Fixed infinite recursion with isDirty: with recursive relation.

Objects. Objects everywhere.

Author: richardjrossiii

Parse/PFObject.m

@@ -657,19 +657,12 @@ - (BOOL)isDirty:(BOOL)considerChildren {
         if (self._state.deleted || dirty || [self _hasChanges]) {
             return YES;
         }
+
         if (considerChildren) {
-            // We only need to consider the currently estimated children here,
-            // because they're the only ones that might need to be saved in a
-            // subsequent call to save, which is the meaning of "dirtiness".
-            __block BOOL retValue = NO;
-            [_estimatedData enumerateKeysAndObjectsUsingBlock:^(NSString *key, id obj, BOOL *stop) {
-                if ([obj isKindOfClass:[PFObject class]] && [obj isDirty]) {
-                    retValue = YES;
-                    *stop = YES;
-                }
-            }];
-            return retValue;
+            NSMutableSet *seen = [NSMutableSet set];
+            return [self _areChildrenDirty:seen];
         }
+
         return NO;
     }
 }
@@ -680,6 +673,32 @@ - (void)_setDirty:(BOOL)aDirty {
     }
 }
 
+- (BOOL)_areChildrenDirty:(NSMutableSet *)seenObjects {
+    if ([seenObjects containsObject:self]) {
+        return NO;
+    }
+    [seenObjects addObject:self];
+
+    @synchronized(lock) {
+        [self checkpointAllMutableContainers];
+        if (self._state.deleted || dirty || [self _hasChanges]) {
+            return YES;
+        }
+
+        // We only need to consider the currently estimated children here,
+        // because they're the only ones that might need to be saved in a
+        // subsequent call to save, which is the meaning of "dirtiness".
+        __block BOOL retValue = NO;
+        [_estimatedData enumerateKeysAndObjectsUsingBlock:^(NSString *key, id obj, BOOL *stop) {
+            if ([obj isKindOfClass:[PFObject class]] && [obj _areChildrenDirty:seenObjects]) {
+                retValue = YES;
+                *stop = YES;
+            }
+        }];
+        return retValue;
+    }
+}
+
 ///--------------------------------------
 #pragma mark - Mutable container management
 ///--------------------------------------

Tests/Unit/ObjectUnitTests.m

@@ -230,8 +230,9 @@ - (void)testRevert {
     NSDate *date = [NSDate date];
     NSNumber *number = @0.75;
     PFObject *object = [PFObject _objectFromDictionary:@{ @"yarr" : date,
-                                                          @"score": number }
-                                      defaultClassName:@"Test" completeData:YES];
+                                                          @"score" : number }
+                                      defaultClassName:@"Test"
+                                          completeData:YES];
     object[@"yarr"] = @"yolo";
     [object revert];
     XCTAssertEqualObjects(object[@"yarr"], date);
@@ -243,12 +244,31 @@ - (void)testRevertObjectForKey {
     NSNumber *number = @0.75;
     PFObject *object = [PFObject _objectFromDictionary:@{ @"yarr" : date,
                                                           @"score" : @1.0 }
-                                      defaultClassName:@"Test" completeData:YES];
+                                      defaultClassName:@"Test"
+                                          completeData:YES];
     object[@"yarr"] = @"yolo";
     object[@"score"] = number;
     [object revertObjectForKey:@"yarr"];
     XCTAssertEqualObjects(object[@"yarr"], date);
     XCTAssertEqualObjects(object[@"score"], number);
 }
 
+#pragma mark Dirty
+
+- (void)testRecursiveDirty {
+    // A -> B -> A is a supported use-case, but it would crash on older SDK versions.
+    PFObject *objectA = [PFObject objectWithClassName:@"A"];
+    PFObject *objectB = [PFObject objectWithClassName:@"B"];
+
+    [objectA _mergeAfterSaveWithResult:@{ @"objectId" : @"foo",
+                                          @"B" : objectB }
+                               decoder:[PFDecoder objectDecoder]];
+
+    [objectB _mergeAfterSaveWithResult:@{ @"objectId" : @"bar",
+                                          @"A" : objectA }
+                               decoder:[PFDecoder objectDecoder]];
+
+    XCTAssertFalse([objectA isDirty]);
+}
+
 @end