Fixed memory leak found during analyzing and profiling phases.

Fixed GC ARC issue which may lead to application crash while retrieving GC released bundle seed identifier string value. For some reasons GC releases the value of string variable on the next method invocation. As a result it becomes a zombie object referencing to an unallocated memory. Assigning its value on the first method call to a static variable by explicit object copy resolves the issue. More info can be found on the following link, however the issue is still very specific for this case: http://stackoverflow.com/questions/6316723/why-retain-a-static-variable
jeremangnr · Nov 18, 2015 · 286d3e0 · 286d3e0
1 parent fde8ba8
commit 286d3e0
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Showing 2 changed files with 41 additions and 28 deletions.
diff --git a/Example/Podfile.lock b/Example/Podfile.lock
@@ -1,6 +1,6 @@
 PODS:
   - Expecta (0.3.1)
-  - JNKeychain (0.1.2)
+  - JNKeychain (0.1.3)
   - Specta (0.2.1)
 
 DEPENDENCIES:
@@ -14,7 +14,7 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   Expecta: a354d4633409dd9fe8c4f5ff5130426adbe31628
-  JNKeychain: 3428e123958aca6672b55d615a8a45cdf7b82c71
+  JNKeychain: 4e3d300a03c6d747309af66edaf161b9b772165f
   Specta: 15a276a6343867b426d5ed135d5aa4d04123a573
 
 COCOAPODS: 0.39.0
diff --git a/Pod/Classes/JNKeychain.m b/Pod/Classes/JNKeychain.m
@@ -36,7 +36,7 @@ + (NSMutableDictionary *)getKeychainQuery:(NSString *)key forAccessGroup:(NSStri
         [keychainQuery setObject:[self getFullAppleIdentifier:group] forKey:(__bridge id)kSecAttrAccessGroup];
     }
 
-    return [keychainQuery mutableCopy];
+    return keychainQuery;
 }
 
 /**
@@ -84,7 +84,7 @@ + (BOOL)deleteValueForKey:(NSString *)key forAccessGroup:(NSString *)group
 
 + (BOOL)deleteValueForKey:(NSString *)key
 {
-    return[self deleteValueForKey:key forAccessGroup:nil];
+    return [self deleteValueForKey:key forAccessGroup:nil];
 }
 
 #pragma mark -
@@ -125,31 +125,44 @@ + (id)loadValueForKey:(NSString *)key
 
 + (NSString *)getBundleSeedIdentifier
 {
-    static NSString *bundleSeedID = nil;
-    static dispatch_once_t _once;
-    dispatch_once(&_once, ^{
-        NSDictionary *query = @{
-                                (__bridge id)kSecClass: (__bridge NSString *)kSecClassGenericPassword,
-                                (__bridge id)kSecAttrAccount: @"bundleSeedID",
-                                (__bridge id)kSecAttrService: @"",
-                                (__bridge id)kSecReturnAttributes: (__bridge id)kCFBooleanTrue
-                                };
-        CFDictionaryRef result = nil;
-        OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&result);
-        if (status == errSecItemNotFound)
-        {
-            status = SecItemAdd((__bridge CFDictionaryRef)query, (CFTypeRef *)&result);
-        }
-        if (status == errSecSuccess)
-        {
-            NSString *accessGroup = [(__bridge NSDictionary *)result objectForKey:(__bridge NSString *)kSecAttrAccessGroup];
-            NSArray *components = [accessGroup componentsSeparatedByString:@"."];
-            bundleSeedID = [[components objectEnumerator] nextObject];
-            CFRelease(result);
+    static __strong NSString *bundleSeedIdentifier = nil;
+
+    if (bundleSeedIdentifier == nil)
+    {
+        @synchronized(self) {
+            if (bundleSeedIdentifier == nil)
+            {
+                NSString *_bundleSeedIdentifier = nil;
+                NSDictionary *query = @{
+                                        (__bridge id)kSecClass: (__bridge NSString *)kSecClassGenericPassword,
+                                        (__bridge id)kSecAttrAccount: @"bundleSeedID",
+                                        (__bridge id)kSecAttrService: @"",
+                                        (__bridge id)kSecReturnAttributes: (__bridge id)kCFBooleanTrue
+                                        };
+                CFDictionaryRef result = nil;
+                OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&result);
+                if (status == errSecItemNotFound)
+                {
+                    status = SecItemAdd((__bridge CFDictionaryRef)query, (CFTypeRef *)&result);
+                }
+                if (status == errSecSuccess)
+                {
+                    NSString *accessGroup = [(__bridge NSDictionary *)result objectForKey:(__bridge NSString *)kSecAttrAccessGroup];
+                    NSArray *components = [accessGroup componentsSeparatedByString:@"."];
+                    _bundleSeedIdentifier = [[components objectEnumerator] nextObject];
+                    CFRelease(result);
+                }
+                //
+                // For some reasons GC releases the value of _bundleSeedIdentifier string variable on the next method invocation.
+                // As a result it becomes a zombie object referencing to an unallocated memory.
+                // Assigning its value on the first method call to a static variable by explicit object copy resolves the issue.
+                //
+                bundleSeedIdentifier = [_bundleSeedIdentifier copy];
+            }
         }
-    });
+    }
 
-    return bundleSeedID;
+    return bundleSeedIdentifier;
 }
 
-@end
+@end