documentation and API improvements

2 files changed, 177 insertions, 14 deletions

diff --git a/storage/filesystem/internal/dotgit/dotgit.go b/storage/filesystem/internal/dotgit/dotgit.go
index 360b3d1..b46f827 100644
--- a/storage/filesystem/internal/dotgit/dotgit.go
+++ b/storage/filesystem/internal/dotgit/dotgit.go
@@ -5,11 +5,12 @@ import (
 	"bufio"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	stdioutil "io/ioutil"
 	"os"
 	"strings"
 
 	"srcd.works/go-git.v4/plumbing"
+	"srcd.works/go-git.v4/utils/ioutil"
 
 	"srcd.works/go-billy.v1"
 )
@@ -25,6 +26,8 @@ const (
 	packPath       = "pack"
 	refsPath       = "refs"
 
+	tmpPackedRefsPrefix = "._packed-refs"
+
 	packExt = ".pack"
 	idxExt  = ".idx"
 )
@@ -269,6 +272,21 @@ func (d *DotGit) Ref(name plumbing.ReferenceName) (*plumbing.Reference, error) {
 	return nil, plumbing.ErrReferenceNotFound
 }
 
+// RemoveRef removes a reference by name.
+func (d *DotGit) RemoveRef(name plumbing.ReferenceName) error {
+	path := d.fs.Join(".", name.String())
+	_, err := d.fs.Stat(path)
+	if err == nil {
+		return d.fs.Remove(path)
+	}
+
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	return d.rewritePackedRefsWithoutRef(name)
+}
+
 func (d *DotGit) addRefsFromPackedRefs(refs *[]*plumbing.Reference) (err error) {
 	f, err := d.fs.Open(packedRefsPath)
 	if err != nil {
@@ -277,12 +295,7 @@ func (d *DotGit) addRefsFromPackedRefs(refs *[]*plumbing.Reference) (err error)
 		}
 		return err
 	}
-
-	defer func() {
-		if errClose := f.Close(); err == nil {
-			err = errClose
-		}
-	}()
+	defer ioutil.CheckClose(f, &err)
 
 	s := bufio.NewScanner(f)
 	for s.Scan() {
@@ -299,8 +312,64 @@ func (d *DotGit) addRefsFromPackedRefs(refs *[]*plumbing.Reference) (err error)
 	return s.Err()
 }
 
+func (d *DotGit) rewritePackedRefsWithoutRef(name plumbing.ReferenceName) (err error) {
+	f, err := d.fs.Open(packedRefsPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+
+		return err
+	}
+	defer ioutil.CheckClose(f, &err)
+
+	// Creating the temp file in the same directory as the target file
+	// improves our chances for rename operation to be atomic.
+	tmp, err := d.fs.TempFile("", tmpPackedRefsPrefix)
+	if err != nil {
+		return err
+	}
+
+	tmpPath := tmp.Filename()
+	defer ioutil.CheckClose(tmp, &err)
+	defer d.fs.Remove(tmpPath)
+
+	s := bufio.NewScanner(f)
+	found := false
+	for s.Scan() {
+		line := s.Text()
+		ref, err := d.processLine(line)
+		if err != nil {
+			return err
+		}
+
+		if ref != nil && ref.Name() == name {
+			found = true
+			continue
+		}
+
+		if _, err := fmt.Fprintln(tmp, line); err != nil {
+			return err
+		}
+	}
+
+	if err := s.Err(); err != nil {
+		return err
+	}
+
+	if !found {
+		return nil
+	}
+
+	return d.fs.Rename(tmpPath, packedRefsPath)
+}
+
 // process lines from a packed-refs file
 func (d *DotGit) processLine(line string) (*plumbing.Reference, error) {
+	if len(line) == 0 {
+		return nil, nil
+	}
+
 	switch line[0] {
 	case '#': // comment - ignore
 		return nil, nil
@@ -374,14 +443,9 @@ func (d *DotGit) readReferenceFile(refsPath, refFile string) (ref *plumbing.Refe
 	if err != nil {
 		return nil, err
 	}
+	defer ioutil.CheckClose(f, &err)
 
-	defer func() {
-		if errClose := f.Close(); err == nil {
-			err = errClose
-		}
-	}()
-
-	b, err := ioutil.ReadAll(f)
+	b, err := stdioutil.ReadAll(f)
 	if err != nil {
 		return nil, err
 	}
diff --git a/storage/filesystem/internal/dotgit/dotgit_test.go b/storage/filesystem/internal/dotgit/dotgit_test.go
index a335e5f..57dfb53 100644
--- a/storage/filesystem/internal/dotgit/dotgit_test.go
+++ b/storage/filesystem/internal/dotgit/dotgit_test.go
@@ -1,6 +1,7 @@
 package dotgit
 
 import (
+	"bufio"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -108,6 +109,96 @@ func (s *SuiteDotGit) TestRefsFromReferenceFile(c *C) {
 
 }
 
+func (s *SuiteDotGit) TestRemoveRefFromReferenceFile(c *C) {
+	fs := fixtures.Basic().ByTag(".git").One().DotGit()
+	dir := New(fs)
+
+	name := plumbing.ReferenceName("refs/remotes/origin/HEAD")
+	err := dir.RemoveRef(name)
+	c.Assert(err, IsNil)
+
+	refs, err := dir.Refs()
+	c.Assert(err, IsNil)
+
+	ref := findReference(refs, string(name))
+	c.Assert(ref, IsNil)
+}
+
+func (s *SuiteDotGit) TestRemoveRefFromPackedRefs(c *C) {
+	fs := fixtures.Basic().ByTag(".git").One().DotGit()
+	dir := New(fs)
+
+	name := plumbing.ReferenceName("refs/remotes/origin/master")
+	err := dir.RemoveRef(name)
+	c.Assert(err, IsNil)
+
+	b, err := ioutil.ReadFile(filepath.Join(fs.Base(), packedRefsPath))
+	c.Assert(err, IsNil)
+
+	c.Assert(string(b), Equals, ""+
+		"# pack-refs with: peeled fully-peeled \n"+
+		"6ecf0ef2c2dffb796033e5a02219af86ec6584e5 refs/heads/master\n"+
+		"e8d3ffab552895c19b9fcf7aa264d277cde33881 refs/remotes/origin/branch\n")
+}
+
+func (s *SuiteDotGit) TestRemoveRefNonExistent(c *C) {
+	fs := fixtures.Basic().ByTag(".git").One().DotGit()
+	dir := New(fs)
+
+	packedRefs := filepath.Join(fs.Base(), packedRefsPath)
+	before, err := ioutil.ReadFile(packedRefs)
+	c.Assert(err, IsNil)
+
+	name := plumbing.ReferenceName("refs/heads/nonexistent")
+	err = dir.RemoveRef(name)
+	c.Assert(err, IsNil)
+
+	after, err := ioutil.ReadFile(packedRefs)
+	c.Assert(err, IsNil)
+
+	c.Assert(string(before), Equals, string(after))
+}
+
+func (s *SuiteDotGit) TestRemoveRefInvalidPackedRefs(c *C) {
+	fs := fixtures.Basic().ByTag(".git").One().DotGit()
+	dir := New(fs)
+
+	packedRefs := filepath.Join(fs.Base(), packedRefsPath)
+	brokenContent := "BROKEN STUFF REALLY BROKEN"
+
+	err := ioutil.WriteFile(packedRefs, []byte(brokenContent), os.FileMode(0755))
+	c.Assert(err, IsNil)
+
+	name := plumbing.ReferenceName("refs/heads/nonexistent")
+	err = dir.RemoveRef(name)
+	c.Assert(err, NotNil)
+
+	after, err := ioutil.ReadFile(filepath.Join(fs.Base(), packedRefsPath))
+	c.Assert(err, IsNil)
+
+	c.Assert(brokenContent, Equals, string(after))
+}
+
+func (s *SuiteDotGit) TestRemoveRefInvalidPackedRefs2(c *C) {
+	fs := fixtures.Basic().ByTag(".git").One().DotGit()
+	dir := New(fs)
+
+	packedRefs := filepath.Join(fs.Base(), packedRefsPath)
+	brokenContent := strings.Repeat("a", bufio.MaxScanTokenSize*2)
+
+	err := ioutil.WriteFile(packedRefs, []byte(brokenContent), os.FileMode(0755))
+	c.Assert(err, IsNil)
+
+	name := plumbing.ReferenceName("refs/heads/nonexistent")
+	err = dir.RemoveRef(name)
+	c.Assert(err, NotNil)
+
+	after, err := ioutil.ReadFile(filepath.Join(fs.Base(), packedRefsPath))
+	c.Assert(err, IsNil)
+
+	c.Assert(brokenContent, Equals, string(after))
+}
+
 func (s *SuiteDotGit) TestRefsFromHEADFile(c *C) {
 	fs := fixtures.Basic().ByTag(".git").One().DotGit()
 	dir := New(fs)
@@ -343,3 +434,11 @@ func (s *SuiteDotGit) TestObjectNotFound(c *C) {
 	c.Assert(err, NotNil)
 	c.Assert(file, IsNil)
 }
+
+func (s *SuiteDotGit) TestSubmodules(c *C) {
+	fs := fixtures.ByTag("submodule").One().DotGit()
+	dir := New(fs)
+
+	m := dir.Module("basic")
+	c.Assert(strings.HasSuffix(m.Base(), ".git/module/basic"), Equals, true)
+}