作者联系方式：李先静

作为Linux下的C程序员，我总是习惯在单元测试通过之后，再用valgrind把程序跑一下，看看有没有内存泄漏和内存越界等问题。可惜的是，有时valgrind并不能很好的工作，像基于DirectFB的多进程程序在valgrind下是跑不起的, 这时我们可以通过内存管理器的钩子函数来跟踪内存泄漏。

先记录分配/释放操作：

/**//*memory_trace.c*/

#include
#include
#include
#include
#include
#include
#include
#include
#include

static void memory_trace_init(void);
static void memory_trace_deinit(void);
static void *my_malloc_hook (size_t size, const void* ptr);
static void my_free_hook (void* ptr, const void* caller);
static void *my_realloc_hook (void *ptr, size_t size, const void *caller);

static void *my_malloc_hook (size_t size, const void* ptr);
static void my_free_hook (void* ptr, const void* caller);
static void *my_realloc_hook (void *ptr, size_t size, const void *caller);

static void *(*old_malloc_hook)(size_t size, const void* ptr);
static void (*old_free_hook)(void* ptr, const void* caller);
static void *(*old_realloc_hook)(void *ptr, size_t size, const void *caller);

#define BACK_TRACE_DEPTH 8
#define CACHE_SIZE 512

static FILE* g_memory_trace_fp = NULL;
static int g_memory_trace_cache_used = 0;
/**//*additional 3 items: alloc/free addr size*/
static void* g_memory_trace_cache[CACHE_SIZE][BACK_TRACE_DEPTH + 3];
static void memory_trace_flush(void);
static void memory_trace_write(int alloc, void* addr, int size);

static void memory_trace_backup(void)
...{
old_malloc_hook = __malloc_hook;
old_free_hook = __free_hook;
old_realloc_hook = __realloc_hook;

return;
}

static void memory_trace_hook(void)
...{
__malloc_hook = my_malloc_hook;
__free_hook = my_free_hook;
__realloc_hook = my_realloc_hook;

return;
}

static void memory_trace_restore(void)
...{
__malloc_hook = old_malloc_hook;
__free_hook = old_free_hook;
__realloc_hook = old_realloc_hook;

return;
}

static void memory_trace_init(void)
...{
if(g_memory_trace_fp == NULL && getenv("MALLOC_TRACE") != NULL)
...{
char file_name[260] = ...{0};
snprintf(file_name, sizeof(file_name), "/tmp/%d_memory.log", getpid());
if((g_memory_trace_fp = fopen(file_name, "wb+")) != NULL)
...{
memory_trace_backup();
memory_trace_hook();
}

atexit(memory_trace_deinit);
}

return;
}

static void memory_trace_deinit(void)
...{
if(g_memory_trace_fp != NULL)
...{
memory_trace_restore();
memory_trace_flush();
fclose(g_memory_trace_fp);
g_memory_trace_fp = NULL;
}

return;
}

void (*__malloc_initialize_hook) (void) = memory_trace_init;

static void * my_malloc_hook (size_t size, const void *caller)
...{
void *result = NULL;
memory_trace_restore();
result = malloc (size);
memory_trace_write(1, result, size);
memory_trace_hook();

return result;
}

static void my_free_hook (void *ptr, const void *caller)
...{
memory_trace_restore();
free (ptr);
memory_trace_write(0, ptr, 0);
memory_trace_hook();

return;
}

static void *my_realloc_hook (void *ptr, size_t size, const void *caller)
...{
void* result = NULL;

memory_trace_restore();
memory_trace_write(0, ptr, 0);
result = realloc(ptr, size);
memory_trace_write(1, result, size);
memory_trace_hook();

return result;
}