Changeset 47092 in webkit for trunk/JavaScriptCore/wtf/FastMalloc.h

Timestamp:

Aug 11, 2009, 11:22:41 PM (16 years ago)

Author:

[email protected]

Message:

Make it harder to misuse try* allocation routines
​https://bugs.webkit.org/show_bug.cgi?id=27469

Reviewed by Gavin Barraclough

Jump through a few hoops to make it much harder to accidentally
miss null-checking of values returned by the try-* allocation
routines.

File:

• trunk/JavaScriptCore/wtf/FastMalloc.h (modified) (2 diffs)

trunk/JavaScriptCore/wtf/FastMalloc.h

@@ -23 +23 @@
 
 #include "Platform.h"
+#include "PossiblyNull.h"
 #include <stdlib.h>
 #include <new>
@@ -34 +35 @@
     void* fastRealloc(void*, size_t);
 
-    // These functions return 0 if an allocation fails.
-    void* tryFastMalloc(size_t);
-    void* tryFastZeroedMalloc(size_t);
-    void* tryFastCalloc(size_t numElements, size_t elementSize);
-    void* tryFastRealloc(void*, size_t);
+    struct TryMallocReturnValue {
+        TryMallocReturnValue(void* data)
+            : m_data(data)
+        {
+        }
+        TryMallocReturnValue(const TryMallocReturnValue& source)
+            : m_data(source.m_data)
+        {
+            source.m_data = 0;
+        }
+        ~TryMallocReturnValue() { ASSERT(!m_data); }
+        template <typename T> bool getValue(T& data) WARN_UNUSED_RETURN;
+        template <typename T> operator PossiblyNull<T>()
+        { 
+            T value; 
+            getValue(value); 
+            return PossiblyNull<T>(value);
+        } 
+    private:
+        mutable void* m_data;
+    };
+    
+    template <typename T> bool TryMallocReturnValue::getValue(T& data) {
+        union u { void* data; T target; } res;
+        res.data = m_data;
+        data = res.target;
+        bool returnValue = !!m_data;
+        m_data = 0;
+        return returnValue;
+    }
+
+    TryMallocReturnValue tryFastMalloc(size_t n);
+    TryMallocReturnValue tryFastZeroedMalloc(size_t n);
+    TryMallocReturnValue tryFastCalloc(size_t n_elements, size_t element_size);
+    TryMallocReturnValue tryFastRealloc(void* p, size_t n);
 
     void fastFree(void*);