PHP Extensions - Still Alive and Full of Hidden Powers

With PHP gaining more and more features, are PHP extensions still necessary? Beyond just accessing system libraries, extensions unlock capabilities that pure PHP code still can’t replicate. Imagine defining custom behaviors for operators, enabling intuitive syntax through operator overloading, or tailoring equality checks with flexible object comparisons—these are things only possible in an extension. Extensions even allow objects to be cast to scalar types like int or string, adding versatility to how they’re used. In this talk, we’ll dive into some of the coolest things extensions make possible, pushing PHP beyond its usual boundaries. And yes, we’ll also explore when extensions can be taken a little too far, showing that just because something can be done doesn’t always mean it should be!

Transcript

1. Still Alive and Full of Hidden Powers PHP Extensions
2. whoami
3. Why Extensions?
4. $this->prop = 'value';
5. zend_update_property_string( showcase_cartesianvector_ce, Z_OBJ_P(getThis()), ZEND_STRL("prop"), "value" );
6. Cartesian Vectors
7. ChatGPT o3-mini-high A Cartesian vector is an ordered tuple of numbers representing a vector’s components along the mutually perpendicular axes of a Cartesian coordinate system.
8. X X Y Y Z Z O O x x y y z z (x,y,z) (x,y,z)
9. final readonly class CartesianVector { public function __construct( public float $x, public float $y, public float $z, ) {} public function equals(self $vector): bool {} public function add(self $vector): self {} public function subtract(self $vector): self {} public function multiply(float $scalar): self {} public function divide(float $scalar): self {} }
10. Comparison
11. $vector = new CartesianVector(1, 2, 3); $other = new CartesianVector(1, 2, 3); var_dump($vector->equals($other)); // bool(true)
12. $vector = new CartesianVector(1, 2, 3); $other = new CartesianVector(1, 2, 3); var_dump($vector == $other); var_dump($vector === $other); // bool(true) // bool(false)
13. var_dump($vector > $other); var_dump($vector == 5); var_dump($vector > 5);
14. bool(false) Notice: Object of class CartesianVector could not be converted to int bool(false) Notice: Object of class CartesianVector could not be converted to int bool(false)
15. Comparison Operators
16. Type Casts
17. var_dump((string) $vector);
18. final readonly class CartesianVector implements Stringable { public function __toString(): string { return sprintf( '(%f, %f, %f)', $this->x, $this->y, $this->z, ); } }
19. var_dump((float) $vector);
20. Warning: Object of class CartesianVector could not be converted to float float(1)
21. Type Casts
22. Arithmetic
23. $vector = new CartesianVector(1, 2, 3); $other = new CartesianVector(2, -3, 5); var_dump($vector->add($other)); var_dump($vector->subtract($other)); var_dump($vector->multiply(2)); var_dump($vector->divide(2));
24. $vector = new CartesianVector(1, 2, 3); $other = new CartesianVector(2, -3, 5); var_dump($vector + $other); var_dump($vector - $other); var_dump($vector * 2); var_dump($vector / 2);
25. Unsupported operand types: CartesianVector + CartesianVector
26. Arithmetic Operators
27. Why Extensions?
28. struct _zend_object_handlers { // ... zend_object_cast_t cast_object; zend_object_do_operation_t do_operation; zend_object_compare_t compare; };
29. final readonly class CartesianVector { public function __construct( public float $x, public float $y, public float $z, ) {} }
30. zend_class_entry ce, *class_entry; INIT_NS_CLASS_ENTRY( ce, "Showcase\\Math", "CartesianVector", class_CartesianVector_methods ); class_entry = zend_register_internal_class_with_flags( &ce, NULL, ZEND_ACC_FINAL|ZEND_ACC_READONLY_CLASS );
31. static const zend_function_entry class_CartesianVector_methods[] = { ZEND_ME( CartesianVector, __construct, arginfo_class_CartesianVector___construct, ZEND_ACC_PUBLIC ) ZEND_FE_END };
32. ZEND_BEGIN_ARG_INFO_EX( arginfo_class_CartesianVector___construct, 0, 0, 3 ) ZEND_ARG_TYPE_INFO(0, x, IS_DOUBLE, 0) ZEND_ARG_TYPE_INFO(0, y, IS_DOUBLE, 0) ZEND_ARG_TYPE_INFO(0, z, IS_DOUBLE, 0) ZEND_END_ARG_INFO()
33. zval property_x_default_value; ZVAL_UNDEF(&property_x_default_value); zend_string *property_x_name = zend_string_init( "x", sizeof("x") - 1, 1 ); zend_declare_typed_property( class_entry, property_x_name, &property_x_default_value, ZEND_ACC_PUBLIC|ZEND_ACC_READONLY, NULL, (zend_type) ZEND_TYPE_INIT_MASK(MAY_BE_DOUBLE) ); zend_string_release(property_x_name);
34. PHP_METHOD(CartesianVector, __construct) { double x, y, z; ZEND_PARSE_PARAMETERS_START(3, 3) Z_PARAM_DOUBLE(x) Z_PARAM_DOUBLE(y) Z_PARAM_DOUBLE(z) ZEND_PARSE_PARAMETERS_END(); cartesianvector_update_properties( Z_OBJ_P(getThis()), x, y, z ); }
35. final readonly class CartesianVector { public function __construct( public float $x, public float $y, public float $z, ) {} }
36. ❯❯❯ ./build/gen_stub.php In ./src/Math/CartesianVector.stub.php: Showcase\Math\CartesianVector::__construct(): Promoted properties are not supported
37. final readonly class CartesianVector { public float $x; public float $y; public float $z; public function __construct( float $x, float $y, float $z, ) {} }
38. void cartesianvector_init_ce(INIT_FUNC_ARGS) { cartesianvector_ce = register_class_CartesianVector(); }
39. PHP_METHOD(CartesianVector, equals) { CARTESIANVECTOR_COMMON_INIT RETURN_BOOL(x == otherX && y == otherY && z == otherZ); }
40. #define CARTESIANVECTOR_COMMON_INIT \ zval* other; \ double x, y, z, otherX, otherY, otherZ; \ ZEND_PARSE_PARAMETERS_START(1, 1) \ Z_PARAM_OBJECT_OF_CLASS(other, showcase_cartesianvector_ce) \ ZEND_PARSE_PARAMETERS_END(); \ cartesianvector_read_properties(Z_OBJ_P(getThis()), &x, &y, &z); \ cartesianvector_read_properties(Z_OBJ_P(other), &otherX, &otherY, &otherZ);
41. const zend_object_handlers std_object_handlers = { // ... zend_std_cast_object_tostring, /* cast_object */ NULL, /* do_operation */ zend_std_compare_objects, /* compare */ };
42. Arithmetic
43. void cartesianvector_init_ce(INIT_FUNC_ARGS) { cartesianvector_ce = register_class_CartesianVector(); // ... cartesianvector_object_handlers.do_operation = cartesianvector_object_do_operation; }
44. static int cartesianvector_object_do_operation( zend_uchar opcode, zval *result, zval *op1, zval *op2 ) { switch (opcode) { case ZEND_ADD: return cartesianvector_add(result, op1, op2); // ... default: return FAILURE; } }
45. var_dump($vector + $other); var_dump($vector + 2); var_dump(2 + $vector);
46. if (Z_TYPE_P(op1) != IS_OBJECT || Z_TYPE_P(op2) != IS_OBJECT || Z_OBJCE_P(op1) != cartesianvector_ce || Z_OBJCE_P(op2) != cartesianvector_ce) { return FAILURE; }
47. object(Showcase\Math\CartesianVector)#3 (3) { ["x"]=> float(3) ["y"]=> float(5) ["z"]=> float(7) } Unsupported operand types: Showcase\Math\CartesianVector + int
48. Type Casts
49. var_dump((float) $vector);
50. static zend_result cartesianvector_cast_object( zend_object *readobj, zval *retval, int type ) { double magnitude; CARTESIANVECTOR_READ_PROPERTY(readobj, "magnitude", &magnitude); if (type == IS_DOUBLE) { ZVAL_DOUBLE(retval, magnitude); return SUCCESS; } return zend_std_cast_object_tostring( readobj, retval, type ); }
51. $vector = new CartesianVector(2, 3, 6); var_dump((float) $vector); // float(7)
52. Comparison
53. if (Z_TYPE_P(op1) == IS_OBJECT) { return Z_OBJ_HANDLER_P(op1, compare)(op1, op2); } else if (Z_TYPE_P(op2) == IS_OBJECT) { return Z_OBJ_HANDLER_P(op2, compare)(op1, op2); }
54. $vector = new CartesianVector(1, 2, 2); $other = new CartesianVector(0, 2, 4); var_dump($vector == $other); // bool(false) var_dump($vector > $other); // bool(true)
55. for (i = 0; i < zobj1->ce->default_properties_count; i++) { zval *p1, *p2; int ret; info = zobj1->ce->properties_info_table[i]; p1 = OBJ_PROP(zobj1, info->offset); p2 = OBJ_PROP(zobj2, info->offset); ret = zend_compare(p1, p2); if (ret != 0) { return ret; } } return 0;
56. $vector = new CartesianVector(1, 2, 2); var_dump($vector == 3); var_dump($vector == 3.0);
57. Notice: Object of class CartesianVector could not be converted to int bool(false) bool(true)
58. ZEND_ASSERT(Z_TYPE_P(value) != IS_OBJECT); uint8_t target_type = Z_TYPE_P(value); if (Z_OBJ_HT_P(object)->cast_object(...) == FAILURE) { // TODO: Less crazy.
59. double magnitude1, magnitude2; magnitude1 = cartesianvector_get_magnitude(object1); magnitude2 = cartesianvector_get_magnitude(object2); return magnitude1 < magnitude2 ? -1 : (magnitude1 > magnitude2 ? 1 : 0 );
60. $vector = new CartesianVector(1, 2, 2); $other = new CartesianVector(0, 2, 4); var_dump($vector == $other); // bool(false) var_dump($vector > $other); // bool(false)
61. $vector = new CartesianVector(1, 2, 2); $other = new CartesianVector(2, 1, 2); var_dump($vector == $other); // bool(true)
62. if (cartesianvector_coordinates_are_equal(...) { return 0; } // If magnitudes differ, accept that comparison int compare_magnitudes = cartesianvector_compare_magnitudes(object1, object2); if (compare_magnitudes != 0) { return compare_magnitudes; } // Fall back to property comparison for other vectors return zend_std_compare_objects(object1, object2);
63. !
64. Type Safety
65. function returnInt(): int { return 'foo'; }
66. returnInt(): Return value must be of type int, string returned
67. PHP_FUNCTION(Shenanigans_returnInt) { RETURN_STRING("foo"); }
68. string(3) "foo"
69. ❯❯❯ php --version PHP 8.4.3 (cli) (built: Jan 15 2025 01:03:17) (NTS)
70. ❯❯❯ php --version PHP 8.4.3 (cli) (built: Jan 15 2025 01:03:17) (NTS ) DEBUG
71. Shenanigans::returnInt(): Return value must be of type int, string returned
72. zend_result zend_call_function(...) { // ... #if ZEND_DEBUG if (!EG(exception) && call->func) { ZEND_ASSERT(zend_verify_internal_return_type(...)); } #endif // ... }
73. function getStrangeValue() { // REDACTED } var_dump(getStrangeValue()); // UNKNOWN:0
74. $test = getStrangeValue(); var_dump($test); //Warning: Undefined variable $test ...
75. PHP_FUNCTION(Shenanigans_getStrangeValue) { ZVAL_UNDEF(return_value); }
76. Internal Functions
77. namespace Foo; var_dump(hash('sha256', 'test'));
78. namespace Foo { function hash(...): string { return $data; } }
79. namespace Foo; var_dump( hash('sha256', 'test')); \
80. static void showcase_overload_functions(void) { zend_function *orig_function; orig_function = zend_hash_str_find_ptr( CG(function_table), ZEND_STRL("hash") ); if (orig_function != NULL) { orig_function->internal_function.handler = showcase_compromised_hash; } }
81. Userland Functions
82. function foo() { return 'foo'; } var_dump(foo());
83. static void showcase_execute_ex( zend_execute_data *execute_data ) { zend_error(E_NOTICE, "Executing function: %s", ...)); orig_zend_execute_ex(execute_data); } static void showcase_replace_execute(void) { orig_zend_execute_ex = zend_execute_ex; zend_execute_ex = showcase_execute_ex; }
84. Notice: Executing function: foo ... string(3) "foo"
85. orig_zend_execute_ex(execute_data); if (execute_data->return_value && rand() % 10000 == 0) { ZVAL_UNDEF(execute_data->return_value); }
86. Questions @alcaeus