification".  Don't drop @errp there.
Instead, rename object_property_add() to object_property_try_add(),
and add the obvious wrapper object_property_add().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-15-armbru@redhat.com>
[Two semantic rebase conflicts resolved]

3 files changed, 102 insertions, 207 deletions

diff --git a/qom/container.c b/qom/container.c
index e635e8ee76..14e7ae485b 100644
--- a/qom/container.c
+++ b/qom/container.c
@@ -39,7 +39,7 @@ Object *container_get(Object *root, const char *path)
         child = object_resolve_path_component(obj, parts[i]);
         if (!child) {
             child = object_new("container");
-            object_property_add_child(obj, parts[i], child, NULL);
+            object_property_add_child(obj, parts[i], child);
             object_unref(child);
         }
     }
diff --git a/qom/object.c b/qom/object.c
index 58a6ec9b1b..23f481ca46 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -557,10 +557,7 @@ void object_initialize_childv(Object *parentobj, const char *propname,
         goto out;
     }
 
-    object_property_add_child(parentobj, propname, obj, &local_err);
-    if (local_err) {
-        goto out;
-    }
+    object_property_add_child(parentobj, propname, obj);
 
     uc = (UserCreatable *)object_dynamic_cast(obj, TYPE_USER_CREATABLE);
     if (uc) {
@@ -745,10 +742,7 @@ Object *object_new_with_propv(const char *typename,
     }
 
     if (id != NULL) {
-        object_property_add_child(parent, id, obj, &local_err);
-        if (local_err) {
-            goto error;
-        }
+        object_property_add_child(parent, id, obj);
     }
 
     uc = (UserCreatable *)object_dynamic_cast(obj, TYPE_USER_CREATABLE);
@@ -1129,12 +1123,12 @@ void object_unref(Object *obj)
     }
 }
 
-ObjectProperty *
-object_property_add(Object *obj, const char *name, const char *type,
-                    ObjectPropertyAccessor *get,
-                    ObjectPropertyAccessor *set,
-                    ObjectPropertyRelease *release,
-                    void *opaque, Error **errp)
+static ObjectProperty *
+object_property_try_add(Object *obj, const char *name, const char *type,
+                        ObjectPropertyAccessor *get,
+                        ObjectPropertyAccessor *set,
+                        ObjectPropertyRelease *release,
+                        void *opaque, Error **errp)
 {
     ObjectProperty *prop;
     size_t name_len = strlen(name);
@@ -1148,8 +1142,8 @@ object_property_add(Object *obj, const char *name, const char *type,
         for (i = 0; ; ++i) {
             char *full_name = g_strdup_printf("%s[%d]", name_no_array, i);
 
-            ret = object_property_add(obj, full_name, type, get, set,
-                                      release, opaque, NULL);
+            ret = object_property_try_add(obj, full_name, type, get, set,
+                                          release, opaque, NULL);
             g_free(full_name);
             if (ret) {
                 break;
@@ -1180,22 +1174,28 @@ object_property_add(Object *obj, const char *name, const char *type,
 }
 
 ObjectProperty *
+object_property_add(Object *obj, const char *name, const char *type,
+                    ObjectPropertyAccessor *get,
+                    ObjectPropertyAccessor *set,
+                    ObjectPropertyRelease *release,
+                    void *opaque)
+{
+    return object_property_try_add(obj, name, type, get, set, release,
+                                   opaque, &error_abort);
+}
+
+ObjectProperty *
 object_class_property_add(ObjectClass *klass,
                           const char *name,
                           const char *type,
                           ObjectPropertyAccessor *get,
                           ObjectPropertyAccessor *set,
                           ObjectPropertyRelease *release,
-                          void *opaque,
-                          Error **errp)
+                          void *opaque)
 {
     ObjectProperty *prop;
 
-    if (object_class_property_find(klass, name, NULL) != NULL) {
-        error_setg(errp, "attempt to add duplicate property '%s' to class (type '%s')",
-                   name, object_class_get_name(klass));
-        return NULL;
-    }
+    assert(!object_class_property_find(klass, name, NULL));
 
     prop = g_malloc0(sizeof(*prop));
 
@@ -1648,24 +1648,17 @@ static void object_finalize_child_property(Object *obj, const char *name,
 
 ObjectProperty *
 object_property_add_child(Object *obj, const char *name,
-                          Object *child, Error **errp)
+                          Object *child)
 {
     g_autofree char *type = NULL;
     ObjectProperty *op;
 
-    if (child->parent != NULL) {
-        error_setg(errp, "child object is already parented");
-        return NULL;
-    }
+    assert(!child->parent);
 
     type = g_strdup_printf("child<%s>", object_get_typename(OBJECT(child)));
 
     op = object_property_add(obj, name, type, object_get_child_property, NULL,
-                             object_finalize_child_property, child, errp);
-    if (!op) {
-        return NULL;
-    }
-
+                             object_finalize_child_property, child);
     op->resolve = object_resolve_child_property;
     object_ref(child);
     child->parent = obj;
@@ -1821,8 +1814,7 @@ object_add_link_prop(Object *obj, const char *name,
                      const char *type, void *ptr,
                      void (*check)(const Object *, const char *,
                                    Object *, Error **),
-                     ObjectPropertyLinkFlags flags,
-                     Error **errp)
+                     ObjectPropertyLinkFlags flags)
 {
     LinkProperty *prop = g_malloc(sizeof(*prop));
     g_autofree char *full_type = NULL;
@@ -1842,13 +1834,7 @@ object_add_link_prop(Object *obj, const char *name,
                              object_get_link_property,
                              check ? object_set_link_property : NULL,
                              object_release_link_property,
-                             prop,
-                             errp);
-    if (!op) {
-        g_free(prop);
-        return NULL;
-    }
-
+                             prop);
     op->resolve = object_resolve_link_property;
     return op;
 }
@@ -1858,11 +1844,9 @@ object_property_add_link(Object *obj, const char *name,
                          const char *type, Object **targetp,
                          void (*check)(const Object *, const char *,
                                        Object *, Error **),
-                         ObjectPropertyLinkFlags flags,
-                         Error **errp)
+                         ObjectPropertyLinkFlags flags)
 {
-    return object_add_link_prop(obj, name, type, targetp, check, flags,
-                                errp);
+    return object_add_link_prop(obj, name, type, targetp, check, flags);
 }
 
 ObjectProperty *
@@ -1871,10 +1855,8 @@ object_class_property_add_link(ObjectClass *oc,
     const char *type, ptrdiff_t offset,
     void (*check)(const Object *obj, const char *name,
                   Object *val, Error **errp),
-    ObjectPropertyLinkFlags flags,
-    Error **errp)
+    ObjectPropertyLinkFlags flags)
 {
-    Error *local_err = NULL;
     LinkProperty *prop = g_new0(LinkProperty, 1);
     char *full_type;
     ObjectProperty *op;
@@ -1889,28 +1871,21 @@ object_class_property_add_link(ObjectClass *oc,
                                    object_get_link_property,
                                    check ? object_set_link_property : NULL,
                                    object_release_link_property,
-                                   prop,
-                                   &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        g_free(prop);
-        goto out;
-    }
+                                   prop);
 
     op->resolve = object_resolve_link_property;
 
-out:
     g_free(full_type);
     return op;
 }
 
 ObjectProperty *
 object_property_add_const_link(Object *obj, const char *name,
-                               Object *target, Error **errp)
+                               Object *target)
 {
     return object_add_link_prop(obj, name,
                                 object_get_typename(target), target,
-                                NULL, OBJ_PROP_LINK_DIRECT, errp);
+                                NULL, OBJ_PROP_LINK_DIRECT);
 }
 
 char *object_get_canonical_path_component(Object *obj)
@@ -2122,51 +2097,36 @@ static void property_release_str(Object *obj, const char *name,
 ObjectProperty *
 object_property_add_str(Object *obj, const char *name,
                         char *(*get)(Object *, Error **),
-                        void (*set)(Object *, const char *, Error **),
-                        Error **errp)
+                        void (*set)(Object *, const char *, Error **))
 {
     StringProperty *prop = g_malloc0(sizeof(*prop));
-    ObjectProperty *op;
 
     prop->get = get;
     prop->set = set;
 
-    op = object_property_add(obj, name, "string",
-                             get ? property_get_str : NULL,
-                             set ? property_set_str : NULL,
-                             property_release_str,
-                             prop, errp);
-    if (!op) {
-        g_free(prop);
-    }
-    return op;
+    return object_property_add(obj, name, "string",
+                               get ? property_get_str : NULL,
+                               set ? property_set_str : NULL,
+                               property_release_str,
+                               prop);
 }
 
 ObjectProperty *
 object_class_property_add_str(ObjectClass *klass, const char *name,
                                    char *(*get)(Object *, Error **),
                                    void (*set)(Object *, const char *,
-                                               Error **),
-                                   Error **errp)
+                                               Error **))
 {
-    Error *local_err = NULL;
     StringProperty *prop = g_malloc0(sizeof(*prop));
-    ObjectProperty *rv;
 
     prop->get = get;
     prop->set = set;
 
-    rv = object_class_property_add(klass, name, "string",
-                              get ? property_get_str : NULL,
-                              set ? property_set_str : NULL,
-                              NULL,
-                              prop, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        g_free(prop);
-    }
-
-    return rv;
+    return object_class_property_add(klass, name, "string",
+                                     get ? property_get_str : NULL,
+                                     set ? property_set_str : NULL,
+                                     NULL,
+                                     prop);
 }
 
 typedef struct BoolProperty
@@ -2217,50 +2177,35 @@ static void property_release_bool(Object *obj, const char *name,
 ObjectProperty *
 object_property_add_bool(Object *obj, const char *name,
                          bool (*get)(Object *, Error **),
-                         void (*set)(Object *, bool, Error **),
-                         Error **errp)
+                         void (*set)(Object *, bool, Error **))
 {
     BoolProperty *prop = g_malloc0(sizeof(*prop));
-    ObjectProperty *op;
 
     prop->get = get;
     prop->set = set;
 
-    op = object_property_add(obj, name, "bool",
-                             get ? property_get_bool : NULL,
-                             set ? property_set_bool : NULL,
-                             property_release_bool,
-                             prop, errp);
-    if (!op) {
-        g_free(prop);
-    }
-    return op;
+    return object_property_add(obj, name, "bool",
+                               get ? property_get_bool : NULL,
+                               set ? property_set_bool : NULL,
+                               property_release_bool,
+                               prop);
 }
 
 ObjectProperty *
 object_class_property_add_bool(ObjectClass *klass, const char *name,
                                     bool (*get)(Object *, Error **),
-                                    void (*set)(Object *, bool, Error **),
-                                    Error **errp)
+                                    void (*set)(Object *, bool, Error **))
 {
-    Error *local_err = NULL;
     BoolProperty *prop = g_malloc0(sizeof(*prop));
-    ObjectProperty *rv;
 
     prop->get = get;
     prop->set = set;
 
-    rv = object_class_property_add(klass, name, "bool",
-                              get ? property_get_bool : NULL,
-                              set ? property_set_bool : NULL,
-                              NULL,
-                              prop, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        g_free(prop);
-    }
-
-    return rv;
+    return object_class_property_add(klass, name, "bool",
+                                     get ? property_get_bool : NULL,
+                                     set ? property_set_bool : NULL,
+                                     NULL,
+                                     prop);
 }
 
 static void property_get_enum(Object *obj, Visitor *v, const char *name,
@@ -2306,25 +2251,19 @@ object_property_add_enum(Object *obj, const char *name,
                          const char *typename,
                          const QEnumLookup *lookup,
                          int (*get)(Object *, Error **),
-                         void (*set)(Object *, int, Error **),
-                         Error **errp)
+                         void (*set)(Object *, int, Error **))
 {
     EnumProperty *prop = g_malloc(sizeof(*prop));
-    ObjectProperty *op;
 
     prop->lookup = lookup;
     prop->get = get;
     prop->set = set;
 
-    op = object_property_add(obj, name, typename,
-                             get ? property_get_enum : NULL,
-                             set ? property_set_enum : NULL,
-                             property_release_enum,
-                             prop, errp);
-    if (!op) {
-        g_free(prop);
-    }
-    return op;
+    return object_property_add(obj, name, typename,
+                               get ? property_get_enum : NULL,
+                               set ? property_set_enum : NULL,
+                               property_release_enum,
+                               prop);
 }
 
 ObjectProperty *
@@ -2332,28 +2271,19 @@ object_class_property_add_enum(ObjectClass *klass, const char *name,
                                     const char *typename,
                                     const QEnumLookup *lookup,
                                     int (*get)(Object *, Error **),
-                                    void (*set)(Object *, int, Error **),
-                                    Error **errp)
+                                    void (*set)(Object *, int, Error **))
 {
-    Error *local_err = NULL;
     EnumProperty *prop = g_malloc(sizeof(*prop));
-    ObjectProperty *rv;
 
     prop->lookup = lookup;
     prop->get = get;
     prop->set = set;
 
-    rv = object_class_property_add(klass, name, typename,
-                              get ? property_get_enum : NULL,
-                              set ? property_set_enum : NULL,
-                              NULL,
-                              prop, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        g_free(prop);
-    }
-
-    return rv;
+    return object_class_property_add(klass, name, typename,
+                                     get ? property_get_enum : NULL,
+                                     set ? property_set_enum : NULL,
+                                     NULL,
+                                     prop);
 }
 
 typedef struct TMProperty {
@@ -2417,45 +2347,29 @@ static void property_release_tm(Object *obj, const char *name,
 
 ObjectProperty *
 object_property_add_tm(Object *obj, const char *name,
-                       void (*get)(Object *, struct tm *, Error **),
-                       Error **errp)
+                       void (*get)(Object *, struct tm *, Error **))
 {
     TMProperty *prop = g_malloc0(sizeof(*prop));
-    ObjectProperty *op;
 
     prop->get = get;
 
-    op = object_property_add(obj, name, "struct tm",
-                             get ? property_get_tm : NULL, NULL,
-                             property_release_tm,
-                             prop, errp);
-    if (!op) {
-        g_free(prop);
-    }
-    return op;
+    return object_property_add(obj, name, "struct tm",
+                               get ? property_get_tm : NULL, NULL,
+                               property_release_tm,
+                               prop);
 }
 
 ObjectProperty *
 object_class_property_add_tm(ObjectClass *klass, const char *name,
-                                  void (*get)(Object *, struct tm *, Error **),
-                                  Error **errp)
+                             void (*get)(Object *, struct tm *, Error **))
 {
-    Error *local_err = NULL;
     TMProperty *prop = g_malloc0(sizeof(*prop));
-    ObjectProperty *rv;
 
     prop->get = get;
 
-    rv = object_class_property_add(klass, name, "struct tm",
-                              get ? property_get_tm : NULL, NULL,
-                              NULL,
-                              prop, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        g_free(prop);
-    }
-
-    return rv;
+    return object_class_property_add(klass, name, "struct tm",
+                                     get ? property_get_tm : NULL,
+                                     NULL, NULL, prop);
 }
 
 static char *qdev_get_type(Object *obj, Error **errp)
@@ -2558,8 +2472,7 @@ static void property_set_uint64_ptr(Object *obj, Visitor *v, const char *name,
 ObjectProperty *
 object_property_add_uint8_ptr(Object *obj, const char *name,
                               const uint8_t *v,
-                              ObjectPropertyFlags flags,
-                              Error **errp)
+                              ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2573,14 +2486,13 @@ object_property_add_uint8_ptr(Object *obj, const char *name,
     }
 
     return object_property_add(obj, name, "uint8",
-                               getter, setter, NULL, (void *)v, errp);
+                               getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_class_property_add_uint8_ptr(ObjectClass *klass, const char *name,
                                     const uint8_t *v,
-                                    ObjectPropertyFlags flags,
-                                    Error **errp)
+                                    ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2594,14 +2506,13 @@ object_class_property_add_uint8_ptr(ObjectClass *klass, const char *name,
     }
 
     return object_class_property_add(klass, name, "uint8",
-                                     getter, setter, NULL, (void *)v, errp);
+                                     getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_property_add_uint16_ptr(Object *obj, const char *name,
                                const uint16_t *v,
-                               ObjectPropertyFlags flags,
-                               Error **errp)
+                               ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2615,14 +2526,13 @@ object_property_add_uint16_ptr(Object *obj, const char *name,
     }
 
     return object_property_add(obj, name, "uint16",
-                               getter, setter, NULL, (void *)v, errp);
+                               getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_class_property_add_uint16_ptr(ObjectClass *klass, const char *name,
                                      const uint16_t *v,
-                                     ObjectPropertyFlags flags,
-                                     Error **errp)
+                                     ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2636,14 +2546,13 @@ object_class_property_add_uint16_ptr(ObjectClass *klass, const char *name,
     }
 
     return object_class_property_add(klass, name, "uint16",
-                                     getter, setter, NULL, (void *)v, errp);
+                                     getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_property_add_uint32_ptr(Object *obj, const char *name,
                                const uint32_t *v,
-                               ObjectPropertyFlags flags,
-                               Error **errp)
+                               ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2657,14 +2566,13 @@ object_property_add_uint32_ptr(Object *obj, const char *name,
     }
 
     return object_property_add(obj, name, "uint32",
-                               getter, setter, NULL, (void *)v, errp);
+                               getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_class_property_add_uint32_ptr(ObjectClass *klass, const char *name,
                                      const uint32_t *v,
-                                     ObjectPropertyFlags flags,
-                                     Error **errp)
+                                     ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2678,14 +2586,13 @@ object_class_property_add_uint32_ptr(ObjectClass *klass, const char *name,
     }
 
     return object_class_property_add(klass, name, "uint32",
-                                     getter, setter, NULL, (void *)v, errp);
+                                     getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_property_add_uint64_ptr(Object *obj, const char *name,
                                const uint64_t *v,
-                               ObjectPropertyFlags flags,
-                               Error **errp)
+                               ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2699,14 +2606,13 @@ object_property_add_uint64_ptr(Object *obj, const char *name,
     }
 
     return object_property_add(obj, name, "uint64",
-                               getter, setter, NULL, (void *)v, errp);
+                               getter, setter, NULL, (void *)v);
 }
 
 ObjectProperty *
 object_class_property_add_uint64_ptr(ObjectClass *klass, const char *name,
                                      const uint64_t *v,
-                                     ObjectPropertyFlags flags,
-                                     Error **errp)
+                                     ObjectPropertyFlags flags)
 {
     ObjectPropertyAccessor *getter = NULL;
     ObjectPropertyAccessor *setter = NULL;
@@ -2720,7 +2626,7 @@ object_class_property_add_uint64_ptr(ObjectClass *klass, const char *name,
     }
 
     return object_class_property_add(klass, name, "uint64",
-                                     getter, setter, NULL, (void *)v, errp);
+                                     getter, setter, NULL, (void *)v);
 }
 
 typedef struct {
@@ -2762,18 +2668,15 @@ static void property_release_alias(Object *obj, const char *name, void *opaque)
 
 ObjectProperty *
 object_property_add_alias(Object *obj, const char *name,
-                          Object *target_obj, const char *target_name,
-                          Error **errp)
+                          Object *target_obj, const char *target_name)
 {
     AliasProperty *prop;
     ObjectProperty *op;
     ObjectProperty *target_prop;
     g_autofree char *prop_type = NULL;
 
-    target_prop = object_property_find(target_obj, target_name, errp);
-    if (!target_prop) {
-        return NULL;
-    }
+    target_prop = object_property_find(target_obj, target_name,
+                                       &error_abort);
 
     if (object_property_is_child(target_prop)) {
         prop_type = g_strdup_printf("link%s",
@@ -2790,12 +2693,7 @@ object_property_add_alias(Object *obj, const char *name,
                              property_get_alias,
                              property_set_alias,
                              property_release_alias,
-                             prop, errp);
-    if (!op) {
-        g_free(prop);
-        return NULL;
-    }
-
+                             prop);
     op->resolve = property_resolve_alias;
     if (target_prop->defval) {
         op->defval = qobject_ref(target_prop->defval);
@@ -2830,7 +2728,7 @@ void object_class_property_set_description(ObjectClass *klass,
 static void object_class_init(ObjectClass *klass, void *data)
 {
     object_class_property_add_str(klass, "type", qdev_get_type,
-                                  NULL, &error_abort);
+                                  NULL);
 }
 
 static void register_types(void)
diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index bc36f96e47..054e75043d 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -83,10 +83,7 @@ Object *user_creatable_add_type(const char *type, const char *id,
 
     if (id != NULL) {
         object_property_add_child(object_get_objects_root(),
-                                  id, obj, &local_err);
-        if (local_err) {
-            goto out;
-        }
+                                  id, obj);
     }
 
     user_creatable_complete(USER_CREATABLE(obj), &local_err);