Possible Leaks

There are two cases where RTC may report a "possible" leak. The first case is when no pointers were found pointing to the beginning of the block, but a pointer was found pointing to the interior of the block. This case is reported as an "Address in Block (aib)" error. If it was a stray pointer that happened to point into the block, this would be a real memory leak. However, some programs deliberately move the only pointer to an array back and forth as needed to access its entries. In this case it would not be a memory leak. Because RTC cannot distinguish these two cases, it reports them as possible leaks, allowing the user to make the determination.

The second type of possible leak occurs when no pointers to a block were found in the data space, but a pointer was found in a register. This case is reported as an "Address in Register (air)" error. If the register happens to point to the block accidentally, or if it is an old copy of a memory pointer that has since been lost, then this is a real leak. However, the compiler can optimize references and place the only pointer to a block in a register without ever writing the pointer to memory. In such cases, this would not be a real leak. Hence, if the program has been optimized and the report was the result of the showleaks command, it is likely not to be a real leak. In all other cases, it is likely to be a real leak.

RTC leak checking requires use of the standard libc malloc/free/realloc functions or allocators based on those functions. For other allocators, see "Runtime Checking Application Programming Interface".