Split-out pthread_testcancel change

Author: kleisauke

system/lib/libc/musl/src/thread/pthread_cancel.c

@@ -3,6 +3,7 @@
 #include "pthread_impl.h"
 #include "syscall.h"
 
+#ifndef __EMSCRIPTEN__
 hidden long __cancel(), __syscall_cp_asm(), __syscall_cp_c();
 
 long __cancel()
@@ -14,7 +15,6 @@ long __cancel()
 	return -ECANCELED;
 }
 
-#ifndef __EMSCRIPTEN__
 long __syscall_cp_asm(volatile void *, syscall_arg_t,
                       syscall_arg_t, syscall_arg_t, syscall_arg_t,
                       syscall_arg_t, syscall_arg_t, syscall_arg_t);
@@ -67,7 +67,6 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 
 	__syscall(SYS_tkill, self->tid, SIGCANCEL);
 }
-#endif
 
 void __testcancel()
 {
@@ -76,7 +75,6 @@ void __testcancel()
 		__cancel();
 }
 
-#ifndef __EMSCRIPTEN__
 static void init_cancellation()
 {
 	struct sigaction sa = {

system/lib/pthread/library_pthread.c

@@ -36,6 +36,8 @@
 
 #include "threading_internal.h"
 
+void __pthread_testcancel();
+
 int emscripten_pthread_attr_gettransferredcanvases(const pthread_attr_t* a, const char** str) {
   *str = a->_a_transferredcanvases;
   return 0;

system/lib/pthread/library_pthread_stub.c

@@ -206,8 +206,6 @@ int pthread_cancel(pthread_t thread) {
   return 0;
 }
 
-void pthread_testcancel() {}
-
 _Noreturn void __pthread_exit(void* status) {
    exit(0);
 }

system/lib/pthread/pthread_testcancel.c

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2021 The Emscripten Authors.  All rights reserved.
+ * Emscripten is available under two separate licenses, the MIT license and the
+ * University of Illinois/NCSA Open Source License.  Both these licenses can be
+ * found in the LICENSE file.
+ */
+
+#include "pthread_impl.h"
+#include <pthread.h>
+
+void __pthread_testcancel() {
+  struct pthread* self = pthread_self();
+  if (self->canceldisable)
+    return;
+  if (self->cancel) {
+    pthread_exit(PTHREAD_CANCELED);
+  }
+}
+
+weak_alias(__pthread_testcancel, pthread_testcancel);

tools/system_libs.py

@@ -827,12 +827,15 @@ def get_files(self):
         'syscall_cp.c', 'tls.c',
         # TODO: Support this. See #12216.
         'pthread_setname_np.c',
+        # TODO: Prefer to use the musl implementation.
+        'pthread_testcancel.c',
       ]
       libc_files += files_in_path(
         path='system/lib/pthread',
         filenames=[
           'library_pthread.c',
           'pthread_create.c',
+          'pthread_testcancel.c',
           'emscripten_proxy_main.c',
           'emscripten_thread_init.c',
           'emscripten_thread_state.S',