From a05d912ac29700014b1d6a894240a62f883e4409 Mon Sep 17 00:00:00 2001

From: Markus Armbruster <armbru@redhat.com>

Date: Mon, 18 Jun 2018 08:43:10 +0200

Subject: [PATCH 03/54] qobject: use a QObjectBase_ struct

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RH-Author: Markus Armbruster <armbru@redhat.com>

Message-id: <20180618084330.30009-4-armbru@redhat.com>

Patchwork-id: 80742

O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 03/23] qobject: use a QObjectBase_ struct

Bugzilla: 1557995

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

From: Marc-André Lureau <marcandre.lureau@redhat.com>

By moving the base fields to a QObjectBase_, QObject can be a type

which also has a 'base' field. This allows writing a generic QOBJECT()

macro that will work with any QObject type, including QObject

itself. The container_of() macro ensures that the object to cast has a

QObjectBase_ base field, giving some type safety guarantees. QObject

must have no members but QObjectBase_ base, or else QOBJECT() breaks.

QObjectBase_ is not a typedef and uses a trailing underscore to make

it obvious it is not for normal use and to avoid potential abuse.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

Message-Id: <20180419150145.24795-3-marcandre.lureau@redhat.com>

Reviewed-by: Markus Armbruster <armbru@redhat.com>

Signed-off-by: Markus Armbruster <armbru@redhat.com>

(cherry picked from commit 3d3eacaeccaab718ea0e2ddaa578bfae9e311c59)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 include/qapi/qmp/qbool.h   |  2 +-

 include/qapi/qmp/qdict.h   |  2 +-

 include/qapi/qmp/qlist.h   |  2 +-

 include/qapi/qmp/qnull.h   |  2 +-

 include/qapi/qmp/qnum.h    |  2 +-

 include/qapi/qmp/qobject.h | 31 ++++++++++++++++++++-----------

 include/qapi/qmp/qstring.h |  2 +-

 qobject/qobject.c          | 12 ++++++------

 tests/check-qdict.c        |  6 +++---

 9 files changed, 35 insertions(+), 26 deletions(-)

diff --git a/include/qapi/qmp/qbool.h b/include/qapi/qmp/qbool.h

index b9a44a1..5f61e38 100644

--- a/include/qapi/qmp/qbool.h

+++ b/include/qapi/qmp/qbool.h

@@ -17,7 +17,7 @@

 #include "qapi/qmp/qobject.h"

 struct QBool {

-    QObject base;

+    struct QObjectBase_ base;

     bool value;

 };

diff --git a/include/qapi/qmp/qdict.h b/include/qapi/qmp/qdict.h

index 2cc3e90..921a28d 100644

--- a/include/qapi/qmp/qdict.h

+++ b/include/qapi/qmp/qdict.h

@@ -25,7 +25,7 @@ typedef struct QDictEntry {

 } QDictEntry;

 struct QDict {

-    QObject base;

+    struct QObjectBase_ base;

     size_t size;

     QLIST_HEAD(,QDictEntry) table[QDICT_BUCKET_MAX];

 };

diff --git a/include/qapi/qmp/qlist.h b/include/qapi/qmp/qlist.h

index 5c673ac..8d2c32c 100644

--- a/include/qapi/qmp/qlist.h

+++ b/include/qapi/qmp/qlist.h

@@ -22,7 +22,7 @@ typedef struct QListEntry {

 } QListEntry;

 struct QList {

-    QObject base;

+    struct QObjectBase_ base;

     QTAILQ_HEAD(,QListEntry) head;

 };

diff --git a/include/qapi/qmp/qnull.h b/include/qapi/qmp/qnull.h

index c992ee2..e8ea2c3 100644

--- a/include/qapi/qmp/qnull.h

+++ b/include/qapi/qmp/qnull.h

@@ -16,7 +16,7 @@

 #include "qapi/qmp/qobject.h"

 struct QNull {

-    QObject base;

+    struct QObjectBase_ base;

 };

 extern QNull qnull_;

diff --git a/include/qapi/qmp/qnum.h b/include/qapi/qmp/qnum.h

index 3e47475..45bf02a 100644

--- a/include/qapi/qmp/qnum.h

+++ b/include/qapi/qmp/qnum.h

@@ -45,7 +45,7 @@ typedef enum {

  * convert under the hood.

  */

 struct QNum {

-    QObject base;

+    struct QObjectBase_ base;

     QNumKind kind;

     union {

         int64_t i64;

diff --git a/include/qapi/qmp/qobject.h b/include/qapi/qmp/qobject.h

index 5206ff9..a713c01 100644

--- a/include/qapi/qmp/qobject.h

+++ b/include/qapi/qmp/qobject.h

@@ -34,13 +34,21 @@

 #include "qapi/qapi-builtin-types.h"

-struct QObject {

+/* Not for use outside include/qapi/qmp/ */

+struct QObjectBase_ {

     QType type;

     size_t refcnt;

 };

-/* Get the 'base' part of an object */

-#define QOBJECT(obj) (&(obj)->base)

+/* this struct must have no other members than base */

+struct QObject {

+    struct QObjectBase_ base;

+};

+

+#define QOBJECT(obj) ({                                         \

+    typeof(obj) _obj = (obj);                                   \

+    _obj ? container_of(&(_obj)->base, QObject, base) : NULL;   \

+})

 /* High-level interface for qobject_incref() */

 #define QINCREF(obj)      \

@@ -68,8 +76,8 @@ QEMU_BUILD_BUG_MSG(QTYPE__MAX != 7,

 static inline void qobject_init(QObject *obj, QType type)

 {

     assert(QTYPE_NONE < type && type < QTYPE__MAX);

-    obj->refcnt = 1;

-    obj->type = type;

+    obj->base.refcnt = 1;

+    obj->base.type = type;

 }

 /**

@@ -77,8 +85,9 @@ static inline void qobject_init(QObject *obj, QType type)

  */

 static inline void qobject_incref(QObject *obj)

 {

-    if (obj)

-        obj->refcnt++;

+    if (obj) {

+        obj->base.refcnt++;

+    }

 }

 /**

@@ -101,8 +110,8 @@ void qobject_destroy(QObject *obj);

  */

 static inline void qobject_decref(QObject *obj)

 {

-    assert(!obj || obj->refcnt);

-    if (obj && --obj->refcnt == 0) {

+    assert(!obj || obj->base.refcnt);

+    if (obj && --obj->base.refcnt == 0) {

         qobject_destroy(obj);

     }

 }

@@ -112,8 +121,8 @@ static inline void qobject_decref(QObject *obj)

  */

 static inline QType qobject_type(const QObject *obj)

 {

-    assert(QTYPE_NONE < obj->type && obj->type < QTYPE__MAX);

-    return obj->type;

+    assert(QTYPE_NONE < obj->base.type && obj->base.type < QTYPE__MAX);

+    return obj->base.type;

 }

 /**

diff --git a/include/qapi/qmp/qstring.h b/include/qapi/qmp/qstring.h

index 30ae260..b3b3d44 100644

--- a/include/qapi/qmp/qstring.h

+++ b/include/qapi/qmp/qstring.h

@@ -16,7 +16,7 @@

 #include "qapi/qmp/qobject.h"

 struct QString {

-    QObject base;

+    struct QObjectBase_ base;

     char *string;

     size_t length;

     size_t capacity;

diff --git a/qobject/qobject.c b/qobject/qobject.c

index 87649c5..cf4b7e2 100644

--- a/qobject/qobject.c

+++ b/qobject/qobject.c

@@ -37,9 +37,9 @@ static void (*qdestroy[QTYPE__MAX])(QObject *) = {

 void qobject_destroy(QObject *obj)

 {

-    assert(!obj->refcnt);

-    assert(QTYPE_QNULL < obj->type && obj->type < QTYPE__MAX);

-    qdestroy[obj->type](obj);

+    assert(!obj->base.refcnt);

+    assert(QTYPE_QNULL < obj->base.type && obj->base.type < QTYPE__MAX);

+    qdestroy[obj->base.type](obj);

 }

@@ -62,11 +62,11 @@ bool qobject_is_equal(const QObject *x, const QObject *y)

         return true;

     }

-    if (!x || !y || x->type != y->type) {

+    if (!x || !y || x->base.type != y->base.type) {

         return false;

     }

-    assert(QTYPE_NONE < x->type && x->type < QTYPE__MAX);

+    assert(QTYPE_NONE < x->base.type && x->base.type < QTYPE__MAX);

-    return qis_equal[x->type](x, y);

+    return qis_equal[x->base.type](x, y);

 }

diff --git a/tests/check-qdict.c b/tests/check-qdict.c

index 08d4303..07bb8f4 100644

--- a/tests/check-qdict.c

+++ b/tests/check-qdict.c

@@ -570,11 +570,11 @@ static void qdict_join_test(void)

         }

         /* Check the references */

-        g_assert(qdict_get(dict1, "foo")->refcnt == 1);

-        g_assert(qdict_get(dict1, "bar")->refcnt == 1);

+        g_assert(qdict_get(dict1, "foo")->base.refcnt == 1);

+        g_assert(qdict_get(dict1, "bar")->base.refcnt == 1);

         if (!overwrite) {

-            g_assert(qdict_get(dict2, "foo")->refcnt == 1);

+            g_assert(qdict_get(dict2, "foo")->base.refcnt == 1);

         }

         /* Clean up */

-- 

1.8.3.1