runtime/cgo: let darwin pthread stacksize follow rlimit

On Mac OS X, the default stack size for non-main threads created by cgo is
fixed at 512KB and cannot be altered by setrlimit. This stack size is too
small for some recursive scenarios. We can solve this problem by explicitly
copying the stack size of the main thread when creating a new thread.

Change-Id: I400d5b2e929a1ee261502914a991e208759f64a8
GitHub-Last-Rev: b29c745
GitHub-Pull-Request: #53667
Reviewed-on: https://go-review.googlesource.com/c/go/+/415915
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: hopehook <hopehook@golangcn.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

Author: fengyoulin

src/runtime/cgo/gcc_darwin_amd64.c

@@ -14,15 +14,12 @@ static void (*setg_gcc)(void*);
 void
 x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
 {
-	pthread_attr_t attr;
 	size_t size;
 
 	setg_gcc = setg;
 
-	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
-	g->stacklo = (uintptr)&attr - size + 4096;
-	pthread_attr_destroy(&attr);
+	size = pthread_get_stacksize_np(pthread_self());
+	g->stacklo = (uintptr)&size - size + 4096;
 }
 
 
@@ -38,8 +35,9 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	sigfillset(&ign);
 	pthread_sigmask(SIG_SETMASK, &ign, &oset);
 
+	size = pthread_get_stacksize_np(pthread_self());
 	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
+	pthread_attr_setstacksize(&attr, size);
 	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
 	ts->g->stackhi = size;
 	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);

src/runtime/cgo/gcc_darwin_arm64.c

@@ -36,8 +36,9 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	sigfillset(&ign);
 	pthread_sigmask(SIG_SETMASK, &ign, &oset);
 
+	size = pthread_get_stacksize_np(pthread_self());
 	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
+	pthread_attr_setstacksize(&attr, size);
 	// Leave stacklo=0 and set stackhi=size; mstart will do the rest.
 	ts->g->stackhi = size;
 	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
@@ -126,15 +127,12 @@ init_working_dir()
 void
 x_cgo_init(G *g, void (*setg)(void*))
 {
-	pthread_attr_t attr;
 	size_t size;
 
 	//fprintf(stderr, "x_cgo_init = %p\n", &x_cgo_init); // aid debugging in presence of ASLR
 	setg_gcc = setg;
-	pthread_attr_init(&attr);
-	pthread_attr_getstacksize(&attr, &size);
-	g->stacklo = (uintptr)&attr - size + 4096;
-	pthread_attr_destroy(&attr);
+	size = pthread_get_stacksize_np(pthread_self());
+	g->stacklo = (uintptr)&size - size + 4096;
 
 #if TARGET_OS_IPHONE
 	darwin_arm_init_mach_exception_handler();