//go:linkname _cgo_panic_internal
//go:linkname cgoAlwaysFalse
//go:linkname cgoUse
//go:linkname cgoCheckPointer
//go:linkname cgoCheckResult
//go:linkname cgoNoCallback
//go:linkname gobytes
//go:linkname gostringn

// used in plugin
//go:linkname doInit

// used in math/bits
//go:linkname overflowError
//go:linkname divideError

// used in tests
//go:linkname extraMInUse
//go:linkname blockevent

func _Cfunc_GoString(p *_Ctype_char) string {
	return _cgo_runtime_gostring(p)
}
`

const goStringNDef = `
//go:linkname _cgo_runtime_gostringn runtime.gostringn
func _cgo_runtime_gostringn(*_Ctype_char, int) string

// GoStringN converts the C data p with explicit length l to a Go string.
func _Cfunc_GoStringN(p *_Ctype_char, l _Ctype_int) string {
	return _cgo_runtime_gostringn(p, int(l))
}
`

//
//go:linkname internal_syscall_gostring internal/syscall/unix.gostring
func internal_syscall_gostring(p *byte) string {
	return gostring(p)
}

func gostringn(p *byte, l int) string {
	if l == 0 {
		return ""
	}
	s, b := rawstring(l)
	memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
	return s
}

const (
	maxUint64 = ^uint64(0)

const greeting = "hello, world"

type testPair struct {
	Name      string
	Got, Want interface{}
}

var testPairs = []testPair{
	{"GoString", C.GoString(C.greeting), greeting},
	{"GoStringN", C.GoStringN(C.greeting, 5), greeting[:5]},
	{"GoBytes", C.GoBytes(unsafe.Pointer(C.greeting), 5), []byte(greeting[:5])},
}

func testHelpers(t *testing.T) {
	for _, pair := range testPairs {

	// if C.free is needed).
	func C.CBytes([]byte) unsafe.Pointer

	// C string to Go string
	func C.GoString(*C.char) string

	// C data with explicit length to Go string
	func C.GoStringN(*C.char, C.int) string

	// C data with explicit length to Go []byte
	func C.GoBytes(unsafe.Pointer, C.int) []byte

As a special case, C.malloc does not call the C library malloc directly