Dynamic Memory Allocation

Collaboration diagram for Dynamic Memory Allocation:

Functions
void *	test_malloc (size_t size)
	Test function overriding malloc.
void *	test_calloc (size_t nmemb, size_t size)
	Test function overriding calloc.
void *	test_realloc (void *ptr, size_t size)
	Test function overriding realloc which detects buffer overruns and memoery leaks.
void	test_free (void *ptr)
	Test function overriding free(3).

Detailed Description

Memory leaks, buffer overflows and underflows can be checked using cmocka.

To test for memory leaks, buffer overflows and underflows a module being tested by cmocka should replace calls to malloc(), calloc() and free() to test_malloc(), test_calloc() and test_free() respectively. Each time a block is deallocated using test_free() it is checked for corruption, if a corrupt block is found a test failure is signalled. All blocks allocated using the test_*() allocation functions are tracked by the cmocka library. When a test completes if any allocated blocks (memory leaks) remain they are reported and a test failure is signalled.

For simplicity cmocka currently executes all tests in one process. Therefore all test cases in a test application share a single address space which means memory corruption from a single test case could potentially cause the test application to exit prematurely.

Function Documentation

test_calloc()

void * test_calloc	(	size_t	nmemb,
		size_t	size
	)

Test function overriding calloc.

The memory is set to zero.

Parameters

[in]	nmemb	The number of elements for an array to be allocated.
[in]	size	The size in bytes of each array element to allocate.

Returns

A pointer to the allocated memory, NULL on error.

See also

calloc(3)

test_free()

void test_free

(

void *

ptr

)

Test function overriding free(3).

Parameters

[in]

ptr

The pointer to the memory space to free.

See also

free(3).

test_malloc()

void * test_malloc

(

size_t

size

)

Test function overriding malloc.

Parameters

[in]

size

The bytes which should be allocated.

Returns

A pointer to the allocated memory or NULL on error.

#ifdef UNIT_TESTING
extern void* _test_malloc(const size_t size, const char* file, const int line);
 
#define malloc(size) _test_malloc(size, __FILE__, __LINE__)
#endif
 
void leak_memory() {
    int * const temporary = (int*)malloc(sizeof(int));
    *temporary = 0;
}

See also

malloc(3)

test_realloc()

void * test_realloc	(	void *	ptr,
		size_t	size
	)

Test function overriding realloc which detects buffer overruns and memoery leaks.

Parameters

[in]	ptr	The memory block which should be changed.
[in]	size	The bytes which should be allocated.

Returns

The newly allocated memory block, NULL on error.