/*
 * Copyright (c) 1999, 2000, 2003, 2005, 2008, 2012 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */

#include "internal.h"

#if TARGET_OS_IPHONE
// malloc_report(ASL_LEVEL_INFO...) on iOS doesn't show up in the Xcode Console log of the device,
// but ASL_LEVEL_NOTICE does.  So raising the log level is helpful.
#undef ASL_LEVEL_INFO
#define ASL_LEVEL_INFO ASL_LEVEL_NOTICE
#endif // TARGET_OS_IPHONE

#define USE_SLEEP_RATHER_THAN_ABORT 0

static _malloc_lock_s _malloc_lock = _MALLOC_LOCK_INIT;
#define MALLOC_LOCK() _malloc_lock_lock(&_malloc_lock)
#define MALLOC_TRY_LOCK() _malloc_lock_trylock(&_malloc_lock)
#define MALLOC_UNLOCK() _malloc_lock_unlock(&_malloc_lock)
#define MALLOC_REINIT_LOCK() _malloc_lock_init(&_malloc_lock)

/* The following variables are exported for the benefit of performance tools
 *
 * It should always be safe to first read malloc_num_zones, then read
 * malloc_zones without taking the lock, if only iteration is required and
 * provided that when malloc_destroy_zone is called all prior operations on that
 * zone are complete and no further calls referencing that zone can be made.
 */
int32_t malloc_num_zones = 0;
int32_t malloc_num_zones_allocated = 0;
malloc_zone_t **malloc_zones = (malloc_zone_t **)0xdeaddeaddeaddead;
malloc_logger_t *malloc_logger = NULL;

static uint32_t initial_num_zones;
static malloc_zone_t *initial_scalable_zone;
static malloc_zone_t *initial_nano_zone;
static malloc_zone_t *initial_default_zone = NULL;

unsigned malloc_debug_flags = 0;
bool malloc_tracing_enabled = false;
bool malloc_space_efficient_enabled = false;
bool malloc_medium_space_efficient_enabled = false;

unsigned malloc_check_start = 0; // 0 means don't check
unsigned malloc_check_counter = 0;
unsigned malloc_check_each = 1000;

static int malloc_check_sleep = 100; // default 100 second sleep
static int malloc_check_abort = 0;   // default is to sleep, not abort

static
struct msl {
	void *dylib;

	void (*handle_memory_event) (unsigned long event);
	boolean_t (*stack_logging_locked) (void);
	void (*fork_prepare) (void);
	void (*fork_parent) (void);
	void (*fork_child) (void);
	
	
	// TODO delete these ones
	kern_return_t (*get_frames_for_address)(task_t task,
											mach_vm_address_t address,
											mach_vm_address_t *stack_frames_buffer,
											uint32_t max_stack_frames,
											uint32_t *count);
	
	uint64_t (*stackid_for_vm_region) (task_t task, mach_vm_address_t address);
	
	kern_return_t (*get_frames_for_stackid) (task_t task,
											 uint64_t stack_identifier,
											 mach_vm_address_t *stack_frames_buffer,
											 uint32_t max_stack_frames,
											 uint32_t *count,
											 bool *last_frame_is_threadid);
	
	
	kern_return_t (*uniquing_table_read_stack) (struct backtrace_uniquing_table *uniquing_table,
												uint64_t stackid,
												mach_vm_address_t *out_frames_buffer,
												uint32_t *out_frames_count,
												uint32_t max_frames);
} msl = {};

/*
 * Counters that coordinate zone destruction (in malloc_zone_unregister) with
 * find_registered_zone (here abbreviated as FRZ).
 */
static int32_t volatile counterAlice = 0, counterBob = 0;
static int32_t volatile * volatile pFRZCounterLive = &counterAlice;
static int32_t volatile * volatile pFRZCounterDrain = &counterBob;

unsigned int _os_cpu_number_override = -1;

static inline malloc_zone_t *inline_malloc_default_zone(void) __attribute__((always_inline));

#define MALLOC_LOG_TYPE_ALLOCATE stack_logging_type_alloc
#define MALLOC_LOG_TYPE_DEALLOCATE stack_logging_type_dealloc
#define MALLOC_LOG_TYPE_HAS_ZONE stack_logging_flag_zone
#define MALLOC_LOG_TYPE_CLEARED stack_logging_flag_cleared

#define DEFAULT_MALLOC_ZONE_STRING "DefaultMallocZone"
#define DEFAULT_PUREGEABLE_ZONE_STRING "DefaultPurgeableMallocZone"
#define MALLOC_HELPER_ZONE_STRING "MallocHelperZone"
#define MALLOC_PGUARD_ZONE_STRING "ProbGuardMallocZone"

MALLOC_NOEXPORT
unsigned int phys_ncpus;

MALLOC_NOEXPORT
unsigned int logical_ncpus;

MALLOC_NOEXPORT
unsigned int hyper_shift;

// Boot argument for max magazine control
static const char max_magazines_boot_arg[] = "malloc_max_magazines";

static const char large_expanded_cache_threshold_boot_arg[] = "malloc_large_expanded_cache_threshold";

#if CONFIG_MEDIUM_ALLOCATOR
static const char medium_enabled_boot_arg[] = "malloc_medium_zone";
static const char max_medium_magazines_boot_arg[] = "malloc_max_medium_magazines";
static const char medium_activation_threshold_boot_arg[] = "malloc_medium_activation_threshold";
static const char medium_space_efficient_boot_arg[] = "malloc_medium_space_efficient";
#endif // CONFIG_MEDIUM_ALLOCATOR

/*********	Utilities	************/
static bool _malloc_entropy_initialized;

#if !TARGET_OS_DRIVERKIT
#include <dlfcn.h>

typedef void * (*dlopen_t) (const char * __path, int __mode);
typedef void * (*dlsym_t) (void * __handle, const char * __symbol);

static dlopen_t _dlopen = NULL;
static dlsym_t _dlsym = NULL;
#else
#define _dlopen(...) NULL
#define _dlsym(...) NULL
#endif // TARGET_OS_DRIVERKIT

void __malloc_init(const char *apple[]);
static void _malloc_initialize(const char *apple[], const char *bootargs);

static int
__entropy_from_kernel(const char *str)
{
	unsigned long long val;
	char tmp[20], *p;
	int idx = 0;

	/* Skip over key to the first value */
	str = strchr(str, '=');
	if (str == NULL) {
		return 0;
	}
	str++;

	while (str && idx < sizeof(malloc_entropy) / sizeof(malloc_entropy[0])) {
		strlcpy(tmp, str, 20);
		p = strchr(tmp, ',');
		if (p) {
			*p = '\0';
		}
		val = strtoull_l(tmp, NULL, 0, NULL);
		malloc_entropy[idx] = (uint64_t)val;
		idx++;
		if ((str = strchr(str, ',')) != NULL) {
			str++;
		}
	}
	return idx;
}

#if TARGET_OS_OSX && defined(__x86_64__)
static uint64_t
__is_translated(void)
{
	return (*(uint64_t*)_COMM_PAGE_CPU_CAPABILITIES64) & kIsTranslated;
}
#endif /* TARGET_OS_OSX */

static void
__malloc_init_from_bootargs(const char *bootargs)
{
	// The maximum number of magazines can be set either via a
	// boot argument or from the environment. Get the boot argument value
	// here and store it. We can't bounds check it until we have phys_ncpus,
	// which happens later in _malloc_initialize(), along with handling
	// of the environment value setting.
	char value_buf[256];
	const char *flag = malloc_common_value_for_key_copy(bootargs,
			max_magazines_boot_arg, value_buf, sizeof(value_buf));
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && value >= 0) {
			max_magazines = (unsigned int)value;
		} else {
			malloc_report(ASL_LEVEL_ERR,
						   "malloc_max_magazines must be positive - ignored.\n");
		}
	}

	flag = malloc_common_value_for_key_copy(bootargs,
			large_expanded_cache_threshold_boot_arg, value_buf, sizeof(value_buf));
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && value >= 0) {
			magazine_large_expanded_cache_threshold = (unsigned int)value;
		} else {
			malloc_report(ASL_LEVEL_ERR,
					"malloc_large_expanded_cache_threshold must be positive - ignored.\n");
		}
	}

#if CONFIG_MEDIUM_ALLOCATOR
#if TARGET_OS_OSX
#if defined(__x86_64__)
	if (__is_translated()) {
		magazine_medium_active_threshold = 0;
	}
#elif defined(__arm64__)
	magazine_medium_active_threshold = 0;
#endif
#endif /* TARGET_OS_OSX */

	flag = malloc_common_value_for_key_copy(bootargs, medium_enabled_boot_arg,
			value_buf, sizeof(value_buf));
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp) {
			magazine_medium_enabled = (value != 0);
		}
	}

	flag = malloc_common_value_for_key_copy(bootargs,
			medium_activation_threshold_boot_arg, value_buf, sizeof(value_buf));
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && value >= 0) {
			magazine_medium_active_threshold = (uint64_t)value;
		} else {
			malloc_report(ASL_LEVEL_ERR,
					"malloc_medium_activation_threshold must be positive - ignored.\n");
		}
	}

	flag = malloc_common_value_for_key_copy(bootargs,
			max_medium_magazines_boot_arg, value_buf, sizeof(value_buf));
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && value >= 0) {
			max_medium_magazines = (int)value;
		} else {
			malloc_report(ASL_LEVEL_ERR,
					"malloc_max_medium_magazines must be positive - ignored.\n");
		}
	}

	flag = malloc_common_value_for_key_copy(bootargs,
			medium_space_efficient_boot_arg, value_buf, sizeof(value_buf));
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp) {
			malloc_medium_space_efficient_enabled = (value != 0);
		}
	}
#endif // CONFIG_MEDIUM_ALLOCATOR
}

extern malloc_zone_t *force_asan_init_if_present(void)
		asm("_malloc_default_zone");

void
__malloc_init(const char *apple[])
{
	// We could try to be clever and cater for arbitrary length bootarg
	// strings, but it's probably not worth it, especially as we would need
	// to temporarily allocate at least a page of memory to read the bootargs
	// into.
	char bootargs[1024] = { '\0' };
	bool allow_bootargs = true;
#if CONFIG_FEATUREFLAGS_SIMPLE
	allow_bootargs &= os_feature_enabled_simple(libmalloc, EnableBootArgs, false);
#endif
#if defined(_COMM_PAGE_DEV_FIRM)
	allow_bootargs &= !!*((uint32_t *)_COMM_PAGE_DEV_FIRM);
#endif // _COMM_PAGE_DEV_FIRM

	size_t len = sizeof(bootargs) - 1;
	if (allow_bootargs &&
			!sysctlbyname("kern.bootargs", bootargs, &len, NULL, 0) &&
			len > 0) {
		bootargs[len + 1] = '\0';
	}

	const char **p;
	for (p = apple; p && *p; p++) {
		if (strstr(*p, "malloc_entropy") == *p) {
			int count = __entropy_from_kernel(*p);
			bzero((void *)*p, strlen(*p));

			if (sizeof(malloc_entropy) / sizeof(malloc_entropy[0]) == count) {
				_malloc_entropy_initialized = true;
			}
			break;
		}
	}
	if (!_malloc_entropy_initialized) {
		getentropy((void*)malloc_entropy, sizeof(malloc_entropy));
		_malloc_entropy_initialized = true;
	}

	__malloc_init_from_bootargs(bootargs);
	mvm_aslr_init();

	/*
	 * This really is a renamed call to malloc_default_zone() which is
	 * interposable and interposed by asan, so that we trigger the lazy
	 * initialization of asan _BEFORE_ _malloc_initialize().
	 *
	 * If we do it after, then _malloc_initialize() then ASAN will replace
	 * the system allocator too late and bad things happen.
	 */
	force_asan_init_if_present();

	_malloc_initialize(apple, bootargs);
}

static void register_pgm_zone(bool internal_diagnostics);
static void stack_logging_early_finished(const struct _malloc_late_init *funcs);

// WARNING: The passed _malloc_late_init is a stack variable in
// libSystem_initializer().  We must not hold on to it.
void
__malloc_late_init(const struct _malloc_late_init *mli)
{
	register_pgm_zone(mli->internal_diagnostics);
	stack_logging_early_finished(mli);
	initial_num_zones = malloc_num_zones;
}

MALLOC_NOEXPORT malloc_zone_t* lite_zone = NULL;

MALLOC_ALWAYS_INLINE
static inline malloc_zone_t *
runtime_default_zone() {
	return (lite_zone) ? lite_zone : inline_malloc_default_zone();
}

static size_t
default_zone_size(malloc_zone_t *zone, const void *ptr)
{
	zone = runtime_default_zone();
	
	return zone->size(zone, ptr);
}

static void *
default_zone_malloc(malloc_zone_t *zone, size_t size)
{
	zone = runtime_default_zone();
	
	return zone->malloc(zone, size);
}

static void *
default_zone_calloc(malloc_zone_t *zone, size_t num_items, size_t size)
{
	zone = runtime_default_zone();
	
	return zone->calloc(zone, num_items, size);
}

static void *
default_zone_valloc(malloc_zone_t *zone, size_t size)
{
	zone = runtime_default_zone();
	
	return zone->valloc(zone, size);
}

static void
default_zone_free(malloc_zone_t *zone, void *ptr)
{
	zone = runtime_default_zone();
	
	return zone->free(zone, ptr);
}

static void *
default_zone_realloc(malloc_zone_t *zone, void *ptr, size_t new_size)
{
	zone = runtime_default_zone();
	
	return zone->realloc(zone, ptr, new_size);
}

static void
default_zone_destroy(malloc_zone_t *zone)
{
	zone = runtime_default_zone();
	
	return zone->destroy(zone);
}

static unsigned
default_zone_batch_malloc(malloc_zone_t *zone, size_t size, void **results, unsigned count)
{
	zone = runtime_default_zone();
	
	return zone->batch_malloc(zone, size, results, count);
}

static void
default_zone_batch_free(malloc_zone_t *zone, void **to_be_freed, unsigned count)
{
	zone = runtime_default_zone();
	
	return zone->batch_free(zone, to_be_freed, count);
}

static void *
default_zone_memalign(malloc_zone_t *zone, size_t alignment, size_t size)
{
	zone = runtime_default_zone();
	
	return zone->memalign(zone, alignment, size);
}

static void
default_zone_free_definite_size(malloc_zone_t *zone, void *ptr, size_t size)
{
	zone = runtime_default_zone();
	
	return zone->free_definite_size(zone, ptr, size);
}

static size_t
default_zone_pressure_relief(malloc_zone_t *zone, size_t goal)
{
	zone = runtime_default_zone();

	return zone->pressure_relief(zone, goal);
}

static boolean_t
default_zone_malloc_claimed_address(malloc_zone_t *zone, void *ptr)
{
	zone = runtime_default_zone();

	return malloc_zone_claimed_address(zone, ptr);
}

static kern_return_t
default_zone_ptr_in_use_enumerator(task_t task,
								   void *context,
								   unsigned type_mask,
								   vm_address_t zone_address,
								   memory_reader_t reader,
								   vm_range_recorder_t recorder)
{
	malloc_zone_t *zone = runtime_default_zone();
	
	return zone->introspect->enumerator(task, context, type_mask, (vm_address_t) zone, reader, recorder);
}

static size_t
default_zone_good_size(malloc_zone_t *zone, size_t size)
{
	zone = runtime_default_zone();
	
	return zone->introspect->good_size(zone, size);
}

static boolean_t
default_zone_check(malloc_zone_t *zone)
{
	zone = runtime_default_zone();
	
	return zone->introspect->check(zone);
}

static void
default_zone_print(malloc_zone_t *zone, boolean_t verbose)
{
	zone = runtime_default_zone();

	return (void)zone->introspect->print(zone, verbose);
}

static void
default_zone_log(malloc_zone_t *zone, void *log_address)
{
	zone = runtime_default_zone();
	
	return zone->introspect->log(zone, log_address);
}

static void
default_zone_force_lock(malloc_zone_t *zone)
{
	zone = runtime_default_zone();
	
	return zone->introspect->force_lock(zone);
}

static void
default_zone_force_unlock(malloc_zone_t *zone)
{
	zone = runtime_default_zone();
	
	return zone->introspect->force_unlock(zone);
}

static void
default_zone_statistics(malloc_zone_t *zone, malloc_statistics_t *stats)
{
	zone = runtime_default_zone();
	
	return zone->introspect->statistics(zone, stats);
}

static boolean_t
default_zone_locked(malloc_zone_t *zone)
{
	zone = runtime_default_zone();
	
	return zone->introspect->zone_locked(zone);
}

static void
default_zone_reinit_lock(malloc_zone_t *zone)
{
	zone = runtime_default_zone();
	
	return zone->introspect->reinit_lock(zone);
}

static struct malloc_introspection_t default_zone_introspect = {
	default_zone_ptr_in_use_enumerator,
	default_zone_good_size,
	default_zone_check,
	default_zone_print,
	default_zone_log,
	default_zone_force_lock,
	default_zone_force_unlock,
	default_zone_statistics,
	default_zone_locked,
	NULL,
	NULL,
	NULL,
	NULL,
	default_zone_reinit_lock
};

typedef struct {
	malloc_zone_t malloc_zone;
	uint8_t pad[PAGE_MAX_SIZE - sizeof(malloc_zone_t)];
} virtual_default_zone_t;

static virtual_default_zone_t virtual_default_zone
__attribute__((section("__DATA,__v_zone")))
__attribute__((aligned(PAGE_MAX_SIZE))) = {
	NULL,
	NULL,
	default_zone_size,
	default_zone_malloc,
	default_zone_calloc,
	default_zone_valloc,
	default_zone_free,
	default_zone_realloc,
	default_zone_destroy,
	DEFAULT_MALLOC_ZONE_STRING,
	default_zone_batch_malloc,
	default_zone_batch_free,
	&default_zone_introspect,
	10,
	default_zone_memalign,
	default_zone_free_definite_size,
	default_zone_pressure_relief,
	default_zone_malloc_claimed_address,
};

static malloc_zone_t *default_zone = &virtual_default_zone.malloc_zone;

MALLOC_NOEXPORT
/*static*/ boolean_t
has_default_zone0(void)
{
	if (!malloc_zones) {
		return false;
	}
	
	return initial_default_zone == malloc_zones[0];
}

static inline malloc_zone_t *find_registered_zone(const void *, size_t *) __attribute__((always_inline));
static inline malloc_zone_t *
find_registered_zone(const void *ptr, size_t *returned_size)
{
	// Returns a zone which contains ptr, else NULL

	if (0 == malloc_num_zones) {
		if (returned_size) {
			*returned_size = 0;
		}
		return NULL;
	}

	// first look in the lite zone
	if (lite_zone) {
		malloc_zone_t *zone = lite_zone;
		size_t size = zone->size(zone, ptr);
		if (size) { // Claimed by this zone?
			if (returned_size) {
				*returned_size = size;
			}
			// Return the virtual default zone instead of the lite zone - see <rdar://problem/24994311>
			return default_zone;
		}
	}

	malloc_zone_t *zone;
	size_t size;

	// We assume that the initial zones will never be unregistered concurrently while this code is running so we can have
	// a fast path without locking.  Callers who really do unregister these (to install their own default zone) need to
	// ensure they establish their zone setup during initialization and before entering a multi-threaded environment.
	for (uint32_t i = 0; i < initial_num_zones; i++) {
		zone = malloc_zones[i];
		size = zone->size(zone, ptr);

		if (size) { // Claimed by this zone?
			if (returned_size) {
				*returned_size = size;
			}

			// Asan and others replace the zone at position 0 with their own zone.
			// In that case just return that zone as they need this information.
			// Otherwise return the virtual default zone, not the actual zone in position 0.
			if (i == 0 && has_default_zone0()) {
				return default_zone;
			}

			return zone;
		}
	}

	int32_t volatile *pFRZCounter = pFRZCounterLive;   // Capture pointer to the counter of the moment
	OSAtomicIncrement32Barrier(pFRZCounter); // Advance this counter -- our thread is in FRZ

	int32_t limit = *(int32_t volatile *)&malloc_num_zones;

	// From this point on, FRZ is accessing the malloc_zones[] array without locking
	// in order to avoid contention on common operations (such as non-default-zone free()).
	// In order to ensure that this is actually safe to do, register/unregister take care
	// to:
	//
	//   1. Register ensures that newly inserted pointers in malloc_zones[] are visible
	//      when malloc_num_zones is incremented. At the moment, we're relying on that store
	//      ordering to work without taking additional steps here to ensure load memory
	//      ordering.
	//
	//   2. Unregister waits for all readers in FRZ to complete their iteration before it
	//      returns from the unregister call (during which, even unregistered zone pointers
	//      are still valid). It also ensures that all the pointers in the zones array are
	//      valid until it returns, so that a stale value in limit is not dangerous.

	for (uint32_t i = initial_num_zones; i < limit; i++) {
		zone = malloc_zones[i];
		size = zone->size(zone, ptr);
		if (size) { // Claimed by this zone?
			goto out;
		}
	}
	// Unclaimed by any zone.
	zone = NULL;
	size = 0;
out:
	if (returned_size) {
		*returned_size = size;
	}
	OSAtomicDecrement32Barrier(pFRZCounter); // our thread is leaving FRZ
	return zone;
}

void
malloc_error_break(void)
{
	// Provides a non-inlined place for various malloc error procedures to call
	// that will be called after an error message appears.  It does not make
	// sense for developers to call this function, so it is marked
	// hidden to prevent it from becoming API.
	MAGMALLOC_MALLOCERRORBREAK(); // DTrace USDT probe
}

int
malloc_gdb_po_unsafe(void)
{
	// In order to implement "po" other data formatters in gdb, the debugger
	// calls functions that call malloc.  The debugger will  only run one thread
	// of the program in this case, so if another thread is holding a zone lock,
	// gdb may deadlock in this case.
	//
	// Iterate over the zones in malloc_zones, and call "trylock" on the zone
	// lock.  If trylock succeeds, unlock it, otherwise return "locked".  Returns
	// 0 == safe, 1 == locked/unsafe.

	if (msl.stack_logging_locked && msl.stack_logging_locked()) {
		return 1;
	}

	malloc_zone_t **zones = malloc_zones;
	unsigned i, e = malloc_num_zones;

	for (i = 0; i != e; ++i) {
		malloc_zone_t *zone = zones[i];

		// Version must be >= 5 to look at the new introspection field.
		if (zone->version < 5) {
			continue;
		}

		if (zone->introspect->zone_locked && zone->introspect->zone_locked(zone)) {
			return 1;
		}
	}
	return 0;
}

/*********	Creation and destruction	************/

static void set_flags_from_environment(void);

MALLOC_NOEXPORT void
malloc_zone_register_while_locked(malloc_zone_t *zone)
{
	size_t protect_size;
	unsigned i;

	/* scan the list of zones, to see if this zone is already registered.  If
	 * so, print an error message and return. */
	for (i = 0; i != malloc_num_zones; ++i) {
		if (zone == malloc_zones[i]) {
			malloc_report(ASL_LEVEL_ERR, "Attempted to register zone more than once: %p\n", zone);
			return;
		}
	}

	if (malloc_num_zones == malloc_num_zones_allocated) {
		size_t malloc_zones_size = malloc_num_zones * sizeof(malloc_zone_t *);
		mach_vm_size_t alloc_size = round_page(malloc_zones_size + vm_page_size);
		mach_vm_address_t vm_addr;
		int alloc_flags = VM_FLAGS_ANYWHERE | VM_MAKE_TAG(VM_MEMORY_MALLOC);

		vm_addr = vm_page_size;
		kern_return_t kr = mach_vm_allocate(mach_task_self(), &vm_addr, alloc_size, alloc_flags);
		if (kr) {
			malloc_report(ASL_LEVEL_ERR, "malloc_zone_register allocation failed: %d\n", kr);
			return;
		}

		malloc_zone_t **new_zones = (malloc_zone_t **)vm_addr;
		/* If there were previously allocated malloc zones, we need to copy them
		 * out of the previous array and into the new zones array */
		if (malloc_zones) {
			memcpy(new_zones, malloc_zones, malloc_zones_size);
			vm_addr = (mach_vm_address_t)malloc_zones;
			mach_vm_size_t dealloc_size = round_page(malloc_zones_size);
			mach_vm_deallocate(mach_task_self(), vm_addr, dealloc_size);
		}

		/* Update the malloc_zones pointer, which we leak if it was previously
		 * allocated, and the number of zones allocated */
		protect_size = (size_t)alloc_size;
		malloc_zones = new_zones;
		malloc_num_zones_allocated = (int32_t)(alloc_size / sizeof(malloc_zone_t *));
	} else {
		/* If we don't need to reallocate zones, we need to briefly change the
		 * page protection the malloc zones to allow writes */
		protect_size = malloc_num_zones_allocated * sizeof(malloc_zone_t *);
		mprotect(malloc_zones, protect_size, PROT_READ | PROT_WRITE);
	}

	/* <rdar://problem/12871662> This store-increment needs to be visible in the correct
	 * order to any threads in find_registered_zone, such that if the incremented value
	 * in malloc_num_zones is visible then the pointer write before it must also be visible.
	 *
	 * While we could be slightly more efficent here with atomic ops the cleanest way to
	 * ensure the proper store-release operation is performed is to use OSAtomic*Barrier
	 * to update malloc_num_zones.
	 */
	malloc_zones[malloc_num_zones] = zone;
	OSAtomicIncrement32Barrier(&malloc_num_zones);

	/* Finally, now that the zone is registered, disallow write access to the
	 * malloc_zones array */
	mprotect(malloc_zones, protect_size, PROT_READ);
	//malloc_report(ASL_LEVEL_INFO, "Registered malloc_zone %p in malloc_zones %p [%u zones, %u bytes]\n", zone, malloc_zones,
	// malloc_num_zones, protect_size);
}

// This used to be called lazyily because it is using
// dyld_process_is_restricted() before dyld_init() has run.
//
// However this function is safe to use, we keep this function separate
// if we ever need to have a 2-stage init in the future.
static void
_malloc_initialize(const char *apple[], const char *bootargs)
{
	phys_ncpus = *(uint8_t *)(uintptr_t)_COMM_PAGE_PHYSICAL_CPUS;
	logical_ncpus = *(uint8_t *)(uintptr_t)_COMM_PAGE_LOGICAL_CPUS;

	if (0 != (logical_ncpus % phys_ncpus)) {
		MALLOC_REPORT_FATAL_ERROR(logical_ncpus % phys_ncpus,
				"logical_ncpus %% phys_ncpus != 0\n");
	}

	switch (logical_ncpus / phys_ncpus) {
	case 1:
		hyper_shift = 0;
		break;
	case 2:
		hyper_shift = 1;
		break;
	case 4:
		hyper_shift = 2;
		break;
	default:
		MALLOC_REPORT_FATAL_ERROR(logical_ncpus / phys_ncpus, "logical_ncpus / phys_ncpus not 1, 2, or 4");
	}

	// max_magazines may already be set from a boot argument. Make sure that it
	// is bounded by the number of CPUs.
	if (max_magazines) {
		max_magazines = MIN(max_magazines, logical_ncpus);
	} else {
		max_magazines = logical_ncpus;
	}

	// similiarly, cap medium magazines at logical_ncpus but don't cap it by
	// the max magazines if it has been set explicitly
	if (max_medium_magazines) {
		max_medium_magazines = MIN(max_medium_magazines, logical_ncpus);
	} else {
		max_medium_magazines = max_magazines;
	}

	set_flags_from_environment(); // will only set flags up to two times

#if CONFIG_NANOZONE
	// TODO: envp should be passed down from Libsystem
	const char **envp = (const char **)*_NSGetEnviron();
	nano_common_init(envp, apple, bootargs);
#endif

	const uint32_t k_max_zones = 2;
	malloc_zone_t *zone_stack[k_max_zones];
	const char *name_stack[k_max_zones];
	uint32_t num_zones = 0;

	initial_scalable_zone = create_scalable_zone(0, malloc_debug_flags);
	zone_stack[num_zones] = initial_scalable_zone;
	name_stack[num_zones] = DEFAULT_MALLOC_ZONE_STRING;
	num_zones++;

#if CONFIG_NANOZONE
	nano_common_configure();

	malloc_zone_t *helper_zone = zone_stack[num_zones - 1];
	malloc_zone_t *nano_zone = NULL;

	if (_malloc_engaged_nano == NANO_V2) {
		nano_zone = nanov2_create_zone(helper_zone, malloc_debug_flags);
	} else if (_malloc_engaged_nano == NANO_V1) {
		nano_zone = nano_create_zone(helper_zone, malloc_debug_flags);
	}

	if (nano_zone) {
		initial_nano_zone = nano_zone;
		zone_stack[num_zones] = nano_zone;
		name_stack[num_zones] = DEFAULT_MALLOC_ZONE_STRING;
		name_stack[num_zones - 1] = MALLOC_HELPER_ZONE_STRING;
		num_zones++;
	}
#endif

	MALLOC_ASSERT(num_zones <= k_max_zones);
	initial_default_zone = zone_stack[num_zones - 1];

	// 2 separate loops: malloc_set_zone_name already requires a working allocator.
	for (int i = num_zones - 1; i >= 0; i--) malloc_zone_register_while_locked(zone_stack[i]);
	for (int i = num_zones - 1; i >= 0; i--) malloc_set_zone_name(zone_stack[i], name_stack[i]);

	initial_num_zones = malloc_num_zones;

	// malloc_report(ASL_LEVEL_INFO, "%d registered zones\n", malloc_num_zones);
	// malloc_report(ASL_LEVEL_INFO, "malloc_zones is at %p; malloc_num_zones is at %p\n", (unsigned)&malloc_zones,
	// (unsigned)&malloc_num_zones);
}

static void make_last_zone_default_zone(void);
static void
register_pgm_zone(bool internal_diagnostics)
{
	if (pguard_enabled(internal_diagnostics)) {
		malloc_zone_t *wrapped_zone = malloc_zones[0];
		malloc_zone_t *pgm_zone = pguard_create_zone(wrapped_zone);
		malloc_zone_register_while_locked(pgm_zone);
		make_last_zone_default_zone();
		initial_default_zone = pgm_zone;
		malloc_set_zone_name(pgm_zone, MALLOC_PGUARD_ZONE_STRING);
	}
}

static inline malloc_zone_t *
inline_malloc_default_zone(void)
{
	// malloc_report(ASL_LEVEL_INFO, "In inline_malloc_default_zone with %d %d\n", malloc_num_zones, malloc_has_debug_zone);
	return malloc_zones[0];
}

malloc_zone_t *
malloc_default_zone(void)
{
	return default_zone;
}

static void *
legacy_zeroing_large_malloc(malloc_zone_t *zone, size_t size)
{
	if (size > LEGACY_ZEROING_THRESHOLD) {
		// Leopard and earlier returned a ZFOD range, so clear to zero always,
		// ham-handedly touching in each page
		return default_zone_calloc(zone, 1, size);
	} else {
		return default_zone_malloc(zone, size);
	}
}

static void *
legacy_zeroing_large_valloc(malloc_zone_t *zone, size_t size)
{
	void *p = default_zone_valloc(zone, size);

	// Leopard and earlier returned a ZFOD range, so ...
	memset(p, 0, size); // Clear to zero always, ham-handedly touching in each page
	return p;
}

void
zeroify_scalable_zone(malloc_zone_t *zone)
{
	// <rdar://problem/27190324> this checkfix should replace the default zone's
	// allocation routines with the zeroing versions. Instead of getting in hot 
	// water with the wrong zone, ensure that we're mutating the zone we expect.
	// 
	// Additionally, the default_zone is no longer PROT_READ, so the two mprotect
	// calls that were here are no longer needed.
	if (zone == default_zone) {
		zone->malloc = (void *)legacy_zeroing_large_malloc;
		zone->valloc = (void *)legacy_zeroing_large_valloc;
	}
}

/*
 * Returns the version of the Nano allocator that's in use, or 0 if not.
 */
int
malloc_engaged_nano(void)
{
#if CONFIG_NANOZONE
	return _malloc_engaged_nano;
#else
	return 0;
#endif
}

malloc_zone_t *
malloc_default_purgeable_zone(void)
{
	static malloc_zone_t *dpz;

	if (!dpz) {
		//
		// PR_7288598: Must pass a *scalable* zone (szone) as the helper for create_purgeable_zone().
		// Take care that the zone so obtained is not subject to interposing.
		//
		malloc_zone_t *tmp = create_purgeable_zone(0, initial_scalable_zone, malloc_debug_flags);
		malloc_zone_register(tmp);
		malloc_set_zone_name(tmp, DEFAULT_PUREGEABLE_ZONE_STRING);
		if (!OSAtomicCompareAndSwapPtrBarrier(NULL, tmp, (void**)&dpz)) {
			malloc_destroy_zone(tmp);
		}
	}
	return dpz;
}

static void
set_flags_from_environment(void)
{
	const char *flag;
	const char **env = (const char **)*_NSGetEnviron();
	const char **p;
	const char *c;

#if __LP64__
	malloc_debug_flags = MALLOC_ABORT_ON_CORRUPTION; // Set always on 64-bit processes
#else
	int libSystemVersion = NSVersionOfLinkTimeLibrary("System");
	if ((-1 != libSystemVersion) && ((libSystemVersion >> 16) < 126) /* Lion or greater */) {
		malloc_debug_flags = 0;
	} else {
		malloc_debug_flags = MALLOC_ABORT_ON_CORRUPTION;
	}
#endif

	/*
	 * Given that all environment variables start with "Malloc" we optimize by scanning quickly
	 * first the environment, therefore avoiding repeated calls to getenv().
	 * If we are setu/gid these flags are ignored to prevent a malicious invoker from changing
	 * our behaviour.
	 */
	for (p = env; (c = *p) != NULL; ++p) {
#if RDAR_48993662
		if (!strncmp(c, "Malloc", 6) || !strncmp(c, "_Malloc", 6)) {
#else // RDAR_48993662
		if (!strncmp(c, "Malloc", 6)) {
#endif // RDAR_48993662
			if (issetugid()) {
				return;
			}
			break;
		}
	}

	/*
	 * Deny certain flags for entitled processes rdar://problem/13521742
	 * MallocLogFile & MallocCorruptionAbort
	 * as these provide the ability to turn *off* aborting in error cases.
	 */
	bool restricted = dyld_process_is_restricted();
	malloc_print_configure(restricted);

	if (c == NULL) {
		return;
	}

	flag = getenv("MallocGuardEdges");
	if (flag) {
		if (!strcmp(flag, "all")) {
			// "MallocGuardEdges=all" adds guard page(s) for every region.
			// Do not do this on 32-bit platforms because there is insufficient
			// address space. These pages are always protected.
#if MALLOC_TARGET_64BIT
			malloc_debug_flags |= MALLOC_GUARD_ALL | MALLOC_ADD_GUARD_PAGE_FLAGS;
			malloc_debug_flags &= ~(MALLOC_DONT_PROTECT_PRELUDE|MALLOC_DONT_PROTECT_POSTLUDE);
			malloc_report(ASL_LEVEL_INFO, "adding guard pages to all regions\n");
#endif // MALLOC_TARGET_64BIT
		} else {
			malloc_debug_flags |= MALLOC_ADD_GUARD_PAGE_FLAGS;
			malloc_debug_flags &= ~MALLOC_GUARD_ALL;
			malloc_report(ASL_LEVEL_INFO, "adding guard pages for large allocator blocks\n");
			if (getenv("MallocDoNotProtectPrelude")) {
				malloc_debug_flags |= MALLOC_DONT_PROTECT_PRELUDE;
				malloc_report(ASL_LEVEL_INFO, "... but not protecting prelude guard page\n");
			}
			if (getenv("MallocDoNotProtectPostlude")) {
				malloc_debug_flags |= MALLOC_DONT_PROTECT_POSTLUDE;
				malloc_report(ASL_LEVEL_INFO, "... but not protecting postlude guard page\n");
			}
		}
	}

	if (getenv("MallocScribble")) {
		malloc_debug_flags |= MALLOC_DO_SCRIBBLE;
		malloc_report(ASL_LEVEL_INFO, "enabling scribbling to detect mods to free blocks\n");
	}
	if (getenv("MallocErrorAbort")) {
		malloc_debug_flags |= MALLOC_ABORT_ON_ERROR;
		malloc_report(ASL_LEVEL_INFO, "enabling abort() on bad malloc or free\n");
	}
	if (getenv("MallocTracing")) {
		malloc_tracing_enabled = true;
	}

#if __LP64__
/* initialization above forces MALLOC_ABORT_ON_CORRUPTION of 64-bit processes */
#else
	flag = getenv("MallocCorruptionAbort");
	if (!restricted && flag && (flag[0] == '0')) { // Set from an environment variable in 32-bit processes
		malloc_debug_flags &= ~MALLOC_ABORT_ON_CORRUPTION;
	} else if (flag) {
		malloc_debug_flags |= MALLOC_ABORT_ON_CORRUPTION;
	}
#endif
	flag = getenv("MallocCheckHeapStart");
	if (flag) {
		malloc_check_start = (unsigned)strtoul(flag, NULL, 0);
		if (malloc_check_start == 0) {
			malloc_check_start = 1;
		}
		if (malloc_check_start == -1) {
			malloc_check_start = 1;
		}
		flag = getenv("MallocCheckHeapEach");
		if (flag) {
			malloc_check_each = (unsigned)strtoul(flag, NULL, 0);
			if (malloc_check_each == 0) {
				malloc_check_each = 1;
			}
			if (malloc_check_each == -1) {
				malloc_check_each = 1;
			}
		}
		malloc_report(ASL_LEVEL_INFO, "checks heap after operation #%d and each %d operations\n", malloc_check_start, malloc_check_each);
		flag = getenv("MallocCheckHeapAbort");
		if (flag) {
			malloc_check_abort = (unsigned)strtol(flag, NULL, 0);
		}
		if (malloc_check_abort) {
			malloc_report(ASL_LEVEL_INFO, "will abort on heap corruption\n");
		} else {
			flag = getenv("MallocCheckHeapSleep");
			if (flag) {
				malloc_check_sleep = (unsigned)strtol(flag, NULL, 0);
			}
			if (malloc_check_sleep > 0) {
				malloc_report(ASL_LEVEL_INFO, "will sleep for %d seconds on heap corruption\n", malloc_check_sleep);
			} else if (malloc_check_sleep < 0) {
				malloc_report(ASL_LEVEL_INFO, "will sleep once for %d seconds on heap corruption\n", -malloc_check_sleep);
			} else {
				malloc_report(ASL_LEVEL_INFO, "no sleep on heap corruption\n");
			}
		}
	}

	flag = getenv("MallocMaxMagazines");
#if RDAR_48993662
	if (!flag) {
		flag = getenv("_MallocMaxMagazines");
	}
#endif // RDAR_48993662
	if (flag) {
		int value = (unsigned)strtol(flag, NULL, 0);
		if (value == 0) {
			malloc_report(ASL_LEVEL_INFO, "Maximum magazines defaulted to %d\n", max_magazines);
		} else if (value < 0) {
			malloc_report(ASL_LEVEL_ERR, "Maximum magazines must be positive - ignored.\n");
		} else if (value > logical_ncpus) {
			max_magazines = logical_ncpus;
			malloc_report(ASL_LEVEL_INFO, "Maximum magazines limited to number of logical CPUs (%d)\n", max_magazines);
		} else {
			max_magazines = value;
			malloc_report(ASL_LEVEL_INFO, "Maximum magazines set to %d\n", max_magazines);
		}
	}

	flag = getenv("MallocLargeExpandedCacheThreshold");
	if (flag) {
		uint64_t value = (uint64_t)strtoull(flag, NULL, 0);
		if (value == 0) {
			malloc_report(ASL_LEVEL_INFO, "Large expanded cache threshold defaulted to %lly\n", magazine_large_expanded_cache_threshold);
		} else if (value < 0) {
			malloc_report(ASL_LEVEL_ERR, "MallocLargeExpandedCacheThreshold must be positive - ignored.\n");
		} else {
			magazine_large_expanded_cache_threshold = value;
			malloc_report(ASL_LEVEL_INFO, "Large expanded cache threshold set to %lly\n", magazine_large_expanded_cache_threshold);
		}
	}

	flag = getenv("MallocLargeDisableASLR");
	if (flag) {
		uint64_t value = (uint64_t)strtoull(flag, NULL, 0);
		if (value == 0) {
			malloc_report(ASL_LEVEL_INFO, "Enabling ASLR slide on large allocations\n");
			malloc_debug_flags &= ~DISABLE_LARGE_ASLR;
		} else if (value != 0) {
			malloc_report(ASL_LEVEL_INFO, "Disabling ASLR slide on large allocations\n");
			malloc_debug_flags |= DISABLE_LARGE_ASLR;
		}
	}

#if CONFIG_AGGRESSIVE_MADVISE || CONFIG_LARGE_CACHE
	// convenience flag to configure policies usually associated with memory-constrained platforms (iOS)
	// that trade some amount of time efficiency for space efficiency
	flag = getenv("MallocSpaceEfficient");
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && endp != flag && (value == 0 || value == 1)) {
#if CONFIG_AGGRESSIVE_MADVISE
			aggressive_madvise_enabled = (value == 1);
#endif // CONFIG_AGGRESSIVE_MADVISE
#if CONFIG_LARGE_CACHE
			large_cache_enabled = (value == 0);
#endif // CONFIG_LARGE_CACHE
			malloc_space_efficient_enabled = (value == 1);
			// consider disabling medium magazine if aggressive madvise is not sufficient
		} else {
			malloc_report(ASL_LEVEL_ERR, "MallocSpaceEfficient must be 0 or 1.\n");
		}
	}
#endif // CONFIG_AGGRESSIVE_MADVISE || CONFIG_LARGE_CACHE

#if CONFIG_MEDIUM_ALLOCATOR
	flag = getenv("MallocMediumZone");
	if (flag) {
		int value = (unsigned)strtol(flag, NULL, 0);
		if (value == 0) {
			magazine_medium_enabled = false;
		} else if (value == 1) {
			magazine_medium_enabled = true;
		}
	}

	flag = getenv("MallocMediumActivationThreshold");
	if (flag) {
		uint64_t value = (uint64_t)strtoull(flag, NULL, 0);
		if (value == 0) {
			malloc_report(ASL_LEVEL_INFO, "Medium activation threshold defaulted to %lly\n", magazine_medium_active_threshold);
		} else if (value < 0) {
			malloc_report(ASL_LEVEL_ERR, "MallocMediumActivationThreshold must be positive - ignored.\n");
		} else {
			magazine_medium_active_threshold = value;
			malloc_report(ASL_LEVEL_INFO, "Medium activation threshold set to %lly\n", magazine_medium_active_threshold);
		}
	}

	flag = getenv("MallocMediumSpaceEfficient");
	if (flag) {
		uint64_t value = (uint64_t)strtoull(flag, NULL, 0);
		if (value == 0) {
			malloc_medium_space_efficient_enabled = false;
		} else if (value == 1) {
			malloc_medium_space_efficient_enabled = true;
		}
	}

	if (malloc_medium_space_efficient_enabled && malloc_space_efficient_enabled) {
		// Bring down MallocMaxMediumMagazines to only a single magazine in
		// space-efficent processes but do this before the envvar so that it
		// can still be overridden at the command line.
		max_medium_magazines = 1;
	}

	flag = getenv("MallocMaxMediumMagazines");
#if RDAR_48993662
	if (!flag) {
		flag = getenv("_MallocMaxMediumMagazines");
	}
#endif // RDAR_48993662
	if (flag) {
		int value = (unsigned)strtol(flag, NULL, 0);
		if (value == 0) {
			malloc_report(ASL_LEVEL_INFO, "Maximum medium magazines defaulted to %d\n", max_magazines);
		} else if (value < 0) {
			malloc_report(ASL_LEVEL_ERR, "Maximum medium magazines must be positive - ignored.\n");
		} else if (value > logical_ncpus) {
			max_medium_magazines = logical_ncpus;
			malloc_report(ASL_LEVEL_INFO, "Maximum medium magazines limited to number of logical CPUs (%d)\n", max_medium_magazines);
		} else {
			max_medium_magazines = value;
			malloc_report(ASL_LEVEL_INFO, "Maximum medium magazines set to %d\n", max_medium_magazines);
		}
	}
#endif // CONFIG_MEDIUM_ALLOCATOR

#if CONFIG_AGGRESSIVE_MADVISE
	flag = getenv("MallocAggressiveMadvise");
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && endp != flag && (value == 0 || value == 1)) {
			aggressive_madvise_enabled = (value == 1);
		} else {
			malloc_report(ASL_LEVEL_ERR, "MallocAggressiveMadvise must be 0 or 1.\n");
		}
	}
#endif // CONFIG_AGGRESSIVE_MADVISE

#if CONFIG_LARGE_CACHE
	flag = getenv("MallocLargeCache");
	if (flag) {
		const char *endp;
		long value = malloc_common_convert_to_long(flag, &endp);
		if (!*endp && endp != flag && (value == 0 || value == 1)) {
			large_cache_enabled = (value == 1);
		} else {
			malloc_report(ASL_LEVEL_ERR, "MallocLargeCache must be 0 or 1.\n");
		}
	}
#endif // CONFIG_LARGE_CACHE

#if CONFIG_RECIRC_DEPOT
	flag = getenv("MallocRecircRetainedRegions");
	if (flag) {
		int value = (int)strtol(flag, NULL, 0);
		if (value > 0) {
			recirc_retained_regions = value;
		} else {
			malloc_report(ASL_LEVEL_ERR, "MallocRecircRetainedRegions must be positive - ignored.\n");
		}
	}
#endif // CONFIG_RECIRC_DEPOT
	if (getenv("MallocHelp")) {
		malloc_report(ASL_LEVEL_INFO,
				"environment variables that can be set for debug:\n"
				"- MallocLogFile <f> to create/append messages to file <f> instead of stderr\n"
				"- MallocGuardEdges to add 2 guard pages for each large block\n"
				"- MallocDoNotProtectPrelude to disable protection (when previous flag set)\n"
				"- MallocDoNotProtectPostlude to disable protection (when previous flag set)\n"
				"- MallocStackLogging to record all stacks.  Tools like leaks can then be applied\n"
				"- MallocStackLoggingNoCompact to record all stacks.  Needed for malloc_history\n"
				"- MallocStackLoggingDirectory to set location of stack logs, which can grow large; default is /tmp\n"
				"- MallocScribble to detect writing on free blocks and missing initializers:\n"
				"  0x55 is written upon free and 0xaa is written on allocation\n"
				"- MallocCheckHeapStart <n> to start checking the heap after <n> operations\n"
				"- MallocCheckHeapEach <s> to repeat the checking of the heap after <s> operations\n"
				"- MallocCheckHeapSleep <t> to sleep <t> seconds on heap corruption\n"
				"- MallocCheckHeapAbort <b> to abort on heap corruption if <b> is non-zero\n"
				"- MallocCorruptionAbort to abort on malloc errors, but not on out of memory for 32-bit processes\n"
				"  MallocCorruptionAbort is always set on 64-bit processes\n"
				"- MallocErrorAbort to abort on any malloc error, including out of memory\n"\
				"- MallocTracing to emit kdebug trace points on malloc entry points\n"\
				"- MallocHelp - this help!\n");
	}
}

malloc_zone_t *
malloc_create_zone(vm_size_t start_size, unsigned flags)
{
	malloc_zone_t *zone;

	/* start_size doesn't actually appear to be used, but we test anyway. */
	if (start_size > MALLOC_ABSOLUTE_MAX_SIZE) {
		return NULL;
	}

	zone = create_scalable_zone(start_size, flags | malloc_debug_flags);
	malloc_zone_register(zone);
	return zone;
}

static void
make_last_zone_default_zone(void)
{
	unsigned protect_size = malloc_num_zones_allocated * sizeof(malloc_zone_t *);
	mprotect(malloc_zones, protect_size, PROT_READ | PROT_WRITE);

	malloc_zone_t *last_zone = malloc_zones[malloc_num_zones - 1];

	// assert(zone == malloc_zones[malloc_num_zones - 1];
	for (int i = malloc_num_zones - 1; i > 0; --i) {
		malloc_zones[i] = malloc_zones[i - 1];
	}
	malloc_zones[0] = last_zone;

	mprotect(malloc_zones, protect_size, PROT_READ);
}

/*
 * For use by CheckFix: establish a new default zone whose behavior is, apart from
 * the use of death-row and per-CPU magazines, that of Leopard.
 */
void
malloc_create_legacy_default_zone(void)
{
	malloc_zone_t *zone;

	zone = create_legacy_scalable_zone(0, malloc_debug_flags);

	MALLOC_LOCK();
	malloc_zone_register_while_locked(zone);

	//
	// Establish the legacy scalable zone just created as the default zone.
	//
	malloc_zone_t *hold = malloc_zones[0];
	if (hold->zone_name && strcmp(hold->zone_name, DEFAULT_MALLOC_ZONE_STRING) == 0) {
		malloc_set_zone_name(hold, NULL);
	}
	malloc_set_zone_name(zone, DEFAULT_MALLOC_ZONE_STRING);

	make_last_zone_default_zone();
	MALLOC_UNLOCK();
}

void
malloc_destroy_zone(malloc_zone_t *zone)
{
	malloc_set_zone_name(zone, NULL); // Deallocate zone name wherever it may reside PR_7701095
	malloc_zone_unregister(zone);
	zone->destroy(zone);
}

static vm_address_t *frames = NULL;
static unsigned num_frames;

MALLOC_NOINLINE
void
malloc_zone_check_fail(const char *msg, const char *fmt, ...)
{
	_SIMPLE_STRING b = _simple_salloc();
	if (b) {
		_simple_sprintf(b, "*** MallocCheckHeap: FAILED check at operation #%d\n", malloc_check_counter - 1);
	} else {
		malloc_report(MALLOC_REPORT_NOLOG, "*** MallocCheckHeap: FAILED check at operation #%d\n", malloc_check_counter - 1);
	}
	if (frames) {
		unsigned index = 1;
		if (b) {
			_simple_sappend(b, "Stack for last operation where the malloc check succeeded: ");
			while (index < num_frames)
				_simple_sprintf(b, "%p ", (void*)frames[index++]);
			malloc_report(MALLOC_REPORT_NOLOG, "%s\n(Use 'atos' for a symbolic stack)\n", _simple_string(b));
		} else {
			/*
			 * Should only get here if vm_allocate() can't get a single page of
			 * memory, implying _simple_asl_log() would also fail.  So we just
			 * print to the file descriptor.
			 */
			malloc_report(MALLOC_REPORT_NOLOG, "Stack for last operation where the malloc check succeeded: ");
			while (index < num_frames) {
				malloc_report(MALLOC_REPORT_NOLOG, "%p ", (void *)frames[index++]);
			}
			malloc_report(MALLOC_REPORT_NOLOG, "\n(Use 'atos' for a symbolic stack)\n");
		}
	}
	if (malloc_check_each > 1) {
		unsigned recomm_each = (malloc_check_each > 10) ? malloc_check_each / 10 : 1;
		unsigned recomm_start =
				(malloc_check_counter > malloc_check_each + 1) ? malloc_check_counter - 1 - malloc_check_each : 1;
		malloc_report(MALLOC_REPORT_NOLOG,
				"*** Recommend using 'setenv MallocCheckHeapStart %d; setenv MallocCheckHeapEach %d' to narrow down failure\n",
				recomm_start, recomm_each);
	}

	if (b) {
		_simple_sfree(b);
	}

	// Use malloc_vreport() to:
	// 	* report the error
	// 	* call malloc_error_break() for a breakpoint
	// 	* sleep or stop for debug
	// 	* set the crash message and crash if malloc_check_abort is set.
	unsigned sleep_time = 0;
	uint32_t report_flags = ASL_LEVEL_ERR | MALLOC_REPORT_DEBUG | MALLOC_REPORT_NOLOG;
	if (malloc_check_abort) {
		report_flags |= MALLOC_REPORT_CRASH;
	} else {
		if (malloc_check_sleep > 0) {
			malloc_report(ASL_LEVEL_NOTICE, "*** Will sleep for %d seconds to leave time to attach\n", malloc_check_sleep);
			sleep_time = malloc_check_sleep;
		} else if (malloc_check_sleep < 0) {
			malloc_report(ASL_LEVEL_NOTICE, "*** Will sleep once for %d seconds to leave time to attach\n", -malloc_check_sleep);
			sleep_time = -malloc_check_sleep;
			malloc_check_sleep = 0;
		}
	}
	va_list ap;
	va_start(ap, fmt);
	malloc_vreport(report_flags, sleep_time, msg, NULL, fmt, ap);
	va_end(ap);
}

/*********	Block creation and manipulation	************/

__attribute__((cold, noinline))
static void
internal_check(void)
{
	if (malloc_check_counter++ < malloc_check_start) {
		return;
	}
	if (malloc_zone_check(NULL)) {
		if (!frames) {
			vm_allocate(mach_task_self(), (void *)&frames, vm_page_size, 1);
		}
		thread_stack_pcs(frames, (unsigned)(vm_page_size / sizeof(vm_address_t) - 1), &num_frames);
	}
	malloc_check_start += malloc_check_each;
}

__options_decl(malloc_zone_options_t, unsigned, {
	MZ_NONE  = 0x0,
	MZ_POSIX = 0x1,
	MZ_C11   = 0x2,
});

static inline void
malloc_set_errno_fast(malloc_zone_options_t mzo, int err)
{
	if (mzo & MZ_POSIX) {
#if TARGET_OS_SIMULATOR
		errno = err;
#else
		(*_pthread_errno_address_direct()) = err;
#endif
	}
}

MALLOC_NOINLINE
static void *
_malloc_zone_malloc(malloc_zone_t *zone, size_t size, malloc_zone_options_t mzo)
{
	MALLOC_TRACE(TRACE_malloc | DBG_FUNC_START, (uintptr_t)zone, size, 0, 0);

	void *ptr = NULL;

	if (malloc_check_start) {
		internal_check();
	}
	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
		goto out;
	}

	ptr = zone->malloc(zone, size);		// if lite zone is passed in then we still call the lite methods

	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
	}

	MALLOC_TRACE(TRACE_malloc | DBG_FUNC_END, (uintptr_t)zone, size, (uintptr_t)ptr, 0);
out:
	if (os_unlikely(ptr == NULL)) {
		malloc_set_errno_fast(mzo, ENOMEM);
	}
	return ptr;
}

void *
malloc_zone_malloc(malloc_zone_t *zone, size_t size)
{
	return _malloc_zone_malloc(zone, size, MZ_NONE);
}

MALLOC_NOINLINE
static void *
_malloc_zone_calloc(malloc_zone_t *zone, size_t num_items, size_t size,
		malloc_zone_options_t mzo)
{
	MALLOC_TRACE(TRACE_calloc | DBG_FUNC_START, (uintptr_t)zone, num_items, size, 0);

	void *ptr;
	if (malloc_check_start) {
		internal_check();
	}

	ptr = zone->calloc(zone, num_items, size);

	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE | MALLOC_LOG_TYPE_CLEARED, (uintptr_t)zone,
				(uintptr_t)(num_items * size), 0, (uintptr_t)ptr, 0);
	}

	MALLOC_TRACE(TRACE_calloc | DBG_FUNC_END, (uintptr_t)zone, num_items, size, (uintptr_t)ptr);
	if (os_unlikely(ptr == NULL)) {
		malloc_set_errno_fast(mzo, ENOMEM);
	}
	return ptr;
}

void *
malloc_zone_calloc(malloc_zone_t *zone, size_t num_items, size_t size)
{
	return _malloc_zone_calloc(zone, num_items, size, MZ_NONE);
}

MALLOC_NOINLINE
static void *
_malloc_zone_valloc(malloc_zone_t *zone, size_t size, malloc_zone_options_t mzo)
{
	MALLOC_TRACE(TRACE_valloc | DBG_FUNC_START, (uintptr_t)zone, size, 0, 0);

	void *ptr = NULL;
	if (malloc_check_start) {
		internal_check();
	}
	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
		goto out;
	}

	ptr = zone->valloc(zone, size);

	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
	}

	MALLOC_TRACE(TRACE_valloc | DBG_FUNC_END, (uintptr_t)zone, size, (uintptr_t)ptr, 0);
out:
	if (os_unlikely(ptr == NULL)) {
		malloc_set_errno_fast(mzo, ENOMEM);
	}
	return ptr;
}

void *
malloc_zone_valloc(malloc_zone_t *zone, size_t size)
{
	return _malloc_zone_valloc(zone, size, MZ_NONE);
}

void *
malloc_zone_realloc(malloc_zone_t *zone, void *ptr, size_t size)
{
	MALLOC_TRACE(TRACE_realloc | DBG_FUNC_START, (uintptr_t)zone, (uintptr_t)ptr, size, 0);

	void *new_ptr;
	if (malloc_check_start) {
		internal_check();
	}
	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
		return NULL;
	}

	new_ptr = zone->realloc(zone, ptr, size);
	
	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone,
				(uintptr_t)ptr, (uintptr_t)size, (uintptr_t)new_ptr, 0);
	}
	MALLOC_TRACE(TRACE_realloc | DBG_FUNC_END, (uintptr_t)zone, (uintptr_t)ptr, size, (uintptr_t)new_ptr);
	return new_ptr;
}

void
malloc_zone_free(malloc_zone_t *zone, void *ptr)
{
	MALLOC_TRACE(TRACE_free, (uintptr_t)zone, (uintptr_t)ptr, (ptr) ? *(uintptr_t*)ptr : 0, 0);

	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)ptr, 0, 0, 0);
	}
	if (malloc_check_start) {
		internal_check();
	}

	zone->free(zone, ptr);
}

static void
malloc_zone_free_definite_size(malloc_zone_t *zone, void *ptr, size_t size)
{
	MALLOC_TRACE(TRACE_free, (uintptr_t)zone, (uintptr_t)ptr, size, (ptr && size) ? *(uintptr_t*)ptr : 0);

	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)ptr, 0, 0, 0);
	}
	if (malloc_check_start) {
		internal_check();
	}

	zone->free_definite_size(zone, ptr, size);
}

malloc_zone_t *
malloc_zone_from_ptr(const void *ptr)
{
	if (!ptr) {
		return NULL;
	} else {
		return find_registered_zone(ptr, NULL);
	}
}

MALLOC_NOINLINE
static void *
_malloc_zone_memalign(malloc_zone_t *zone, size_t alignment, size_t size,
		malloc_zone_options_t mzo)
{
	MALLOC_TRACE(TRACE_memalign | DBG_FUNC_START, (uintptr_t)zone, alignment, size, 0);

	void *ptr = NULL;
	int err = ENOMEM;
	if (zone->version < 5) { // Version must be >= 5 to look at the new memalign field.
		goto out;
	}
	if (malloc_check_start) {
		internal_check();
	}
	if (size > MALLOC_ABSOLUTE_MAX_SIZE) {
		goto out;
	}
	if (alignment < sizeof(void *) ||			  // excludes 0 == alignment
			0 != (alignment & (alignment - 1))) { // relies on sizeof(void *) being a power of two.
		err = EINVAL;
		goto out;
	}
	if ((mzo & MZ_C11) && (size & (alignment - 1)) != 0) { /* C11 requires size to be a multiple of alignment */
		err = EINVAL;
		goto out;
	}

	if (!(zone->memalign)) {
		goto out;
	}
	ptr = zone->memalign(zone, alignment, size);

	if (os_unlikely(malloc_logger)) {
		malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0, (uintptr_t)ptr, 0);
	}

	MALLOC_TRACE(TRACE_memalign | DBG_FUNC_END, (uintptr_t)zone, alignment, size, (uintptr_t)ptr);

out:
	if (os_unlikely(ptr == NULL)) {
		if (mzo & MZ_POSIX) {
			malloc_set_errno_fast(mzo, err);
		}
	}
	return ptr;
}

void *
malloc_zone_memalign(malloc_zone_t *zone, size_t alignment, size_t size)
{
	return _malloc_zone_memalign(zone, alignment, size, MZ_NONE);
}

boolean_t
malloc_zone_claimed_address(malloc_zone_t *zone, void *ptr)
{
	if (!ptr) {
		// NULL is not a member of any zone.
		return false;
	}

	if (malloc_check_start) {
		internal_check();
	}

	if (zone->version < 10 || !zone->claimed_address) {
		// For zones that have not implemented claimed_address, we always have
		// to return true to avoid a false negative.
		return true;
	}

	return zone->claimed_address(zone, ptr);
}

/*********	Functions for zone implementors	************/

void
malloc_zone_register(malloc_zone_t *zone)
{
	MALLOC_LOCK();
	malloc_zone_register_while_locked(zone);
	MALLOC_UNLOCK();
}

void
malloc_zone_unregister(malloc_zone_t *z)
{
	unsigned index;

	if (malloc_num_zones == 0) {
		return;
	}

	MALLOC_LOCK();
	for (index = 0; index < malloc_num_zones; ++index) {
		if (z != malloc_zones[index]) {
			continue;
		}

		// Modify the page to be allow write access, so that we can update the
		// malloc_zones array.
		size_t protect_size = malloc_num_zones_allocated * sizeof(malloc_zone_t *);
		mprotect(malloc_zones, protect_size, PROT_READ | PROT_WRITE);

		// If we found a match, replace it with the entry at the end of the list, shrink the list,
		// and leave the end of the list intact to avoid racing with find_registered_zone().

		malloc_zones[index] = malloc_zones[malloc_num_zones - 1];
		--malloc_num_zones;

		mprotect(malloc_zones, protect_size, PROT_READ);

		// MAX(num_zones, 1) enables the fast path in find_registered_zone() for zone 0 even
		// if it is a custom zone, e.g., ASan and user zones.
		initial_num_zones = MIN(MAX(malloc_num_zones, 1), initial_num_zones);

		// Exchange the roles of the FRZ counters. The counter that has captured the number of threads presently
		// executing *inside* find_registered_zone is swapped with the counter drained to zero last time through.
		// The former is then allowed to drain to zero while this thread yields.
		int32_t volatile *p = pFRZCounterLive;
		pFRZCounterLive = pFRZCounterDrain;
		pFRZCounterDrain = p;
		OSMemoryBarrier(); // Full memory barrier

		while (0 != *pFRZCounterDrain) {
			yield();
		}

		MALLOC_UNLOCK();

		return;
	}
	MALLOC_UNLOCK();
	malloc_report(ASL_LEVEL_ERR, "*** malloc_zone_unregister() failed for %p\n", z);
}

void
malloc_set_zone_name(malloc_zone_t *z, const char *name)
{
	char *newName;

	mprotect(z, sizeof(malloc_zone_t), PROT_READ | PROT_WRITE);
	if (z->zone_name) {
		free((char *)z->zone_name);
		z->zone_name = NULL;
	}
	if (name) {
		size_t buflen = strlen(name) + 1;
		newName = _malloc_zone_malloc(z, buflen, MZ_NONE);
		if (newName) {
			strlcpy(newName, name, buflen);
			z->zone_name = (const char *)newName;
		} else {
			z->zone_name = NULL;
		}
	}
	mprotect(z, sizeof(malloc_zone_t), PROT_READ);
}

const char *
malloc_get_zone_name(malloc_zone_t *zone)
{
	return zone->zone_name;
}


/*********	Generic ANSI callouts	************/

void *
malloc(size_t size)
{
	return _malloc_zone_malloc(default_zone, size, MZ_POSIX);
}

void *
aligned_alloc(size_t alignment, size_t size)
{
	return _malloc_zone_memalign(default_zone, alignment, size,
	    MZ_POSIX | MZ_C11);
}

void *
calloc(size_t num_items, size_t size)
{
	return _malloc_zone_calloc(default_zone, num_items, size, MZ_POSIX);
}

void
free(void *ptr)
{
	malloc_zone_t *zone;
	size_t size;
	if (!ptr) {
		return;
	}

	zone = find_registered_zone(ptr, &size);
	if (!zone) {
		int flags = MALLOC_REPORT_DEBUG | MALLOC_REPORT_NOLOG;
		if ((malloc_debug_flags & (MALLOC_ABORT_ON_CORRUPTION | MALLOC_ABORT_ON_ERROR))) {
			flags = MALLOC_REPORT_CRASH | MALLOC_REPORT_NOLOG;
		}
		malloc_report(flags,
				"*** error for object %p: pointer being freed was not allocated\n", ptr);
	} else if (zone->version >= 6 && zone->free_definite_size) {
		malloc_zone_free_definite_size(zone, ptr, size);
	} else {
		malloc_zone_free(zone, ptr);
	}
}

void *
realloc(void *in_ptr, size_t new_size)
{
	void *retval = NULL;
	void *old_ptr;
	malloc_zone_t *zone;

	// SUSv3: "If size is 0 and ptr is not a null pointer, the object
	// pointed to is freed. If the space cannot be allocated, the object
	// shall remain unchanged."  Also "If size is 0, either a null pointer
	// or a unique pointer that can be successfully passed to free() shall
	// be returned."  We choose to allocate a minimum size object by calling
	// malloc_zone_malloc with zero size, which matches "If ptr is a null
	// pointer, realloc() shall be equivalent to malloc() for the specified
	// size."  So we only free the original memory if the allocation succeeds.
	old_ptr = (new_size == 0) ? NULL : in_ptr;
	if (!old_ptr) {
		retval = malloc_zone_malloc(default_zone, new_size);
	} else {
		zone = find_registered_zone(old_ptr, NULL);
		if (!zone) {
			int flags = MALLOC_REPORT_DEBUG | MALLOC_REPORT_NOLOG;
			if (malloc_debug_flags & (MALLOC_ABORT_ON_CORRUPTION | MALLOC_ABORT_ON_ERROR)) {
				flags = MALLOC_REPORT_CRASH | MALLOC_REPORT_NOLOG;
			}
			malloc_report(flags, "*** error for object %p: pointer being realloc'd was not allocated\n", in_ptr);
		} else {
			retval = malloc_zone_realloc(zone, old_ptr, new_size);
		}
	}

	if (retval == NULL) {
		malloc_set_errno_fast(MZ_POSIX, ENOMEM);
	} else if (new_size == 0) {
		free(in_ptr);
	}
	return retval;
}

void *
valloc(size_t size)
{
	return _malloc_zone_valloc(default_zone, size, MZ_POSIX);
}

extern void
vfree(void *ptr)
{
	free(ptr);
}

size_t
malloc_size(const void *ptr)
{
	size_t size = 0;

	if (!ptr) {
		return size;
	}

	(void)find_registered_zone(ptr, &size);
	return size;
}

size_t
malloc_good_size(size_t size)
{
	malloc_zone_t *zone = default_zone;
	return zone->introspect->good_size(zone, size);
}

/*
 * The posix_memalign() function shall allocate size bytes aligned on a boundary specified by alignment,
 * and shall return a pointer to the allocated memory in memptr.
 * The value of alignment shall be a multiple of sizeof( void *), that is also a power of two.
 * Upon successful completion, the value pointed to by memptr shall be a multiple of alignment.
 *
 * Upon successful completion, posix_memalign() shall return zero; otherwise,
 * an error number shall be returned to indicate the error.
 *
 * The posix_memalign() function shall fail if:
 * EINVAL
 *	The value of the alignment parameter is not a power of two multiple of sizeof( void *).
 * ENOMEM
 *	There is insufficient memory available with the requested alignment.
 */

int
posix_memalign(void **memptr, size_t alignment, size_t size)
{
	void *retval;

	/* POSIX is silent on NULL == memptr !?! */

	retval = malloc_zone_memalign(default_zone, alignment, size);
	if (retval == NULL) {
		// To avoid testing the alignment constraints redundantly, we'll rely on the
		// test made in malloc_zone_memalign to vet each request. Only if that test fails
		// and returns NULL, do we arrive here to detect the bogus alignment and give the
		// required EINVAL return.
		if (alignment < sizeof(void *) ||			  // excludes 0 == alignment
				0 != (alignment & (alignment - 1))) { // relies on sizeof(void *) being a power of two.
			return EINVAL;
		}
		return ENOMEM;
	} else {
		*memptr = retval; // Set iff allocation succeeded
		return 0;
	}
}

boolean_t
malloc_claimed_address(void *ptr)
{
	// We need to check with each registered zone whether it claims "ptr".
	// Use logic similar to that in find_registered_zone().
	if (malloc_num_zones == 0) {
		return false;
	}

	// Start with the lite zone, if it's in use.
	if (lite_zone && malloc_zone_claimed_address(lite_zone, ptr)) {
		return true;
	}

	// Next, try the initial zones.
	for (uint32_t i = 0; i < initial_num_zones; i++) {
		if (malloc_zone_claimed_address(malloc_zones[i], ptr)) {
			return true;
		}
	}

	// Try all the other zones. Increment the FRZ barrier so that we can
	// walk the zones array without a lock (see find_registered_zone() for
	// the details).
	int32_t volatile *pFRZCounter = pFRZCounterLive;
	OSAtomicIncrement32Barrier(pFRZCounter);

	int32_t limit = *(int32_t volatile *)&malloc_num_zones;
	boolean_t result = false;
	for (uint32_t i = initial_num_zones; i < limit; i++) {
		malloc_zone_t *zone = malloc_zones[i];
		if (malloc_zone_claimed_address(zone, ptr)) {
			result = true;
			break;
		}
	}

	OSAtomicDecrement32Barrier(pFRZCounter);
	return result;
}

void *
reallocarray(void * in_ptr, size_t nmemb, size_t size){
	size_t alloc_size;
	if (os_mul_overflow(nmemb, size, &alloc_size)){
		malloc_set_errno_fast(MZ_POSIX, ENOMEM);
		return NULL;
	}
	return realloc(in_ptr, alloc_size);
}

void *
reallocarrayf(void * in_ptr, size_t nmemb, size_t size){
	size_t alloc_size;
	if (os_mul_overflow(nmemb, size, &alloc_size)){
		malloc_set_errno_fast(MZ_POSIX, ENOMEM);
		return NULL;
	}
	return reallocf(in_ptr, alloc_size);
}

static malloc_zone_t *
find_registered_purgeable_zone(void *ptr)
{
	if (!ptr) {
		return NULL;
	}

	/*
	 * Look for a zone which contains ptr.  If that zone does not have the purgeable malloc flag
	 * set, or the allocation is too small, do nothing.  Otherwise, set the allocation volatile.
	 * FIXME: for performance reasons, we should probably keep a separate list of purgeable zones
	 * and only search those.
	 */
	size_t size = 0;
	malloc_zone_t *zone = find_registered_zone(ptr, &size);

	/* FIXME: would really like a zone->introspect->flags->purgeable check, but haven't determined
	 * binary compatibility impact of changing the introspect struct yet. */
	if (!zone) {
		return NULL;
	}

	/* Check to make sure pointer is page aligned and size is multiple of page size */
	if ((size < vm_page_size) || ((size % vm_page_size) != 0)) {
		return NULL;
	}

	return zone;
}

void
malloc_make_purgeable(void *ptr)
{
	malloc_zone_t *zone = find_registered_purgeable_zone(ptr);
	if (!zone) {
		return;
	}

	int state = VM_PURGABLE_VOLATILE;
	vm_purgable_control(mach_task_self(), (vm_address_t)ptr, VM_PURGABLE_SET_STATE, &state);
	return;
}

/* Returns true if ptr is valid.  Ignore the return value from vm_purgeable_control and only report
 * state. */
int
malloc_make_nonpurgeable(void *ptr)
{
	malloc_zone_t *zone = find_registered_purgeable_zone(ptr);
	if (!zone) {
		return 0;
	}

	int state = VM_PURGABLE_NONVOLATILE;
	vm_purgable_control(mach_task_self(), (vm_address_t)ptr, VM_PURGABLE_SET_STATE, &state);

	if (state == VM_PURGABLE_EMPTY) {
		return EFAULT;
	}

	return 0;
}

void
malloc_enter_process_memory_limit_warn_mode(void)
{
	// <rdar://problem/25063714>
}



// Note that malloc_memory_event_handler is not thread-safe, and we are relying on the callers of this for synchronization
void
malloc_memory_event_handler(unsigned long event)
{
	if (event & NOTE_MEMORYSTATUS_PRESSURE_WARN) {
		malloc_zone_pressure_relief(0, 0);
	}

	if ((event & NOTE_MEMORYSTATUS_MSL_STATUS) != 0 && (event & ~NOTE_MEMORYSTATUS_MSL_STATUS) == 0) {
		malloc_register_stack_logger();
	}

#if ENABLE_MEMORY_RESOURCE_EXCEPTION_HANDLING
	if (event & (NOTE_MEMORYSTATUS_PROC_LIMIT_WARN | NOTE_MEMORYSTATUS_PROC_LIMIT_CRITICAL | NOTE_MEMORYSTATUS_PRESSURE_CRITICAL)) {
		malloc_register_stack_logger();
	}
#endif // ENABLE_MEMORY_RESOURCE_EXCEPTION_HANDLING
	
	if (msl.handle_memory_event) {
		// Let MSL see the event.
		msl.handle_memory_event(event);
	}
}

size_t
malloc_zone_pressure_relief(malloc_zone_t *zone, size_t goal)
{
	if (!zone) {
		unsigned index = 0;
		size_t total = 0;

		// Take lock to defend against malloc_destroy_zone()
		MALLOC_LOCK();
		while (index < malloc_num_zones) {
			zone = malloc_zones[index++];
			if (zone->version < 8) {
				continue;
			}
			if (NULL == zone->pressure_relief) {
				continue;
			}
			if (0 == goal) { /* Greedy */
				total += zone->pressure_relief(zone, 0);
			} else if (goal > total) {
				total += zone->pressure_relief(zone, goal - total);
			} else { /* total >= goal */
				break;
			}
		}
		MALLOC_UNLOCK();
		return total;
	} else {
		// Assumes zone is not destroyed for the duration of this call
		if (zone->version < 8) {
			return 0;
		}
		if (NULL == zone->pressure_relief) {
			return 0;
		}
		return zone->pressure_relief(zone, goal);
	}
}

/*********	Batch methods	************/

unsigned
malloc_zone_batch_malloc(malloc_zone_t *zone, size_t size, void **results, unsigned num_requested)
{
	if (!zone->batch_malloc) {
		return 0;
	}
	if (malloc_check_start) {
		internal_check();
	}
	unsigned batched = zone->batch_malloc(zone, size, results, num_requested);
	
	if (os_unlikely(malloc_logger)) {
		unsigned index = 0;
		while (index < batched) {
			malloc_logger(MALLOC_LOG_TYPE_ALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)size, 0,
					(uintptr_t)results[index], 0);
			index++;
		}
	}
	return batched;
}

void
malloc_zone_batch_free(malloc_zone_t *zone, void **to_be_freed, unsigned num)
{
	if (malloc_check_start) {
		internal_check();
	}
	if (os_unlikely(malloc_logger)) {
		unsigned index = 0;
		while (index < num) {
			malloc_logger(
					MALLOC_LOG_TYPE_DEALLOCATE | MALLOC_LOG_TYPE_HAS_ZONE, (uintptr_t)zone, (uintptr_t)to_be_freed[index], 0, 0, 0);
			index++;
		}
	}
	
	if (zone->batch_free) {
		zone->batch_free(zone, to_be_freed, num);
	} else {
		void (*free_fun)(malloc_zone_t *, void *) = zone->free;
		
		while (num--) {
			void *ptr = *to_be_freed++;
			free_fun(zone, ptr);
		}
	}
}

/*********	Functions for performance tools	************/

kern_return_t
malloc_get_all_zones(task_t task, memory_reader_t reader, vm_address_t **addresses, unsigned *count)
{
	// Note that the 2 following addresses are not correct if the address of the target is different from your own.  This notably
	// occurs if the address of System.framework is slid (e.g. different than at B & I )
	vm_address_t remote_malloc_zones = (vm_address_t)&malloc_zones;
	vm_address_t remote_malloc_num_zones = (vm_address_t)&malloc_num_zones;
	kern_return_t err;
	vm_address_t zones_address;
	vm_address_t *zones_address_ref;
	unsigned num_zones;
	unsigned *num_zones_ref;
	if (!reader) {
		reader = _malloc_default_reader;
	}
	// printf("Read malloc_zones at address %p should be %p\n", &malloc_zones, malloc_zones);
	err = reader(task, remote_malloc_zones, sizeof(void *), (void **)&zones_address_ref);
	// printf("Read malloc_zones[%p]=%p\n", remote_malloc_zones, *zones_address_ref);
	if (err) {
		malloc_report(ASL_LEVEL_ERR, "*** malloc_get_all_zones: error reading zones_address at %p\n", (void *)remote_malloc_zones);
		return err;
	}
	zones_address = *zones_address_ref;
	// printf("Reading num_zones at address %p\n", remote_malloc_num_zones);
	err = reader(task, remote_malloc_num_zones, sizeof(unsigned), (void **)&num_zones_ref);
	if (err) {
		malloc_report(ASL_LEVEL_ERR, "*** malloc_get_all_zones: error reading num_zones at %p\n", (void *)remote_malloc_num_zones);
		return err;
	}
	num_zones = *num_zones_ref;
	// printf("Read malloc_num_zones[%p]=%d\n", remote_malloc_num_zones, num_zones);
	*count = num_zones;
	// printf("malloc_get_all_zones succesfully found %d zones\n", num_zones);
	err = reader(task, zones_address, sizeof(malloc_zone_t *) * num_zones, (void **)addresses);
	if (err) {
		malloc_report(ASL_LEVEL_ERR, "*** malloc_get_all_zones: error reading zones at %p\n", &zones_address);
		return err;
	}
	// printf("malloc_get_all_zones succesfully read %d zones\n", num_zones);
	return err;
}

/*********	Debug helpers	************/

void
malloc_zone_print_ptr_info(void *ptr)
{
	malloc_zone_t *zone;
	if (!ptr) {
		return;
	}
	zone = malloc_zone_from_ptr(ptr);
	if (zone) {
		printf("ptr %p in registered zone %p\n", ptr, zone);
	} else {
		printf("ptr %p not in heap\n", ptr);
	}
}

boolean_t
malloc_zone_check(malloc_zone_t *zone)
{
	boolean_t ok = 1;
	if (!zone) {
		unsigned index = 0;
		while (index < malloc_num_zones) {
			zone = malloc_zones[index++];
			if (!zone->introspect->check(zone)) {
				ok = 0;
			}
		}
	} else {
		ok = zone->introspect->check(zone);
	}
	return ok;
}

void
malloc_zone_print(malloc_zone_t *zone, boolean_t verbose)
{
	if (!zone) {
		unsigned index = 0;
		while (index < malloc_num_zones) {
			zone = malloc_zones[index++];
			zone->introspect->print(zone, verbose);
		}
	} else {
		zone->introspect->print(zone, verbose);
	}
}

void
malloc_zone_statistics(malloc_zone_t *zone, malloc_statistics_t *stats)
{
	if (!zone) {
		memset(stats, 0, sizeof(*stats));
		unsigned index = 0;
		while (index < malloc_num_zones) {
			zone = malloc_zones[index++];
			malloc_statistics_t this_stats;
			zone->introspect->statistics(zone, &this_stats);
			stats->blocks_in_use += this_stats.blocks_in_use;
			stats->size_in_use += this_stats.size_in_use;
			stats->max_size_in_use += this_stats.max_size_in_use;
			stats->size_allocated += this_stats.size_allocated;
		}
	} else {
		zone->introspect->statistics(zone, stats);
	}
}

void
malloc_zone_log(malloc_zone_t *zone, void *address)
{
	if (!zone) {
		unsigned index = 0;
		while (index < malloc_num_zones) {
			zone = malloc_zones[index++];
			zone->introspect->log(zone, address);
		}
	} else {
		zone->introspect->log(zone, address);
	}
}

/*********	Misc other entry points	************/

void
mag_set_thread_index(unsigned int index)
{
	_os_cpu_number_override = index;
#if CONFIG_NANOZONE
	nano_common_cpu_number_override_set();
#endif // CONFIG_NANOZONE
}

static void
DefaultMallocError(int x)
{
#if USE_SLEEP_RATHER_THAN_ABORT
	malloc_report(ASL_LEVEL_ERR, "*** error %d\n", x);
	sleep(3600);
#else
	_SIMPLE_STRING b = _simple_salloc();
	if (b) {
		_simple_sprintf(b, "*** error %d", x);
		malloc_report(MALLOC_REPORT_NOLOG, "%s\n", _simple_string(b));
		_os_set_crash_log_message_dynamic(_simple_string(b));
	} else {
		malloc_report(MALLOC_REPORT_NOLOG, "*** error %d\n", x);
		_os_set_crash_log_message("*** DefaultMallocError called");
	}
	abort();
#endif
}

void (*malloc_error(void (*func)(int)))(int)
{
	return DefaultMallocError;
}

static void
_malloc_lock_all(void (*callout)(void))
{
	unsigned index = 0;
	MALLOC_LOCK();
	while (index < malloc_num_zones) {
		malloc_zone_t *zone = malloc_zones[index++];
		zone->introspect->force_lock(zone);
	}
	if (callout) {
		callout();
	}
}

static void
_malloc_unlock_all(void (*callout)(void))
{
	unsigned index = 0;
	if (callout) {
		callout();
	}
	while (index < malloc_num_zones) {
		malloc_zone_t *zone = malloc_zones[index++];
		zone->introspect->force_unlock(zone);
	}
	MALLOC_UNLOCK();
}

static void
_malloc_reinit_lock_all(void (*callout)(void))
{
	unsigned index = 0;
	if (callout) {
		callout();
	}
	while (index < malloc_num_zones) {
		malloc_zone_t *zone = malloc_zones[index++];
		if (zone->version < 9) { // Version must be >= 9 to look at reinit_lock
			zone->introspect->force_unlock(zone);
		} else {
			zone->introspect->reinit_lock(zone);
		}
	}
	MALLOC_REINIT_LOCK();
}


// Called prior to fork() to guarantee that malloc is not in any critical
// sections during the fork(); prevent any locks from being held by non-
// surviving threads after the fork.
void
_malloc_fork_prepare(void)
{
	return _malloc_lock_all(msl.fork_prepare);
}

// Called in the parent process after fork() to resume normal operation.
void
_malloc_fork_parent(void)
{
	return _malloc_unlock_all(msl.fork_parent);
}

// Called in the child process after fork() to resume normal operation.
void
_malloc_fork_child(void)
{
#if CONFIG_NANOZONE
	if (_malloc_entropy_initialized) {
		if (_malloc_engaged_nano == NANO_V2) {
			nanov2_forked_zone((nanozonev2_t *)initial_nano_zone);
		} else if (_malloc_engaged_nano == NANO_V1) {
			nano_forked_zone((nanozone_t *)initial_nano_zone);
		}
	}
#endif
	return _malloc_reinit_lock_all(msl.fork_child);
}

/*
 * A Glibc-like mstats() interface.
 *
 * Note that this interface really isn't very good, as it doesn't understand
 * that we may have multiple allocators running at once.  We just massage
 * the result from malloc_zone_statistics in any case.
 */
struct mstats
mstats(void)
{
	malloc_statistics_t s;
	struct mstats m;

	malloc_zone_statistics(NULL, &s);
	m.bytes_total = s.size_allocated;
	m.chunks_used = s.blocks_in_use;
	m.bytes_used = s.size_in_use;
	m.chunks_free = 0;
	m.bytes_free = m.bytes_total - m.bytes_used; /* isn't this somewhat obvious? */

	return (m);
}

boolean_t
malloc_zone_enable_discharge_checking(malloc_zone_t *zone)
{
	if (zone->version < 7) { // Version must be >= 7 to look at the new discharge checking fields.
		return FALSE;
	}
	if (NULL == zone->introspect->enable_discharge_checking) {
		return FALSE;
	}
	return zone->introspect->enable_discharge_checking(zone);
}

void
malloc_zone_disable_discharge_checking(malloc_zone_t *zone)
{
	if (zone->version < 7) { // Version must be >= 7 to look at the new discharge checking fields.
		return;
	}
	if (NULL == zone->introspect->disable_discharge_checking) {
		return;
	}
	zone->introspect->disable_discharge_checking(zone);
}

void
malloc_zone_discharge(malloc_zone_t *zone, void *memory)
{
	if (NULL == zone) {
		zone = malloc_zone_from_ptr(memory);
	}
	if (NULL == zone) {
		return;
	}
	if (zone->version < 7) { // Version must be >= 7 to look at the new discharge checking fields.
		return;
	}
	if (NULL == zone->introspect->discharge) {
		return;
	}
	zone->introspect->discharge(zone, memory);
}

void
malloc_zone_enumerate_discharged_pointers(malloc_zone_t *zone, void (^report_discharged)(void *memory, void *info))
{
	if (!zone) {
		unsigned index = 0;
		while (index < malloc_num_zones) {
			zone = malloc_zones[index++];
			if (zone->version < 7) {
				continue;
			}
			if (NULL == zone->introspect->enumerate_discharged_pointers) {
				continue;
			}
			zone->introspect->enumerate_discharged_pointers(zone, report_discharged);
		}
	} else {
		if (zone->version < 7) {
			return;
		}
		if (NULL == zone->introspect->enumerate_discharged_pointers) {
			return;
		}
		zone->introspect->enumerate_discharged_pointers(zone, report_discharged);
	}
}

/*****************	OBSOLETE ENTRY POINTS	********************/

#if PHASE_OUT_OLD_MALLOC
#error PHASE OUT THE FOLLOWING FUNCTIONS
#endif

void
set_malloc_singlethreaded(boolean_t single)
{
	static boolean_t warned = 0;
	if (!warned) {
#if PHASE_OUT_OLD_MALLOC
		malloc_report(ASL_LEVEL_ERR, "*** OBSOLETE: set_malloc_singlethreaded(%d)\n", single);
#endif
		warned = 1;
	}
}

void
malloc_singlethreaded(void)
{
	static boolean_t warned = 0;
	if (!warned) {
		malloc_report(ASL_LEVEL_ERR, "*** OBSOLETE: malloc_singlethreaded()\n");
		warned = 1;
	}
}

int
malloc_debug(int level)
{
	malloc_report(ASL_LEVEL_ERR, "*** OBSOLETE: malloc_debug()\n");
	return 0;
}

#pragma mark -
#pragma mark Malloc Stack Logging


/* this is called from libsystem during initialization. */
static void
stack_logging_early_finished(const struct _malloc_late_init *funcs)
{
#if !TARGET_OS_DRIVERKIT
	_dlopen = funcs->dlopen;
	_dlsym = funcs->dlsym;
#endif
	const char **env = (const char**) *_NSGetEnviron();
	for (const char **e = env; *e; e++) {
		if (0==strncmp(*e, "MallocStackLogging", 18)) {
			malloc_register_stack_logger();
			void (*msl_set_flags_from_environment) (const char **env);
			msl_set_flags_from_environment = _dlsym(msl.dylib, "msl_set_flags_from_environment");
			if (msl_set_flags_from_environment) {
				msl_set_flags_from_environment(env);
			}
			break;
		}
	}
	if (msl.dylib) {
		void (*initialize) () = _dlsym(msl.dylib, "msl_initialize");
		if (initialize) {
			initialize();
		}
	}
}


static os_once_t _register_msl_dylib_pred;

static void
register_msl_dylib(void *dylib)
{
	if (!dylib) {
		return;
	}
	msl.dylib = dylib;
	msl.handle_memory_event = _dlsym(dylib, "msl_handle_memory_event");
	msl.stack_logging_locked = _dlsym(dylib, "msl_stack_logging_locked");
	msl.fork_prepare = _dlsym(dylib, "msl_fork_prepare");
	msl.fork_child = _dlsym(dylib, "msl_fork_child");
	msl.fork_parent = _dlsym(dylib, "msl_fork_parent");
	
	// TODO delete these ones
	msl.get_frames_for_address = _dlsym(dylib, "msl_get_frames_for_address");
	msl.stackid_for_vm_region = _dlsym(dylib, "msl_stackid_for_vm_region");
	msl.get_frames_for_stackid = _dlsym(dylib, "msl_get_frames_for_stackid");
	msl.uniquing_table_read_stack = _dlsym(dylib, "msl_uniquing_table_read_stack");

	void (*msl_copy_msl_lite_hooks) (struct _malloc_msl_lite_hooks_s *hooksp, size_t size);
	msl_copy_msl_lite_hooks = _dlsym(dylib, "msl_copy_msl_lite_hooks");
	if (msl_copy_msl_lite_hooks) {
		set_msl_lite_hooks(msl_copy_msl_lite_hooks);
	}
}

MALLOC_EXPORT
boolean_t
malloc_register_stack_logger(void)
{
	if (msl.dylib != NULL) {
		return true;
	}
	void *dylib = _dlopen("/System/Library/PrivateFrameworks/MallocStackLogging.framework/MallocStackLogging", RTLD_GLOBAL);
	if (dylib == NULL) {
		return false;	
	}
	os_once(&_register_msl_dylib_pred, dylib, register_msl_dylib);
	if (!msl.dylib) {
		malloc_report(ASL_LEVEL_WARNING, "failed to load MallocStackLogging.framework\n");
	}
	return msl.dylib == dylib;
}

/* Symbolication.framework looks up this symbol by name inside libsystem_malloc.dylib. */
uint64_t __mach_stack_logging_shared_memory_address = 0;


#pragma mark -
#pragma mark Malloc Stack Logging - Legacy stubs

/*
 * legacy API for MallocStackLogging.
 *
 * TODO, deprecate this, move clients off it and delete it.   Clients should move
 * to MallocStackLogging.framework for these APIs.
 */

MALLOC_EXPORT
boolean_t
turn_on_stack_logging(stack_logging_mode_type mode)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return false;
	}
	boolean_t (*msl_turn_on_stack_logging) (stack_logging_mode_type mode);
	msl_turn_on_stack_logging = _dlsym(msl.dylib, "msl_turn_on_stack_logging");
	if (!msl_turn_on_stack_logging) {
		return false;
	}
	return msl_turn_on_stack_logging(mode);
}

MALLOC_EXPORT
void turn_off_stack_logging(void)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return;
	}
	void (*msl_turn_off_stack_logging) ();
	msl_turn_off_stack_logging = _dlsym(msl.dylib, "msl_turn_off_stack_logging");
	if (msl_turn_off_stack_logging) {
		msl_turn_off_stack_logging();
	}
}

kern_return_t
__mach_stack_logging_start_reading(task_t task, vm_address_t shared_memory_address, boolean_t *uses_lite_mode)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return KERN_FAILURE;
	}
	kern_return_t (*f) (task_t task, vm_address_t shared_memory_address, boolean_t *uses_lite_mode);
	f = _dlsym(msl.dylib, "msl_start_reading");
	if (!f) {
		return KERN_FAILURE;
	}
	return f(task, shared_memory_address, uses_lite_mode);
}

kern_return_t
__mach_stack_logging_stop_reading(task_t task)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return KERN_FAILURE;
	}
	kern_return_t (*f) (task_t task);
	f = _dlsym(msl.dylib, "msl_stop_reading");
	if (!f) {
		return KERN_FAILURE;
	}
	return f(task);
}

kern_return_t
__mach_stack_logging_get_frames(task_t task,
								mach_vm_address_t address,
								mach_vm_address_t *stack_frames_buffer,
								uint32_t max_stack_frames,
								uint32_t *count)
{
	malloc_register_stack_logger();
	if (!msl.get_frames_for_address) {
		return KERN_FAILURE;
	}
	return msl.get_frames_for_address(task, address, stack_frames_buffer, max_stack_frames, count);
}

uint64_t
__mach_stack_logging_stackid_for_vm_region(task_t task, mach_vm_address_t address)
{
	malloc_register_stack_logger();
	if (!msl.stackid_for_vm_region) {
		return -1ull;
	}
	return msl.stackid_for_vm_region(task, address);
}


kern_return_t
__mach_stack_logging_frames_for_uniqued_stack(task_t task,
											  uint64_t stack_identifier,
											  mach_vm_address_t *stack_frames_buffer,
											  uint32_t max_stack_frames,
											  uint32_t *count)
{
	malloc_register_stack_logger();
	if (!msl.get_frames_for_stackid) {
		return KERN_FAILURE;
	}
	return msl.get_frames_for_stackid(task, stack_identifier, stack_frames_buffer, max_stack_frames, count, NULL);
}

kern_return_t
__mach_stack_logging_get_frames_for_stackid(task_t task,
											uint64_t stack_identifier,
											mach_vm_address_t *stack_frames_buffer,
											uint32_t max_stack_frames,
											uint32_t *count,
											bool *last_frame_is_threadid)
{
	malloc_register_stack_logger();
	if (!msl.get_frames_for_stackid) {
		return KERN_FAILURE;
	}
	return msl.get_frames_for_stackid(task, stack_identifier, stack_frames_buffer, max_stack_frames, count, last_frame_is_threadid);
}

kern_return_t
__mach_stack_logging_uniquing_table_read_stack(struct backtrace_uniquing_table *uniquing_table,
											   uint64_t stackid,
											   mach_vm_address_t *out_frames_buffer,
											   uint32_t *out_frames_count,
											   uint32_t max_frames)
{
	malloc_register_stack_logger();
	if (!msl.uniquing_table_read_stack) {
		return KERN_FAILURE;
	}
	return msl.uniquing_table_read_stack(uniquing_table, stackid, out_frames_buffer, out_frames_count, max_frames);
}

kern_return_t
__mach_stack_logging_enumerate_records(task_t task,
									   mach_vm_address_t address,
									   void enumerator(mach_stack_logging_record_t, void *),
									   void *context)
{
	malloc_register_stack_logger();
	kern_return_t (*f) (task_t task,
						mach_vm_address_t address,
						void enumerator(mach_stack_logging_record_t, void *),
						void *context);
	if (!msl.dylib) {
		return KERN_FAILURE;
	}
	f = _dlsym(msl.dylib, "msl_disk_stack_logs_enumerate_from_task");
	if (!f) {
		return KERN_FAILURE;
	}
	return f(task, address, enumerator, context);
}

struct backtrace_uniquing_table *
__mach_stack_logging_copy_uniquing_table(task_t task)
{
	malloc_register_stack_logger();
	struct backtrace_uniquing_table * (*f) (task_t task);
	if (!msl.dylib) {
		return NULL;
	}
	f = _dlsym(msl.dylib, "msl_uniquing_table_copy_from_task");
	if (!f) {
		return NULL;
	}
	return f(task);
}

struct backtrace_uniquing_table *
__mach_stack_logging_uniquing_table_copy_from_serialized(void *buffer, size_t size)
{
	malloc_register_stack_logger();
	struct backtrace_uniquing_table * (*f) (void *buffer, size_t size);
	if (!msl.dylib) {
		return NULL;
	}
	f = _dlsym(msl.dylib, "msl_uniquing_table_copy_from_serialized");
	if (!f) {
		return NULL;
	}
	return f(buffer, size);
}

void
__mach_stack_logging_uniquing_table_release(struct backtrace_uniquing_table *table)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return;
	}
	void (*f) (struct backtrace_uniquing_table *table);
	f = _dlsym(msl.dylib, "msl_uniquing_table_release");
	if (f) {
		f(table);
	}
}

void
__mach_stack_logging_uniquing_table_retain(struct backtrace_uniquing_table *table)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return;
	}
	void (*f) (struct backtrace_uniquing_table *table);
	f = _dlsym(msl.dylib, "msl_uniquing_table_retain");
	if (f) {
		f(table);
	}
}

extern
size_t
__mach_stack_logging_uniquing_table_sizeof(struct backtrace_uniquing_table *table)
{
	malloc_register_stack_logger();
	size_t (*f) (struct backtrace_uniquing_table *table);
	f = _dlsym(msl.dylib, "msl_uniquing_table_retain");
	return f(table);
}

void *
__mach_stack_logging_uniquing_table_serialize(struct backtrace_uniquing_table *table, mach_vm_size_t *size)
{
	malloc_register_stack_logger();
	if (!msl.dylib) {
		return NULL;
	}
	void * (*f) (struct backtrace_uniquing_table *table, mach_vm_size_t *size);
	f = _dlsym(msl.dylib, "msl_uniquing_table_serialize");
	if (!f) {
		return NULL;
	}
	return f(table, size);
}

kern_return_t
__mach_stack_logging_set_file_path(task_t task, char* file_path)
{
	return KERN_SUCCESS;
}

/* WeChat references this, only god knows why.  This symbol does nothing. */
int stack_logging_enable_logging = 0;

/* vim: set noet:ts=4:sw=4:cindent: */