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]

1 files changed, 25 insertions, 56 deletions

diff --git a/include/qom/object.h b/include/qom/object.h
index 1f0386a..990e28e 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -1036,7 +1036,6 @@ void object_unref(Object *obj);
  *   meant to allow a property to free its opaque upon object
  *   destruction.  This may be NULL.
  * @opaque: an opaque pointer to pass to the callbacks for the property
- * @errp: returns an error if this function fails
  *
  * Returns: The #ObjectProperty; this can be used to set the @resolve
  * callback for child and link properties.
@@ -1046,7 +1045,7 @@ ObjectProperty *object_property_add(Object *obj, const char *name,
                                     ObjectPropertyAccessor *get,
                                     ObjectPropertyAccessor *set,
                                     ObjectPropertyRelease *release,
-                                    void *opaque, Error **errp);
+                                    void *opaque);
 
 void object_property_del(Object *obj, const char *name, Error **errp);
 
@@ -1055,7 +1054,7 @@ ObjectProperty *object_class_property_add(ObjectClass *klass, const char *name,
                                           ObjectPropertyAccessor *get,
                                           ObjectPropertyAccessor *set,
                                           ObjectPropertyRelease *release,
-                                          void *opaque, Error **errp);
+                                          void *opaque);
 
 /**
  * object_property_set_default_bool:
@@ -1480,7 +1479,6 @@ Object *object_resolve_path_component(Object *parent, const char *part);
  * @obj: the object to add a property to
  * @name: the name of the property
  * @child: the child object
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Child properties form the composition tree.  All objects need to be a child
  * of another object.  Objects can only be a child of one object.
@@ -1495,7 +1493,7 @@ Object *object_resolve_path_component(Object *parent, const char *part);
  * Returns: The newly added property on success, or %NULL on failure.
  */
 ObjectProperty *object_property_add_child(Object *obj, const char *name,
-                                          Object *child, Error **errp);
+                                          Object *child);
 
 typedef enum {
     /* Unref the link pointer when the property is deleted */
@@ -1524,7 +1522,6 @@ void object_property_allow_set_link(const Object *, const char *,
  * @targetp: a pointer to where the link object reference is stored
  * @check: callback to veto setting or NULL if the property is read-only
  * @flags: additional options for the link
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Links establish relationships between objects.  Links are unidirectional
  * although two links can be combined to form a bidirectional relationship
@@ -1551,16 +1548,14 @@ ObjectProperty *object_property_add_link(Object *obj, const char *name,
                               const char *type, Object **targetp,
                               void (*check)(const Object *obj, const char *name,
                                             Object *val, Error **errp),
-                              ObjectPropertyLinkFlags flags,
-                              Error **errp);
+                              ObjectPropertyLinkFlags flags);
 
 ObjectProperty *object_class_property_add_link(ObjectClass *oc,
                               const char *name,
                               const char *type, ptrdiff_t offset,
                               void (*check)(const Object *obj, const char *name,
                                             Object *val, Error **errp),
-                              ObjectPropertyLinkFlags flags,
-                              Error **errp);
+                              ObjectPropertyLinkFlags flags);
 
 /**
  * object_property_add_str:
@@ -1569,7 +1564,6 @@ ObjectProperty *object_class_property_add_link(ObjectClass *oc,
  * @get: the getter or NULL if the property is write-only.  This function must
  *   return a string to be freed by g_free().
  * @set: the setter or NULL if the property is read-only
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add a string property using getters/setters.  This function will add a
  * property of type 'string'.
@@ -1578,15 +1572,13 @@ ObjectProperty *object_class_property_add_link(ObjectClass *oc,
  */
 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 **));
 
 ObjectProperty *object_class_property_add_str(ObjectClass *klass,
                                    const char *name,
                                    char *(*get)(Object *, Error **),
                                    void (*set)(Object *, const char *,
-                                               Error **),
-                                   Error **errp);
+                                               Error **));
 
 /**
  * object_property_add_bool:
@@ -1594,7 +1586,6 @@ ObjectProperty *object_class_property_add_str(ObjectClass *klass,
  * @name: the name of the property
  * @get: the getter or NULL if the property is write-only.
  * @set: the setter or NULL if the property is read-only
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add a bool property using getters/setters.  This function will add a
  * property of type 'bool'.
@@ -1603,14 +1594,12 @@ ObjectProperty *object_class_property_add_str(ObjectClass *klass,
  */
 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 **));
 
 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 **));
 
 /**
  * object_property_add_enum:
@@ -1619,7 +1608,6 @@ ObjectProperty *object_class_property_add_bool(ObjectClass *klass,
  * @typename: the name of the enum data type
  * @get: the getter or %NULL if the property is write-only.
  * @set: the setter or %NULL if the property is read-only
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an enum property using getters/setters.  This function will add a
  * property of type '@typename'.
@@ -1630,23 +1618,20 @@ ObjectProperty *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 **));
 
 ObjectProperty *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 **));
 
 /**
  * object_property_add_tm:
  * @obj: the object to add a property to
  * @name: the name of the property
  * @get: the getter or NULL if the property is write-only.
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add a read-only struct tm valued property using a getter function.
  * This function will add a property of type 'struct tm'.
@@ -1654,13 +1639,11 @@ ObjectProperty *object_class_property_add_enum(ObjectClass *klass,
  * Returns: The newly added property on success, or %NULL on failure.
  */
 ObjectProperty *object_property_add_tm(Object *obj, const char *name,
-                            void (*get)(Object *, struct tm *, Error **),
-                            Error **errp);
+                            void (*get)(Object *, struct tm *, Error **));
 
 ObjectProperty *object_class_property_add_tm(ObjectClass *klass,
-                                  const char *name,
-                                  void (*get)(Object *, struct tm *, Error **),
-                                  Error **errp);
+                            const char *name,
+                            void (*get)(Object *, struct tm *, Error **));
 
 typedef enum {
     /* Automatically add a getter to the property */
@@ -1677,7 +1660,6 @@ typedef enum {
  * @name: the name of the property
  * @v: pointer to value
  * @flags: bitwise-or'd ObjectPropertyFlags
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an integer property in memory.  This function will add a
  * property of type 'uint8'.
@@ -1685,14 +1667,13 @@ typedef enum {
  * Returns: The newly added property on success, or %NULL on failure.
  */
 ObjectProperty *object_property_add_uint8_ptr(Object *obj, const char *name,
-                                   const uint8_t *v, ObjectPropertyFlags flags,
-                                   Error **errp);
+                                              const uint8_t *v,
+                                              ObjectPropertyFlags flags);
 
 ObjectProperty *object_class_property_add_uint8_ptr(ObjectClass *klass,
                                          const char *name,
                                          const uint8_t *v,
-                                         ObjectPropertyFlags flags,
-                                         Error **errp);
+                                         ObjectPropertyFlags flags);
 
 /**
  * object_property_add_uint16_ptr:
@@ -1700,7 +1681,6 @@ ObjectProperty *object_class_property_add_uint8_ptr(ObjectClass *klass,
  * @name: the name of the property
  * @v: pointer to value
  * @flags: bitwise-or'd ObjectPropertyFlags
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an integer property in memory.  This function will add a
  * property of type 'uint16'.
@@ -1709,14 +1689,12 @@ ObjectProperty *object_class_property_add_uint8_ptr(ObjectClass *klass,
  */
 ObjectProperty *object_property_add_uint16_ptr(Object *obj, const char *name,
                                     const uint16_t *v,
-                                    ObjectPropertyFlags flags,
-                                    Error **errp);
+                                    ObjectPropertyFlags flags);
 
 ObjectProperty *object_class_property_add_uint16_ptr(ObjectClass *klass,
                                           const char *name,
                                           const uint16_t *v,
-                                          ObjectPropertyFlags flags,
-                                          Error **errp);
+                                          ObjectPropertyFlags flags);
 
 /**
  * object_property_add_uint32_ptr:
@@ -1724,7 +1702,6 @@ ObjectProperty *object_class_property_add_uint16_ptr(ObjectClass *klass,
  * @name: the name of the property
  * @v: pointer to value
  * @flags: bitwise-or'd ObjectPropertyFlags
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an integer property in memory.  This function will add a
  * property of type 'uint32'.
@@ -1733,14 +1710,12 @@ ObjectProperty *object_class_property_add_uint16_ptr(ObjectClass *klass,
  */
 ObjectProperty *object_property_add_uint32_ptr(Object *obj, const char *name,
                                     const uint32_t *v,
-                                    ObjectPropertyFlags flags,
-                                    Error **errp);
+                                    ObjectPropertyFlags flags);
 
 ObjectProperty *object_class_property_add_uint32_ptr(ObjectClass *klass,
                                           const char *name,
                                           const uint32_t *v,
-                                          ObjectPropertyFlags flags,
-                                          Error **errp);
+                                          ObjectPropertyFlags flags);
 
 /**
  * object_property_add_uint64_ptr:
@@ -1748,7 +1723,6 @@ ObjectProperty *object_class_property_add_uint32_ptr(ObjectClass *klass,
  * @name: the name of the property
  * @v: pointer to value
  * @flags: bitwise-or'd ObjectPropertyFlags
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an integer property in memory.  This function will add a
  * property of type 'uint64'.
@@ -1757,14 +1731,12 @@ ObjectProperty *object_class_property_add_uint32_ptr(ObjectClass *klass,
  */
 ObjectProperty *object_property_add_uint64_ptr(Object *obj, const char *name,
                                     const uint64_t *v,
-                                    ObjectPropertyFlags flags,
-                                    Error **Errp);
+                                    ObjectPropertyFlags flags);
 
 ObjectProperty *object_class_property_add_uint64_ptr(ObjectClass *klass,
                                           const char *name,
                                           const uint64_t *v,
-                                          ObjectPropertyFlags flags,
-                                          Error **Errp);
+                                          ObjectPropertyFlags flags);
 
 /**
  * object_property_add_alias:
@@ -1772,7 +1744,6 @@ ObjectProperty *object_class_property_add_uint64_ptr(ObjectClass *klass,
  * @name: the name of the property
  * @target_obj: the object to forward property access to
  * @target_name: the name of the property on the forwarded object
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an alias for a property on an object.  This function will add a property
  * of the same type as the forwarded property.
@@ -1785,15 +1756,13 @@ ObjectProperty *object_class_property_add_uint64_ptr(ObjectClass *klass,
  * Returns: The newly added property on success, or %NULL on failure.
  */
 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);
 
 /**
  * object_property_add_const_link:
  * @obj: the object to add a property to
  * @name: the name of the property
  * @target: the object to be referred by the link
- * @errp: if an error occurs, a pointer to an area to store the error
  *
  * Add an unmodifiable link for a property on an object.  This function will
  * add a property of type link<TYPE> where TYPE is the type of @target.
@@ -1806,7 +1775,7 @@ ObjectProperty *object_property_add_alias(Object *obj, const char *name,
  * Returns: The newly added property on success, or %NULL on failure.
  */
 ObjectProperty *object_property_add_const_link(Object *obj, const char *name,
-                                    Object *target, Error **errp);
+                                               Object *target);
 
 /**
  * object_property_set_description: