Thread-safety fixes.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@39902 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -6,6 +6,8 @@
 	* Source/NSOperation.m: When starting an operation, have it retain
 	itself in case it'ss removed from the queue and released while
 	running.
+	* Headers/Foundation/NSDistributedLock.h: Add lock ivar.
+	* Source/NSDistributedLock.m: Make class thread-safe using lock.
 
 2016-06-19  Richard Frith-Macdonald <rfm@gnu.org>
 

Headers/Foundation/NSDistributedLock.h

@@ -27,8 +27,10 @@
 #import	<GNUstepBase/GSVersionMacros.h>
 
 #import	<Foundation/NSObject.h>
-#import	<Foundation/NSString.h>
+
-#import	<Foundation/NSDate.h>
+@class	NSDate;
+@class	NSLock;
+@class	NSString;
 
 #if	defined(__cplusplus)
 extern "C" {
@@ -39,6 +41,7 @@ extern "C" {
 #if	GS_EXPOSE(NSDistributedLock)
   NSString	*_lockPath;
   NSDate	*_lockTime;
+  NSLock	*_localLock;
 #endif
 #if     GS_NONFRAGILE
 #else

Source/NSDistributedLock.m

@@ -28,8 +28,9 @@
 #import "common.h"
 #define	EXPOSE_NSDistributedLock_IVARS	1
 #import "Foundation/NSDistributedLock.h"
-#import "Foundation/NSFileManager.h"
 #import "Foundation/NSException.h"
+#import "Foundation/NSFileManager.h"
+#import "Foundation/NSLock.h"
 #import "Foundation/NSValue.h"
 #import "GSPrivate.h"
 
@@ -73,6 +74,9 @@ static NSFileManager	*mgr = nil;
  * Raises an NSGenericException if unable to remove the lock.
  */
 - (void) breakLock
+{
+  [_localLock lock];
+  NS_DURING
     {
       NSDictionary	*attributes;
 
@@ -86,7 +90,8 @@ static NSFileManager	*mgr = nil;
 	    {
 	      NSString	*err = [[NSError _last] localizedDescription];
 
-	  attributes = [mgr fileAttributesAtPath: _lockPath traverseLink: YES];
+	      attributes = [mgr fileAttributesAtPath: _lockPath
+					traverseLink: YES];
 	      if ([modDate isEqual: [attributes fileModificationDate]] == YES)
 		{
 		  [NSException raise: NSGenericException
@@ -96,6 +101,14 @@ static NSFileManager	*mgr = nil;
 	    }
 	}
     }
+  NS_HANDLER
+    {
+      [_localLock unlock];
+      [localException raise];
+    }
+  NS_ENDHANDLER
+  [_localLock unlock];
+}
 
 - (void) dealloc
 {
@@ -107,21 +120,27 @@ static NSFileManager	*mgr = nil;
     }
   RELEASE(_lockPath);
   RELEASE(_lockTime);
+  RELEASE(_localLock);
   [super dealloc];
 }
 
 - (NSString*) description
 {
+  NSString	*result;
+
+  [_localLock lock];
   if (_lockTime == nil)
     {
-      return [[super description] stringByAppendingFormat:
+      result = [[super description] stringByAppendingFormat:
         @" path '%@' not locked", _lockPath];
     }
   else
     {
-      return [[super description] stringByAppendingFormat:
+      result = [[super description] stringByAppendingFormat:
         @" path '%@' locked at %@", _lockPath, _lockTime];
     }
+  [_localLock unlock];
+  return result;
 }
 
 /**
@@ -137,6 +156,7 @@ static NSFileManager	*mgr = nil;
   NSString	*lockDir;
   BOOL		isDirectory;
 
+  _localLock = [NSLock new];
   _lockPath = [[aPath stringByStandardizingPath] copy];
   _lockTime = nil;
 
@@ -188,11 +208,21 @@ static NSFileManager	*mgr = nil;
  * May raise an NSGenericException if a problem occurs.
  */
 - (BOOL) tryLock
+{
+  BOOL		locked = NO;
+
+  [_localLock lock];
+  NS_DURING
     {
       NSMutableDictionary	*attributesToSet;
       NSDictionary		*attributes;
-  BOOL			locked;
 
+      if (nil != _lockTime)
+	{
+	  [NSException raise: NSGenericException
+		      format: @"Attempt to re-lock distributed lock %@",
+	    _lockPath];
+        }
       attributesToSet = [NSMutableDictionary dictionaryWithCapacity: 1];
       [attributesToSet setObject: [NSNumber numberWithUnsignedInt: 0755]
 			  forKey: NSFilePosixPermissions];
@@ -201,14 +231,14 @@ static NSFileManager	*mgr = nil;
 	      withIntermediateDirectories: YES
 			       attributes: attributesToSet
 				    error: NULL];
-  if (locked == NO)
+      if (NO == locked)
 	{
 	  BOOL	dir;
 
-      /*
+	  /* We expect the directory creation to have failed because
-       * We expect the directory creation to have failed because it already
+	   * it already exists as another processes lock.
-       * exists as another processes lock.  If the directory doesn't exist,
+	   * If the directory doesn't exist, then either the other
-       * then either the other process has removed it's lock (and we can retry)
+	   * process has removed it's lock (and we can retry)
 	   * or we have a severe problem!
 	   */
 	  if ([mgr fileExistsAtPath: _lockPath isDirectory: &dir] == NO)
@@ -217,7 +247,7 @@ static NSFileManager	*mgr = nil;
 		      withIntermediateDirectories: YES
 				       attributes: attributesToSet
 					    error: NULL];
-	  if (locked == NO)
+	      if (NO == locked)
 		{
 		  NSLog(@"Failed to create lock directory '%@' - %@",
 		    _lockPath, [NSError _last]);
@@ -225,11 +255,7 @@ static NSFileManager	*mgr = nil;
 	    }
 	}
 
-  if (locked == NO)
+      if (YES == locked)
-    {
-      return NO;
-    }
-  else
 	{
 	  attributes = [mgr fileAttributesAtPath: _lockPath
 				    traverseLink: YES];
@@ -240,9 +266,23 @@ static NSFileManager	*mgr = nil;
 		_lockPath];
 	    }
 	  ASSIGN(_lockTime, [attributes fileModificationDate]);
-      return YES;
+	  if (nil == _lockTime)
+	    {
+	      [NSException raise: NSGenericException
+		format: @"Unable to get date of lock file we made at %@",
+		_lockPath];
 	    }
 	}
+    }
+  NS_HANDLER
+    {
+      [_localLock unlock];
+      [localException raise];
+    }
+  NS_ENDHANDLER
+  [_localLock unlock];
+  return locked;
+}
 
 /**
  * Releases the lock.  Raises an NSGenericException if unable to release
@@ -250,6 +290,9 @@ static NSFileManager	*mgr = nil;
  * process has broken it).
  */
 - (void) unlock
+{
+  [_localLock lock];
+  NS_DURING
     {
       NSDictionary	*attributes;
 
@@ -258,8 +301,7 @@ static NSFileManager	*mgr = nil;
 	  [NSException raise: NSGenericException format: @"not locked by us"];
 	}
 
-  /*
+      /* Don't remove the lock if it has already been broken by someone
-   *	Don't remove the lock if it has already been broken by someone
        * else and re-created.  Unfortunately, there is a window between
        * testing and removing, but we do the bset we can.
        */
@@ -289,5 +331,13 @@ static NSFileManager	*mgr = nil;
 	}
       DESTROY(_lockTime);
     }
+  NS_HANDLER
+    {
+      [_localLock unlock];
+      [localException raise];
+    }
+  NS_ENDHANDLER
+  [_localLock unlock];
+}
 
 @end