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/*
* Copyright (c) 2004i-2010 Alex Pankratov. All rights reserved.
*
* Hierarchical memory allocator, 1.2.1
* http://swapped.cc/halloc
*/
/*
* The program is distributed under terms of BSD license.
* You can obtain the copy of the license by visiting:
*
* http://www.opensource.org/licenses/bsd-license.php
*/
#include <stdlib.h> /* realloc */
#include <string.h> /* memset & co */
#include "third_party/nestegg/halloc/halloc.h"
#include "align.h"
#include "hlist.h"
/*
* block control header
*/
typedef struct hblock
{
#ifndef NDEBUG
#define HH_MAGIC 0x20040518L
long magic;
#endif
hlist_item_t siblings; /* 2 pointers */
hlist_head_t children; /* 1 pointer */
max_align_t data[1]; /* not allocated, see below */
} hblock_t;
#define sizeof_hblock offsetof(hblock_t, data)
/*
*
*/
realloc_t halloc_allocator = NULL;
#define allocator halloc_allocator
/*
* static methods
*/
static void _set_allocator(void);
static void * _realloc(void * ptr, size_t n);
static int _relate(hblock_t * b, hblock_t * p);
static void _free_children(hblock_t * p);
/*
* Core API
*/
void * halloc(void * ptr, size_t len)
{
hblock_t * p;
/* set up default allocator */
if (! allocator)
{
_set_allocator();
assert(allocator);
}
/* calloc */
if (! ptr)
{
if (! len)
return NULL;
p = allocator(0, len + sizeof_hblock);
if (! p)
return NULL;
#ifndef NDEBUG
p->magic = HH_MAGIC;
#endif
hlist_init(&p->children);
hlist_init_item(&p->siblings);
return p->data;
}
p = structof(ptr, hblock_t, data);
assert(p->magic == HH_MAGIC);
/* realloc */
if (len)
{
p = allocator(p, len + sizeof_hblock);
if (! p)
return NULL;
hlist_relink(&p->siblings);
hlist_relink_head(&p->children);
return p->data;
}
/* free */
_free_children(p);
hlist_del(&p->siblings);
allocator(p, 0);
return NULL;
}
void hattach(void * block, void * parent)
{
hblock_t * b, * p;
if (! block)
{
assert(! parent);
return;
}
/* detach */
b = structof(block, hblock_t, data);
assert(b->magic == HH_MAGIC);
hlist_del(&b->siblings);
if (! parent)
return;
/* attach */
p = structof(parent, hblock_t, data);
assert(p->magic == HH_MAGIC);
/* sanity checks */
assert(b != p); /* trivial */
assert(! _relate(p, b)); /* heavy ! */
hlist_add(&p->children, &b->siblings);
}
/*
* malloc/free api
*/
void * h_malloc(size_t len)
{
return halloc(0, len);
}
void * h_calloc(size_t n, size_t len)
{
void * ptr = halloc(0, len*=n);
return ptr ? memset(ptr, 0, len) : NULL;
}
void * h_realloc(void * ptr, size_t len)
{
return halloc(ptr, len);
}
void h_free(void * ptr)
{
halloc(ptr, 0);
}
char * h_strdup(const char * str)
{
size_t len = strlen(str);
char * ptr = halloc(0, len + 1);
return ptr ? (ptr[len] = 0, memcpy(ptr, str, len)) : NULL;
}
/*
* static stuff
*/
static void _set_allocator(void)
{
void * p;
assert(! allocator);
/*
* the purpose of the test below is to check the behaviour
* of realloc(ptr, 0), which is defined in the standard
* as an implementation-specific. if it returns zero,
* then it's equivalent to free(). it can however return
* non-zero, in which case it cannot be used for freeing
* memory blocks and we'll need to supply our own version
*
* Thanks to Stan Tobias for pointing this tricky part out.
*/
allocator = realloc;
if (! (p = malloc(1)))
/* hmm */
return;
if ((p = realloc(p, 0)))
{
/* realloc cannot be used as free() */
allocator = _realloc;
free(p);
}
}
static void * _realloc(void * ptr, size_t n)
{
/*
* free'ing realloc()
*/
if (n)
return realloc(ptr, n);
free(ptr);
return NULL;
}
static int _relate(hblock_t * b, hblock_t * p)
{
hlist_item_t * i;
if (!b || !p)
return 0;
/*
* since there is no 'parent' pointer, which would've allowed
* O(log(n)) upward traversal, the check must use O(n) downward
* iteration of the entire hierarchy; and this can be VERY SLOW
*/
hlist_for_each(i, &p->children)
{
hblock_t * q = structof(i, hblock_t, siblings);
if (q == b || _relate(b, q))
return 1;
}
return 0;
}
static void _free_children(hblock_t * p)
{
hlist_item_t * i, * tmp;
#ifndef NDEBUG
/*
* this catches loops in hierarchy with almost zero
* overhead (compared to _relate() running time)
*/
assert(p && p->magic == HH_MAGIC);
p->magic = 0;
#endif
hlist_for_each_safe(i, tmp, &p->children)
{
hblock_t * q = structof(i, hblock_t, siblings);
_free_children(q);
allocator(q, 0);
}
}
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