/src/php-src/Zend/zend_weakrefs.c

Source
/*
   +----------------------------------------------------------------------+
   | Copyright © The PHP Group and Contributors.                          |
   +----------------------------------------------------------------------+
   | This source file is subject to the Modified BSD License that is      |
   | bundled with this package in the file LICENSE, and is available      |
   | through the World Wide Web at <https://www.php.net/license/>.        |
   |                                                                      |
   | SPDX-License-Identifier: BSD-3-Clause                                |
   +----------------------------------------------------------------------+
   | Authors: krakjoe@php.net                                             |
   +----------------------------------------------------------------------+
*/

#include "zend.h"
#include "zend_interfaces.h"
#include "zend_objects_API.h"
#include "zend_types.h"
#include "zend_weakrefs.h"
#include "zend_weakrefs_arginfo.h"

typedef struct _zend_weakref {
  zend_object *referent;
  zend_object std;
} zend_weakref;

typedef struct _zend_weakmap {
  HashTable ht;
  zend_object std;
} zend_weakmap;

typedef struct _zend_weakmap_iterator {
  zend_object_iterator it;
  uint32_t ht_iter;
} zend_weakmap_iterator;

/* EG(weakrefs) is a map from a key corresponding to a zend_object pointer to all the WeakReference, WeakMap, and/or bare HashTable entries relating to that pointer.
 *
 * 1. For a single WeakReference,
 *    the HashTable's corresponding value's tag is a ZEND_WEAKREF_TAG_REF and the pointer is a singleton WeakReference instance (zend_weakref *) for that zend_object pointer (from WeakReference::create()).
 * 2. For a single WeakMap, the HashTable's corresponding value's tag is a ZEND_WEAKREF_TAG_MAP and the pointer is a WeakMap instance (zend_weakmap *).
 * 3. For a single bare HashTable, the HashTable's corresponding value's tag is a ZEND_WEAKREF_TAG_BARE_HT and the pointer is a HashTable*.
 * 4. For multiple values associated with the same zend_object pointer, the HashTable entry's tag is a ZEND_WEAKREF_TAG_HT with a HashTable mapping
 *    tagged pointers of at most 1 WeakReference and 1 or more WeakMap or bare HashTable to the same tagged pointer.
 *
 * ZEND_MM_ALIGNED_OFFSET_LOG2 is at least 2 on supported architectures (pointers to the objects in question are aligned to 4 bytes (1<<2) even on 32-bit systems),
 * i.e. the least two significant bits of the pointer can be used as a tag (ZEND_WEAKREF_TAG_*). */
#define ZEND_WEAKREF_TAG_REF     0
#define ZEND_WEAKREF_TAG_MAP     1
#define ZEND_WEAKREF_TAG_HT      2
#define ZEND_WEAKREF_TAG_BARE_HT 3
#define ZEND_WEAKREF_GET_TAG(p) (((uintptr_t) (p)) & 3)
#define ZEND_WEAKREF_GET_PTR(p) ((void *) (((uintptr_t) (p)) & ~3))
#define ZEND_WEAKREF_ENCODE(p, t) ((void *) (((uintptr_t) (p)) | (t)))

zend_class_entry *zend_ce_weakref;
static zend_class_entry *zend_ce_weakmap;
static zend_object_handlers zend_weakref_handlers;
static zend_object_handlers zend_weakmap_handlers;

#define zend_weakref_from(o) (ZEND_CONTAINER_OF(o, zend_weakref, std))
#define zend_weakref_fetch(z) zend_weakref_from(Z_OBJ_P(z))

#define zend_weakmap_from(o) (ZEND_CONTAINER_OF(o, zend_weakmap, std))
#define zend_weakmap_fetch(z) zend_weakmap_from(Z_OBJ_P(z))

static inline void zend_weakref_unref_single(
    void *ptr, uintptr_t tag, zend_object *object)
{
  if (tag == ZEND_WEAKREF_TAG_REF) {
    /* Unreferencing WeakReference (at ptr) singleton that pointed to object. */
    zend_weakref *wr = ptr;
    wr->referent = NULL;
  } else {
    /* unreferencing WeakMap or bare HashTable entry (at ptr) with a key of object. */
    ZEND_ASSERT(tag == ZEND_WEAKREF_TAG_MAP || tag == ZEND_WEAKREF_TAG_BARE_HT);
    zend_hash_index_del((HashTable *) ptr, zend_object_to_weakref_key(object));
  }
}

static void zend_weakref_unref(zend_object *object, void *tagged_ptr) {
  void *ptr = ZEND_WEAKREF_GET_PTR(tagged_ptr);
  uintptr_t tag = ZEND_WEAKREF_GET_TAG(tagged_ptr);
  if (tag == ZEND_WEAKREF_TAG_HT) {
    HashTable *ht = ptr;
    ZEND_HASH_MAP_FOREACH_PTR(ht, tagged_ptr) {
      zend_weakref_unref_single(
        ZEND_WEAKREF_GET_PTR(tagged_ptr), ZEND_WEAKREF_GET_TAG(tagged_ptr), object);
    } ZEND_HASH_FOREACH_END();
    zend_hash_destroy(ht);
    FREE_HASHTABLE(ht);
  } else {
    zend_weakref_unref_single(ptr, tag, object);
  }
}

static void zend_weakref_register(zend_object *object, void *payload) {
  GC_ADD_FLAGS(object, IS_OBJ_WEAKLY_REFERENCED);

  zend_ulong obj_key = zend_object_to_weakref_key(object);
  zval *zv = zend_hash_index_lookup(&EG(weakrefs), obj_key);
  if (Z_TYPE_P(zv) == IS_NULL) {
    ZVAL_PTR(zv, payload);
    return;
  }

  void *tagged_ptr = Z_PTR_P(zv);
  if (ZEND_WEAKREF_GET_TAG(tagged_ptr) == ZEND_WEAKREF_TAG_HT) {
    HashTable *ht = ZEND_WEAKREF_GET_PTR(tagged_ptr);
    zend_hash_index_add_new_ptr(ht, (zend_ulong)(uintptr_t) payload, payload);
    return;
  }

  /* Convert simple pointer to hashtable. */
  HashTable *ht = emalloc(sizeof(HashTable));
  zend_hash_init(ht, 0, NULL, NULL, 0);
  zend_hash_index_add_new_ptr(ht, (zend_ulong)(uintptr_t) tagged_ptr, tagged_ptr);
  zend_hash_index_add_new_ptr(ht, (zend_ulong)(uintptr_t) payload, payload);
  /* Replace the single WeakMap or WeakReference entry in EG(weakrefs) with a HashTable with 2 entries in place. */
  ZVAL_PTR(zv, ZEND_WEAKREF_ENCODE(ht, ZEND_WEAKREF_TAG_HT));
}

static void zend_weakref_unregister(zend_object *object, void *payload, bool weakref_free) {
  zend_ulong obj_key = zend_object_to_weakref_key(object);
  void *tagged_ptr = zend_hash_index_find_ptr(&EG(weakrefs), obj_key);
  ZEND_ASSERT(tagged_ptr && "Weakref not registered?");

  void *ptr = ZEND_WEAKREF_GET_PTR(tagged_ptr);
  uintptr_t tag = ZEND_WEAKREF_GET_TAG(tagged_ptr);
  if (tag != ZEND_WEAKREF_TAG_HT) {
    ZEND_ASSERT(tagged_ptr == payload);
    zend_hash_index_del(&EG(weakrefs), obj_key);
    GC_DEL_FLAGS(object, IS_OBJ_WEAKLY_REFERENCED);

    /* Do this last, as it may destroy the object. */
    if (weakref_free) {
      zend_weakref_unref_single(ptr, tag, object);
    } else {
      /* The optimization of skipping unref is used for zend_weakrefs_hash_clean_ex() */
      ZEND_ASSERT(ZEND_WEAKREF_GET_TAG(payload) == ZEND_WEAKREF_TAG_MAP || ZEND_WEAKREF_GET_TAG(payload) == ZEND_WEAKREF_TAG_BARE_HT);
    }
    return;
  }

  HashTable *ht = ptr;
#if ZEND_DEBUG
  void *old_payload = zend_hash_index_find_ptr(ht, (zend_ulong)(uintptr_t) payload);
  ZEND_ASSERT(old_payload && "Weakref not registered?");
  ZEND_ASSERT(old_payload == payload);
#endif
  zend_hash_index_del(ht, (zend_ulong)(uintptr_t) payload);
  if (zend_hash_num_elements(ht) == 0) {
    GC_DEL_FLAGS(object, IS_OBJ_WEAKLY_REFERENCED);
    zend_hash_destroy(ht);
    FREE_HASHTABLE(ht);
    zend_hash_index_del(&EG(weakrefs), obj_key);
  }

  /* Do this last, as it may destroy the object. */
  if (weakref_free)  {
    zend_weakref_unref_single(
      ZEND_WEAKREF_GET_PTR(payload), ZEND_WEAKREF_GET_TAG(payload), object);
  } else {
    /* The optimization of skipping unref is used for zend_weakrefs_hash_clean_ex() */
    ZEND_ASSERT(ZEND_WEAKREF_GET_TAG(payload) == ZEND_WEAKREF_TAG_MAP || ZEND_WEAKREF_GET_TAG(payload) == ZEND_WEAKREF_TAG_BARE_HT);
  }
}

/* Insert 'pData' into bare HashTable 'ht', with the given 'key'. 'key' is
 * weakly referenced. 'ht' is considered to be a bare HashTable, not a WeakMap. */
ZEND_API zval *zend_weakrefs_hash_add(HashTable *ht, zend_object *key, zval *pData) {
  zval *zv = zend_hash_index_add(ht, zend_object_to_weakref_key(key), pData);
  if (zv) {
    zend_weakref_register(key, ZEND_WEAKREF_ENCODE(ht, ZEND_WEAKREF_TAG_BARE_HT));
  }
  return zv;
}

ZEND_API zend_result zend_weakrefs_hash_del(HashTable *ht, zend_object *key) {
  zval *zv = zend_hash_index_find(ht, zend_object_to_weakref_key(key));
  if (zv) {
    zend_weakref_unregister(key, ZEND_WEAKREF_ENCODE(ht, ZEND_WEAKREF_TAG_BARE_HT), true);
    return SUCCESS;
  }
  return FAILURE;
}

static void zend_weakrefs_hash_clean_ex(HashTable *ht, int type) {
  zend_ulong obj_key;
  ZEND_HASH_MAP_FOREACH_NUM_KEY(ht, obj_key) {
    /* Optimization: Don't call zend_weakref_unref_single to free individual entries from ht when unregistering (which would do a hash table lookup, call zend_hash_index_del, and skip over any bucket collisions).
     * Let freeing the corresponding values for WeakMap entries be done in zend_hash_clean, freeing objects sequentially.
     * The performance difference is notable for larger WeakMaps with worse cache locality. */
    zend_weakref_unregister(
      zend_weakref_key_to_object(obj_key), ZEND_WEAKREF_ENCODE(ht, type), false);
  } ZEND_HASH_FOREACH_END();
  zend_hash_clean(ht);
}

ZEND_API void zend_weakrefs_hash_clean(HashTable *ht) {
  zend_weakrefs_hash_clean_ex(ht, ZEND_WEAKREF_TAG_BARE_HT);
}

void zend_weakrefs_init(void) {
  zend_hash_init(&EG(weakrefs), 8, NULL, NULL, 0);
}

/* This is called when the object is garbage collected
 * to remove all WeakReference and WeakMap entries weakly referencing that object. */
void zend_weakrefs_notify(zend_object *object) {
  /* Annoyingly we can't use the HT destructor here, because we need access to the key (which
   * is the object address), which is not provided to the dtor. */
  const zend_ulong obj_key = zend_object_to_weakref_key(object);
  void *tagged_ptr = zend_hash_index_find_ptr(&EG(weakrefs), obj_key);
#if ZEND_DEBUG
  ZEND_ASSERT(tagged_ptr && "Tracking of the IS_OBJ_WEAKLY_REFERENCE flag should be precise");
#endif
  if (tagged_ptr) {
    zend_weakref_unref(object, tagged_ptr);
    zend_hash_index_del(&EG(weakrefs), obj_key);
  }
}

void zend_weakrefs_shutdown(void) {
  zend_hash_destroy(&EG(weakrefs));
}

static zend_object* zend_weakref_new(zend_class_entry *ce) {
  zend_weakref *wr = zend_object_alloc(sizeof(zend_weakref), zend_ce_weakref);

  zend_object_std_init(&wr->std, zend_ce_weakref);
  return &wr->std;
}

static zend_always_inline bool zend_weakref_find(zend_object *referent, zval *return_value) {
  void *tagged_ptr = zend_hash_index_find_ptr(&EG(weakrefs), zend_object_to_weakref_key(referent));
  if (!tagged_ptr) {
    return false;
  }

  void *ptr = ZEND_WEAKREF_GET_PTR(tagged_ptr);
  uintptr_t tag = ZEND_WEAKREF_GET_TAG(tagged_ptr);
  if (tag == ZEND_WEAKREF_TAG_REF) {
    zend_weakref *wr;
found_weakref:
    wr = ptr;
    RETVAL_OBJ_COPY(&wr->std);
    return true;
  }

  if (tag == ZEND_WEAKREF_TAG_HT) {
    ZEND_HASH_MAP_FOREACH_PTR(ptr, tagged_ptr) {
      if (ZEND_WEAKREF_GET_TAG(tagged_ptr) == ZEND_WEAKREF_TAG_REF) {
        ptr = ZEND_WEAKREF_GET_PTR(tagged_ptr);
        goto found_weakref;
      }
    } ZEND_HASH_FOREACH_END();
  }

  return false;
}

static zend_always_inline void zend_weakref_create(zend_object *referent, zval *return_value) {
  zend_weakref *wr;

  object_init_ex(return_value, zend_ce_weakref);

  wr = zend_weakref_fetch(return_value);
  wr->referent = referent;

  zend_weakref_register(wr->referent, ZEND_WEAKREF_ENCODE(wr, ZEND_WEAKREF_TAG_REF));
}

static zend_always_inline void zend_weakref_get(zval *weakref, zval *return_value) {
  zend_weakref *wr = zend_weakref_fetch(weakref);

  if (wr->referent) {
    RETVAL_OBJ_COPY(wr->referent);
  }
}

static void zend_weakref_free(zend_object *zo) {
  zend_weakref *wr = zend_weakref_from(zo);

  if (wr->referent) {
    zend_weakref_unregister(wr->referent, ZEND_WEAKREF_ENCODE(wr, ZEND_WEAKREF_TAG_REF), true);
  }

  zend_object_std_dtor(&wr->std);
}

static HashTable *zend_weakref_get_debug_info(zend_object *object, int *is_temp)
{
  *is_temp = 1;

  HashTable *ht = zend_new_array(1);

  zend_object *referent = zend_weakref_from(object)->referent;
  zval value;
  if (referent) {
    ZVAL_OBJ_COPY(&value, referent);
  } else {
    ZVAL_NULL(&value);
  }

  zend_hash_update(ht, ZSTR_KNOWN(ZEND_STR_OBJECT), &value);

  return ht;
}

ZEND_COLD ZEND_METHOD(WeakReference, __construct)
{
  zend_throw_error(NULL, "Direct instantiation of WeakReference is not allowed, use WeakReference::create instead");
}

ZEND_METHOD(WeakReference, create)
{
  zend_object *referent;

  ZEND_PARSE_PARAMETERS_START(1,1)
    Z_PARAM_OBJ(referent)
  ZEND_PARSE_PARAMETERS_END();

  if (zend_weakref_find(referent, return_value)) {
      return;
  }

  zend_weakref_create(referent, return_value);
}

ZEND_METHOD(WeakReference, get)
{
  ZEND_PARSE_PARAMETERS_NONE();

  zend_weakref_get(ZEND_THIS, return_value);
}

static zend_object *zend_weakmap_create_object(zend_class_entry *ce)
{
  zend_weakmap *wm = zend_object_alloc(sizeof(zend_weakmap), ce);
  zend_object_std_init(&wm->std, ce);

  zend_hash_init(&wm->ht, 0, NULL, ZVAL_PTR_DTOR, 0);
  return &wm->std;
}

static void zend_weakmap_free_obj(zend_object *object)
{
  zend_weakmap *wm = zend_weakmap_from(object);
  zend_weakrefs_hash_clean_ex(&wm->ht, ZEND_WEAKREF_TAG_MAP);
  zend_hash_destroy(&wm->ht);
  zend_object_std_dtor(&wm->std);
}

static zval *zend_weakmap_read_dimension(zend_object *object, zval *offset, int type, zval *rv)
{
  if (offset == NULL) {
    zend_throw_error(NULL, "Cannot append to WeakMap");
    return NULL;
  }

  ZVAL_DEREF(offset);
  if (Z_TYPE_P(offset) != IS_OBJECT) {
    zend_type_error("WeakMap key must be an object");
    return NULL;
  }

  zend_weakmap *wm = zend_weakmap_from(object);
  zend_object *obj_addr = Z_OBJ_P(offset);
  zval *zv = zend_hash_index_find(&wm->ht, zend_object_to_weakref_key(obj_addr));
  if (type == BP_VAR_W || type == BP_VAR_RW) {
    if (zv == NULL) {
      zval value;
      zend_weakref_register(obj_addr, ZEND_WEAKREF_ENCODE(&wm->ht, ZEND_WEAKREF_TAG_MAP));
      ZVAL_NULL(&value);
      zv = zend_hash_index_add_new(&wm->ht, zend_object_to_weakref_key(obj_addr), &value);
    }
    ZVAL_MAKE_REF(zv);
  } else {
    if (zv == NULL) {
      if (type != BP_VAR_IS) {
        zend_throw_error(NULL,
          "Object %s#%d not contained in WeakMap", ZSTR_VAL(obj_addr->ce->name), obj_addr->handle);
        return NULL;
      }
      return NULL;
    }
  }

  return zv;
}

static void zend_weakmap_write_dimension(zend_object *object, zval *offset, zval *value)
{
  if (offset == NULL) {
    zend_throw_error(NULL, "Cannot append to WeakMap");
    return;
  }

  ZVAL_DEREF(offset);
  if (Z_TYPE_P(offset) != IS_OBJECT) {
    zend_type_error("WeakMap key must be an object");
    return;
  }

  zend_weakmap *wm = zend_weakmap_from(object);
  zend_object *obj_addr = Z_OBJ_P(offset);
  zend_ulong obj_key = zend_object_to_weakref_key(obj_addr);
  Z_TRY_ADDREF_P(value);

  zval *zv = zend_hash_index_find(&wm->ht, obj_key);
  if (zv) {
    /* Because the destructors can have side effects such as resizing or rehashing the WeakMap storage,
     * free the zval only after overwriting the original value. */
    zval zv_orig;
    ZVAL_COPY_VALUE(&zv_orig, zv);
    ZVAL_COPY_VALUE(zv, value);
    zval_ptr_dtor(&zv_orig);
    return;
  }

  zend_weakref_register(obj_addr, ZEND_WEAKREF_ENCODE(&wm->ht, ZEND_WEAKREF_TAG_MAP));
  zend_hash_index_add_new(&wm->ht, obj_key, value);
}

// todo: make zend_weakmap_has_dimension return bool as well
/* int return and check_empty due to Object Handler API */
static int zend_weakmap_has_dimension(zend_object *object, zval *offset, int check_empty)
{
  ZVAL_DEREF(offset);
  if (Z_TYPE_P(offset) != IS_OBJECT) {
    zend_type_error("WeakMap key must be an object");
    return 0;
  }

  zend_weakmap *wm = zend_weakmap_from(object);
  zval *zv = zend_hash_index_find(&wm->ht, zend_object_to_weakref_key(Z_OBJ_P(offset)));
  if (!zv) {
    return 0;
  }

  if (check_empty) {
    return i_zend_is_true(zv);
  }
  return Z_TYPE_P(zv) != IS_NULL;
}

static void zend_weakmap_unset_dimension(zend_object *object, zval *offset)
{
  ZVAL_DEREF(offset);
  if (Z_TYPE_P(offset) != IS_OBJECT) {
    zend_type_error("WeakMap key must be an object");
    return;
  }

  zend_weakmap *wm = zend_weakmap_from(object);
  zend_object *obj_addr = Z_OBJ_P(offset);
  if (!zend_hash_index_exists(&wm->ht, zend_object_to_weakref_key(obj_addr))) {
    /* Object not in WeakMap, do nothing. */
    return;
  }

  zend_weakref_unregister(obj_addr, ZEND_WEAKREF_ENCODE(&wm->ht, ZEND_WEAKREF_TAG_MAP), true);
}

static zend_result zend_weakmap_count_elements(zend_object *object, zend_long *count)
{
  zend_weakmap *wm = zend_weakmap_from(object);
  *count = zend_hash_num_elements(&wm->ht);
  return SUCCESS;
}

static HashTable *zend_weakmap_get_properties_for(zend_object *object, zend_prop_purpose purpose)
{
  if (purpose != ZEND_PROP_PURPOSE_DEBUG) {
    return NULL;
  }

  zend_weakmap *wm = zend_weakmap_from(object);
  HashTable *ht;
  ALLOC_HASHTABLE(ht);
  zend_hash_init(ht, zend_hash_num_elements(&wm->ht), NULL, ZVAL_PTR_DTOR, 0);

  zend_ulong obj_key;
  zval *val;
  ZEND_HASH_MAP_FOREACH_NUM_KEY_VAL(&wm->ht, obj_key, val) {
    zend_object *obj = zend_weakref_key_to_object(obj_key);
    zval pair;
    array_init(&pair);

    GC_ADDREF(obj);
    add_assoc_object(&pair, "key", obj);
    Z_TRY_ADDREF_P(val);
    add_assoc_zval(&pair, "value", val);

    zend_hash_next_index_insert_new(ht, &pair);
  } ZEND_HASH_FOREACH_END();

  return ht;
}

HashTable *zend_weakmap_get_gc(zend_object *object, zval **table, int *n)
{
  zend_weakmap *wm = zend_weakmap_from(object);
  zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
  zval *val;
  ZEND_HASH_MAP_FOREACH_VAL(&wm->ht, val) {
    zend_get_gc_buffer_add_zval(gc_buffer, val);
  } ZEND_HASH_FOREACH_END();
  zend_get_gc_buffer_use(gc_buffer, table, n);
  return NULL;
}

HashTable *zend_weakmap_get_key_entry_gc(zend_object *object, zval **table, int *n)
{
  zend_weakmap *wm = zend_weakmap_from(object);
  zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
  zend_ulong h;
  zval *val;
  ZEND_HASH_MAP_FOREACH_NUM_KEY_VAL(&wm->ht, h, val) {
    zend_object *key = zend_weakref_key_to_object(h);
    zend_get_gc_buffer_add_obj(gc_buffer, key);
    zend_get_gc_buffer_add_ptr(gc_buffer, val);
  } ZEND_HASH_FOREACH_END();
  zend_get_gc_buffer_use(gc_buffer, table, n);
  return NULL;
}

HashTable *zend_weakmap_get_entry_gc(zend_object *object, zval **table, int *n)
{
  zend_weakmap *wm = zend_weakmap_from(object);
  zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
  zval *val;
  ZEND_HASH_MAP_FOREACH_VAL(&wm->ht, val) {
    zend_get_gc_buffer_add_ptr(gc_buffer, val);
  } ZEND_HASH_FOREACH_END();
  zend_get_gc_buffer_use(gc_buffer, table, n);
  return NULL;
}

HashTable *zend_weakmap_get_object_key_entry_gc(zend_object *object, zval **table, int *n)
{
  zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
  const zend_ulong obj_key = zend_object_to_weakref_key(object);
  void *tagged_ptr = zend_hash_index_find_ptr(&EG(weakrefs), obj_key);
#if ZEND_DEBUG
  ZEND_ASSERT(tagged_ptr && "Tracking of the IS_OBJ_WEAKLY_REFERENCE flag should be precise");
#endif
  void *ptr = ZEND_WEAKREF_GET_PTR(tagged_ptr);
  uintptr_t tag = ZEND_WEAKREF_GET_TAG(tagged_ptr);

  if (tag == ZEND_WEAKREF_TAG_HT) {
    HashTable *ht = ptr;
    ZEND_HASH_MAP_FOREACH_PTR(ht, tagged_ptr) {
      if (ZEND_WEAKREF_GET_TAG(tagged_ptr) == ZEND_WEAKREF_TAG_MAP) {
        zend_weakmap *wm = (zend_weakmap*) ZEND_WEAKREF_GET_PTR(tagged_ptr);
        zval *zv = zend_hash_index_find(&wm->ht, obj_key);
        ZEND_ASSERT(zv);
        zend_get_gc_buffer_add_ptr(gc_buffer, zv);
        zend_get_gc_buffer_add_obj(gc_buffer, &wm->std);
      } else if (ZEND_WEAKREF_GET_TAG(tagged_ptr) == ZEND_WEAKREF_TAG_BARE_HT) {
        /* Bare HashTables are intentionally ignored, since they are
         * intended for internal usage by extensions and might not be
         * collectable. */
      }
    } ZEND_HASH_FOREACH_END();
  } else if (tag == ZEND_WEAKREF_TAG_MAP) {
    zend_weakmap *wm = (zend_weakmap*) ptr;
    zval *zv = zend_hash_index_find(&wm->ht, obj_key);
    ZEND_ASSERT(zv);
    zend_get_gc_buffer_add_ptr(gc_buffer, zv);
    zend_get_gc_buffer_add_obj(gc_buffer, &wm->std);
  } else if (tag == ZEND_WEAKREF_TAG_BARE_HT) {
    /* Bare HashTables are intentionally ignored (see above) */
  }

  zend_get_gc_buffer_use(gc_buffer, table, n);

  return NULL;
}

HashTable *zend_weakmap_get_object_entry_gc(zend_object *object, zval **table, int *n)
{
  zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
  const zend_ulong obj_key = zend_object_to_weakref_key(object);
  void *tagged_ptr = zend_hash_index_find_ptr(&EG(weakrefs), obj_key);
#if ZEND_DEBUG
  ZEND_ASSERT(tagged_ptr && "Tracking of the IS_OBJ_WEAKLY_REFERENCE flag should be precise");
#endif
  void *ptr = ZEND_WEAKREF_GET_PTR(tagged_ptr);
  uintptr_t tag = ZEND_WEAKREF_GET_TAG(tagged_ptr);

  if (tag == ZEND_WEAKREF_TAG_HT) {
    HashTable *ht = ptr;
    ZEND_HASH_MAP_FOREACH_PTR(ht, tagged_ptr) {
      if (ZEND_WEAKREF_GET_TAG(tagged_ptr) == ZEND_WEAKREF_TAG_MAP) {
        zend_weakmap *wm = (zend_weakmap*) ZEND_WEAKREF_GET_PTR(tagged_ptr);
        zval *zv = zend_hash_index_find(&wm->ht, obj_key);
        ZEND_ASSERT(zv);
        zend_get_gc_buffer_add_ptr(gc_buffer, zv);
      } else if (ZEND_WEAKREF_GET_TAG(tagged_ptr) == ZEND_WEAKREF_TAG_BARE_HT) {
        /* Bare HashTables are intentionally ignored
         * (see zend_weakmap_get_object_key_entry_gc) */
      }
    } ZEND_HASH_FOREACH_END();
  } else if (tag == ZEND_WEAKREF_TAG_MAP) {
    zend_weakmap *wm = (zend_weakmap*) ptr;
    zval *zv = zend_hash_index_find(&wm->ht, obj_key);
    ZEND_ASSERT(zv);
    zend_get_gc_buffer_add_ptr(gc_buffer, zv);
  } else if (tag == ZEND_WEAKREF_TAG_BARE_HT) {
    /* Bare HashTables are intentionally ignored
     * (see zend_weakmap_get_object_key_entry_gc) */
  }

  zend_get_gc_buffer_use(gc_buffer, table, n);

  return NULL;
}

static zend_object *zend_weakmap_clone_obj(zend_object *old_object)
{
  zend_object *new_object = zend_weakmap_create_object(zend_ce_weakmap);
  zend_weakmap *old_wm = zend_weakmap_from(old_object);
  zend_weakmap *new_wm = zend_weakmap_from(new_object);
  zend_hash_copy(&new_wm->ht, &old_wm->ht, NULL);

  zend_ulong obj_key;
  zval *val;
  ZEND_HASH_MAP_FOREACH_NUM_KEY_VAL(&new_wm->ht, obj_key, val) {
    zend_weakref_register(
      zend_weakref_key_to_object(obj_key), ZEND_WEAKREF_ENCODE(new_wm, ZEND_WEAKREF_TAG_MAP));
    zval_add_ref(val);
  } ZEND_HASH_FOREACH_END();
  return new_object;
}

static HashPosition *zend_weakmap_iterator_get_pos_ptr(zend_weakmap_iterator *iter) {
  ZEND_ASSERT(iter->ht_iter != (uint32_t) -1);
  return &EG(ht_iterators)[iter->ht_iter].pos;
}

static void zend_weakmap_iterator_dtor(zend_object_iterator *obj_iter)
{
  zend_weakmap_iterator *iter = (zend_weakmap_iterator *) obj_iter;
  zend_hash_iterator_del(iter->ht_iter);
  zval_ptr_dtor(&iter->it.data);
}

static zend_result zend_weakmap_iterator_valid(zend_object_iterator *obj_iter)
{
  zend_weakmap_iterator *iter = (zend_weakmap_iterator *) obj_iter;
  zend_weakmap *wm = zend_weakmap_fetch(&iter->it.data);
  HashPosition *pos = zend_weakmap_iterator_get_pos_ptr(iter);
  return zend_hash_has_more_elements_ex(&wm->ht, pos);
}

static zval *zend_weakmap_iterator_get_current_data(zend_object_iterator *obj_iter)
{
  zend_weakmap_iterator *iter = (zend_weakmap_iterator *) obj_iter;
  zend_weakmap *wm = zend_weakmap_fetch(&iter->it.data);
  HashPosition *pos = zend_weakmap_iterator_get_pos_ptr(iter);
  return zend_hash_get_current_data_ex(&wm->ht, pos);
}

static void zend_weakmap_iterator_get_current_key(zend_object_iterator *obj_iter, zval *key)
{
  zend_weakmap_iterator *iter = (zend_weakmap_iterator *) obj_iter;
  zend_weakmap *wm = zend_weakmap_fetch(&iter->it.data);
  HashPosition *pos = zend_weakmap_iterator_get_pos_ptr(iter);

  zend_string *string_key;
  zend_ulong num_key;
  zend_hash_key_type key_type = zend_hash_get_current_key_ex(&wm->ht, &string_key, &num_key, pos);
  if (key_type == HASH_KEY_NON_EXISTENT) {
    ZVAL_NULL(key);
    return;
  }
  if (key_type != HASH_KEY_IS_LONG) {
    ZEND_ASSERT(0 && "Must have integer key");
  }

  ZVAL_OBJ_COPY(key, zend_weakref_key_to_object(num_key));
}

static void zend_weakmap_iterator_move_forward(zend_object_iterator *obj_iter)
{
  zend_weakmap_iterator *iter = (zend_weakmap_iterator *) obj_iter;
  zend_weakmap *wm = zend_weakmap_fetch(&iter->it.data);
  HashPosition *pos = zend_weakmap_iterator_get_pos_ptr(iter);
  zend_hash_move_forward_ex(&wm->ht, pos);
}

static void zend_weakmap_iterator_rewind(zend_object_iterator *obj_iter)
{
  zend_weakmap_iterator *iter = (zend_weakmap_iterator *) obj_iter;
  zend_weakmap *wm = zend_weakmap_fetch(&iter->it.data);
  HashPosition *pos = zend_weakmap_iterator_get_pos_ptr(iter);
  zend_hash_internal_pointer_reset_ex(&wm->ht, pos);
}

static const zend_object_iterator_funcs zend_weakmap_iterator_funcs = {
  zend_weakmap_iterator_dtor,
  zend_weakmap_iterator_valid,
  zend_weakmap_iterator_get_current_data,
  zend_weakmap_iterator_get_current_key,
  zend_weakmap_iterator_move_forward,
  zend_weakmap_iterator_rewind,
  NULL,
  NULL, /* get_gc */
};

/* by_ref is int due to Iterator API */
static zend_object_iterator *zend_weakmap_get_iterator(
    zend_class_entry *ce, zval *object, int by_ref)
{
  zend_weakmap *wm = zend_weakmap_fetch(object);
  zend_weakmap_iterator *iter = emalloc(sizeof(zend_weakmap_iterator));
  zend_iterator_init(&iter->it);
  iter->it.funcs = &zend_weakmap_iterator_funcs;
  ZVAL_COPY(&iter->it.data, object);
  iter->ht_iter = zend_hash_iterator_add(&wm->ht, 0);
  return &iter->it;
}

ZEND_METHOD(WeakMap, offsetGet)
{
  zval *key;

  if (zend_parse_parameters(ZEND_NUM_ARGS(), "z", &key) == FAILURE) {
    RETURN_THROWS();
  }

  zval *zv = zend_weakmap_read_dimension(Z_OBJ_P(ZEND_THIS), key, BP_VAR_R, NULL);
  if (!zv) {
    RETURN_THROWS();
  }

  RETURN_COPY_DEREF(zv);
}

ZEND_METHOD(WeakMap, offsetSet)
{
  zval *key, *value;

  if (zend_parse_parameters(ZEND_NUM_ARGS(), "zz", &key, &value) == FAILURE) {
    RETURN_THROWS();
  }

  zend_weakmap_write_dimension(Z_OBJ_P(ZEND_THIS), key, value);
}

ZEND_METHOD(WeakMap, offsetExists)
{
  zval *key;

  if (zend_parse_parameters(ZEND_NUM_ARGS(), "z", &key) == FAILURE) {
    RETURN_THROWS();
  }

  RETURN_BOOL(zend_weakmap_has_dimension(Z_OBJ_P(ZEND_THIS), key, /* check_empty */ 0));
}

ZEND_METHOD(WeakMap, offsetUnset)
{
  zval *key;

  if (zend_parse_parameters(ZEND_NUM_ARGS(), "z", &key) == FAILURE) {
    RETURN_THROWS();
  }

  zend_weakmap_unset_dimension(Z_OBJ_P(ZEND_THIS), key);
}

ZEND_METHOD(WeakMap, count)
{
  ZEND_PARSE_PARAMETERS_NONE();

  zend_long count;
  zend_weakmap_count_elements(Z_OBJ_P(ZEND_THIS), &count);
  RETURN_LONG(count);
}

ZEND_METHOD(WeakMap, getIterator)
{
  ZEND_PARSE_PARAMETERS_NONE();

  zend_create_internal_iterator_zval(return_value, ZEND_THIS);
}

void zend_register_weakref_ce(void) /* {{{ */
{
  zend_ce_weakref = register_class_WeakReference();

  zend_ce_weakref->create_object = zend_weakref_new;
  zend_ce_weakref->default_object_handlers = &zend_weakref_handlers;

  memcpy(&zend_weakref_handlers, zend_get_std_object_handlers(), sizeof(zend_object_handlers));
  zend_weakref_handlers.offset = offsetof(zend_weakref, std);

  zend_weakref_handlers.free_obj = zend_weakref_free;
  zend_weakref_handlers.get_debug_info = zend_weakref_get_debug_info;
  zend_weakref_handlers.clone_obj = NULL;

  zend_ce_weakmap = register_class_WeakMap(zend_ce_arrayaccess, zend_ce_countable, zend_ce_aggregate);

  zend_ce_weakmap->create_object = zend_weakmap_create_object;
  zend_ce_weakmap->get_iterator = zend_weakmap_get_iterator;
  zend_ce_weakmap->default_object_handlers = &zend_weakmap_handlers;

  memcpy(&zend_weakmap_handlers, zend_get_std_object_handlers(), sizeof(zend_object_handlers));
  zend_weakmap_handlers.offset = offsetof(zend_weakmap, std);
  zend_weakmap_handlers.free_obj = zend_weakmap_free_obj;
  zend_weakmap_handlers.read_dimension = zend_weakmap_read_dimension;
  zend_weakmap_handlers.write_dimension = zend_weakmap_write_dimension;
  zend_weakmap_handlers.has_dimension = zend_weakmap_has_dimension;
  zend_weakmap_handlers.unset_dimension = zend_weakmap_unset_dimension;
  zend_weakmap_handlers.count_elements = zend_weakmap_count_elements;
  zend_weakmap_handlers.get_properties_for = zend_weakmap_get_properties_for;
  zend_weakmap_handlers.get_gc = zend_weakmap_get_gc;
  zend_weakmap_handlers.clone_obj = zend_weakmap_clone_obj;
}
/* }}} */


Coverage Report

Created: 2026-06-02 06:39