PartitionAlloc: Leave bucket in valid state when allocation fails

Source/wtf/PartitionAllocTest.cpp

Index: Source/wtf/PartitionAllocTest.cpp
diff --git a/Source/wtf/PartitionAllocTest.cpp b/Source/wtf/PartitionAllocTest.cpp
index 7adc14a566f339f2e3d63fd5062b2d0f94f0a692..c1f2f2a5bdedd732066e19fe16741a23bc262420 100644
--- a/Source/wtf/PartitionAllocTest.cpp
+++ b/Source/wtf/PartitionAllocTest.cpp
@@ -1097,6 +1097,35 @@ TEST(PartitionAllocTest, LostFreePagesBug)
     TestShutdown();
 }
 
+// Tests that if an allocation fails in "return null" mode, repeating it doesn't
+// crash, and still returns null.  The test allocates 6 GB of memory in 512 kB
+// blocks. This may never fail on 64-bit systems, in which case this test fails

[Jens Widell, 2014/10/22 19:40:12]

To make these allocations fail on 64-bit, I've been using "ulimit -v 2000000" to
set a 2 GB address space limit before running wtf_unittests. Is there anything
in the testing framework/infrastructure that could be used to the same effect to
ensure this test is meaningful?

Oh, if only we hadn't just dropped PartitionAlloc's 2 GB address space limit...
:-)

+// to test what it sets out to test.
+TEST(PartitionAllocTest, RepeatedReturnNull)
+{
+    TestSetup();
+
+    void* ptrs[8192];
+    int i;
+
+    for (i = 0; i < 6144; ++i) {
+        ptrs[i] = partitionAllocGenericFlags(genericAllocator.root(), WTF::PartitionAllocReturnNull, 512*1024);
+        if (!ptrs[i]) {
+            ptrs[i] = partitionAllocGenericFlags(genericAllocator.root(), WTF::PartitionAllocReturnNull, 512*1024);
+            EXPECT_FALSE(ptrs[i]);
+            break;
+        }
+    }
+
+    for (--i; i >= 0; --i) {
+        partitionFreeGeneric(genericAllocator.root(), ptrs[i]);
+        ptrs[i] = partitionAllocGenericFlags(genericAllocator.root(), WTF::PartitionAllocReturnNull, 512*1024);
+        partitionFreeGeneric(genericAllocator.root(), ptrs[i]);
+    }
+
+    TestShutdown();
+}
+
 #if !OS(ANDROID)
 
 // Make sure that malloc(-1) dies.