/**
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* \file
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* ObjectiveC hacks to improve our changes with thread shutdown
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*
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* Author:
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* Rodrigo Kumpera (kumpera@gmail.com)
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*
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* (C) 2014 Xamarin Inc
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*/
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#include "config.h"
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#if defined(__MACH__)
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#include <stdio.h>
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#include <objc/runtime.h>
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#include <objc/message.h>
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#include <mono/utils/mono-compiler.h>
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/*
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* We cannot include mono-threads.h as this includes io-layer internal types
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* which conflicts with objc.
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* Hence the hack here.
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*/
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void mono_threads_init_dead_letter (void);
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void mono_threads_install_dead_letter (void);
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void mono_thread_info_detach (void);
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static Class nsobject, nsthread, mono_dead_letter_class;
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static SEL dealloc, release, currentThread, threadDictionary, init, alloc, objectForKey, setObjectForKey;
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static id mono_dead_letter_key;
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/*
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* Our Mach bindings have a problem in that they might need to attach
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* the runtime after the the user tls keys have been destroyed.
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*
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* This happens when a bound object is retained by NSThread, which is
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* released very late in the TLS cleanup process.
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*
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* At that point, attaching the runtime leaves us in no position to
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* detach it later using TLS destructors as pthread is done with user
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* keys. This leaves us with a dead thread registered, which can cause
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* all sorts of terrible problems.
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*
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* The tipical crash is when another thread is created at the exact
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* same address of the previous one, cause thread registration to abort
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* due to duplicate entries.
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*
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* So what do we do here?
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*
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* Experimentation showns that threadDictionary is destroied after the
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* problematic keys, so we add our dead letter object as an aditional
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* way to be notified of thread death.
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*/
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static void
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mono_dead_letter_dealloc (id self, SEL _cmd)
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{
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struct objc_super super;
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super.receiver = self;
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super.class = nsobject;
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objc_msgSendSuper (&super, dealloc);
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mono_thread_info_detach ();
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}
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void
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mono_threads_install_dead_letter (void)
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{
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id cur, dict;
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/*
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* See the 'Dispatch Objective-C Messages Using the Method Function’s Prototype' section in
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* the '64-Bit Transition Guide for Cocoa Touch' as to why this is required.
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*
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* It doesn't hurt on other architectures either, so no need to #ifdef it only for ARM64.
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*/
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id (*id_objc_msgSend_id)(id, SEL, id) = (id (*)(id, SEL, id)) objc_msgSend;
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void (*objc_msgSend_id_id)(id, SEL, id, id) = (void (*)(id, SEL, id, id)) objc_msgSend;
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cur = objc_msgSend ((id)nsthread, currentThread);
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if (!cur)
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return;
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dict = objc_msgSend (cur, threadDictionary);
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if (dict && id_objc_msgSend_id (dict, objectForKey, mono_dead_letter_key) == nil) {
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id value = objc_msgSend (objc_msgSend ((id)mono_dead_letter_class, alloc), init);
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objc_msgSend_id_id (dict, setObjectForKey, value, mono_dead_letter_key);
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objc_msgSend (value, release);
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}
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}
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void
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mono_threads_init_dead_letter (void)
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{
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id nsstring = (id) objc_getClass ("NSString");
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id nsautoreleasepool = (id) objc_getClass ("NSAutoreleasePool");
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SEL stringWithUTF8String = sel_registerName ("stringWithUTF8String:");
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SEL retain = sel_registerName ("retain");
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id pool;
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nsthread = (Class)objc_getClass ("NSThread");
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nsobject = (Class)objc_getClass ("NSObject");
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init = sel_registerName ("init");
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alloc = sel_registerName ("alloc");
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release = sel_registerName ("release");
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dealloc = sel_registerName ("dealloc");
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currentThread = sel_registerName ("currentThread");
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threadDictionary = sel_registerName ("threadDictionary");
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setObjectForKey = sel_registerName ("setObject:forKey:");
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objectForKey = sel_registerName ("objectForKey:");
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// define the dead letter class
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mono_dead_letter_class = objc_allocateClassPair (nsobject, "MonoDeadLetter", 0);
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class_addMethod (mono_dead_letter_class, dealloc, (IMP)mono_dead_letter_dealloc, "v@:");
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objc_registerClassPair (mono_dead_letter_class);
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// create the dict key
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pool = objc_msgSend (objc_msgSend (nsautoreleasepool, alloc), init);
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id (*objc_msgSend_char)(id, SEL, const char*) = (id (*)(id, SEL, const char*)) objc_msgSend;
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mono_dead_letter_key = objc_msgSend_char (nsstring, stringWithUTF8String, "mono-dead-letter");
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objc_msgSend (mono_dead_letter_key, retain);
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objc_msgSend (pool, release);
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}
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#endif
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