Cleanup ... avoid accessing the 'isa' variable directly.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@32247 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,27 @@
+2011-02-20  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSMethodSignature.m:
+	* Source/GSArray.m:
+	* Source/NSKeyValueObserving.m:
+	* Source/GSPrivate.h:
+	* Source/GSDictionary.m:
+	* Source/NSURLProtocol.m:
+	* Source/NSURL.m:
+	* Source/NSObject.m:
+	* Source/NSDecimalNumber.m:
+	* Source/Additions/GSObjCRuntime.m:
+	* Source/Additions/GSInsensitiveDictionary.m:
+	* Source/Additions/GSLock.m:
+	* Source/GSSet.m:
+	* Source/GSString.m:
+	* Source/NSConnection.m:
+	* Source/NSData.m:
+	* Headers/Additions/GNUstepBase/GSObjCRuntime.h:
+	Expose class pointer swizzling function in GSObjCRuntime.
+	Replace direct references to 'isa' pointer with objc_getClass() and
+	objcSetClass() calls (or occasionally calls to the -class method if
+	it seems more appropriate).
+
 2011-02-20  Fred Kiefer <FredKiefer@gmx.de>
 
 	* Source/NSNumberFormatter.m (-init): Only check the formatter in

Headers/Additions/GNUstepBase/GSObjCRuntime.h

@@ -416,6 +416,15 @@ GSObjCAllSubclassesOfClass(Class cls);
 GS_EXPORT NSArray *
 GSObjCDirectSubclassesOfClass(Class cls);
 
+/** Function to change the class of the specified instance to newClass.
+ * This handles memory debugging issues in GNUstep-base and also
+ * deals with class finalisation issues in a garbage collecting
+ * environment, so you should use this function rather than attempting
+ * to swizzle class pointers directly.
+ */
+GS_EXPORT void
+GSClassSwizzle(id instance, Class newClass);
+
 #if GS_API_VERSION(GS_API_ANY,011500)
 
 GS_EXPORT const char *

Source/Additions/GSInsensitiveDictionary.m

@@ -372,13 +372,7 @@ static SEL	objSel;
 
 - (id) makeImmutableCopyOnFail: (BOOL)force
 {
-#if     !defined(NDEBUG) && defined(GNUSTEP_BASE_LIBRARY)
-  GSDebugAllocationRemove(isa, self);
-#endif
-  isa = [_GSInsensitiveDictionary class];
-#if     !defined(NDEBUG) && defined(GNUSTEP_BASE_LIBRARY)
-  GSDebugAllocationAdd(isa, self);
-#endif
+  GSClassSwizzle(self, [_GSInsensitiveDictionary class]);
   return self;
 }
 

Source/Additions/GSLock.m

@@ -54,7 +54,7 @@
 - (void) _becomeThreaded: (NSNotification*)n
 {
   [[NSNotificationCenter defaultCenter] removeObserver: self];
-  isa = [NSLock class];
+  object_setClass(self, [NSLock class]);
   if (locked == YES)
     {
       if ([self tryLock] == NO)
@@ -196,7 +196,7 @@
 - (void) _becomeThreaded: (NSNotification*)n
 {
   [[NSNotificationCenter defaultCenter] removeObserver: self];
-  isa = [NSRecursiveLock class];
+  object_setClass(self, [NSRecursiveLock class]);
   while (counter-- > 0)
     {
       if ([self tryLock] == NO)

Source/Additions/GSObjCRuntime.m

@@ -1961,3 +1961,68 @@ GSPrintf (FILE *fptr, NSString* format, ...)
   RELEASE(arp);
   return ok;
 }
+
+#if     defined(GNUSTEP_BASE_LIBRARY)
+# if	GS_WITH_GC
+static BOOL
+GSIsFinalizable(Class c)
+{
+  static IMP	finalizeIMP = 0;
+
+  if (0 == finalizeIMP)
+    {
+      finalizeIMP = [NSObject instanceMethodForSelector: @selector(finalize)];
+    }
+  if (class_getMethodImplementation(c, @selector(finalize)) != finalizeIMP)
+    return YES;
+  return NO;
+}
+# endif	/* GS_WITH_GC */
+#endif	/* defined(GNUSTEP_BASE_LIBRARY) */
+
+void
+GSClassSwizzle(id instance, Class newClass)
+{
+  Class	oldClass = object_getClass(instance);
+
+#ifndef	NDEBUG
+#define	AADD(c, o) GSDebugAllocationAdd(c, o)
+#define	AREM(c, o) GSDebugAllocationRemove(c, o)
+#else
+#define	AADD(c, o) 
+#define	AREM(c, o) 
+#endif
+
+  if (oldClass != newClass)
+    {
+#if     defined(GNUSTEP_BASE_LIBRARY)
+# if	GS_WITH_GC
+      /* We only do allocation counting for objects that can be
+       * finalised - for other objects we have no way of decrementing
+       * the count when the object is collected.
+       */
+      if (GSIsFinalizable(oldClass))
+	{
+	  /* Already finalizable, so we just need to do any allocation
+	   * accounting.
+	   */
+          AREM(oldClass, instance);
+          AADD(newClass, instance);
+	}
+      else if (GSIsFinalizable(newClass))
+	{
+	  /* New class is finalizable, so we must register the instance
+	   * for finalisation and do allocation acounting for it.
+	   */
+	  AADD(newClass, instance);
+	  GC_REGISTER_FINALIZER (instance, GSFinalize, NULL, NULL, NULL);
+	}
+# else
+      AREM(oldClass, instance);
+      AADD(newClass, instance);
+# endif	/* GS_WITH_GC */
+#endif	/* defined(GNUSTEP_BASE_LIBRARY) */
+      object_setClass(instance, newClass);
+    }
+}
+

Source/GSArray.m

@@ -635,13 +635,7 @@ static Class	GSInlineArrayClass;
 
 - (id) makeImmutableCopyOnFail: (BOOL)force
 {
-#ifndef NDEBUG
-  GSDebugAllocationRemove(isa, self);
-#endif
-  isa = [GSArray class];
-#ifndef NDEBUG
-  GSDebugAllocationAdd(isa, self);
-#endif
+  GSClassSwizzle(self, [GSArray class]);
   return self;
 }
 

Source/GSDictionary.m

@@ -394,13 +394,7 @@ static SEL	objSel;
 
 - (id) makeImmutableCopyOnFail: (BOOL)force
 {
-#ifndef NDEBUG
-  GSDebugAllocationRemove(isa, self);
-#endif
-  isa = [GSDictionary class];
-#ifndef NDEBUG
-  GSDebugAllocationAdd(isa, self);
-#endif
+  GSClassSwizzle(self, [GSDictionary class]);
   return self;
 }
 

Source/GSPrivate.h

@@ -531,12 +531,6 @@ GSPrivateUnloadModule(FILE *errorStream,
 - (void) protect;
 @end
 
-/* Function to safely change the class of an object by 'isa' swizzling
- * wile maintaining allocation accounting and finalization in a GC world.
- */
-void
-GSPrivateSwizzle(id o, Class c) GS_ATTRIB_PRIVATE;
-
 BOOL
 GSPrivateIsCollectable(const void *ptr) GS_ATTRIB_PRIVATE;
 

Source/GSSet.m

@@ -657,13 +657,7 @@ static Class	mutableSetClass;
 
 - (id) makeImmutableCopyOnFail: (BOOL)force
 {
-#ifndef NDEBUG
-  GSDebugAllocationRemove(isa, self);
-#endif
-  isa = [GSSet class];
-#ifndef NDEBUG
-  GSDebugAllocationAdd(isa, self);
-#endif
+  GSClassSwizzle(self, [GSSet class]);
   return self;
 }
 

Source/GSString.m

@@ -4311,20 +4311,14 @@ NSAssert(_flags.owned == 1 && _zone != 0, NSInternalInconsistencyException);
 - (id) makeImmutableCopyOnFail: (BOOL)force
 {
 NSAssert(_flags.owned == 1 && _zone != 0, NSInternalInconsistencyException);
-#ifndef NDEBUG
-  GSDebugAllocationRemove(isa, self);
-#endif
   if (_flags.wide == 1)
     {
-      isa = [GSUnicodeBufferString class];
+      GSClassSwizzle(self, [GSUnicodeBufferString class]);
     }
   else
     {
-      isa = [GSCBufferString class];
+      GSClassSwizzle(self, [GSCBufferString class]);
     }
-#ifndef NDEBUG
-  GSDebugAllocationAdd(isa, self);
-#endif
   return self;
 }
 

Source/NSConnection.m

@@ -3046,7 +3046,7 @@ static NSLock	*cached_proxies_gate = nil;
 
   /* xxx We should make sure that TARGET is a valid object. */
   /* Not actually a Proxy, but we avoid the warnings "id" would have made. */
-  m = GSGetMethod(((NSDistantObject*)o)->isa, sel, YES, YES);
+  m = GSGetMethod(object_getClass(o), sel, YES, YES);
   /* Perhaps I need to be more careful in the line above to get the
      version of the method types that has the type qualifiers in it.
      Search the protocols list. */
@@ -3883,9 +3883,10 @@ static NSLock	*cached_proxies_gate = nil;
 
   /* Don't assert (IisValid); */
   NSParameterAssert(aTarget > 0);
-  NSParameterAssert(aProxy==nil || aProxy->isa == distantObjectClass);
-  NSParameterAssert(aProxy==nil || [aProxy connectionForProxy] == self);
-  NSParameterAssert(aProxy==nil || aTarget == aProxy->_handle);
+  NSParameterAssert(aProxy == nil
+    || object_getClass(aProxy) == distantObjectClass);
+  NSParameterAssert(aProxy == nil || [aProxy connectionForProxy] == self);
+  NSParameterAssert(aProxy == nil || aTarget == aProxy->_handle);
 
   M_LOCK(IrefGate);
   node = GSIMapNodeForKey(IremoteProxies, (GSIMapKey)aTarget);

Source/NSData.m

@@ -2942,12 +2942,12 @@ getBytes(void* dst, void* src, unsigned len, unsigned limit, unsigned *pos)
     }
   if (shouldFree == NO)
     {
-      GSPrivateSwizzle(self, dataStatic);
+      GSClassSwizzle(self, dataStatic);
     }
 #if	GS_WITH_GC
   else if (aBuffer != 0 && GSPrivateIsCollectable(aBuffer) == NO)
     {
-      GSPrivateSwizzle(self, dataFinalized);
+      GSClassSwizzle(self, dataFinalized);
     }
 #endif
   bytes = aBuffer;
@@ -3245,7 +3245,7 @@ getBytes(void* dst, void* src, unsigned len, unsigned limit, unsigned *pos)
 #if	GS_WITH_GC
   if (shouldFree == YES && GSPrivateIsCollectable(aBuffer) == NO)
     {
-      GSPrivateSwizzle(self, mutableDataFinalized);
+      GSClassSwizzle(self, mutableDataFinalized);
     }
 #endif
   self = [self initWithCapacity: 0];

Source/NSDecimalNumber.m

@@ -742,7 +742,7 @@ static NSDecimalNumber *one;
 - (NSDecimalNumber*) decimalNumberByAdding: (NSDecimalNumber*)decimalNumber
 {
   return [self decimalNumberByAdding: decimalNumber
-			withBehavior: [isa defaultBehavior]];
+			withBehavior: [[self class] defaultBehavior]];
 }
 
 - (NSDecimalNumber*) decimalNumberByAdding: (NSDecimalNumber*)decimalNumber
@@ -771,7 +771,7 @@ static NSDecimalNumber *one;
 - (NSDecimalNumber*) decimalNumberBySubtracting: (NSDecimalNumber*)decimalNumber
 {
   return [self decimalNumberBySubtracting: decimalNumber
-			     withBehavior: [isa defaultBehavior]];
+			     withBehavior: [[self class] defaultBehavior]];
 }
 
 - (NSDecimalNumber*) decimalNumberBySubtracting: (NSDecimalNumber*)decimalNumber
@@ -801,7 +801,7 @@ static NSDecimalNumber *one;
   (NSDecimalNumber*)decimalNumber
 {
   return [self decimalNumberByMultiplyingBy: decimalNumber
-			       withBehavior: [isa defaultBehavior]];
+			       withBehavior: [[self class] defaultBehavior]];
 }
 
 - (NSDecimalNumber*) decimalNumberByMultiplyingBy:
@@ -831,7 +831,7 @@ static NSDecimalNumber *one;
 - (NSDecimalNumber*) decimalNumberByDividingBy: (NSDecimalNumber*)decimalNumber
 {
   return [self decimalNumberByDividingBy: decimalNumber
-			    withBehavior: [isa defaultBehavior]];
+			    withBehavior: [[self class] defaultBehavior]];
 }
 
 - (NSDecimalNumber*) decimalNumberByDividingBy: (NSDecimalNumber*)decimalNumber
@@ -860,7 +860,7 @@ static NSDecimalNumber *one;
 - (NSDecimalNumber*) decimalNumberByMultiplyingByPowerOf10: (short)power
 {
   return [self decimalNumberByMultiplyingByPowerOf10: power
-					withBehavior: [isa defaultBehavior]];
+					withBehavior: [[self class] defaultBehavior]];
 }
 
 - (NSDecimalNumber*) decimalNumberByMultiplyingByPowerOf10: (short)power
@@ -889,7 +889,7 @@ static NSDecimalNumber *one;
 - (NSDecimalNumber*) decimalNumberByRaisingToPower: (NSUInteger)power
 {
   return [self decimalNumberByRaisingToPower: power
-				withBehavior: [isa defaultBehavior]];
+				withBehavior: [[self class] defaultBehavior]];
 }
 
 - (NSDecimalNumber*) decimalNumberByRaisingToPower: (NSUInteger)power
@@ -932,20 +932,20 @@ static NSDecimalNumber *one;
 				  leftOperand: (NSDecimalNumber*)leftOperand
 				 rightOperand: (NSDecimalNumber*)rightOperand
 {
-  return [[isa defaultBehavior] exceptionDuringOperation: method
-						   error: error
-					     leftOperand: leftOperand
-					    rightOperand: rightOperand];
+  return [[[self class] defaultBehavior] exceptionDuringOperation: method
+    error: error
+    leftOperand: leftOperand
+    rightOperand: rightOperand];
 }
 
 - (NSRoundingMode) roundingMode
 {
-  return [[isa defaultBehavior] roundingMode];
+  return [[[self class] defaultBehavior] roundingMode];
 }
 
 - (short) scale
 {
-  return [[isa defaultBehavior] scale];
+  return [[[self class] defaultBehavior] scale];
 }
 
 - (Class) classForCoder

Source/NSKeyValueObserving.m

@@ -47,7 +47,7 @@
 /*
  * IMPLEMENTATION NOTES
  *
- * Originally, I wanted to do KVO via a proxy, with isa swizzling
+ * Originally, I wanted to do KVO via a proxy, with class pointer swizzling
  * to turn the original instance into an instance of the proxy class.
  * However, I couldn't figure a way to get decent performance out of
  * this model, as every message to the instance would have to be
@@ -57,7 +57,7 @@
  * So, instead I arrived at the mechanism of creating a subclass of
  * each class being observed, with a few subclass methods overriding
  * those of the original, but most remaining the same.
- * The same isa swizzling technique was used to convert between the
+ * The same class pointer swizzling technique was used to convert between the
  * original class and the superclass.
  * This subclass basically overrides several standard methods with
  * those from a template class, and then overrides any setter methods
@@ -211,7 +211,7 @@ static inline void setup()
 {
   // Turn off KVO for self ... then call the real dealloc implementation.
   [self setObservationInfo: nil];
-  isa = [self class];
+  object_setClass(self, [self class]);
   [self dealloc];
   GSNOSUPERDEALLOC;
 }
@@ -1471,7 +1471,7 @@ replacementForClass(Class c)
     {
       info = [[GSKVOInfo alloc] initWithInstance: self];
       [self setObservationInfo: info];
-      isa = [r replacement];
+      object_setClass(self, [r replacement]);
     }
 
   /*
@@ -1521,7 +1521,7 @@ replacementForClass(Class c)
        * The instance is no longer being observed ... so we can
        * turn off key-value-observing for it.
        */
-      isa = [self class];
+      object_setClass(self, [self class]);
       IF_NO_GC(AUTORELEASE(info);)
       [self setObservationInfo: nil];
     }

Source/NSMethodSignature.m

@@ -528,7 +528,7 @@ next_arg(const char *typePtr, NSArgumentInfo *info, char *outTypes)
     {
       return NO;
     }
-  if (((NSMethodSignature *)other)->isa != isa)
+  if (object_getClass(other) != object_getClass(self))
     {
       return NO;
     }

Source/NSObject.m

@@ -700,44 +700,6 @@ NSDeallocateObject(id anObject)
 
 #endif	/* GS_WITH_GC */
 
-
-void
-GSPrivateSwizzle(id o, Class c)
-{
-  Class	oc = object_getClass(o);
-
-  if (oc != c)
-    {
-#if	GS_WITH_GC
-      /* We only do allocation counting for objects that can be
-       * finalised - for other objects we have no way of decrementing
-       * the count when the object is collected.
-       */
-      if (GSIsFinalizable(oc))
-	{
-	  /* Already finalizable, so we just need to do any allocation
-	   * accounting.
-	   */
-          AREM(oc, o);
-          AADD(c, o);
-	}
-      else if (GSIsFinalizable(c))
-	{
-	  /* New class is finalizable, so we must register the instance
-	   * for finalisation and do allocation acounting for it.
-	   */
-	  AADD(c, o);
-	  GC_REGISTER_FINALIZER (o, GSFinalize, NULL, NULL, NULL);
-	}
-#else
-      AREM(oc, o);
-      AADD(c, o);
-#endif	/* GS_WITH_GC */
-      object_setClass(o, c);
-    }
-}
-
-
 BOOL
 NSShouldRetainWithZone (NSObject *anObject, NSZone *requestedZone)
 {
@@ -1024,10 +986,9 @@ objc_create_block_classes_as_subclasses_of(Class super) __attribute__((weak));
  * <p>
  *   Memory for an instance of the receiver is allocated; a
  *   pointer to this newly created instance is returned.  All
- *   instance variables are set to 0 except the
- *   <code>isa</code> pointer which is set to point to the
- *   object class.  No initialization of the instance is
- *   performed: it is your responsibility to initialize the
+ *   instance variables are set to 0.  No initialization of the
+ *   instance is performed apart from setup to be an instance of
+ *   the correct class: it is your responsibility to initialize the
  *   instance by calling an appropriate <code>init</code>
  *   method.  If you are not using the garbage collector, it is
  *   also your responsibility to make sure the returned
@@ -1135,11 +1096,10 @@ objc_create_block_classes_as_subclasses_of(Class super) __attribute__((weak));
 
 /**
  * Returns the class of which the receiver is an instance.<br />
- * The default implementation returns the private <code>isa</code>
- * instance variable of NSObject, which is used to store a pointer
- * to the objects class.<br />
- * NB.  When NSZombie is enabled (see NSDebug.h) this pointer is
- * changed upon object deallocation.
+ * The default implementation returns the actual class that the
+ * receiver is an instance of.<br />
+ * NB.  When NSZombie is enabled (see NSDebug.h) this is changed
+ * to be the NSZombie class upon object deallocation.
  */
 - (Class) class
 {

Source/NSProxy.m

@@ -49,9 +49,9 @@ extern BOOL __objc_responds_to(id, SEL);
  * implement -forwardInvocation: to these <em>real</em> objects.</p>
  *
  * <p>Note that <code>NSProxy</code> is a different sort of class than others
- *  in the GNUstep Base library in that it is the only example of a root class
- *  besides [NSObject].  Thus, it defines its own <code><em>isa</em></code>
- *  variable and implements the <code>NSObject</code> protocol.</p>
+ * in the GNUstep Base library in that it is the only example of a root class
+ * besides [NSObject].  Thus, it implements the <code>NSObject</code> protocol
+ * but is not a subclass of NSObject.</p>
  */
 @implementation NSProxy
 

Source/NSURL.m

@@ -1206,8 +1206,8 @@ static unsigned	urlAlign;
 {
   if (NSShouldRetainWithZone(self, zone) == NO)
     {
-      return [[isa allocWithZone: zone] initWithString: _urlString
-					 relativeToURL: _baseURL];
+      return [[[self class] allocWithZone: zone] initWithString: _urlString
+						  relativeToURL: _baseURL];
     }
   else
     {

Source/NSURLProtocol.m

@@ -462,7 +462,9 @@ static NSURLProtocol	*placeholder = nil;
 {
   if ((self = [super init]) != nil)
     {
-      if (isa != abstractClass && isa != placeholderClass)
+      Class	c = object_getClass(self);
+
+      if (c != abstractClass && c != placeholderClass)
 	{
 	  _NSURLProtocolInternal = NSZoneCalloc([self zone],
 	    1, sizeof(Internal));
@@ -475,7 +477,9 @@ static NSURLProtocol	*placeholder = nil;
 	cachedResponse: (NSCachedURLResponse *)cachedResponse
 		client: (id <NSURLProtocolClient>)client
 {
-  if (isa == abstractClass || isa == placeholderClass)
+  Class	c = object_getClass(self);
+
+  if (c == abstractClass || c == placeholderClass)
     {
       unsigned	count;