squilu/discount/amalloc.c

/*
 * debugging malloc()/realloc()/calloc()/free() that attempts
 * to keep track of just what's been allocated today.
 */

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

#define MAGIC 0x1f2e3d4c

struct alist { int magic, size, index; int *end; struct alist *next, *last; };

static struct alist list =  { 0, 0, 0, 0 };

static int mallocs=0;
static int reallocs=0;
static int frees=0;

static int index = 0;

static void
die(char *msg, int index)
{
    fprintf(stderr, msg, index);
    abort();
}


void *
acalloc(int count, int size)
{
    struct alist *ret;

    if ( size > 1 ) {
	count *= size;
	size = 1;
    }

    if ( ret = calloc(count + sizeof(struct alist) + sizeof(int), size) ) {
	ret->magic = MAGIC;
	ret->size = size * count;
	ret->index = index ++;
	ret->end = (int*)(count + (char*) (ret + 1));
	*(ret->end) = ~MAGIC;
	if ( list.next ) {
	    ret->next = list.next;
	    ret->last = &list;
	    ret->next->last = ret;
	    list.next = ret;
	}
	else {
	    ret->last = ret->next = &list;
	    list.next = list.last = ret;
	}
	++mallocs;
	return ret+1;
    }
    return 0;
}


void*
amalloc(int size)
{
    return acalloc(size,1);
}


void
afree(void *ptr)
{
    struct alist *p2 = ((struct alist*)ptr)-1;

    if ( p2->magic == MAGIC ) {
	if ( ! (p2->end && *(p2->end) == ~MAGIC) )
	    die("goddam: corrupted memory block %d in free()!\n", p2->index);
	p2->last->next = p2->next;
	p2->next->last = p2->last;
	++frees;
	free(p2);
    }
    else
	free(ptr);
}


void *
arealloc(void *ptr, int size)
{
    struct alist *p2 = ((struct alist*)ptr)-1;
    struct alist save;

    if ( p2->magic == MAGIC ) {
	if ( ! (p2->end && *(p2->end) == ~MAGIC) )
	    die("goddam: corrupted memory block %d in realloc()!\n", p2->index);
	save.next = p2->next;
	save.last = p2->last;
	p2 = realloc(p2, sizeof(int) + sizeof(*p2) + size);

	if ( p2 ) {
	    p2->size = size;
	    p2->end = (int*)(size + (char*) (p2 + 1));
	    *(p2->end) = ~MAGIC;
	    p2->next->last = p2;
	    p2->last->next = p2;
	    ++reallocs;
	    return p2+1;
	}
	else {
	    save.next->last = save.last;
	    save.last->next = save.next;
	    return 0;
	}
    }
    return realloc(ptr, size);
}


void
adump()
{
    struct alist *p;


    for ( p = list.next; p && (p != &list); p = p->next ) {
	fprintf(stderr, "allocated: %d byte%s\n", p->size, (p->size==1) ? "" : "s");
	fprintf(stderr, "           [%.*s]\n", p->size, (char*)(p+1));
    }

    if ( getenv("AMALLOC_STATISTICS") ) {
	fprintf(stderr, "%d malloc%s\n", mallocs, (mallocs==1)?"":"s");
	fprintf(stderr, "%d realloc%s\n", reallocs, (reallocs==1)?"":"s");
	fprintf(stderr, "%d free%s\n", frees, (frees==1)?"":"s");
    }
}