objc4 runtime

简体中文

This project is a buildable and debuggable version of latest Objective-C runtime (objc4-818.2) on Apple Open Source

• Which version to use
• Installation
• Usage
• objc4 tarballs
• Build Phases
• Build Setting
• License

Which Version To Use

macOS	macOS Version	Xcode Version	objc4 tarball version
			objc4-818.2
			objc4-787.1
			objc4-781
			objc4-723

Installation

Manually

Download zip or clone this repo, select objc scheme and build.

Usage

After building the objc scheme, manually integrate generated libobjc.A.dylib into your project manually. Or you can use objc-inspect scheme which is a preset inspector for debugging objc4 runtime.

objc4 tarballs

• objc4-818.2
• xnu-7195.50.7.100.1
• Libc-1439.40.11
• dyld-832.7.1
• libauto-187.tar.gz
• libclosure-74
• libdispatch-1173.40.5
• libplatform-220
• libpthread-416.40.3

Build Phases

Private Header

objc header	#include	tarball
objc-os.h	#include <sys/reason.h>	/xnu-6153.41.3/bsd/sys/reason.h
objc-os.h	#include <mach-o/dyld_priv.h>	/dyld-733.6/include/mach-o/dyld_priv.h
objc-os.h	#include <os/lock_private.h>	/libplatform-220/private/os/lock_private.h
lock_private.h	#include <os/base_private.h>	/libplatform-220/private/os/base_private.h
objc-os.h	#include <System/pthread_machdep.h>	removed in latest Libc tarball (Libc-1353.41.1), this header should be commented-out
objc-class.mm	#include <os/linker_set.h>	/xnu-7195.50.7.100.1/os/linker_set.h
pthread_machdep.h	#include <System/machine/cpu_capabilities.h>	/xnu-6153.41.3/osfmk/machine/cpu_capabilities.h
objc-os.h	#include <pthread/workqueue_private.h>	/libpthread-416.40.3/private/workqueue_private.h
objc-os.h	#include <objc-shared-cache.h>	/dyld-733.6/include/objc-shared-cache.h
objc-errors.mm	#include <_simple.h>	/libplatform-220/private/_simple.h
objc-block-trampolines.mm	#include <Block_private.h>	/libclosure-74/Block_private.h
objc-os.h	#include <crt_externs.h>	/Libc-1353.41.1/include/crt_externs.h
objc-runtime-new.mm	#include <mach/shared_region.h>	/xnu-6153.41.3/osfmk/mach/shared_region.h
objc-cache.mm	#include <kern/restartable.h>	/xnu-6153.41.3/osfmk/mach/restartable.defs, build from xnu kernel
objc-os.h	#include_next <CrashReporterClient.h> => #include <CrashReporterClient.h>	/Libc-825.24/include/CrashReporterClient.h
NSObject.mm	#include <os/reason_private.h>	/xnu-7195.50.7.100.1/os/reason_private
NSObject.mm	#include <os/variant_private.h>	/xnu-7195.50.7.100.1/os/reason_private
objc-exception.mm	#include <objc/objc-abi.h>	removed
objc-gdb.h	#include <objc/maptable.h>	removed

Private Header Included Header

private header	#include	tarball
tsd_private.h	#include <os/tsd.h>	/xnu-6153.41.3/libsyscall/os/tsd.h
tsd_private.h	#include <pthread/spinlock_private.h>	/libpthread-416.40.3/private/spinlock_private.h
lock_private.h	#include <pthread/tsd_private.h>	/libpthread-416.40.3/private/tsd_private.h
workqueue_private.h	#include <pthread/qos_private.h>	/llibpthread-416.40.3/private/qos_private.h
qos_private.h	#include <sys/qos_private.h>	/libpthread-416.40.3/sys/qos_private.h

Bridge OS

In public macosx sdk (latest Xcode 12.3), bridgeos (e.g. __has_feature(attribute_availability_bridgeos)) is unavailable, bridgeos availability should be removed or commented-out.

dyld

In latest dyld-733.6 (dyld-421.2 later), apple use this ruby script to expand versions, platfrom versions from a versionSets which defined in a YAML file, code generated by this script will be inserted after @MAC_VERSION_DEFS@, @IOS_VERSION_DEFS@, @WATCHOS_VERSION_DEFS@, @TVOS_VERSION_DEFS@ and @BRIDGEOS_VERSION_DEFS@ in dyld_priv.h. For more detail please refer to dyld.

XNU

<kern/restartable.h> is generated form restartable.defs in xnu tarball during building xun kernel, which is a little different from the one that shipped with public sdk that located in /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers/kern/restartable.h.

Cambria framework

Have no idea about this framework so far, maybe related with -loah for lib oah. Related Code should be commented out for now.

// File objc-cache.mm
// 
// Line 87 ~ 88
#include <Cambria/Traps.h>
#include <Cambria/Cambria.h>
// 
// ···
//
// Line 1121 ～ 1128 
if (oah_is_current_process_translated()) {
    kern_return_t ret = objc_thread_get_rip(threads[count], (uint64_t*)&pc);
    if (ret != KERN_SUCCESS) {
        pc = PC_SENTINEL;
    }
} else {
    pc = _get_pc_for_thread (threads[count]);
}

#include <os/feature_private.h>

Have no idea about this haeder so far. Related Code should be commented out for now.

// File objc-runtime.mm
// 
// ···
//
// Line 36
#include <os/feature_private.h> // os_feature_enabled_simple()
//
// ···
//
// Line 444 ～ 446
if (!os_feature_enabled_simple(objc4, preoptimizedCaches, true)) {
    DisablePreoptCaches = true;
}
// 

dyld_fall_2020_os_versions, dyld_fall_2018_os_versions

Found releated source in xnu-7195.50.7.100.1/bsd/kern/kern_mman.c.

static uint32_t
proc_2020_fall_os_sdk(void)

Maybe these function is releated to dyld build-scripts. Comment out for now.

dyld_platform_version_macOS_, dyld_platform_version_iOS_, dyld_platform_version_tvOS_, dyld_platform_version_watchOS_, dyld_platform_version_bridgeOS_

This Marco is generated by dyld build-scripts, comment out for now.

STATIC_ASSERT

objc4/runtime/objc-runtime-new.mm:176:1: '_static_assert' declared as an array with a negative size

Comment out for now.

Build Setting

Declaration	Value
HEADER_SEARCH_PATHS	$(SRCROOT)/../macosx.internal/System/Library/Frameworks/System.framework/PrivateHeaders, also append $(inherited) to target objc
GCC_PREPROCESSOR_DEFINITIONS	LIBC_NO_LIBCRASHREPORTERCLIENT, also append $(inherited) to target objc
ORDER_FILE	$(SRCROOT)/libobjc.order
OTHER_LDFLAGS[sdk=macosx*]	-lc++abi -Xlinker -sectalign -Xlinker __DATA -Xlinker __objc_data -Xlinker 0x1000 -Xlinker -interposable_list -Xlinker interposable.txt, remove build setting in target objc
OTHER_LDFLAGS[sdk=iphoneos*][arch=*]	-lc++abi -Wl,-segalign,0x4000 -Xlinker -sectalign -Xlinker __DATA -Xlinker __objc_data -Xlinker 0x1000 -Xlinker -interposable_list -Xlinker interposable.txt, remove build setting in target objc
OTHER_LDFLAGS[sdk=iphonesimulator*][arch=*]	-lc++abi -Xlinker -interposable_list -Xlinker interposable.txt, remove build setting in target objc

Run Script

Evidently public macosx sdk is our only choice, we need to update value of parameter -sdk from macosx.internal to macosx in run script of objc target.

License

This project is released under the MIT License. The objc4 project is released under the APPLE PUBLIC SOURCE LICENSE Version 2.0.