Question

I am getting that data from an CGImageRef and then setting a structure I created to point to this data:

        CFDataRef data = CGDataProviderCopyData(CGImageGetDataProvider(imageRef));
        const UInt8 * imageData = CFDataGetBytePtr(data);
        myPix->data = (l_uint32 *) imageData;

However I am getting an memory leak warning when I do Product -> Analyze.

I think the reason is because I don’t do CFRelease(data). However if I do that myPix -> data gets modified. How can I get rid of the memory leak warning but get it to work properly?

Answer 1

you’re just assigning a pointer there – casting away const (undefined behavior if you write to it), and disposing of the owner (freeing the allocation assigned to data — also undefined behavior when you read or write to that memory region).

if you want a mutable copy of that data, you must create your own mutable copy. the you can safely call CFRelease(data).

there are two immediate ways to create a mutable copy:

1) using malloc

• Create a new allocation using malloc
• then copy the buffer from data to your buffer
• then assign the buffer to myPix->data
• when you are done with the allocation myPix->data references, call free(myPix->data);

2) Create a mutable copy of the CFData.

CFMutableDataRef mutableData = CFDataCreateMutableCopy(0, 0, data);
myPix->data = (l_uint32 *)CFDataGetMutableBytePtr(mutableData);

when you are done with the allocation myPix->data references, call CFRelease(mutableData);