1 files changed, 171 insertions, 0 deletions
diff --git a/src/runtime/cgo/gcc_libinit.c b/src/runtime/cgo/gcc_libinit.c
new file mode 100644
index 0000000..68f4a02
--- /dev/null
+++ b/src/runtime/cgo/gcc_libinit.c
@@ -0,0 +1,171 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+#include <pthread.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h> // strerror
+#include <time.h>
+#include "libcgo.h"
+#include "libcgo_unix.h"
+
+static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER;
+static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
+static int runtime_init_done;
+
+// pthread_g is a pthread specific key, for storing the g that binded to the C thread.
+// The registered pthread_key_destructor will dropm, when the pthread-specified value g is not NULL,
+// while a C thread is exiting.
+static pthread_key_t pthread_g;
+static void pthread_key_destructor(void* g);
+uintptr_t x_cgo_pthread_key_created;
+void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
+
+// The context function, used when tracing back C calls into Go.
+static void (*cgo_context_function)(struct context_arg*);
+
+void
+x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
+	pthread_t p;
+	int err = _cgo_try_pthread_create(&p, NULL, func, arg);
+	if (err != 0) {
+		fprintf(stderr, "pthread_create failed: %s", strerror(err));
+		abort();
+	}
+}
+
+uintptr_t
+_cgo_wait_runtime_init_done(void) {
+	void (*pfn)(struct context_arg*);
+	pfn = __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
+
+	int done = 2;
+	if (__atomic_load_n(&runtime_init_done, __ATOMIC_CONSUME) != done) {
+		pthread_mutex_lock(&runtime_init_mu);
+		while (__atomic_load_n(&runtime_init_done, __ATOMIC_CONSUME) == 0) {
+			pthread_cond_wait(&runtime_init_cond, &runtime_init_mu);
+		}
+
+		// The key and x_cgo_pthread_key_created are for the whole program,
+		// whereas the specific and destructor is per thread.
+		if (x_cgo_pthread_key_created == 0 && pthread_key_create(&pthread_g, pthread_key_destructor) == 0) {
+			x_cgo_pthread_key_created = 1;
+		}
+
+
+		// TODO(iant): For the case of a new C thread calling into Go, such
+		// as when using -buildmode=c-archive, we know that Go runtime
+		// initialization is complete but we do not know that all Go init
+		// functions have been run. We should not fetch cgo_context_function
+		// until they have been, because that is where a call to
+		// SetCgoTraceback is likely to occur. We are going to wait for Go
+		// initialization to be complete anyhow, later, by waiting for
+		// main_init_done to be closed in cgocallbackg1. We should wait here
+		// instead. See also issue #15943.
+		pfn = __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
+
+		__atomic_store_n(&runtime_init_done, done, __ATOMIC_RELEASE);
+		pthread_mutex_unlock(&runtime_init_mu);
+	}
+
+	if (pfn != nil) {
+		struct context_arg arg;
+
+		arg.Context = 0;
+		(*pfn)(&arg);
+		return arg.Context;
+	}
+	return 0;
+}
+
+// _cgo_set_stacklo sets g->stacklo based on the stack size.
+// This is common code called from x_cgo_init, which is itself
+// called by rt0_go in the runtime package.
+void _cgo_set_stacklo(G *g, uintptr *pbounds)
+{
+	uintptr bounds[2];
+
+	// pbounds can be passed in by the caller; see gcc_linux_amd64.c.
+	if (pbounds == NULL) {
+		pbounds = &bounds[0];
+	}
+
+	x_cgo_getstackbound(pbounds);
+
+	g->stacklo = *pbounds;
+
+	// Sanity check the results now, rather than getting a
+	// morestack on g0 crash.
+	if (g->stacklo >= g->stackhi) {
+		fprintf(stderr, "runtime/cgo: bad stack bounds: lo=%p hi=%p\n", (void*)(g->stacklo), (void*)(g->stackhi));
+		abort();
+	}
+}
+
+// Store the g into a thread-specific value associated with the pthread key pthread_g.
+// And pthread_key_destructor will dropm when the thread is exiting.
+void x_cgo_bindm(void* g) {
+	// We assume this will always succeed, otherwise, there might be extra M leaking,
+	// when a C thread exits after a cgo call.
+	// We only invoke this function once per thread in runtime.needAndBindM,
+	// and the next calls just reuse the bound m.
+	pthread_setspecific(pthread_g, g);
+}
+
+void
+x_cgo_notify_runtime_init_done(void* dummy __attribute__ ((unused))) {
+	pthread_mutex_lock(&runtime_init_mu);
+	__atomic_store_n(&runtime_init_done, 1, __ATOMIC_RELEASE);
+	pthread_cond_broadcast(&runtime_init_cond);
+	pthread_mutex_unlock(&runtime_init_mu);
+}
+
+// Sets the context function to call to record the traceback context
+// when calling a Go function from C code. Called from runtime.SetCgoTraceback.
+void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
+	__atomic_store_n(&cgo_context_function, context, __ATOMIC_RELEASE);
+}
+
+// Gets the context function.
+void (*(_cgo_get_context_function(void)))(struct context_arg*) {
+	return __atomic_load_n(&cgo_context_function, __ATOMIC_CONSUME);
+}
+
+// _cgo_try_pthread_create retries pthread_create if it fails with
+// EAGAIN.
+int
+_cgo_try_pthread_create(pthread_t* thread, const pthread_attr_t* attr, void* (*pfn)(void*), void* arg) {
+	int tries;
+	int err;
+	struct timespec ts;
+
+	for (tries = 0; tries < 20; tries++) {
+		err = pthread_create(thread, attr, pfn, arg);
+		if (err == 0) {
+			pthread_detach(*thread);
+			return 0;
+		}
+		if (err != EAGAIN) {
+			return err;
+		}
+		ts.tv_sec = 0;
+		ts.tv_nsec = (tries + 1) * 1000 * 1000; // Milliseconds.
+		nanosleep(&ts, nil);
+	}
+	return EAGAIN;
+}
+
+static void
+pthread_key_destructor(void* g) {
+	if (x_crosscall2_ptr != NULL) {
+		// fn == NULL means dropm.
+		// We restore g by using the stored g, before dropm in runtime.cgocallback,
+		// since the g stored in the TLS by Go might be cleared in some platforms,
+		// before this destructor invoked.
+		x_crosscall2_ptr(NULL, g, 0, 0);
+	}
+}