syscallcompat: Drop Mkdirat emulation on macOS.

internal/syscallcompat/emulate.go

@@ -30,26 +30,6 @@ func emulateMknodat(dirfd int, path string, mode uint32, dev int) error {
 	return syscall.Mknod(path, mode, dev)
 }
 
-// emulateMkdirat emulates the syscall for platforms that don't have it
-// in the kernel (darwin).
-func emulateMkdirat(dirfd int, path string, mode uint32) (err error) {
-	if !filepath.IsAbs(path) {
-		chdirMutex.Lock()
-		defer chdirMutex.Unlock()
-		cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
-		if err != nil {
-			return err
-		}
-		defer syscall.Close(cwd)
-		err = syscall.Fchdir(dirfd)
-		if err != nil {
-			return err
-		}
-		defer syscall.Fchdir(cwd)
-	}
-	return syscall.Mkdir(path, mode)
-}
-
 // emulateFstatat emulates the syscall for platforms that don't have it
 // in the kernel (darwin).
 func emulateFstatat(dirfd int, path string, stat *unix.Stat_t, flags int) (err error) {

internal/syscallcompat/emulate_test.go

@@ -27,32 +27,6 @@ func TestEmulateMknodat(t *testing.T) {
 	}
 }
 
-func TestEmulateMkdirat(t *testing.T) {
-	err := emulateMkdirat(tmpDirFd, "mkdirat", 0700)
-	if err != nil {
-		t.Fatal(err)
-	}
-	fi, err := os.Stat(tmpDir + "/mkdirat")
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !fi.IsDir() {
-		t.Fatalf("mkdirat did not create a directory")
-	}
-	// Test with absolute path
-	err = emulateMkdirat(-1, tmpDir+"/mkdirat2", 0700)
-	if err != nil {
-		t.Fatal(err)
-	}
-	fi, err = os.Stat(tmpDir + "/mkdirat2")
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !fi.IsDir() {
-		t.Fatalf("mkdirat did not create a directory")
-	}
-}
-
 func TestEmulateFstatat(t *testing.T) {
 	var st unix.Stat_t
 	// stat a normal file (size 3)

internal/syscallcompat/sys_common.go

@@ -92,6 +92,11 @@ func Symlinkat(oldpath string, newdirfd int, newpath string) (err error) {
 	return unix.Symlinkat(oldpath, newdirfd, newpath)
 }
 
+// Mkdirat syscall.
+func Mkdirat(dirfd int, path string, mode uint32) (err error) {
+	return unix.Mkdirat(dirfd, path, mode)
+}
+
 const XATTR_SIZE_MAX = 65536
 
 // Make the buffer 1kB bigger so we can detect overflows

internal/syscallcompat/sys_common_test.go

@@ -247,3 +247,29 @@ func TestSymlinkat(t *testing.T) {
 	}
 	symlinkCheckMode(t, st)
 }
+
+func TestMkdirat(t *testing.T) {
+	err := Mkdirat(tmpDirFd, "mkdirat", 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+	fi, err := os.Stat(tmpDir + "/mkdirat")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !fi.IsDir() {
+		t.Fatalf("mkdirat did not create a directory")
+	}
+	// Test with absolute path
+	err = Mkdirat(-1, tmpDir+"/mkdirat2", 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+	fi, err = os.Stat(tmpDir + "/mkdirat2")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !fi.IsDir() {
+		t.Fatalf("mkdirat did not create a directory")
+	}
+}

internal/syscallcompat/sys_darwin.go

@@ -117,10 +117,6 @@ func SymlinkatUser(oldpath string, newdirfd int, newpath string, context *fuse.C
 	return Symlinkat(oldpath, newdirfd, newpath)
 }
 
-func Mkdirat(dirfd int, path string, mode uint32) (err error) {
-	return emulateMkdirat(dirfd, path, mode)
-}
-
 func MkdiratUser(dirfd int, path string, mode uint32, context *fuse.Context) (err error) {
 	if context != nil {
 		runtime.LockOSThread()

internal/syscallcompat/sys_linux.go

@@ -176,11 +176,6 @@ func SymlinkatUser(oldpath string, newdirfd int, newpath string, context *fuse.C
 	return Symlinkat(oldpath, newdirfd, newpath)
 }
 
-// Mkdirat syscall.
-func Mkdirat(dirfd int, path string, mode uint32) (err error) {
-	return syscall.Mkdirat(dirfd, path, mode)
-}
-
 // MkdiratUser runs the Mkdirat syscall in the context of a different user.
 func MkdiratUser(dirfd int, path string, mode uint32, context *fuse.Context) (err error) {
 	if context != nil {