Java: initial experimentation

Author: Jami Cogswell

java/ql/src/Likely Bugs/Concurrency/UnreleasedLock.ql

@@ -112,6 +112,11 @@ predicate failedLock(LockType t, BasicBlock lockblock, BasicBlock exblock) {
 predicate heldByCurrentThreadCheck(LockType t, BasicBlock checkblock, BasicBlock falsesucc) {
   exists(ConditionBlock conditionBlock |
     conditionBlock.getCondition() = t.getIsHeldByCurrentThreadAccess()
+    or
+    // Assume that a boolean variable condition check that controls an unlock call
+    // is checking the lock state similar to `isHeldByCurrentThread`.
+    conditionBlock.getCondition() = any(VarAccess v | v.getType() instanceof BooleanType) and
+    conditionBlock.controls(t.getUnlockAccess().getBasicBlock(), true)
   |
     conditionBlock.getBasicBlock() = checkblock and
     conditionBlock.getTestSuccessor(false) = falsesucc

java/ql/test/query-tests/UnreleasedLock/UnreleasedLock.java

@@ -5,18 +5,18 @@ void lock() throws RuntimeException { }
 		void unlock() { }
 		boolean isHeldByCurrentThread() { return true; }
 	}
-	
+
 	void f() throws RuntimeException { }
 	void g() throws RuntimeException { }
-	
+
 	MyLock mylock = new MyLock();
-	
+
 	void bad1() {
 		mylock.lock();
 		f();
 		mylock.unlock();
 	}
-	
+
 	void good2() {
 		mylock.lock();
 		try {
@@ -25,7 +25,7 @@ void good2() {
 			mylock.unlock();
 		}
 	}
-	
+
 	void bad3() {
 		mylock.lock();
 		f();
@@ -35,7 +35,7 @@ void bad3() {
 			mylock.unlock();
 		}
 	}
-	
+
 	void bad4() {
 		mylock.lock();
 		try {
@@ -45,7 +45,7 @@ void bad4() {
 			mylock.unlock();
 		}
 	}
-	
+
 	void bad5(boolean lockmore) {
 		mylock.lock();
 		try {
@@ -58,7 +58,7 @@ void bad5(boolean lockmore) {
 			mylock.unlock();
 		}
 	}
-	
+
 	void good6() {
 		if (!mylock.tryLock()) { return; }
 		try {
@@ -67,7 +67,7 @@ void good6() {
 			mylock.unlock();
 		}
 	}
-	
+
 	void bad7() {
 		if (!mylock.tryLock()) { return; }
 		f();
@@ -95,4 +95,62 @@ void good8() {
 			mylock.unlock();
 		}
 	}
+
+	// * New testing
+
+	void good9() { // * PASSES
+		boolean locked = mylock.tryLock();
+		if (!locked) { return; }
+		try {
+			f();
+		} finally {
+			if (locked) {
+				mylock.unlock();
+			}
+		}
+	}
+
+	void good10() { // ! FAILS
+		boolean locked = false;
+		try {
+			locked = mylock.tryLock();
+			if (!locked) { return; }
+		} finally {
+			if (locked) {
+				mylock.unlock();
+			}
+			// else { // * PASSES when add this
+			// 	mylock.unlock();
+			// }
+		}
+	}
+
+	void good11() { // * PASSES
+		boolean locked = false;
+		try {
+			locked = mylock.tryLock();
+			if (!locked) { return; }
+		} finally {
+			mylock.unlock();
+		}
+	}
+
+	void good12() { // * PASSES
+		boolean locked = mylock.tryLock();
+		if (locked){
+			try {
+				f();
+			} finally {
+				mylock.unlock();
+			}
+		}
+	}
+
+	void good13() { // * PASSES
+		try {
+			mylock.lock();
+		} finally {
+			mylock.unlock();
+		}
+	}
 }