copy: add fast copy path for darwin

copy/copy.go

@@ -329,21 +329,6 @@ func ensureEmptyFileTarget(dst string) error {
 	return os.Remove(dst)
 }
 
-func copyFile(source, target string) error {
-	src, err := os.Open(source)
-	if err != nil {
-		return errors.Wrapf(err, "failed to open source %s", source)
-	}
-	defer src.Close()
-	tgt, err := os.Create(target)
-	if err != nil {
-		return errors.Wrapf(err, "failed to open target %s", target)
-	}
-	defer tgt.Close()
-
-	return copyFileContent(tgt, src)
-}
-
 func containsWildcards(name string) bool {
 	isWindows := runtime.GOOS == "windows"
 	for i := 0; i < len(name); i++ {

copy/copy_darwin.go

@@ -0,0 +1,84 @@
+// +build darwin
+
+package fs
+
+import (
+	"io"
+	"os"
+	"syscall"
+	"unsafe"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
+)
+
+// <sys/clonefile.h
+// int clonefileat(int, const char *, int, const char *, uint32_t) __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0) __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0);
+
+const CLONE_NOFOLLOW = 0x0001    /* Don't follow symbolic links */
+const CLONE_NOOWNERCOPY = 0x0002 /* Don't copy ownership information from */
+
+func copyFile(source, target string) error {
+	if err := clonefile(source, target); err != nil {
+		if err != unix.EINVAL {
+			return err
+		}
+	} else {
+		return nil
+	}
+
+	src, err := os.Open(source)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open source %s", source)
+	}
+	defer src.Close()
+	tgt, err := os.Create(target)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open target %s", target)
+	}
+	defer tgt.Close()
+
+	return copyFileContent(tgt, src)
+}
+
+func copyFileContent(dst, src *os.File) error {
+	buf := bufferPool.Get().(*[]byte)
+	_, err := io.CopyBuffer(dst, src, *buf)
+	bufferPool.Put(buf)
+
+	return err
+}
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return nil
+	case unix.EAGAIN:
+		return syscall.EAGAIN
+	case unix.EINVAL:
+		return syscall.EINVAL
+	case unix.ENOENT:
+		return syscall.ENOENT
+	}
+	return e
+}
+
+func clonefile(src, dst string) (err error) {
+	var _p0, _p1 *byte
+	_p0, err = unix.BytePtrFromString(src)
+	if err != nil {
+		return
+	}
+	_p1, err = unix.BytePtrFromString(dst)
+	if err != nil {
+		return
+	}
+	fdcwd := unix.AT_FDCWD
+	_, _, e1 := unix.Syscall6(unix.SYS_CLONEFILEAT, uintptr(fdcwd), uintptr(unsafe.Pointer(_p0)), uintptr(fdcwd), uintptr(unsafe.Pointer(_p1)), uintptr(CLONE_NOFOLLOW), 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}

copy/copy_linux.go

@@ -52,6 +52,21 @@ func (c *copier) copyFileInfo(fi os.FileInfo, name string) error {
 	return nil
 }
 
+func copyFile(source, target string) error {
+	src, err := os.Open(source)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open source %s", source)
+	}
+	defer src.Close()
+	tgt, err := os.Create(target)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open target %s", target)
+	}
+	defer tgt.Close()
+
+	return copyFileContent(tgt, src)
+}
+
 func copyFileContent(dst, src *os.File) error {
 	st, err := src.Stat()
 	if err != nil {

copy/copy_test.go

@@ -220,6 +220,10 @@ func TestCopyWildcards(t *testing.T) {
 }
 
 func TestCopyExistingDirDest(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip()
+	}
+
 	t1, err := ioutil.TempDir("", "test")
 	require.NoError(t, err)
 	defer os.RemoveAll(t1)

copy/copy_unix.go

@@ -3,7 +3,6 @@
 package fs
 
 import (
-	"io"
 	"os"
 	"syscall"
 
@@ -51,14 +50,6 @@ func (c *copier) copyFileInfo(fi os.FileInfo, name string) error {
 	return nil
 }
 
-func copyFileContent(dst, src *os.File) error {
-	buf := bufferPool.Get().(*[]byte)
-	_, err := io.CopyBuffer(dst, src, *buf)
-	bufferPool.Put(buf)
-
-	return err
-}
-
 func copyDevice(dst string, fi os.FileInfo) error {
 	st, ok := fi.Sys().(*syscall.Stat_t)
 	if !ok {

copy/copy_windows.go

@@ -17,6 +17,21 @@ func (c *copier) copyFileInfo(fi os.FileInfo, name string) error {
 	return nil
 }
 
+func copyFile(source, target string) error {
+	src, err := os.Open(source)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open source %s", source)
+	}
+	defer src.Close()
+	tgt, err := os.Create(target)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open target %s", target)
+	}
+	defer tgt.Close()
+
+	return copyFileContent(tgt, src)
+}
+
 func copyFileContent(dst, src *os.File) error {
 	buf := bufferPool.Get().(*[]byte)
 	_, err := io.CopyBuffer(dst, src, *buf)