malloc/free debug stuff

// debug.h

#pragma once

#define CHILL_DEBUG
// #define CHILL_DEBUG_PRINTF_MALLOC_FREE

#ifdef CHILL_DEBUG
# define CHILL_DEBUG_INIT chill_debug_init()
# define CHILL_DEBUG_EXIT chill_debug_exit()

void chill_debug_init();
void chill_debug_exit();
void *chill_debug_malloc(const char *lineinfo, size_t size);
void chill_debug_free(const char *lineinfo, void *ptr);
void chill_debug_unfreed();

# define PLS_STRINGIFY(stuff) #stuff
# define STRINGIFY(stuff) PLS_STRINGIFY(stuff)
# define CHILL_HERE __FILE__ ":" STRINGIFY(__LINE__)
# define malloc(size) chill_debug_malloc(CHILL_HERE, (size))
# define free(ptr) chill_debug_free(CHILL_HERE, (ptr))
#else
# define CHILL_DEBUG_INIT
# define CHILL_DEBUG_EXIT
#endif


// debug.c

#include <stdlib.h>
#include <stdio.h>

typedef void *(*MALLOCPROC)(size_t);
typedef void (*FREEPROC)(void *);

static MALLOCPROC chill_debug_pmalloc = malloc;
static FREEPROC chill_debug_pfree = free;

#include "debug.h"

typedef struct _chill_debug_memblock_s
{
    struct _chill_debug_memblock_s *prev, *next;
    const char *lineinfo;
    size_t size;
} chill_debug_memblock_t;

static int unfreed_memblock_num;
static chill_debug_memblock_t first_memblock_fake, last_memblock_fake;
static chill_debug_memblock_t *first_memblock, *last_memblock;

void chill_debug_unfreed()
{
    for (chill_debug_memblock_t *memblock = first_memblock->next; memblock->next; memblock = memblock->next)
    {
        printf("%s: %li bytes of memory\n", memblock->lineinfo, memblock->size);
    }
}

void chill_debug_init()
{
    unfreed_memblock_num = 0;
    first_memblock = &first_memblock_fake;
    last_memblock = &last_memblock_fake;
    first_memblock->prev = NULL;
    first_memblock->next = last_memblock;
    last_memblock->prev = first_memblock;
    last_memblock->next = NULL;
}

void chill_debug_exit()
{
    if (unfreed_memblock_num)
    {
        printf("DEBUG WARNING: There are %i unfreed memory blocks:\n", unfreed_memblock_num);
        chill_debug_unfreed();
    }
}

void *chill_debug_malloc(const char *lineinfo, size_t size)
{
#ifdef CHILL_DEBUG_PRINTF_MALLOC_FREE
    printf("%s: attempting to malloc %li bytes of memory ... ", lineinfo, size);
#endif

    size_t offset = sizeof(chill_debug_memblock_t);
    void *result = chill_debug_pmalloc(size + offset);
    if (!result)
    {
#ifdef CHILL_DEBUG_PRINTF_MALLOC_FREE
        puts("fail. exit.\n");
#endif
        exit(1);
    }

    chill_debug_memblock_t *memblock = result;
    memblock->lineinfo = lineinfo;
    memblock->size = size;
    memblock->prev = last_memblock->prev;
    memblock->next = last_memblock;
    memblock->prev->next = memblock;
    memblock->next->prev = memblock;

#ifdef CHILL_DEBUG_PRINTF_MALLOC_FREE
    puts("ok.\n");
#endif

    ++unfreed_memblock_num;

    return result + offset;
}

void chill_debug_free(const char *lineinfo, void *ptr)
{
    size_t offset = sizeof(chill_debug_memblock_t);

    chill_debug_memblock_t *memblock = ptr - offset;
    memblock->prev->next = memblock->next;
    memblock->next->prev = memblock->prev;

#ifdef CHILL_DEBUG_PRINTF_MALLOC_FREE
    printf("%s: freeing %li bytes of memory allocated at %s\n", lineinfo, memblock->size, memblock->lineinfo);
#endif

    chill_debug_pfree(memblock);

    --unfreed_memblock_num;
}