worktree: symlink support

utils/merkletrie/filesystem/node.go

@@ -136,25 +136,54 @@ func (n *node) calculateHash(path string, file os.FileInfo) ([]byte, error) {
 		return make([]byte, 24), nil
 	}
 
-	f, err := n.fs.Open(path)
+	var hash plumbing.Hash
+	var err error
+	if file.Mode()&os.ModeSymlink != 0 {
+		hash, err = n.doCalculateHashForSymlink(path, file)
+	} else {
+		hash, err = n.doCalculateHashForRegular(path, file)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	mode, err := filemode.NewFromOSFileMode(file.Mode())
 	if err != nil {
 		return nil, err
 	}
 
+	return append(hash[:], mode.Bytes()...), nil
+}
+
+func (n *node) doCalculateHashForRegular(path string, file os.FileInfo) (plumbing.Hash, error) {
+	f, err := n.fs.Open(path)
+	if err != nil {
+		return plumbing.ZeroHash, err
+	}
+
 	defer f.Close()
 
 	h := plumbing.NewHasher(plumbing.BlobObject, file.Size())
 	if _, err := io.Copy(h, f); err != nil {
-		return nil, err
+		return plumbing.ZeroHash, err
 	}
 
-	mode, err := filemode.NewFromOSFileMode(file.Mode())
+	return h.Sum(), nil
+}
+
+func (n *node) doCalculateHashForSymlink(path string, file os.FileInfo) (plumbing.Hash, error) {
+	target, err := n.fs.Readlink(path)
 	if err != nil {
-		return nil, err
+		return plumbing.ZeroHash, err
 	}
 
-	hash := h.Sum()
-	return append(hash[:], mode.Bytes()...), nil
+	h := plumbing.NewHasher(plumbing.BlobObject, file.Size())
+	if _, err := h.Write([]byte(target)); err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	return h.Sum(), nil
 }
 
 func (n *node) String() string {

utils/merkletrie/filesystem/node_test.go

@@ -25,11 +25,13 @@ func (s *NoderSuite) TestDiff(c *C) {
 	WriteFile(fsA, "foo", []byte("foo"), 0644)
 	WriteFile(fsA, "qux/bar", []byte("foo"), 0644)
 	WriteFile(fsA, "qux/qux", []byte("foo"), 0644)
+	fsA.Symlink("foo", "bar")
 
 	fsB := memfs.New()
 	WriteFile(fsB, "foo", []byte("foo"), 0644)
 	WriteFile(fsB, "qux/bar", []byte("foo"), 0644)
 	WriteFile(fsB, "qux/qux", []byte("foo"), 0644)
+	fsB.Symlink("foo", "bar")
 
 	ch, err := merkletrie.DiffTree(
 		NewRootNode(fsA, nil),
@@ -41,6 +43,23 @@ func (s *NoderSuite) TestDiff(c *C) {
 	c.Assert(ch, HasLen, 0)
 }
 
+func (s *NoderSuite) TestDiffChangeLink(c *C) {
+	fsA := memfs.New()
+	fsA.Symlink("qux", "foo")
+
+	fsB := memfs.New()
+	fsB.Symlink("bar", "foo")
+
+	ch, err := merkletrie.DiffTree(
+		NewRootNode(fsA, nil),
+		NewRootNode(fsB, nil),
+		IsEquals,
+	)
+
+	c.Assert(err, IsNil)
+	c.Assert(ch, HasLen, 1)
+}
+
 func (s *NoderSuite) TestDiffChangeContent(c *C) {
 	fsA := memfs.New()
 	WriteFile(fsA, "foo", []byte("foo"), 0644)

worktree.go

@@ -4,7 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
+	stdioutil "io/ioutil"
 	"os"
 	"path/filepath"
 
@@ -15,6 +15,7 @@ import (
 	"gopkg.in/src-d/go-git.v4/plumbing/format/index"
 	"gopkg.in/src-d/go-git.v4/plumbing/object"
 	"gopkg.in/src-d/go-git.v4/utils/merkletrie"
+	"gopkg.in/src-d/go-git/utils/ioutil"
 
 	"gopkg.in/src-d/go-billy.v3"
 )
@@ -327,29 +328,49 @@ func (w *Worktree) checkoutChangeRegularFile(name string,
 	return nil
 }
 
-func (w *Worktree) checkoutFile(f *object.File) error {
-	from, err := f.Reader()
+func (w *Worktree) checkoutFile(f *object.File) (err error) {
+	mode, err := f.Mode.ToOSFileMode()
 	if err != nil {
-		return err
+		return
 	}
-	defer from.Close()
 
-	mode, err := f.Mode.ToOSFileMode()
+	if mode&os.ModeSymlink != 0 {
+		return w.checkoutFileSymlink(f)
+	}
+
+	from, err := f.Reader()
 	if err != nil {
-		return err
+		return
 	}
 
+	defer ioutil.CheckClose(from, &err)
+
 	to, err := w.fs.OpenFile(f.Name, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, mode.Perm())
 	if err != nil {
-		return err
+		return
 	}
-	defer to.Close()
 
-	if _, err := io.Copy(to, from); err != nil {
-		return err
+	defer ioutil.CheckClose(to, &err)
+
+	_, err = io.Copy(to, from)
+	return
+}
+
+func (w *Worktree) checkoutFileSymlink(f *object.File) (err error) {
+	from, err := f.Reader()
+	if err != nil {
+		return
+	}
+
+	defer ioutil.CheckClose(from, &err)
+
+	bytes, err := stdioutil.ReadAll(from)
+	if err != nil {
+		return
 	}
 
-	return err
+	err = w.fs.Symlink(string(bytes), f.Name)
+	return
 }
 
 func (w *Worktree) addIndexFromTreeEntry(name string, f *object.TreeEntry, idx *index.Index) error {
@@ -363,7 +384,7 @@ func (w *Worktree) addIndexFromTreeEntry(name string, f *object.TreeEntry, idx *
 }
 
 func (w *Worktree) addIndexFromFile(name string, h plumbing.Hash, idx *index.Index) error {
-	fi, err := w.fs.Stat(name)
+	fi, err := w.fs.Lstat(name)
 	if err != nil {
 		return err
 	}
@@ -477,7 +498,7 @@ func (w *Worktree) readGitmodulesFile() (*config.Modules, error) {
 		return nil, err
 	}
 
-	input, err := ioutil.ReadAll(f)
+	input, err := stdioutil.ReadAll(f)
 	if err != nil {
 		return nil, err
 	}

worktree_commit.go

@@ -2,6 +2,7 @@ package git
 
 import (
 	"io"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -186,11 +187,15 @@ func (h *commitIndexHelper) copyIndexEntryToStorage(e *index.Entry) error {
 }
 
 func (h *commitIndexHelper) doCopyIndexEntryToStorage(e *index.Entry) (err error) {
-	fi, err := h.fs.Stat(e.Name)
+	fi, err := h.fs.Lstat(e.Name)
 	if err != nil {
 		return err
 	}
 
+	if fi.Mode()&os.ModeSymlink != 0 {
+		return h.doCopyIndexEntryFromSymlinkToStorage(e, fi)
+	}
+
 	obj := h.s.NewEncodedObject()
 	obj.SetType(plumbing.BlobObject)
 	obj.SetSize(fi.Size())
@@ -217,6 +222,31 @@ func (h *commitIndexHelper) doCopyIndexEntryToStorage(e *index.Entry) (err error
 	return err
 }
 
+func (h *commitIndexHelper) doCopyIndexEntryFromSymlinkToStorage(e *index.Entry, fi os.FileInfo) error {
+	obj := h.s.NewEncodedObject()
+	obj.SetType(plumbing.BlobObject)
+	obj.SetSize(fi.Size())
+
+	writer, err := obj.Writer()
+	if err != nil {
+		return err
+	}
+
+	defer ioutil.CheckClose(writer, &err)
+
+	target, err := h.fs.Readlink(e.Name)
+	if err != nil {
+		return err
+	}
+
+	if _, err := writer.Write([]byte(target)); err != nil {
+		return err
+	}
+
+	_, err = h.s.SetEncodedObject(obj)
+	return err
+}
+
 func (h *commitIndexHelper) copyTreeToStorageRecursive(parent string, t *object.Tree) (plumbing.Hash, error) {
 	for i, e := range t.Entries {
 		if e.Mode != filemode.Dir && !e.Hash.IsZero() {

worktree_status.go

@@ -212,11 +212,15 @@ func (w *Worktree) Add(path string) (plumbing.Hash, error) {
 }
 
 func (w *Worktree) calculateBlobHash(filename string) (hash plumbing.Hash, err error) {
-	fi, err := w.fs.Stat(filename)
+	fi, err := w.fs.Lstat(filename)
 	if err != nil {
 		return plumbing.ZeroHash, err
 	}
 
+	if fi.Mode()&os.ModeSymlink != 0 {
+		return w.calculateBlobHashFromSymlink(filename)
+	}
+
 	f, err := w.fs.Open(filename)
 	if err != nil {
 		return plumbing.ZeroHash, err
@@ -233,6 +237,21 @@ func (w *Worktree) calculateBlobHash(filename string) (hash plumbing.Hash, err e
 	return
 }
 
+func (w *Worktree) calculateBlobHashFromSymlink(link string) (plumbing.Hash, error) {
+	target, err := w.fs.Readlink(link)
+	if err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	h := plumbing.NewHasher(plumbing.BlobObject, int64(len(target)))
+	_, err = h.Write([]byte(target))
+	if err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	return h.Sum(), nil
+}
+
 func (w *Worktree) addOrUpdateFileToIndex(filename string, h plumbing.Hash) error {
 	idx, err := w.r.Storer.Index()
 	if err != nil {
@@ -265,20 +284,22 @@ func (w *Worktree) doAddFileToIndex(idx *index.Index, filename string, h plumbin
 }
 
 func (w *Worktree) doUpdateFileToIndex(e *index.Entry, filename string, h plumbing.Hash) error {
-	info, err := w.fs.Stat(filename)
+	info, err := w.fs.Lstat(filename)
 	if err != nil {
 		return err
 	}
 
 	e.Hash = h
 	e.ModifiedAt = info.ModTime()
 	e.Mode, err = filemode.NewFromOSFileMode(info.Mode())
-	e.Size = uint32(info.Size())
-
 	if err != nil {
 		return err
 	}
 
+	if e.Mode.IsRegular() {
+		e.Size = uint32(info.Size())
+	}
+
 	fillSystemInfo(e, info.Sys())
 	return nil
 }
@@ -319,11 +340,11 @@ func (w *Worktree) deleteFromFilesystem(path string) error {
 // Move moves or rename a file in the worktree and the index, directories are
 // not supported.
 func (w *Worktree) Move(from, to string) (plumbing.Hash, error) {
-	if _, err := w.fs.Stat(from); err != nil {
+	if _, err := w.fs.Lstat(from); err != nil {
 		return plumbing.ZeroHash, err
 	}
 
-	if _, err := w.fs.Stat(to); err == nil {
+	if _, err := w.fs.Lstat(to); err == nil {
 		return plumbing.ZeroHash, ErrDestinationExists
 	}
 

worktree_test.go

@@ -56,6 +56,35 @@ func (s *WorktreeSuite) TestCheckout(c *C) {
 	c.Assert(idx.Entries, HasLen, 9)
 }
 
+func (s *WorktreeSuite) TestCheckoutSymlink(c *C) {
+	dir, err := ioutil.TempDir("", "checkout")
+	defer os.RemoveAll(dir)
+
+	r, err := PlainInit(dir, false)
+	c.Assert(err, IsNil)
+
+	w, err := r.Worktree()
+	c.Assert(err, IsNil)
+
+	w.fs.Symlink("not-exists", "bar")
+	w.Add("bar")
+	w.Commit("foo", &CommitOptions{Author: defaultSignature()})
+
+	r.Storer.SetIndex(&index.Index{Version: 2})
+	w.fs = osfs.New(filepath.Join(dir, "worktree-empty"))
+
+	err = w.Checkout(&CheckoutOptions{})
+	c.Assert(err, IsNil)
+
+	status, err := w.Status()
+	c.Assert(err, IsNil)
+	c.Assert(status.IsClean(), Equals, true)
+
+	target, err := w.fs.Readlink("bar")
+	c.Assert(target, Equals, "not-exists")
+	c.Assert(err, IsNil)
+}
+
 func (s *WorktreeSuite) TestCheckoutSubmodule(c *C) {
 	url := "https://github.com/git-fixtures/submodule.git"
 	w := &Worktree{
@@ -591,6 +620,28 @@ func (s *WorktreeSuite) TestAddUnmodified(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *WorktreeSuite) TestAddSymlink(c *C) {
+	dir, err := ioutil.TempDir("", "checkout")
+	defer os.RemoveAll(dir)
+
+	r, err := PlainInit(dir, false)
+	c.Assert(err, IsNil)
+	err = util.WriteFile(r.wt, "foo", []byte("qux"), 0644)
+	c.Assert(err, IsNil)
+	err = r.wt.Symlink("foo", "bar")
+	c.Assert(err, IsNil)
+
+	w, err := r.Worktree()
+	c.Assert(err, IsNil)
+	h, err := w.Add("foo")
+	c.Assert(err, IsNil)
+	c.Assert(h, Not(Equals), plumbing.NewHash("19102815663d23f8b75a47e7a01965dcdc96468c"))
+
+	h, err = w.Add("bar")
+	c.Assert(err, IsNil)
+	c.Assert(h, Equals, plumbing.NewHash("19102815663d23f8b75a47e7a01965dcdc96468c"))
+}
+
 func (s *WorktreeSuite) TestRemove(c *C) {
 	fs := memfs.New()
 	w := &Worktree{