/src/php-src/Zend/zend_generators.c

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/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) Zend Technologies Ltd. (http://www.zend.com)           |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: Nikita Popov <nikic@php.net>                                |
   |          Bob Weinand <bobwei9@hotmail.com>                           |
   +----------------------------------------------------------------------+
*/

#include "zend.h"
#include "zend_API.h"
#include "zend_hash.h"
#include "zend_interfaces.h"
#include "zend_exceptions.h"
#include "zend_generators.h"
#include "zend_closures.h"
#include "zend_generators_arginfo.h"
#include "zend_observer.h"
#include "zend_vm_opcodes.h"

ZEND_API zend_class_entry *zend_ce_generator;
ZEND_API zend_class_entry *zend_ce_ClosedGeneratorException;
static zend_object_handlers zend_generator_handlers;

static zend_object *zend_generator_create(zend_class_entry *class_type);

ZEND_API void zend_generator_restore_call_stack(zend_generator *generator) /* {{{ */
{
  zend_execute_data *call, *new_call, *prev_call = NULL;

  call = generator->frozen_call_stack;
  do {
    new_call = zend_vm_stack_push_call_frame(
      (ZEND_CALL_INFO(call) & ~ZEND_CALL_ALLOCATED),
      call->func,
      ZEND_CALL_NUM_ARGS(call),
      Z_PTR(call->This));
    memcpy(((zval*)new_call) + ZEND_CALL_FRAME_SLOT, ((zval*)call) + ZEND_CALL_FRAME_SLOT, ZEND_CALL_NUM_ARGS(call) * sizeof(zval));
    new_call->extra_named_params = call->extra_named_params;
    new_call->prev_execute_data = prev_call;
    prev_call = new_call;

    call = call->prev_execute_data;
  } while (call);
  generator->execute_data->call = prev_call;
  efree(generator->frozen_call_stack);
  generator->frozen_call_stack = NULL;
}
/* }}} */

ZEND_API zend_execute_data* zend_generator_freeze_call_stack(zend_execute_data *execute_data) /* {{{ */
{
  size_t used_stack;
  zend_execute_data *call, *new_call, *prev_call = NULL;
  zval *stack;

  /* calculate required stack size */
  used_stack = 0;
  call = EX(call);
  do {
    used_stack += ZEND_CALL_FRAME_SLOT + ZEND_CALL_NUM_ARGS(call);
    call = call->prev_execute_data;
  } while (call);

  stack = emalloc(used_stack * sizeof(zval));

  /* save stack, linking frames in reverse order */
  call = EX(call);
  do {
    size_t frame_size = ZEND_CALL_FRAME_SLOT + ZEND_CALL_NUM_ARGS(call);

    new_call = (zend_execute_data*)(stack + used_stack - frame_size);
    memcpy(new_call, call, frame_size * sizeof(zval));
    used_stack -= frame_size;
    new_call->prev_execute_data = prev_call;
    prev_call = new_call;

    new_call = call->prev_execute_data;
    zend_vm_stack_free_call_frame(call);
    call = new_call;
  } while (call);

  execute_data->call = NULL;
  ZEND_ASSERT(prev_call == (zend_execute_data*)stack);

  return prev_call;
}
/* }}} */

static zend_execute_data* zend_generator_revert_call_stack(zend_execute_data *call)
{
  zend_execute_data *prev = NULL;

  do {
    zend_execute_data *next = call->prev_execute_data;
    call->prev_execute_data = prev;
    prev = call;
    call = next;
  } while (call);

  return prev;
}

static void zend_generator_cleanup_unfinished_execution(
    zend_generator *generator, zend_execute_data *execute_data, uint32_t catch_op_num) /* {{{ */
{
  zend_op_array *op_array = &execute_data->func->op_array;
  if (execute_data->opline != op_array->opcodes) {
    uint32_t op_num = execute_data->opline - op_array->opcodes;

    if (UNEXPECTED(generator->frozen_call_stack)) {
      /* Temporarily restore generator->execute_data if it has been NULLed out already. */
      zend_execute_data *save_ex = generator->execute_data;
      generator->execute_data = execute_data;
      zend_generator_restore_call_stack(generator);
      generator->execute_data = save_ex;
    }

    zend_cleanup_unfinished_execution(execute_data, op_num, catch_op_num);
  }
}
/* }}} */

ZEND_API void zend_generator_close(zend_generator *generator, bool finished_execution) /* {{{ */
{
  if (EXPECTED(generator->execute_data)) {
    zend_execute_data *execute_data = generator->execute_data;
    /* Null out execute_data early, to prevent double frees if GC runs while we're
     * already cleaning up execute_data. */
    generator->execute_data = NULL;

    if (EX_CALL_INFO() & ZEND_CALL_HAS_SYMBOL_TABLE) {
      zend_clean_and_cache_symbol_table(execute_data->symbol_table);
    }
    /* always free the CV's, in the symtable are only not-free'd IS_INDIRECT's */
    zend_free_compiled_variables(execute_data);
    if (EX_CALL_INFO() & ZEND_CALL_HAS_EXTRA_NAMED_PARAMS) {
      zend_free_extra_named_params(execute_data->extra_named_params);
    }

    if (EX_CALL_INFO() & ZEND_CALL_RELEASE_THIS) {
      OBJ_RELEASE(Z_OBJ(execute_data->This));
    }

    /* A fatal error / die occurred during the generator execution.
     * Trying to clean up the stack may not be safe in this case. */
    if (UNEXPECTED(CG(unclean_shutdown))) {
      generator->execute_data = NULL;
      return;
    }

    zend_vm_stack_free_extra_args(execute_data);

    /* Some cleanups are only necessary if the generator was closed
     * before it could finish execution (reach a return statement). */
    if (UNEXPECTED(!finished_execution)) {
      zend_generator_cleanup_unfinished_execution(generator, execute_data, 0);
    }

    efree(execute_data);
  }
}
/* }}} */

static void zend_generator_remove_child(zend_generator_node *node, zend_generator *child)
{
  ZEND_ASSERT(node->children >= 1);
  if (node->children == 1) {
    node->child.single = NULL;
  } else {
    HashTable *ht = node->child.ht;
    zend_hash_index_del(ht, (zend_ulong) child);
    if (node->children == 2) {
      zend_generator *other_child;
      ZEND_HASH_FOREACH_PTR(ht, other_child) {
        node->child.single = other_child;
        break;
      } ZEND_HASH_FOREACH_END();
      zend_hash_destroy(ht);
      efree(ht);
    }
  }
  node->children--;
}

static zend_always_inline zend_generator *clear_link_to_leaf(zend_generator *generator) {
  ZEND_ASSERT(!generator->node.parent);
  zend_generator *leaf = generator->node.ptr.leaf;
  if (leaf) {
    leaf->node.ptr.root = NULL;
    generator->node.ptr.leaf = NULL;
    return leaf;
  }
  return NULL;
}

static zend_always_inline void clear_link_to_root(zend_generator *generator) {
  ZEND_ASSERT(generator->node.parent);
  if (generator->node.ptr.root) {
    generator->node.ptr.root->node.ptr.leaf = NULL;
    generator->node.ptr.root = NULL;
  }
}

/* Check if the node 'generator' is running in a fiber */
static inline bool check_node_running_in_fiber(zend_generator *generator) {
  ZEND_ASSERT(generator->execute_data);

  if (EXPECTED(generator->flags & ZEND_GENERATOR_IN_FIBER)) {
    return true;
  }

  if (EXPECTED(generator->node.children == 0)) {
    return false;
  }

  if (generator->node.children == 1) {
    return check_node_running_in_fiber(generator->node.child.single);
  }

  zend_generator *child;
  ZEND_HASH_FOREACH_PTR(generator->node.child.ht, child) {
    if (check_node_running_in_fiber(child)) {
      return true;
    }
  } ZEND_HASH_FOREACH_END();

  return false;
}

static void zend_generator_dtor_storage(zend_object *object) /* {{{ */
{
  zend_generator *generator = (zend_generator*) object;
  zend_generator *current_generator = zend_generator_get_current(generator);
  zend_execute_data *ex = generator->execute_data;
  uint32_t op_num, try_catch_offset;
  int i;

  /* If current_generator is running in a fiber, there are 2 cases to consider:
   *  - If generator is also marked with ZEND_GENERATOR_IN_FIBER, then the
   *    entire path from current_generator to generator is executing in a
   *    fiber. Do not dtor now: These will be dtor when terminating the fiber.
   *  - If generator is not marked with ZEND_GENERATOR_IN_FIBER, and has a
   *    child marked with ZEND_GENERATOR_IN_FIBER, then this an intermediate
   *    node of case 1. Otherwise generator is not executing in a fiber and we
   *    can dtor.
   */
  if (current_generator->flags & ZEND_GENERATOR_IN_FIBER) {
    if (check_node_running_in_fiber(generator)) {
      /* Prevent finally blocks from yielding */
      generator->flags |= ZEND_GENERATOR_FORCED_CLOSE;
      return;
    }
  }

  /* leave yield from mode to properly allow finally execution */
  if (UNEXPECTED(Z_TYPE(generator->values) != IS_UNDEF)) {
    zval_ptr_dtor(&generator->values);
    ZVAL_UNDEF(&generator->values);
  }

  zend_generator *parent = generator->node.parent;
  if (parent) {
    zend_generator_remove_child(&parent->node, generator);
    clear_link_to_root(generator);
    generator->node.parent = NULL;
    OBJ_RELEASE(&parent->std);
  } else {
    clear_link_to_leaf(generator);
  }

  if (EXPECTED(!ex) || EXPECTED(!(ex->func->op_array.fn_flags & ZEND_ACC_HAS_FINALLY_BLOCK))
      || CG(unclean_shutdown)) {
    zend_generator_close(generator, 0);
    return;
  }

  op_num = ex->opline - ex->func->op_array.opcodes;
  try_catch_offset = -1;

  /* Find the innermost try/catch that we are inside of. */
  for (i = 0; i < ex->func->op_array.last_try_catch; i++) {
    zend_try_catch_element *try_catch = &ex->func->op_array.try_catch_array[i];
    if (op_num < try_catch->try_op) {
      break;
    }
    if (op_num < try_catch->catch_op || op_num < try_catch->finally_end) {
      try_catch_offset = i;
    }
  }

  /* Walk try/catch/finally structures upwards, performing the necessary actions. */
  while (try_catch_offset != (uint32_t) -1) {
    zend_try_catch_element *try_catch = &ex->func->op_array.try_catch_array[try_catch_offset];

    if (op_num < try_catch->finally_op) {
      /* Go to finally block */
      zval *fast_call =
        ZEND_CALL_VAR(ex, ex->func->op_array.opcodes[try_catch->finally_end].op1.var);

      zend_generator_cleanup_unfinished_execution(generator, ex, try_catch->finally_op);
      zend_object *old_exception = EG(exception);
      const zend_op *old_opline_before_exception = EG(opline_before_exception);
      EG(exception) = NULL;
      Z_OBJ_P(fast_call) = NULL;
      Z_OPLINE_NUM_P(fast_call) = (uint32_t)-1;

      /* -1 because zend_generator_resume() will increment it */
      ex->opline = &ex->func->op_array.opcodes[try_catch->finally_op] - 1;
      generator->flags |= ZEND_GENERATOR_FORCED_CLOSE;
      zend_generator_resume(generator);

      if (old_exception) {
        EG(opline_before_exception) = old_opline_before_exception;
        if (EG(exception)) {
          zend_exception_set_previous(EG(exception), old_exception);
        } else {
          EG(exception) = old_exception;
        }
      }

      /* TODO: If we hit another yield inside try/finally,
       * should we also jump to the next finally block? */
      break;
    } else if (op_num < try_catch->finally_end) {
      zval *fast_call =
        ZEND_CALL_VAR(ex, ex->func->op_array.opcodes[try_catch->finally_end].op1.var);
      /* Clean up incomplete return statement */
      if (Z_OPLINE_NUM_P(fast_call) != (uint32_t) -1) {
        zend_op *retval_op = &ex->func->op_array.opcodes[Z_OPLINE_NUM_P(fast_call)];
        if (retval_op->op2_type & (IS_TMP_VAR | IS_VAR)) {
          zval_ptr_dtor(ZEND_CALL_VAR(ex, retval_op->op2.var));
        }
      }
      /* Clean up backed-up exception */
      if (Z_OBJ_P(fast_call)) {
        OBJ_RELEASE(Z_OBJ_P(fast_call));
      }
    }

    try_catch_offset--;
  }

  zend_generator_close(generator, 0);
}
/* }}} */

static void zend_generator_free_storage(zend_object *object) /* {{{ */
{
  zend_generator *generator = (zend_generator*) object;

  zend_generator_close(generator, 0);

  if (generator->func && (generator->func->common.fn_flags & ZEND_ACC_CLOSURE)) {
    OBJ_RELEASE(ZEND_CLOSURE_OBJECT(generator->func));
  }

  /* we can't immediately free them in zend_generator_close() else yield from won't be able to fetch it */
  zval_ptr_dtor(&generator->value);
  zval_ptr_dtor(&generator->key);

  if (EXPECTED(!Z_ISUNDEF(generator->retval))) {
    zval_ptr_dtor(&generator->retval);
  }

  if (UNEXPECTED(generator->node.children > 1)) {
    zend_hash_destroy(generator->node.child.ht);
    efree(generator->node.child.ht);
  }

  zend_object_std_dtor(&generator->std);
}
/* }}} */

HashTable *zend_generator_frame_gc(zend_get_gc_buffer *gc_buffer, zend_generator *generator)
{
  zend_execute_data *execute_data = generator->execute_data;
  zend_execute_data *call = NULL;

  zend_get_gc_buffer_add_zval(gc_buffer, &generator->value);
  zend_get_gc_buffer_add_zval(gc_buffer, &generator->key);
  zend_get_gc_buffer_add_zval(gc_buffer, &generator->retval);
  zend_get_gc_buffer_add_zval(gc_buffer, &generator->values);

  if (UNEXPECTED(generator->frozen_call_stack)) {
    /* The frozen stack is linked in reverse order */
    call = zend_generator_revert_call_stack(generator->frozen_call_stack);
  }

  HashTable *ht = zend_unfinished_execution_gc_ex(execute_data, call, gc_buffer, true);

  if (UNEXPECTED(generator->frozen_call_stack)) {
    zend_generator_revert_call_stack(call);
  }

  if (generator->node.parent) {
    zend_get_gc_buffer_add_obj(gc_buffer, &generator->node.parent->std);
  }

  return ht;
}

static HashTable *zend_generator_get_gc(zend_object *object, zval **table, int *n) /* {{{ */
{
  zend_generator *generator = (zend_generator*)object;
  zend_execute_data *execute_data = generator->execute_data;

  if (!execute_data) {
    if (UNEXPECTED(generator->func->common.fn_flags & ZEND_ACC_CLOSURE)) {
      zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
      zend_get_gc_buffer_add_zval(gc_buffer, &generator->value);
      zend_get_gc_buffer_add_zval(gc_buffer, &generator->key);
      zend_get_gc_buffer_add_zval(gc_buffer, &generator->retval);
      zend_get_gc_buffer_add_obj(gc_buffer, ZEND_CLOSURE_OBJECT(generator->func));
      zend_get_gc_buffer_use(gc_buffer, table, n);
    } else {
      /* If the non-closure generator has been closed, it can only hold on to three values: The value, key
       * and retval. These three zvals are stored sequentially starting at &generator->value. */
      *table = &generator->value;
      *n = 3;
    }
    return NULL;
  }

  if (generator->flags & ZEND_GENERATOR_CURRENTLY_RUNNING) {
    /* If the generator is currently running, we certainly won't be able to GC any values it
     * holds on to. The execute_data state might be inconsistent during execution (e.g. because
     * GC has been triggered in the middle of a variable reassignment), so we should not try
     * to inspect it here. */
    *table = NULL;
    *n = 0;
    return NULL;
  }

  zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
  HashTable *ht = zend_generator_frame_gc(gc_buffer, generator);
  zend_get_gc_buffer_use(gc_buffer, table, n);

  return ht;
}
/* }}} */

static zend_object *zend_generator_create(zend_class_entry *class_type) /* {{{ */
{
  zend_generator *generator = emalloc(sizeof(zend_generator));
  memset(generator, 0, sizeof(zend_generator));

  /* The key will be incremented on first use, so it'll start at 0 */
  generator->largest_used_integer_key = -1;

  ZVAL_UNDEF(&generator->retval);
  ZVAL_UNDEF(&generator->values);

  /* By default we have a tree of only one node */
  generator->node.parent = NULL;
  generator->node.children = 0;
  generator->node.ptr.root = NULL;

  zend_object_std_init(&generator->std, class_type);
  return (zend_object*)generator;
}
/* }}} */

static ZEND_COLD zend_function *zend_generator_get_constructor(zend_object *object) /* {{{ */
{
  zend_throw_error(NULL, "The \"Generator\" class is reserved for internal use and cannot be manually instantiated");

  return NULL;
}
/* }}} */

ZEND_API zend_execute_data *zend_generator_check_placeholder_frame(zend_execute_data *ptr)
{
  if (!ptr->func && Z_TYPE(ptr->This) == IS_OBJECT) {
    if (Z_OBJCE(ptr->This) == zend_ce_generator) {
      zend_generator *generator = (zend_generator *) Z_OBJ(ptr->This);
      zend_execute_data *prev = ptr->prev_execute_data;
      ZEND_ASSERT(generator->node.parent && "Placeholder only used with delegation");
      while (generator->node.parent->node.parent) {
        generator->execute_data->prev_execute_data = prev;
        prev = generator->execute_data;
        generator = generator->node.parent;
      }
      generator->execute_data->prev_execute_data = prev;
      ptr = generator->execute_data;
    }
  }
  return ptr;
}

static void zend_generator_throw_exception(zend_generator *generator, zval *exception)
{
  zend_execute_data *original_execute_data = EG(current_execute_data);

  /* Throw the exception in the context of the generator. Decrementing the opline
   * to pretend the exception happened during the YIELD opcode. */
  EG(current_execute_data) = generator->execute_data;
  generator->execute_data->prev_execute_data = original_execute_data;

  if (exception) {
    zend_throw_exception_object(exception);
  } else {
    zend_rethrow_exception(EG(current_execute_data));
  }

  /* if we don't stop an array/iterator yield from, the exception will only reach the generator after the values were all iterated over */
  if (UNEXPECTED(Z_TYPE(generator->values) != IS_UNDEF)) {
    zval_ptr_dtor(&generator->values);
    ZVAL_UNDEF(&generator->values);
  }

  EG(current_execute_data) = original_execute_data;
}

static void zend_generator_add_child(zend_generator *generator, zend_generator *child)
{
  zend_generator_node *node = &generator->node;

  if (node->children == 0) {
    node->child.single = child;
  } else {
    if (node->children == 1) {
      HashTable *ht = emalloc(sizeof(HashTable));
      zend_hash_init(ht, 0, NULL, NULL, 0);
      zend_hash_index_add_new_ptr(ht,
        (zend_ulong) node->child.single, node->child.single);
      node->child.ht = ht;
    }

    zend_hash_index_add_new_ptr(node->child.ht, (zend_ulong) child, child);
  }

  ++node->children;
}

void zend_generator_yield_from(zend_generator *generator, zend_generator *from)
{
  ZEND_ASSERT(!generator->node.parent && "Already has parent?");
  zend_generator *leaf = clear_link_to_leaf(generator);
  if (leaf && !from->node.parent && !from->node.ptr.leaf) {
    from->node.ptr.leaf = leaf;
    leaf->node.ptr.root = from;
  }
  generator->node.parent = from;
  zend_generator_add_child(from, generator);
  generator->flags |= ZEND_GENERATOR_DO_INIT;
}

ZEND_API zend_generator *zend_generator_update_root(zend_generator *generator)
{
  zend_generator *root = generator->node.parent;
  while (root->node.parent) {
    root = root->node.parent;
  }

  clear_link_to_leaf(root);
  root->node.ptr.leaf = generator;
  generator->node.ptr.root = root;
  return root;
}

static zend_generator *get_new_root(zend_generator *generator, zend_generator *root)
{
  while (!root->execute_data && root->node.children == 1) {
    root = root->node.child.single;
  }

  if (root->execute_data) {
    return root;
  }

  /* We have reached a multi-child node haven't found the root yet. We don't know which
   * child to follow, so perform the search from the other direction instead. */
  while (generator->node.parent->execute_data) {
    generator = generator->node.parent;
  }

  return generator;
}

ZEND_API zend_generator *zend_generator_update_current(zend_generator *generator)
{
  zend_generator *old_root = generator->node.ptr.root;
  ZEND_ASSERT(!old_root->execute_data && "Nothing to update?");

  zend_generator *new_root = get_new_root(generator, old_root);

  ZEND_ASSERT(old_root->node.ptr.leaf == generator);
  generator->node.ptr.root = new_root;
  new_root->node.ptr.leaf = generator;
  old_root->node.ptr.leaf = NULL;

  zend_generator *new_root_parent = new_root->node.parent;
  ZEND_ASSERT(new_root_parent);
  zend_generator_remove_child(&new_root_parent->node, new_root);

  if (EXPECTED(EG(exception) == NULL) && EXPECTED((OBJ_FLAGS(&generator->std) & IS_OBJ_DESTRUCTOR_CALLED) == 0)) {
    zend_op *yield_from = (zend_op *) new_root->execute_data->opline;

    if (yield_from->opcode == ZEND_YIELD_FROM) {
      if (Z_ISUNDEF(new_root_parent->retval)) {
        /* Throw the exception in the context of the generator */
        zend_execute_data *original_execute_data = EG(current_execute_data);
        EG(current_execute_data) = new_root->execute_data;

        if (new_root == generator) {
          new_root->execute_data->prev_execute_data = original_execute_data;
        } else {
          new_root->execute_data->prev_execute_data = &generator->execute_fake;
          generator->execute_fake.prev_execute_data = original_execute_data;
        }

        zend_throw_exception(zend_ce_ClosedGeneratorException, "Generator yielded from aborted, no return value available", 0);

        EG(current_execute_data) = original_execute_data;

        if (!(old_root->flags & ZEND_GENERATOR_CURRENTLY_RUNNING)) {
          new_root->node.parent = NULL;
          OBJ_RELEASE(&new_root_parent->std);
          zend_generator_resume(generator);
          return zend_generator_get_current(generator);
        }
      } else {
        zval_ptr_dtor(&new_root->value);
        ZVAL_COPY(&new_root->value, &new_root_parent->value);
        ZVAL_COPY(ZEND_CALL_VAR(new_root->execute_data, yield_from->result.var), &new_root_parent->retval);
      }
    }
  }

  new_root->node.parent = NULL;
  OBJ_RELEASE(&new_root_parent->std);

  return new_root;
}

static zend_result zend_generator_get_next_delegated_value(zend_generator *generator) /* {{{ */
{
  zval *value;
  if (Z_TYPE(generator->values) == IS_ARRAY) {
    HashTable *ht = Z_ARR(generator->values);
    HashPosition pos = Z_FE_POS(generator->values);

    if (HT_IS_PACKED(ht)) {
      do {
        if (UNEXPECTED(pos >= ht->nNumUsed)) {
          /* Reached end of array */
          goto failure;
        }

        value = &ht->arPacked[pos];
        pos++;
      } while (Z_ISUNDEF_P(value));

      zval_ptr_dtor(&generator->value);
      ZVAL_COPY(&generator->value, value);

      zval_ptr_dtor(&generator->key);
      ZVAL_LONG(&generator->key, pos - 1);
    } else {
      Bucket *p;

      do {
        if (UNEXPECTED(pos >= ht->nNumUsed)) {
          /* Reached end of array */
          goto failure;
        }

        p = &ht->arData[pos];
        value = &p->val;
        pos++;
      } while (Z_ISUNDEF_P(value));

      zval_ptr_dtor(&generator->value);
      ZVAL_COPY(&generator->value, value);

      zval_ptr_dtor(&generator->key);
      if (p->key) {
        ZVAL_STR_COPY(&generator->key, p->key);
      } else {
        ZVAL_LONG(&generator->key, p->h);
      }
    }
    Z_FE_POS(generator->values) = pos;
  } else {
    zend_object_iterator *iter = (zend_object_iterator *) Z_OBJ(generator->values);

    if (iter->index++ > 0) {
      iter->funcs->move_forward(iter);
      if (UNEXPECTED(EG(exception) != NULL)) {
        goto failure;
      }
    }

    if (iter->funcs->valid(iter) == FAILURE) {
      /* reached end of iteration */
      goto failure;
    }

    value = iter->funcs->get_current_data(iter);
    if (UNEXPECTED(EG(exception) != NULL) || UNEXPECTED(!value)) {
      goto failure;
    }

    zval_ptr_dtor(&generator->value);
    ZVAL_COPY(&generator->value, value);

    zval_ptr_dtor(&generator->key);
    if (iter->funcs->get_current_key) {
      iter->funcs->get_current_key(iter, &generator->key);
      if (UNEXPECTED(EG(exception) != NULL)) {
        ZVAL_UNDEF(&generator->key);
        goto failure;
      }
    } else {
      ZVAL_LONG(&generator->key, iter->index);
    }
  }

  return SUCCESS;

failure:
  zval_ptr_dtor(&generator->values);
  ZVAL_UNDEF(&generator->values);

  return FAILURE;
}
/* }}} */

ZEND_API void zend_generator_resume(zend_generator *orig_generator) /* {{{ */
{
  zend_generator *generator = zend_generator_get_current(orig_generator);

  /* The generator is already closed, thus can't resume */
  if (UNEXPECTED(!generator->execute_data)) {
    return;
  }

try_again:
  if (generator->flags & ZEND_GENERATOR_CURRENTLY_RUNNING) {
    zend_throw_error(NULL, "Cannot resume an already running generator");
    return;
  }

  if (UNEXPECTED((orig_generator->flags & ZEND_GENERATOR_DO_INIT) != 0 && !Z_ISUNDEF(generator->value))) {
    /* We must not advance Generator if we yield from a Generator being currently run */
    orig_generator->flags &= ~ZEND_GENERATOR_DO_INIT;
    return;
  }

  if (EG(active_fiber)) {
    orig_generator->flags |= ZEND_GENERATOR_IN_FIBER;
    generator->flags |= ZEND_GENERATOR_IN_FIBER;
  }

  /* Drop the AT_FIRST_YIELD flag */
  orig_generator->flags &= ~ZEND_GENERATOR_AT_FIRST_YIELD;

  /* Backup executor globals */
  zend_execute_data *original_execute_data = EG(current_execute_data);
  uint32_t original_jit_trace_num = EG(jit_trace_num);

  /* Set executor globals */
  EG(current_execute_data) = generator->execute_data;
  EG(jit_trace_num) = 0;

  /* We want the backtrace to look as if the generator function was
   * called from whatever method we are current running (e.g. next()).
   * So we have to link generator call frame with caller call frame. */
  if (generator == orig_generator) {
    generator->execute_data->prev_execute_data = original_execute_data;
  } else {
    /* We need some execute_data placeholder in stacktrace to be replaced
     * by the real stack trace when needed */
    generator->execute_data->prev_execute_data = &orig_generator->execute_fake;
    orig_generator->execute_fake.prev_execute_data = original_execute_data;
  }

  /* Ensure this is run after executor_data swap to have a proper stack trace */
  if (UNEXPECTED(!Z_ISUNDEF(generator->values))) {
    if (EXPECTED(zend_generator_get_next_delegated_value(generator) == SUCCESS)) {
      /* Restore executor globals */
      EG(current_execute_data) = original_execute_data;
      EG(jit_trace_num) = original_jit_trace_num;

      orig_generator->flags &= ~(ZEND_GENERATOR_DO_INIT | ZEND_GENERATOR_IN_FIBER);
      generator->flags &= ~ZEND_GENERATOR_IN_FIBER;
      return;
    }
    /* If there are no more delegated values, resume the generator
     * after the "yield from" expression. */
  }

  if (UNEXPECTED(generator->frozen_call_stack)) {
    /* Restore frozen call-stack */
    zend_generator_restore_call_stack(generator);
  }

  /* Resume execution */
  ZEND_ASSERT(generator->execute_data->opline->opcode == ZEND_GENERATOR_CREATE
      || generator->execute_data->opline->opcode == ZEND_YIELD
      || generator->execute_data->opline->opcode == ZEND_YIELD_FROM
      /* opline points to EG(exception_op), which is a sequence of
       * ZEND_HANDLE_EXCEPTION ops, so the following increment is safe */
      || generator->execute_data->opline->opcode == ZEND_HANDLE_EXCEPTION
      /* opline points to the start of a finally block minus one op to
       * account for the following increment */
      || (generator->flags & ZEND_GENERATOR_FORCED_CLOSE));
  generator->execute_data->opline++;
  generator->flags |= ZEND_GENERATOR_CURRENTLY_RUNNING;
  if (!ZEND_OBSERVER_ENABLED) {
    zend_execute_ex(generator->execute_data);
  } else {
    zend_observer_generator_resume(generator->execute_data);
    zend_execute_ex(generator->execute_data);
    if (generator->execute_data) {
      /* On the final return, this will be called from ZEND_GENERATOR_RETURN */
      zend_observer_fcall_end(generator->execute_data, &generator->value);
    }
  }
  generator->flags &= ~(ZEND_GENERATOR_CURRENTLY_RUNNING | ZEND_GENERATOR_IN_FIBER);

  generator->frozen_call_stack = NULL;
  if (EXPECTED(generator->execute_data) &&
    UNEXPECTED(generator->execute_data->call)) {
    /* Frize call-stack */
    generator->frozen_call_stack = zend_generator_freeze_call_stack(generator->execute_data);
  }

  /* Restore executor globals */
  EG(current_execute_data) = original_execute_data;
  EG(jit_trace_num) = original_jit_trace_num;

  /* If an exception was thrown in the generator we have to internally
   * rethrow it in the parent scope.
   * In case we did yield from, the Exception must be rethrown into
   * its calling frame (see above in if (check_yield_from). */
  if (UNEXPECTED(EG(exception) != NULL)) {
    if (generator == orig_generator) {
      zend_generator_close(generator, 0);
      if (!EG(current_execute_data)) {
        zend_throw_exception_internal(NULL);
      } else if (EG(current_execute_data)->func &&
          ZEND_USER_CODE(EG(current_execute_data)->func->common.type)) {
        zend_rethrow_exception(EG(current_execute_data));
      }
    } else {
      generator = zend_generator_get_current(orig_generator);
      zend_generator_throw_exception(generator, NULL);
      orig_generator->flags &= ~ZEND_GENERATOR_DO_INIT;
      goto try_again;
    }
  }

  /* yield from was used, try another resume. */
  if (UNEXPECTED((generator != orig_generator && !Z_ISUNDEF(generator->retval)) || (generator->execute_data && generator->execute_data->opline->opcode == ZEND_YIELD_FROM))) {
    generator = zend_generator_get_current(orig_generator);
    goto try_again;
  }

  orig_generator->flags &= ~(ZEND_GENERATOR_DO_INIT | ZEND_GENERATOR_IN_FIBER);
}
/* }}} */

static inline void zend_generator_ensure_initialized(zend_generator *generator) /* {{{ */
{
  if (UNEXPECTED(Z_TYPE(generator->value) == IS_UNDEF) && EXPECTED(generator->execute_data) && EXPECTED(generator->node.parent == NULL)) {
    zend_generator_resume(generator);
    generator->flags |= ZEND_GENERATOR_AT_FIRST_YIELD;
  }
}
/* }}} */

static inline void zend_generator_rewind(zend_generator *generator) /* {{{ */
{
  zend_generator_ensure_initialized(generator);

  if (!(generator->flags & ZEND_GENERATOR_AT_FIRST_YIELD)) {
    zend_throw_exception(NULL, "Cannot rewind a generator that was already run", 0);
  }
}
/* }}} */

/* {{{ Rewind the generator */
ZEND_METHOD(Generator, rewind)
{
  zend_generator *generator;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_rewind(generator);
}
/* }}} */

/* {{{ Check whether the generator is valid */
ZEND_METHOD(Generator, valid)
{
  zend_generator *generator;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);

  zend_generator_get_current(generator);

  RETURN_BOOL(EXPECTED(generator->execute_data != NULL));
}
/* }}} */

/* {{{ Get the current value */
ZEND_METHOD(Generator, current)
{
  zend_generator *generator, *root;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);

  root = zend_generator_get_current(generator);
  if (EXPECTED(generator->execute_data != NULL && Z_TYPE(root->value) != IS_UNDEF)) {
    RETURN_COPY_DEREF(&root->value);
  }
}
/* }}} */

/* {{{ Get the current key */
ZEND_METHOD(Generator, key)
{
  zend_generator *generator, *root;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);

  root = zend_generator_get_current(generator);
  if (EXPECTED(generator->execute_data != NULL && Z_TYPE(root->key) != IS_UNDEF)) {
    RETURN_COPY_DEREF(&root->key);
  }
}
/* }}} */

/* {{{ Advances the generator */
ZEND_METHOD(Generator, next)
{
  zend_generator *generator;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);

  zend_generator_resume(generator);
}
/* }}} */

/* {{{ Sends a value to the generator */
ZEND_METHOD(Generator, send)
{
  zval *value;
  zend_generator *generator, *root;

  ZEND_PARSE_PARAMETERS_START(1, 1)
    Z_PARAM_ZVAL(value)
  ZEND_PARSE_PARAMETERS_END();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);

  /* The generator is already closed, thus can't send anything */
  if (UNEXPECTED(!generator->execute_data)) {
    return;
  }

  root = zend_generator_get_current(generator);
  /* Put sent value in the target VAR slot, if it is used */
  if (root->send_target && !(root->flags & ZEND_GENERATOR_CURRENTLY_RUNNING)) {
    ZVAL_COPY(root->send_target, value);
  }

  zend_generator_resume(generator);

  root = zend_generator_get_current(generator);
  if (EXPECTED(generator->execute_data)) {
    RETURN_COPY_DEREF(&root->value);
  }
}
/* }}} */

/* {{{ Throws an exception into the generator */
ZEND_METHOD(Generator, throw)
{
  zval *exception;
  zend_generator *generator;

  ZEND_PARSE_PARAMETERS_START(1, 1)
    Z_PARAM_OBJECT_OF_CLASS(exception, zend_ce_throwable);
  ZEND_PARSE_PARAMETERS_END();

  Z_TRY_ADDREF_P(exception);

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);

  if (generator->execute_data) {
    zend_generator *root = zend_generator_get_current(generator);

    zend_generator_throw_exception(root, exception);

    zend_generator_resume(generator);

    root = zend_generator_get_current(generator);
    if (generator->execute_data) {
      RETURN_COPY_DEREF(&root->value);
    }
  } else {
    /* If the generator is already closed throw the exception in the
     * current context */
    zend_throw_exception_object(exception);
  }
}
/* }}} */

/* {{{ Retrieves the return value of the generator */
ZEND_METHOD(Generator, getReturn)
{
  zend_generator *generator;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  zend_generator_ensure_initialized(generator);
  if (UNEXPECTED(EG(exception))) {
    return;
  }

  if (Z_ISUNDEF(generator->retval)) {
    /* Generator hasn't returned yet -> error! */
    zend_throw_exception(NULL,
      "Cannot get return value of a generator that hasn't returned", 0);
    return;
  }

  ZVAL_COPY(return_value, &generator->retval);
}
/* }}} */

ZEND_METHOD(Generator, __debugInfo)
{
  zend_generator *generator;

  ZEND_PARSE_PARAMETERS_NONE();

  generator = (zend_generator *) Z_OBJ_P(ZEND_THIS);

  array_init(return_value);

  zend_function *func = generator->func;

  zval val;
  if (func->common.scope) {
    zend_string *class_name = func->common.scope->name;
    zend_string *func_name = func->common.function_name;
    zend_string *combined = zend_string_concat3(
      ZSTR_VAL(class_name), ZSTR_LEN(class_name),
      "::", strlen("::"),
      ZSTR_VAL(func_name), ZSTR_LEN(func_name)
    );
    ZVAL_NEW_STR(&val, combined);
  } else {
    ZVAL_STR_COPY(&val, func->common.function_name);
  }

  zend_hash_update(Z_ARR_P(return_value), ZSTR_KNOWN(ZEND_STR_FUNCTION), &val);
}

/* get_iterator implementation */

static void zend_generator_iterator_dtor(zend_object_iterator *iterator) /* {{{ */
{
  zval_ptr_dtor(&iterator->data);
}
/* }}} */

static zend_result zend_generator_iterator_valid(zend_object_iterator *iterator) /* {{{ */
{
  zend_generator *generator = (zend_generator*)Z_OBJ(iterator->data);

  zend_generator_ensure_initialized(generator);

  zend_generator_get_current(generator);

  return generator->execute_data ? SUCCESS : FAILURE;
}
/* }}} */

static zval *zend_generator_iterator_get_data(zend_object_iterator *iterator) /* {{{ */
{
  zend_generator *generator = (zend_generator*)Z_OBJ(iterator->data), *root;

  zend_generator_ensure_initialized(generator);

  root = zend_generator_get_current(generator);

  return &root->value;
}
/* }}} */

static void zend_generator_iterator_get_key(zend_object_iterator *iterator, zval *key) /* {{{ */
{
  zend_generator *generator = (zend_generator*)Z_OBJ(iterator->data), *root;

  zend_generator_ensure_initialized(generator);

  root = zend_generator_get_current(generator);

  if (EXPECTED(Z_TYPE(root->key) != IS_UNDEF)) {
    zval *zv = &root->key;

    ZVAL_COPY_DEREF(key, zv);
  } else {
    ZVAL_NULL(key);
  }
}
/* }}} */

static void zend_generator_iterator_move_forward(zend_object_iterator *iterator) /* {{{ */
{
  zend_generator *generator = (zend_generator*)Z_OBJ(iterator->data);

  zend_generator_ensure_initialized(generator);

  zend_generator_resume(generator);
}
/* }}} */

static void zend_generator_iterator_rewind(zend_object_iterator *iterator) /* {{{ */
{
  zend_generator *generator = (zend_generator*)Z_OBJ(iterator->data);

  zend_generator_rewind(generator);
}
/* }}} */

static HashTable *zend_generator_iterator_get_gc(
    zend_object_iterator *iterator, zval **table, int *n)
{
  *table = &iterator->data;
  *n = 1;
  return NULL;
}

static const zend_object_iterator_funcs zend_generator_iterator_functions = {
  zend_generator_iterator_dtor,
  zend_generator_iterator_valid,
  zend_generator_iterator_get_data,
  zend_generator_iterator_get_key,
  zend_generator_iterator_move_forward,
  zend_generator_iterator_rewind,
  NULL,
  zend_generator_iterator_get_gc,
};

/* by_ref is int due to Iterator API */
static zend_object_iterator *zend_generator_get_iterator(zend_class_entry *ce, zval *object, int by_ref) /* {{{ */
{
  zend_object_iterator *iterator;
  zend_generator *generator = (zend_generator*)Z_OBJ_P(object);

  if (!generator->execute_data) {
    zend_throw_exception(NULL, "Cannot traverse an already closed generator", 0);
    return NULL;
  }

  if (UNEXPECTED(by_ref) && !(generator->execute_data->func->op_array.fn_flags & ZEND_ACC_RETURN_REFERENCE)) {
    zend_throw_exception(NULL, "You can only iterate a generator by-reference if it declared that it yields by-reference", 0);
    return NULL;
  }

  iterator = emalloc(sizeof(zend_object_iterator));
  zend_iterator_init(iterator);

  iterator->funcs = &zend_generator_iterator_functions;
  ZVAL_OBJ_COPY(&iterator->data, Z_OBJ_P(object));

  return iterator;
}
/* }}} */

void zend_register_generator_ce(void) /* {{{ */
{
  zend_ce_generator = register_class_Generator(zend_ce_iterator);
  zend_ce_generator->create_object = zend_generator_create;
  /* get_iterator has to be assigned *after* implementing the interface */
  zend_ce_generator->get_iterator = zend_generator_get_iterator;
  zend_ce_generator->default_object_handlers = &zend_generator_handlers;

  memcpy(&zend_generator_handlers, &std_object_handlers, sizeof(zend_object_handlers));
  zend_generator_handlers.free_obj = zend_generator_free_storage;
  zend_generator_handlers.dtor_obj = zend_generator_dtor_storage;
  zend_generator_handlers.get_gc = zend_generator_get_gc;
  zend_generator_handlers.clone_obj = NULL;
  zend_generator_handlers.get_constructor = zend_generator_get_constructor;

  zend_ce_ClosedGeneratorException = register_class_ClosedGeneratorException(zend_ce_exception);
}
/* }}} */

Coverage Report

Created: 2025-06-13 06:43