GCC/XCode equivalent of _CrtCheckMemory?

Question

When dealing with random memory overwrites, in MSVC it is possible to validate the state of the heap at various points with a call to _CrtCheckMemory, and know with at least a small level of confidence that the code up until the check was not responsible for any errors that might cause new or malloc to fail later.

In XCode, whats the equivalent way to try and box in a memory overwrite? All I have at the moment is a random failure of a call to new, somewhere deep in the bowels of some code with no real idea of how long the code has been running with a corrupt heap up until that point.

Answer 1

This doesn't address your question directly, but I felt compelled to respond. As you say, tools like the CRT check functions only give you a small level of confidence, and don't address resource leaks other than memory. If you find yourself depending on such tools I would say there is something very, very wrong with your approach to C++ development. In the past 10 years, I have not had a single problem in my code associated with memory leakage. This is not because I am some C++ coding god, but because I use the basic tools of RAII, smart pointers and standard library collections in my code, and wherever possible avoid explicit dynamic memory allocation using new. Whenever you find yourself writing a line of code like:

Something * p = new Something;

stop, and ask yourself "Is there some way I could avoid doing this?" and if the answer is "no", then ask yourself why you are allocating memory to a raw pointer, and if you can't find any way around that (which should very rarely be the case, immediately write the code to manage the pointers de-allocation, and make sure that that code is exception-safe.

If you take this approach, you won't need tools like special CRT functions or Valgrind, and you will save yourself oceans of time in debugging.

Answer 2

As it is only implied in Neil's answer, lets make this explicit:

As far as I know there isn't any tool that is as readily available as _CrtCheckMemory for gcc. IIRC there are some checked malloc libraries out there, but I didn't find them as usable as _CrtCheckMemory. There is however Valgrind which is deployed unintrusively, and gives you a much more throughout result.

Answer 3

This feature IS actually built into the heap in GCC. As described here The easiest way to enable it is on the XCode::Run menu: Enable Guard Malloc