From 229a9da74bc0839e2cd481f701c877708b080ede Mon Sep 17 00:00:00 2001
From: Sebastian Lackner
Date: Mon, 14 Jan 2019 02:38:34 +0100
Subject: syscallcompat: Drop Unlinkat emulation on macOS.

---
 internal/syscallcompat/emulate.go         | 23 -------------
 internal/syscallcompat/emulate_test.go    | 53 -----------------------------
 internal/syscallcompat/sys_common.go      |  5 +++
 internal/syscallcompat/sys_common_test.go | 55 +++++++++++++++++++++++++++++++
 internal/syscallcompat/sys_darwin.go      |  4 ---
 internal/syscallcompat/sys_linux.go       |  5 ---
 6 files changed, 60 insertions(+), 85 deletions(-)

diff --git a/internal/syscallcompat/emulate.go b/internal/syscallcompat/emulate.go
index 7fea3a8..360c0ac 100644
--- a/internal/syscallcompat/emulate.go
+++ b/internal/syscallcompat/emulate.go
@@ -11,29 +11,6 @@ import (
 
 var chdirMutex sync.Mutex
 
-// emulateUnlinkat emulates the syscall for platforms that don't have it
-// in the kernel (darwin).
-func emulateUnlinkat(dirfd int, path string, flags int) (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)
-	}
-	if (flags & unix.AT_REMOVEDIR) != 0 {
-		return syscall.Rmdir(path)
-	}
-	return syscall.Unlink(path)
-}
-
 // emulateMknodat emulates the syscall for platforms that don't have it
 // in the kernel (darwin).
 func emulateMknodat(dirfd int, path string, mode uint32, dev int) error {
diff --git a/internal/syscallcompat/emulate_test.go b/internal/syscallcompat/emulate_test.go
index 7d34c0c..2747cc1 100644
--- a/internal/syscallcompat/emulate_test.go
+++ b/internal/syscallcompat/emulate_test.go
@@ -9,59 +9,6 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func TestEmulateUnlinkat(t *testing.T) {
-	os.Mkdir(tmpDir+"/unlink1", 0700)
-	dirfd, err := os.Open(tmpDir + "/unlink1")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer dirfd.Close()
-	// Try to delete file
-	fd, err := os.Create(tmpDir + "/unlink1/f1")
-	if err != nil {
-		t.Fatal(err)
-	}
-	fd.Close()
-	err = emulateUnlinkat(int(dirfd.Fd()), "f1", 0)
-	if err != nil {
-		t.Fatal(err)
-	}
-	_, err = os.Stat(tmpDir + "/unlink1/f1")
-	if err == nil {
-		t.Fatalf("file not deleted!")
-	}
-	// Try to delete dir
-	err = os.Mkdir(tmpDir+"/unlink1/d1", 0700)
-	if err != nil {
-		t.Fatal(err)
-	}
-	err = emulateUnlinkat(int(dirfd.Fd()), "d1", 0)
-	if err == nil {
-		t.Fatalf("this should fail due to missing AT_REMOVEDIR flag")
-	}
-	err = emulateUnlinkat(int(dirfd.Fd()), "d1", unix.AT_REMOVEDIR)
-	if err != nil {
-		t.Fatal(err)
-	}
-	_, err = os.Stat(tmpDir + "/unlink1/d1")
-	if err == nil {
-		t.Fatalf("dir not deleted!")
-	}
-	// Test with absolute path
-	err = os.Mkdir(tmpDir+"/unlink1/d1", 0700)
-	if err != nil {
-		t.Fatal(err)
-	}
-	err = emulateUnlinkat(-1, tmpDir+"/unlink1/d1", unix.AT_REMOVEDIR)
-	if err != nil {
-		t.Fatal(err)
-	}
-	_, err = os.Stat(tmpDir + "/unlink1/d1")
-	if err == nil {
-		t.Fatalf("dir not deleted!")
-	}
-}
-
 func TestEmulateMknodat(t *testing.T) {
 	err := emulateMknodat(tmpDirFd, "fifo1", unix.S_IFIFO, 0)
 	if err != nil {
diff --git a/internal/syscallcompat/sys_common.go b/internal/syscallcompat/sys_common.go
index d4b2e0d..75d2509 100644
--- a/internal/syscallcompat/sys_common.go
+++ b/internal/syscallcompat/sys_common.go
@@ -67,6 +67,11 @@ func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err e
 	return unix.Renameat(olddirfd, oldpath, newdirfd, newpath)
 }
 
+// Unlinkat syscall.
+func Unlinkat(dirfd int, path string, flags int) (err error) {
+	return unix.Unlinkat(dirfd, path, flags)
+}
+
 // Linkat exists both in Linux and in MacOS 10.10+.
 func Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error) {
 	return unix.Linkat(olddirfd, oldpath, newdirfd, newpath, flags)
diff --git a/internal/syscallcompat/sys_common_test.go b/internal/syscallcompat/sys_common_test.go
index 3e38eb2..4556279 100644
--- a/internal/syscallcompat/sys_common_test.go
+++ b/internal/syscallcompat/sys_common_test.go
@@ -5,6 +5,8 @@ import (
 	"os"
 	"syscall"
 	"testing"
+
+	"golang.org/x/sys/unix"
 )
 
 func TestReadlinkat(t *testing.T) {
@@ -100,6 +102,59 @@ func TestRenameat(t *testing.T) {
 	}
 }
 
+func TestUnlinkat(t *testing.T) {
+	os.Mkdir(tmpDir+"/unlink1", 0700)
+	dirfd, err := os.Open(tmpDir + "/unlink1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dirfd.Close()
+	// Try to delete file
+	fd, err := os.Create(tmpDir + "/unlink1/f1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	fd.Close()
+	err = Unlinkat(int(dirfd.Fd()), "f1", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = os.Stat(tmpDir + "/unlink1/f1")
+	if err == nil {
+		t.Fatalf("file not deleted!")
+	}
+	// Try to delete dir
+	err = os.Mkdir(tmpDir+"/unlink1/d1", 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = Unlinkat(int(dirfd.Fd()), "d1", 0)
+	if err == nil {
+		t.Fatalf("this should fail due to missing AT_REMOVEDIR flag")
+	}
+	err = Unlinkat(int(dirfd.Fd()), "d1", unix.AT_REMOVEDIR)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = os.Stat(tmpDir + "/unlink1/d1")
+	if err == nil {
+		t.Fatalf("dir not deleted!")
+	}
+	// Test with absolute path
+	err = os.Mkdir(tmpDir+"/unlink1/d1", 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = Unlinkat(-1, tmpDir+"/unlink1/d1", unix.AT_REMOVEDIR)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = os.Stat(tmpDir + "/unlink1/d1")
+	if err == nil {
+		t.Fatalf("dir not deleted!")
+	}
+}
+
 func TestFchmodat(t *testing.T) {
 	regular := "TestFchmodat_Regular"
 	f, err := os.OpenFile(tmpDir+"/"+regular, os.O_CREATE|os.O_WRONLY, 0000)
diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go
index f49e41a..92639cf 100644
--- a/internal/syscallcompat/sys_darwin.go
+++ b/internal/syscallcompat/sys_darwin.go
@@ -72,10 +72,6 @@ func OpenatUser(dirfd int, path string, flags int, mode uint32, context *fuse.Co
 	return Openat(dirfd, path, flags, mode)
 }
 
-func Unlinkat(dirfd int, path string, flags int) (err error) {
-	return emulateUnlinkat(dirfd, path, flags)
-}
-
 func Mknodat(dirfd int, path string, mode uint32, dev int) (err error) {
 	return emulateMknodat(dirfd, path, mode, dev)
 }
diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go
index c58f51d..28a7149 100644
--- a/internal/syscallcompat/sys_linux.go
+++ b/internal/syscallcompat/sys_linux.go
@@ -80,11 +80,6 @@ func OpenatUser(dirfd int, path string, flags int, mode uint32, context *fuse.Co
 	return Openat(dirfd, path, flags, mode)
 }
 
-// Unlinkat syscall.
-func Unlinkat(dirfd int, path string, flags int) (err error) {
-	return unix.Unlinkat(dirfd, path, flags)
-}
-
 // Mknodat wraps the Mknodat syscall.
 func Mknodat(dirfd int, path string, mode uint32, dev int) (err error) {
 	return syscall.Mknodat(dirfd, path, mode, dev)
-- 
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