Pasted MknodTest from googlecloudplatform/gcsfuse@ff8a3f0.

samples/memfs/memfs_test.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"os/user"
 	"path"
+	"runtime"
 	"strconv"
 	"syscall"
 	"testing"
@@ -87,21 +88,25 @@ func applyUmask(m os.FileMode) os.FileMode {
 // Boilerplate
 ////////////////////////////////////////////////////////////////////////
 
-type MemFSTest struct {
+type memFSTest struct {
 	samples.SampleTest
 }
 
-func init() { RegisterTestSuite(&MemFSTest{}) }
-
-func (t *MemFSTest) SetUp(ti *TestInfo) {
+func (t *memFSTest) SetUp(ti *TestInfo) {
 	t.Server = memfs.NewMemFS(currentUid(), currentGid())
 	t.SampleTest.SetUp(ti)
 }
 
 ////////////////////////////////////////////////////////////////////////
-// Test functions
+// Basics
 ////////////////////////////////////////////////////////////////////////
 
+type MemFSTest struct {
+	memFSTest
+}
+
+func init() { RegisterTestSuite(&MemFSTest{}) }
+
 func (t *MemFSTest) ContentsOfEmptyFileSystem() {
 	entries, err := fusetesting.ReadDirPicky(t.Dir)
 
@@ -1614,3 +1619,91 @@ func (t *MemFSTest) RenameNonExistentFile() {
 	err = os.Rename(path.Join(t.Dir, "foo"), path.Join(t.Dir, "bar"))
 	ExpectThat(err, Error(HasSubstr("no such file")))
 }
+
+////////////////////////////////////////////////////////////////////////
+// Mknod
+////////////////////////////////////////////////////////////////////////
+
+type MknodTest struct {
+	memFSTest
+}
+
+func init() { RegisterTestSuite(&MknodTest{}) }
+
+func (t *MknodTest) File() {
+	// mknod(2) only works for root on OS X.
+	if runtime.GOOS == "darwin" {
+		return
+	}
+
+	var err error
+	p := path.Join(t.mfs.Dir(), "foo")
+
+	// Create
+	err = syscall.Mknod(p, syscall.S_IFREG|0600, 0)
+	AssertEq(nil, err)
+
+	// Stat
+	fi, err := os.Stat(p)
+	AssertEq(nil, err)
+
+	ExpectEq(path.Base(p), fi.Name())
+	ExpectEq(0, fi.Size())
+	ExpectEq(filePerms, fi.Mode())
+
+	// Read
+	contents, err := ioutil.ReadFile(p)
+	AssertEq(nil, err)
+	ExpectEq("", string(contents))
+}
+
+func (t *MknodTest) Directory() {
+	// mknod(2) only works for root on OS X.
+	if runtime.GOOS == "darwin" {
+		return
+	}
+
+	var err error
+	p := path.Join(t.mfs.Dir(), "foo")
+
+	// Quoth `man 2 mknod`: "Under Linux, this call cannot be used to create
+	// directories."
+	err = syscall.Mknod(p, syscall.S_IFDIR|0700, 0)
+	ExpectEq(syscall.EPERM, err)
+}
+
+func (t *MknodTest) AlreadyExists() {
+	// mknod(2) only works for root on OS X.
+	if runtime.GOOS == "darwin" {
+		return
+	}
+
+	var err error
+	p := path.Join(t.mfs.Dir(), "foo")
+
+	// Create (first)
+	err = ioutil.WriteFile(p, []byte("taco"), 0600)
+	AssertEq(nil, err)
+
+	// Create (second)
+	err = syscall.Mknod(p, syscall.S_IFREG|0600, 0)
+	ExpectEq(syscall.EEXIST, err)
+
+	// Read
+	contents, err := ioutil.ReadFile(p)
+	AssertEq(nil, err)
+	ExpectEq("taco", string(contents))
+}
+
+func (t *MknodTest) NonExistentParent() {
+	// mknod(2) only works for root on OS X.
+	if runtime.GOOS == "darwin" {
+		return
+	}
+
+	var err error
+	p := path.Join(t.mfs.Dir(), "foo/bar")
+
+	err = syscall.Mknod(p, syscall.S_IFREG|0600, 0)
+	ExpectEq(syscall.ENOENT, err)
+}