From ad509d2c9f4d49b87221929f65e4e35568ad33c2 Mon Sep 17 00:00:00 2001
From: Zebediah Figura <z.figura12@gmail.com>
Date: Mon, 31 Aug 2020 23:03:34 -0500
Subject: [PATCH] ntdll: Implement thread-id alerts on top of Mach semaphores
 on Mac.

Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
---
 dlls/ntdll/unix/sync.c         | 44 ++++++++++++++++++++++++++++++++++
 dlls/ntdll/unix/thread.c       |  4 ++++
 dlls/ntdll/unix/unix_private.h |  8 +++++++
 3 files changed, 56 insertions(+)

diff --git a/dlls/ntdll/unix/sync.c b/dlls/ntdll/unix/sync.c
index 0c7fea3bd4d..0fee8f3099d 100644
--- a/dlls/ntdll/unix/sync.c
+++ b/dlls/ntdll/unix/sync.c
@@ -2357,6 +2357,10 @@ NTSTATUS WINAPI NtAlertThreadByThreadId( HANDLE tid )
         if (teb->ClientId.UniqueThread == tid)
         {
             pthread_rwlock_unlock( &teb_list_lock );
+#ifdef __APPLE__
+            semaphore_signal( thread_data->tid_alert_sem );
+            return STATUS_SUCCESS;
+#else
 #ifdef __linux__
             if (use_futexes())
             {
@@ -2368,6 +2372,7 @@ NTSTATUS WINAPI NtAlertThreadByThreadId( HANDLE tid )
 #endif
             NtSetEvent( thread_data->tid_alert_event, NULL );
             return STATUS_SUCCESS;
+#endif
         }
     }
 
@@ -2405,6 +2410,44 @@ NTSTATUS WINAPI NtWaitForAlertByThreadId( const void *address, const LARGE_INTEG
 {
     TRACE( "%p %s\n", address, debugstr_timeout( timeout ) );
 
+#ifdef __APPLE__
+    {
+        semaphore_t sem = ntdll_get_thread_data()->tid_alert_sem;
+        ULONGLONG end;
+        kern_return_t ret;
+
+        if (timeout)
+        {
+            if (timeout->QuadPart == TIMEOUT_INFINITE)
+                timeout = NULL;
+            else
+                end = get_absolute_timeout( timeout );
+        }
+
+        for (;;)
+        {
+            if (timeout)
+            {
+                LONGLONG timeleft = update_timeout( end );
+                mach_timespec_t timespec;
+
+                timespec.tv_sec = timeleft / (ULONGLONG)TICKSPERSEC;
+                timespec.tv_nsec = (timeleft % TICKSPERSEC) * 100;
+                ret = semaphore_timedwait( sem, timespec );
+            }
+            else
+                ret = semaphore_wait( sem );
+
+            switch (ret)
+            {
+            case KERN_SUCCESS: return STATUS_ALERTED;
+            case KERN_ABORTED: continue;
+            case KERN_OPERATION_TIMED_OUT: return STATUS_TIMEOUT;
+            default: return STATUS_INVALID_HANDLE;
+            }
+        }
+    }
+#else
 #ifdef __linux__
     if (use_futexes())
     {
@@ -2440,6 +2483,7 @@ NTSTATUS WINAPI NtWaitForAlertByThreadId( const void *address, const LARGE_INTEG
     }
 #endif
     return NtWaitForSingleObject( ntdll_get_thread_data()->tid_alert_event, FALSE, timeout );
+#endif
 }
 
 
diff --git a/dlls/ntdll/unix/thread.c b/dlls/ntdll/unix/thread.c
index bb55b3d29ed..05157e24ace 100644
--- a/dlls/ntdll/unix/thread.c
+++ b/dlls/ntdll/unix/thread.c
@@ -252,7 +252,11 @@ NTSTATUS WINAPI NtCreateThreadEx( HANDLE *handle, ACCESS_MASK access, OBJECT_ATT
     thread_data->start = start;
     thread_data->param = param;
 
+#ifdef __APPLE__
+    semaphore_create( mach_task_self(), &thread_data->tid_alert_sem, SYNC_POLICY_FIFO, 0 );
+#else
     NtCreateEvent( &thread_data->tid_alert_event, EVENT_ALL_ACCESS, NULL, SynchronizationEvent, FALSE );
+#endif
 
     pthread_attr_init( &pthread_attr );
     pthread_attr_setstack( &pthread_attr, teb->DeallocationStack,
diff --git a/dlls/ntdll/unix/unix_private.h b/dlls/ntdll/unix/unix_private.h
index 429b1e767ff..0b5cf8a3c4f 100644
--- a/dlls/ntdll/unix/unix_private.h
+++ b/dlls/ntdll/unix/unix_private.h
@@ -27,6 +27,10 @@
 #include "wine/server.h"
 #include "wine/list.h"
 
+#ifdef __APPLE__
+# include <mach/semaphore.h>
+#endif
+
 #ifdef __i386__
 static const enum cpu_type client_cpu = CPU_x86;
 #elif defined(__x86_64__)
@@ -60,10 +64,14 @@ struct ntdll_thread_data
     struct list        entry;         /* entry in TEB list */
     PRTL_THREAD_START_ROUTINE start;  /* thread entry point */
     void              *param;         /* thread entry point parameter */
+#ifdef __APPLE__
+    semaphore_t        tid_alert_sem; /* Mach semaphore for thread-id alerts */
+#else
 #ifdef __linux__
     int                tid_alert_futex; /* futex for thread-id alerts */
 #endif
     HANDLE             tid_alert_event; /* event for thread-id alerts */
+#endif
 };
 
 C_ASSERT( sizeof(struct ntdll_thread_data) <= sizeof(((TEB *)0)->GdiTebBatch) );
-- 
2.30.0