Implement Linkat() syscall wrapper.

fuse/misc.go

@@ -159,3 +159,18 @@ func VerboseTest() bool {
 	flag := flag.Lookup("test.v")
 	return flag != nil && flag.Value.String() == "true"
 }
+
+const AT_FDCWD = -100
+func Linkat(fd1 int, n1 string, fd2 int, n2 string) int {
+	b1 := syscall.StringBytePtr(n1)
+	b2 := syscall.StringBytePtr(n2)
+
+	_, _, errNo := syscall.Syscall6(
+		syscall.SYS_LINKAT,
+		uintptr(fd1),
+		uintptr(unsafe.Pointer(b1)),
+		uintptr(fd2),
+		uintptr(unsafe.Pointer(b2)),
+		0, 0)
+	return int(errNo)
+}

fuse/misc_test.go

 package fuse
 
 import (
+	"io/ioutil"
 	"os"
 	"testing"
 	"syscall"
@@ -24,3 +25,26 @@ func TestOsErrorToErrno(t *testing.T) {
 		t.Errorf("Wrong conversion %v != %v", errNo, syscall.ENOENT)
 	}
 }
+
+func TestLinkAt(t *testing.T) {
+	dir, _ := ioutil.TempDir("", "go-fuse")
+	ioutil.WriteFile(dir + "/a", []byte{42}, 0644)
+	f, _ := os.Open(dir)
+	e := Linkat(f.Fd(), "a", f.Fd(), "b")
+	if e != 0 {
+		t.Fatalf("Linkat %d", e)
+	}
+
+	f1, err := os.Lstat(dir + "/a")
+	if err != nil {
+		t.Fatalf("Lstat a: %v", err)
+	}
+	f2, err := os.Lstat(dir + "/b")
+	if err != nil {
+		t.Fatalf("Lstat b: %v", err)
+	}
+
+	if f1.Ino != f2.Ino {
+		t.Fatal("Ino mismatch", f1, f2)
+	}
+}