CF* 객체는 CoreFoundation에서 제공되며, CFString, CFNumber 또는 CFAllocator와 같은 50개 이상의 객체 클래스를 제공합니다.
이 모든 클래스는 CFRuntimeClass 클래스의 인스턴스이며, 호출되면 __CFRuntimeClassTable에 대한 인덱스를 반환합니다. CFRuntimeClass는 CFRuntime.h에서 정의됩니다:
// Some comments were added to the original code
enum { // Version field constants
_kCFRuntimeScannedObject = (1UL << 0),
_kCFRuntimeResourcefulObject = (1UL << 2), // tells CFRuntime to make use of the reclaim field
_kCFRuntimeCustomRefCount = (1UL << 3), // tells CFRuntime to make use of the refcount field
_kCFRuntimeRequiresAlignment = (1UL << 4), // tells CFRuntime to make use of the requiredAlignment field
};
typedef struct __CFRuntimeClass {
CFIndex version; // This is made a bitwise OR with the relevant previous flags
const char *className; // must be a pure ASCII string, nul-terminated
void (*init)(CFTypeRef cf); // Initializer function
CFTypeRef (*copy)(CFAllocatorRef allocator, CFTypeRef cf); // Copy function, taking CFAllocatorRef and CFTypeRef to copy
void (*finalize)(CFTypeRef cf); // Finalizer function
Boolean (*equal)(CFTypeRef cf1, CFTypeRef cf2); // Function to be called by CFEqual()
CFHashCode (*hash)(CFTypeRef cf); // Function to be called by CFHash()
CFStringRef (*copyFormattingDesc)(CFTypeRef cf, CFDictionaryRef formatOptions); // Provides a CFStringRef with a textual description of the object// return str with retain
CFStringRef (*copyDebugDesc)(CFTypeRef cf); // CFStringRed with textual description of the object for CFCopyDescription
#define CF_RECLAIM_AVAILABLE 1
void (*reclaim)(CFTypeRef cf); // Or in _kCFRuntimeResourcefulObject in the .version to indicate this field should be used
// It not null, it's called when the last reference to the object is released
#define CF_REFCOUNT_AVAILABLE 1
// If not null, the following is called when incrementing or decrementing reference count
uint32_t (*refcount)(intptr_t op, CFTypeRef cf); // Or in _kCFRuntimeCustomRefCount in the .version to indicate this field should be used
// this field must be non-NULL when _kCFRuntimeCustomRefCount is in the .version field
// - if the callback is passed 1 in 'op' it should increment the 'cf's reference count and return 0
// - if the callback is passed 0 in 'op' it should return the 'cf's reference count, up to 32 bits
// - if the callback is passed -1 in 'op' it should decrement the 'cf's reference count; if it is now zero, 'cf' should be cleaned up and deallocated (the finalize callback above will NOT be called unless the process is running under GC, and CF does not deallocate the memory for you; if running under GC, finalize should do the object tear-down and free the object memory); then return 0
// remember to use saturation arithmetic logic and stop incrementing and decrementing when the ref count hits UINT32_MAX, or you will have a security bug
// remember that reference count incrementing/decrementing must be done thread-safely/atomically
// objects should be created/initialized with a custom ref-count of 1 by the class creation functions
// do not attempt to use any bits within the CFRuntimeBase for your reference count; store that in some additional field in your CF object
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
#define CF_REQUIRED_ALIGNMENT_AVAILABLE 1
// If not 0, allocation of object must be on this boundary
uintptr_t requiredAlignment; // Or in _kCFRuntimeRequiresAlignment in the .version field to indicate this field should be used; the allocator to _CFRuntimeCreateInstance() will be ignored in this case; if this is less than the minimum alignment the system supports, you'll get higher alignment; if this is not an alignment the system supports (e.g., most systems will only support powers of two, or if it is too high), the result (consequences) will be up to CF or the system to decide
} CFRuntimeClass;
Objective-C
Memory sections used
Most of the data used by ObjectiveC runtime will change during the execution, therefore it uses some sections from the __DATA segment in memory:
__objc_msgrefs (message_ref_t): 메시지 참조
__objc_ivar (ivar): 인스턴스 변수
__objc_data (...): 변경 가능한 데이터
__objc_classrefs (Class): 클래스 참조
__objc_superrefs (Class): 슈퍼클래스 참조
__objc_protorefs (protocol_t *): 프로토콜 참조
__objc_selrefs (SEL): 선택자 참조
__objc_const (...): 클래스 r/o 데이터 및 기타 (희망적으로) 상수 데이터
__objc_imageinfo (version, flags): 이미지 로드 중 사용: 현재 버전 0; 플래그는 사전 최적화된 GC 지원 등을 지정
__objc_protolist (protocol_t *): 프로토콜 목록
__objc_nlcatlist (category_t): 이 바이너리에서 정의된 비지연 카테고리에 대한 포인터
__objc_catlist (category_t): 이 바이너리에서 정의된 카테고리에 대한 포인터
__objc_nlclslist (classref_t): 이 바이너리에서 정의된 비지연 Objective-C 클래스에 대한 포인터
__objc_classlist (classref_t): 이 바이너리에서 정의된 모든 Objective-C 클래스에 대한 포인터
It also uses a few sections in the __TEXT segment to store constan values of it's not possible to write in this section:
__objc_methname (C-String): 메서드 이름
__objc_classname (C-String): 클래스 이름
__objc_methtype (C-String): 메서드 유형
Type Encoding
Objective-c uses some mangling to encode selector and variable types of simple and complex types:
Primitive types use their first letter of the type i for int, c for char, l for long... and uses the capital letter in case it's unsigned (L for unsigned Long).
Other data types whose letters are used or are special, use other letters or symbols like q for long long, b for bitfields, B for booleans, # for classes, @ for id, * for char pointers , ^ for generic pointers and ? for undefined.
그런 다음, 구조체는 디스크에 저장된 class_ro_t 구조체에 대한 포인터를 가지고 있으며, 이 구조체는 클래스의 이름, 기본 메서드, 속성 및 인스턴스 변수와 같은 속성을 포함합니다.
런타임 동안에는 메서드, 프로토콜, 속성 등을 변경할 수 있는 포인터를 포함하는 추가 구조체 class_rw_t가 사용됩니다.
