Study from open source code -- malloc trace （1）

for working on fsck the disk mounted on board, i read the the code of the e2fsck, study some useful skills, such like this:

 

malloc_trace.

 

we malloc or free the memory in programes, some skills will be useful for us to debug

 

if want get more information, please 'man malloc_hook'

 

a example follw:

/* * ===================================================================================== * * Filename: mtrace.c * * Description: trace the malloc in heap, that may be helpful for our debugging * * Version: 1.0 * Created: 2010年08月19日 15时48分15秒 * Revision: none * Compiler: gcc * * Author: StrongMouse (), [e-mail] * Company: Besovideo * * ===================================================================================== */#include <stdio.h>#include <malloc.h>typedef void * _ptr_t;//global variable for storage the old hookstatic void (*tr_old_free_hook)(_ptr_t ptr, const void *caller);static _ptr_t (*tr_old_malloc_hook)(size_t size, const void *caller);static _ptr_t (*tr_old_realloc_hook)(_ptr_t ptr, size_t size, const void *caller);//just as extern, decalare onlystatic void my_free_hook(_ptr_t ptr, const void *caller);static _ptr_t my_malloc_hook(size_t size, const void *caller);static _ptr_t my_realloc_hook(_ptr_t ptr, size_t size, const void *caller);static void my_init_hook(void);//malloc will call this function, once when implement of malloc funcvoid (*__malloc_initialize_hook)(void) = my_init_hook;static void (my_init_hook)(void){tr_old_free_hook = __free_hook;__free_hook = my_free_hook;tr_old_malloc_hook = __malloc_hook;__malloc_hook = my_malloc_hook;tr_old_realloc_hook = __realloc_hook;__realloc_hook = my_realloc_hook;printf("in func %s/n", __func__);};static void (my_free_hook)(_ptr_t ptr, const void *caller){__free_hook = tr_old_free_hook;printf("free the %p/n", ptr);free(ptr);__free_hook = my_free_hook;}static _ptr_t my_malloc_hook(size_t size, const void *caller){_ptr_t hdr = NULL;__malloc_hook = tr_old_malloc_hook;hdr = malloc(size);printf("malloc size %d %p/n", size, hdr);__malloc_hook = my_malloc_hook;return hdr;}static _ptr_t my_realloc_hook(_ptr_t ptr, size_t size, const void *caller){_ptr_t hdr = NULL;__realloc_hook = tr_old_realloc_hook;hdr = realloc(ptr, size);printf("realloc <%p> %p,%d/n", ptr, hdr, size);__realloc_hook = my_realloc_hook;return hdr;}int main(int argc, const char *argv[]){int i = 0;_ptr_t ptr = NULL;for(i = 0; i < 10; i++){ptr = malloc(i);free(ptr);}return 0;}