在golang中使用 cgo，如何让被嵌入的c语言代码调用golang
// Copyright 2011 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.
package cgotest
/*
void callback(void *f);
void callGoFoo(void);
void callGoStackCheck(void);
void callPanic(void);
int callGoReturnVal(void);
int returnAfterGrow(void);
int returnAfterGrowFromGo(void);
void callGoWithString(void);
*/
import "C"
import (
"path"
"runtime"
"strings"
"sync"
"testing"
"unsafe"
)
// Pass a func value from nestedCall to goCallback using an integer token.
var callbackMutex sync.Mutex
var callbackToken int
var callbackFuncs = make(mapfunc())
// nestedCall calls into C, back into Go, and finally to f.
func nestedCall(f func()) {
// callback(x) calls goCallback(x)
callbackMutex.Lock()
callbackToken++
i := callbackToken
callbackFuncs = f
callbackMutex.Unlock()
// Pass the address of i because the C function was written to
// take a pointer.We could pass an int if we felt like
// rewriting the C code.
C.callback(unsafe.Pointer(&i))
callbackMutex.Lock()
delete(callbackFuncs, i)
callbackMutex.Unlock()
}
//export goCallback
func goCallback(p unsafe.Pointer) {
i := *(*int)(p)
callbackMutex.Lock()
f := callbackFuncs
callbackMutex.Unlock()
if f == nil {
panic("missing callback function")
}
f()
}
func testCallback(t *testing.T) {
var x = false
nestedCall(func() { x = true })
if !x {
t.Fatal("nestedCall did not call func")
}
}
func testCallbackGC(t *testing.T) {
nestedCall(runtime.GC)
}
func testCallbackPanic(t *testing.T) {
// Make sure panic during callback unwinds properly.
if lockedOSThread() {
t.Fatal("locked OS thread on entry to TestCallbackPanic")
}
defer func() {
s := recover()
if s == nil {
t.Fatal("did not panic")
}
if s.(string) != "callback panic" {
t.Fatal("wrong panic:", s)
}
if lockedOSThread() {
t.Fatal("locked OS thread on exit from TestCallbackPanic")
}
}()
nestedCall(func() { panic("callback panic") })
panic("nestedCall returned")
}
func testCallbackPanicLoop(t *testing.T) {
// Make sure we don't blow out m->g0 stack.
for i := 0; i < 100000; i++ {
testCallbackPanic(t)
}
}
func testCallbackPanicLocked(t *testing.T) {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
if !lockedOSThread() {
t.Fatal("runtime.LockOSThread didn't")
}
defer func() {
s := recover()
if s == nil {
t.Fatal("did not panic")
}
if s.(string) != "callback panic" {
t.Fatal("wrong panic:", s)
}
if !lockedOSThread() {
t.Fatal("lost lock on OS thread after panic")
}
}()
nestedCall(func() { panic("callback panic") })
panic("nestedCall returned")
}
// Callback with zero arguments used to make the stack misaligned,
// which broke the garbage collector and other things.
func testZeroArgCallback(t *testing.T) {
defer func() {
s := recover()
if s != nil {
t.Fatal("panic during callback:", s)
}
}()
C.callGoFoo()
}
//export goFoo
func goFoo() {
x := 1
for i := 0; i < 10000; i++ {
// variadic call mallocs + writes to
variadic(x, x, x)
if x != 1 {
panic("bad x")
}
}
}
func variadic(x ...interface{}) {}
func testBlocking(t *testing.T) {
c := make(chan int)
go func() {
for i := 0; i < 10; i++ {
c
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