Kernel+LibC: Add exit_thread() syscall.

Kernel/Process.cpp

@@ -2443,6 +2443,18 @@ int Process::sys$create_thread(int(*entry)(void*), void* argument)
     return 0;
 }
 
+void Process::sys$exit_thread(int code)
+{
+    InterruptDisabler disabler;
+    if (&current->process().main_thread() == current) {
+        sys$exit(code);
+        return;
+    }
+    current->set_state(Thread::State::Dying);
+    Scheduler::pick_next_and_switch_now();
+    ASSERT_NOT_REACHED();
+}
+
 int Process::sys$gettid()
 {
     return current->tid();

Kernel/Process.h

@@ -175,6 +175,7 @@ public:
     int sys$setsockopt(const Syscall::SC_setsockopt_params*);
     int sys$restore_signal_mask(dword mask);
     int sys$create_thread(int(*)(void*), void*);
+    void sys$exit_thread(int code);
     int sys$rename(const char* oldpath, const char* newpath);
     int sys$systrace(pid_t);
 

Kernel/Syscall.cpp

@@ -118,6 +118,11 @@ static dword handle(RegisterDump& regs, dword function, dword arg1, dword arg2,
         current->process().sys$exit((int)arg1);
         ASSERT_NOT_REACHED();
         return 0;
+    case Syscall::SC_exit_thread:
+        cli();
+        current->process().sys$exit_thread((int)arg1);
+        ASSERT_NOT_REACHED();
+        break;
     case Syscall::SC_chdir:
         return current->process().sys$chdir((const char*)arg1);
     case Syscall::SC_uname:

Kernel/Syscall.h

@@ -100,6 +100,7 @@
     __ENUMERATE_SYSCALL(shm_close) \
     __ENUMERATE_SYSCALL(ftruncate) \
     __ENUMERATE_SYSCALL(systrace) \
+    __ENUMERATE_SYSCALL(exit_thread) \
 
 
 namespace Syscall {

LibC/unistd.cpp

@@ -451,6 +451,12 @@ int create_thread(int(*entry)(void*), void* argument)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int exit_thread(int code)
+{
+    int rc = syscall(SC_exit_thread, code);
+    __RETURN_WITH_ERRNO(rc, rc, -1);
+}
+
 int ftruncate(int fd, off_t length)
 {
     int rc = syscall(SC_ftruncate, fd, length);

LibC/unistd.h

@@ -18,6 +18,7 @@ int systrace(pid_t);
 int gettid();
 int donate(int tid);
 int create_thread(int(*)(void*), void*);
+void exit_thread(int);
 int create_shared_buffer(pid_t peer_pid, int, void** buffer);
 void* get_shared_buffer(int shared_buffer_id);
 int release_shared_buffer(int shared_buffer_id);