Implemented NSZombie stuff

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@13247 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,11 @@
+2002-03-27  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/GSPrivate.h: Added function to fetch boolean value from env
+	* Source/NSException.m: Use new function.
+	* Source/NSProcesInfo.m: Implement new function.
+	* Source/NSObject.m: Implement NSZombie functionality.
+	* Headers/Foundation/NSDebug.h: Document NSZombie functionality.
+
 2002-03-25  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSTask.m: Implement code to watch for child process exit

Headers/gnustep/base/NSDebug.h

@@ -111,6 +111,43 @@ GS_EXPORT NSString*	GSDebugMethodMsg(id obj, SEL sel, const char *file,
 				int line, NSString *fmt);
 #endif
 
+/**
+ * Enable/disable zombies.
+ * <p>When an object is deallocated, its isa pointer is normally modified
+ * to the hexadecimal value 0xdeadface, so that any attempt to send a
+ * message to the deallocated object will cause a crash, and examination
+ * of the object within the debugger will show the 0xdeadface value ...
+ * making it obvious why the program crashed.
+ * </p>
+ * <p>Turning on zombies changes this behavior so that the isa pointer
+ * is modified to be that of the NSZombie class.  When messages are
+ * sent to the object, intead of crashing, NSZombie will use NSLog() to
+ * produce an error message.  By default the memory used by the object
+ * will not really be freed, so error messages will continue to
+ * be generated whenever a message is sent to the object, and the object
+ * instance variables will remain available for examination by the debugger.
+ * </p>
+ * The default value of this boolean is NO, but this can be controlled
+ * by the NSZombieEnabled environment variable.
+ */
+GS_EXPORT BOOL NSZombieEnabled;
+
+/**
+ * Enable/disable object deallocation.
+ * <p>If zombies are enabled, objects are by default <em>not</em>
+ * deallocated, and memory leaks.  The NSDeallocateZombies variable
+ * lets you say that the the memory used by zombies should be freed.
+ * </p>
+ * <p>Doing this makes the behavior of zombies similar to that when zombies
+ * are not enabled ... the memory occupied by the zombie may be re-used for
+ * other purposes, at which time the isa pointer may be overwritten and the
+ * zombie behavior will cease.
+ * </p>
+ * The default value of this boolean is NO, but this can be controlled
+ * by the NSDeallocateZombies environment variable.
+ */
+GS_EXPORT BOOL NSDeallocateZombies;
+
 
 
 /* Debug logging which can be enabled/disabled by defining GSDIAGNOSE

Source/GSPrivate.h

@@ -80,7 +80,12 @@ NSDictionary	*GSUserDefaultsDictionaryRepresentation();
 /*
  * Get one of several potentially useful flags.
  */
-BOOL		GSUserDefaultsFlag(GSUserDefaultFlagType type);
+BOOL	GSUserDefaultsFlag(GSUserDefaultFlagType type);
+
+/**
+ * Get a flag from an environment variable - return def if not defined.
+ */
+BOOL	GSEnvironmentFlag(const char *name, BOOL def);
 
 #endif /* __GSPrivate_h_ */
 

Source/NSException.m

@@ -33,7 +33,8 @@
 #include <Foundation/NSThread.h>
 #include <Foundation/NSDictionary.h>
 #include <stdio.h>
-#include <stdlib.h>		// for getenv()
+
+#include "GSPrivate.h"
 
 static void
 _preventRecursion (NSException *exception)
@@ -43,7 +44,6 @@ _preventRecursion (NSException *exception)
 static void
 _NSFoundationUncaughtExceptionHandler (NSException *exception)
 {
-  const char	*c = getenv("CRASH_ON_ABORT");
   BOOL		a;
 
   _NSUncaughtExceptionHandler = _preventRecursion;
@@ -60,33 +60,7 @@ _NSFoundationUncaughtExceptionHandler (NSException *exception)
 #else
   a = NO;		// exit() by default.
 #endif
-  if (c != 0)
-    {
-      /*
-       * Use the CRASH_ON_ABORT environment variable ... if it's defined
-       * then we use abort(), unless it's 'no', 'false', or '0, in which
-       * case we use exit()
-       */
-      if (c[0] == '0' && c[1] == 0)
-	{
-	  a = NO;
-	}
-      else if ((c[0] == 'n' || c[0] == 'N') && (c[1] == 'o' || c[1] == 'O')
-	&& c[2] == 0)
-	{
-	  a = NO;
-	}
-      else if ((c[0] == 'f' || c[0] == 'F') && (c[1] == 'a' || c[1] == 'A')
-	&& (c[2] == 'l' || c[2] == 'L') && (c[3] == 's' || c[3] == 'S')
-	&& (c[4] == 'e' || c[4] == 'E') && c[5] == 0)
-	{
-	  a = NO;
-	}
-      else
-	{
-	  a = YES;
-	}
-    }
+  a = GSEnvironmentFlag("CRASH_ON_ABORT", a);
   if (a == YES)
     {
       abort();

Source/NSObject.m

@@ -42,8 +42,10 @@
 #include <Foundation/NSThread.h>
 #include <Foundation/NSNotification.h>
 #include <Foundation/NSObjCRuntime.h>
+#include <Foundation/NSMapTable.h>
 #include <limits.h>
 
+#include "GSPrivate.h"
 
 
 #ifndef NeXT_RUNTIME
@@ -61,6 +63,68 @@ static Class	NSConstantStringClass;
 
 static BOOL deallocNotifications = NO;
 
+/*
+ * allocationLock is needed when running multi-threaded for retain/release
+ * to work reliably.
+ * We also use it for protecting the map table of zombie information.
+ */
+static objc_mutex_t allocationLock = NULL;
+
+
+BOOL	NSZombieEnabled = NO;
+BOOL	NSDeallocateZombies = NO;
+
+@class	NSZombie;
+static Class		zombieClass;
+static NSMapTable	zombieMap;
+
+static void GSMakeZombie(NSObject *o)
+{
+  Class	c = ((id)o)->class_pointer;
+
+  ((id)o)->class_pointer = zombieClass;
+  if (NSDeallocateZombies == NO)
+    {
+      if (allocationLock == 0)
+	{
+	  objc_mutex_lock(allocationLock);
+	}
+      NSMapInsert(zombieMap, (void*)o, (void*)c);
+      if (allocationLock == 0)
+	{
+	  objc_mutex_unlock(allocationLock);
+	}
+    }
+}
+
+static void GSLogZombie(id o, SEL sel)
+{
+  Class	c = 0;
+
+  if (NSDeallocateZombies == NO)
+    {
+      if (allocationLock == 0)
+	{
+	  objc_mutex_lock(allocationLock);
+	}
+      c = NSMapGet(zombieMap, (void*)o);
+      if (allocationLock == 0)
+	{
+	  objc_mutex_unlock(allocationLock);
+	}
+    }
+  if (c == 0)
+    {
+      NSLog(@"Deallocated object (0x%x) sent %@",
+	o, NSStringFromSelector(sel));
+    }
+  else
+    {
+      NSLog(@"Deallocated %@ (0x%x) sent %@",
+	NSStringFromClass(c), o, NSStringFromSelector(sel));
+    }
+}
+
 
 /*
  *	Reference count and memory management
@@ -76,12 +140,6 @@ static BOOL deallocNotifications = NO;
  */
 
 
-/*
- * retain_counts_gate is needed when running multi-threaded for retain/release
- * to work reliably.
- */
-static objc_mutex_t retain_counts_gate = NULL;
-
 #if	GS_WITH_GC == 0 && !defined(NeXT_RUNTIME)
 #define	REFCNT_LOCAL	1
 #define	CACHE_ZONE	1
@@ -165,11 +223,11 @@ NSExtraRefCount(id anObject)
 void
 NSIncrementExtraRefCount(id anObject)
 {
-  if (retain_counts_gate != 0)
+  if (allocationLock != 0)
     {
-      objc_mutex_lock(retain_counts_gate);
+      objc_mutex_lock(allocationLock);
       ((obj)anObject)[-1].retained++;
-      objc_mutex_unlock (retain_counts_gate);
+      objc_mutex_unlock (allocationLock);
     }
   else
     {
@@ -178,11 +236,11 @@ NSIncrementExtraRefCount(id anObject)
 }
 
 #define	NSIncrementExtraRefCount(X) ({ \
-  if (retain_counts_gate != 0) \
+  if (allocationLock != 0) \
     { \
-      objc_mutex_lock(retain_counts_gate); \
+      objc_mutex_lock(allocationLock); \
       ((obj)(X))[-1].retained++;            \
-      objc_mutex_unlock(retain_counts_gate); \
+      objc_mutex_unlock(allocationLock); \
     } \
   else \
     { \
@@ -193,17 +251,17 @@ NSIncrementExtraRefCount(id anObject)
 BOOL
 NSDecrementExtraRefCountWasZero(id anObject)
 {
-  if (retain_counts_gate != 0)
+  if (allocationLock != 0)
     {
-      objc_mutex_lock(retain_counts_gate);
+      objc_mutex_lock(allocationLock);
       if (((obj)anObject)[-1].retained-- == 0)
 	{
-	  objc_mutex_unlock(retain_counts_gate);
+	  objc_mutex_unlock(allocationLock);
 	  return YES;
 	}
       else
 	{
-	  objc_mutex_unlock(retain_counts_gate);
+	  objc_mutex_unlock(allocationLock);
 	  return NO;
 	}
     }
@@ -245,9 +303,9 @@ NSIncrementExtraRefCount (id anObject)
 {
   GSIMapNode	node;
 
-  if (retain_counts_gate != 0)
+  if (allocationLock != 0)
     {
-      objc_mutex_lock(retain_counts_gate);
+      objc_mutex_lock(allocationLock);
       node = GSIMapNodeForKey(&retain_counts, (GSIMapKey)anObject);
       if (node != 0)
 	{
@@ -257,7 +315,7 @@ NSIncrementExtraRefCount (id anObject)
 	{
 	  GSIMapAddPair(&retain_counts, (GSIMapKey)anObject, (GSIMapVal)1);
 	}
-      objc_mutex_unlock(retain_counts_gate);
+      objc_mutex_unlock(allocationLock);
     }
   else
     {
@@ -278,13 +336,13 @@ NSDecrementExtraRefCountWasZero (id anObject)
 {
   GSIMapNode	node;
 
-  if (retain_counts_gate != 0)
+  if (allocationLock != 0)
     {
-      objc_mutex_lock(retain_counts_gate);
+      objc_mutex_lock(allocationLock);
       node = GSIMapNodeForKey(&retain_counts, (GSIMapKey)anObject);
       if (node == 0)
 	{
-	  objc_mutex_unlock(retain_counts_gate);
+	  objc_mutex_unlock(allocationLock);
 	  return YES;
 	}
       NSCAssert(node->value.uint > 0, NSInternalInconsistencyException);
@@ -292,7 +350,7 @@ NSDecrementExtraRefCountWasZero (id anObject)
 	{
 	  GSIMapRemoveKey((GSIMapTable)&retain_counts, (GSIMapKey)anObject);
 	}
-      objc_mutex_unlock(retain_counts_gate);
+      objc_mutex_unlock(allocationLock);
     }
   else
     {
@@ -316,9 +374,9 @@ NSExtraRefCount (id anObject)
   GSIMapNode	node;
   unsigned	ret;
 
-  if (retain_counts_gate != 0)
+  if (allocationLock != 0)
     {
-      objc_mutex_lock(retain_counts_gate);
+      objc_mutex_lock(allocationLock);
       node = GSIMapNodeForKey(&retain_counts, (GSIMapKey)anObject);
       if (node == 0)
 	{
@@ -328,7 +386,7 @@ NSExtraRefCount (id anObject)
 	{
 	  ret = node->value.uint;
 	}
-      objc_mutex_unlock(retain_counts_gate);
+      objc_mutex_unlock(allocationLock);
     }
   else
     {
@@ -501,8 +559,19 @@ NSDeallocateObject(NSObject *anObject)
 #ifndef	NDEBUG
       GSDebugAllocationRemove(((id)anObject)->class_pointer, (id)anObject);
 #endif
-      ((id)anObject)->class_pointer = (void*) 0xdeadface;
-      NSZoneFree(z, o);
+      if (NSZombieEnabled == YES)
+	{
+	  GSMakeZombie(anObject);
+	  if (NSDeallocateZombies == YES)
+	    {
+	      NSZoneFree(z, o);
+	    }
+	}
+      else
+	{
+	  ((id)anObject)->class_pointer = (void*) 0xdeadface;
+	  NSZoneFree(z, o);
+	}
     }
   return;
 }
@@ -545,8 +614,19 @@ NSDeallocateObject(NSObject *anObject)
 #ifndef	NDEBUG
       GSDebugAllocationRemove(((id)anObject)->class_pointer, (id)anObject);
 #endif
-      ((id)anObject)->class_pointer = (void*) 0xdeadface;
-      NSZoneFree(z, anObject);
+      if (NSZombieEnabled == YES)
+	{
+	  GSMakeZombie(anObject);
+	  if (NSDeallocateZombies == YES)
+	    {
+	      NSZoneFree(z, anObject);
+	    }
+	}
+      else
+	{
+	  ((id)anObject)->class_pointer = (void*) 0xdeadface;
+	  NSZoneFree(z, anObject);
+	}
     }
   return;
 }
@@ -562,7 +642,7 @@ NSShouldRetainWithZone (NSObject *anObject, NSZone *requestedZone)
   return YES;
 #else
   return (!requestedZone || requestedZone == NSDefaultMallocZone()
-	  || GSObjCZone(anObject) == requestedZone);
+    || GSObjCZone(anObject) == requestedZone);
 #endif
 }
 
@@ -587,9 +667,9 @@ static BOOL double_release_check_enabled = NO;
 
 + (void) _becomeMultiThreaded: (NSNotification)aNotification
 {
-  if (retain_counts_gate == 0)
+  if (allocationLock == 0)
     {
-      retain_counts_gate = objc_mutex_allocate();
+      allocationLock = objc_mutex_allocate();
     }
 }
 
@@ -630,6 +710,14 @@ static BOOL double_release_check_enabled = NO;
 
       // Create the global lock
       gnustep_global_lock = [[NSRecursiveLock alloc] init];
+
+      // Zombie management stuff.
+      zombieClass = [NSZombie class];
+      zombieMap = NSCreateMapTable(NSNonOwnedPointerMapKeyCallBacks,
+	NSNonOwnedPointerMapValueCallBacks, 0);
+      NSZombieEnabled = GSEnvironmentFlag("NSZombieEnabled", NO);
+      NSDeallocateZombies = GSEnvironmentFlag("NSDeallocateZombies", NO);
+
       autorelease_class = [NSAutoreleasePool class];
       autorelease_sel = @selector(addObject:);
       autorelease_imp = [autorelease_class methodForSelector: autorelease_sel];
@@ -1542,3 +1630,28 @@ _fastMallocBuffer(unsigned size)
 }
 @end
 
+
+
+@interface	NSZombie
+- (retval_t) forward:(SEL)aSel :(arglist_t)argFrame;
+- (void) forwardInvocation: (NSInvocation*)anInvocation;
+@end
+
+@implementation	NSZombie
+- (retval_t) forward:(SEL)aSel :(arglist_t)argFrame
+{
+  GSLogZombie(self, aSel);
+  return 0;
+}
+- (void) forwardInvocation: (NSInvocation*)anInvocation
+{
+  unsigned	size = [[anInvocation methodSignature] methodReturnLength];
+  unsigned char	v[size];
+
+  memset(v, '\0', size);
+  GSLogZombie(self, [anInvocation selector]);
+  [anInvocation setReturnValue: (void*)v];
+  return;
+}
+@end
+

Source/NSProcessInfo.m

@@ -78,6 +78,8 @@
 #include <Foundation/NSAutoreleasePool.h>
 #include <Foundation/NSHost.h>
 
+#include "GSPrivate.h"
+
 /* This error message should be called only if the private main function
  * was not executed successfully. This may happen ONLY if another library
  * or kit defines its own main function (as gnustep-base does).
@@ -679,3 +681,32 @@ BOOL GSDebugSet(NSString *level)
   return YES;
 }
 
+
+BOOL
+GSEnvironmentFlag(const char *name, BOOL def)
+{
+  const char	*c = getenv(name);
+  BOOL		a = def;
+
+  if (c != 0)
+    {
+      a = NO;
+      if ((c[0] == 'y' || c[0] == 'Y') && (c[1] == 'e' || c[1] == 'E')
+	&& (c[2] == 's' || c[2] == 'S') && c[3] == 0)
+	{
+	  a = YES;
+	}
+      else if ((c[0] == 't' || c[0] == 'T') && (c[1] == 'r' || c[1] == 'R')
+	&& (c[2] == 'u' || c[2] == 'U') && (c[3] == 'e' || c[3] == 'E')
+	&& c[4] == 0)
+	{
+	  a = YES;
+	}
+      else if (isdigit(c[0]) && c[0] != '0')
+	{
+	  a = YES;
+	}
+    }
+  return a;
+}
+

Testing/basic.m

@@ -9,6 +9,7 @@ int main ()
   id	o = [NSObject new];
   printf ("Hello from object at 0x%x\n", (unsigned)[o self]);
 
+  [o release];
   o = [NSString stringWithFormat: @"/proc/%d/status", getpid()];
   NSLog(@"'%@'", o);
   o = [NSString stringWithContentsOfFile: o];