Fix reading git notes from nested trees (#8026)

* Fix reading notes from nested trees

The GIT documentation for notes states "Permitted pathnames have the
form ab/cd/ef/.../abcdef...: a sequence of directory names of two
hexadecimal digits each followed by a filename with the rest of
the object ID."

* Add test case

* Fix new lines

modules/git/notes.go

@@ -6,6 +6,8 @@ package git
 
 import (
 	"io/ioutil"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/object"
 )
 
 // NotesRef is the git ref where Gitea will look for git-notes data.
@@ -25,13 +27,28 @@ func GetNote(repo *Repository, commitID string, note *Note) error {
 		return err
 	}
 
-	entry, err := notes.GetTreeEntryByPath(commitID)
+	remainingCommitID := commitID
+	path := ""
+	currentTree := notes.Tree.gogitTree
+	var file *object.File
+	for len(remainingCommitID) > 2 {
+		file, err = currentTree.File(remainingCommitID)
+		if err == nil {
+			path += remainingCommitID
+			break
+		}
+		if err == object.ErrFileNotFound {
+			currentTree, err = currentTree.Tree(remainingCommitID[0:2])
+			path += remainingCommitID[0:2] + "/"
+			remainingCommitID = remainingCommitID[2:]
+		}
 		if err != nil {
 			return err
 		}
+	}
 
-	blob := entry.Blob()
-	dataRc, err := blob.DataAsync()
+	blob := file.Blob
+	dataRc, err := blob.Reader()
 	if err != nil {
 		return err
 	}
@@ -43,26 +60,21 @@ func GetNote(repo *Repository, commitID string, note *Note) error {
 	}
 	note.Message = d
 
-	commit, err := repo.gogitRepo.CommitObject(notes.ID)
-	if err != nil {
-		return err
-	}
-
 	commitNodeIndex, commitGraphFile := repo.CommitNodeIndex()
 	if commitGraphFile != nil {
 		defer commitGraphFile.Close()
 	}
 
-	commitNode, err := commitNodeIndex.Get(commit.Hash)
+	commitNode, err := commitNodeIndex.Get(notes.ID)
 	if err != nil {
-		return nil
+		return err
 	}
 
-	lastCommits, err := getLastCommitForPaths(commitNode, "", []string{commitID})
+	lastCommits, err := getLastCommitForPaths(commitNode, "", []string{path})
 	if err != nil {
 		return err
 	}
-	note.Commit = convertCommit(lastCommits[commitID])
+	note.Commit = convertCommit(lastCommits[path])
 
 	return nil
 }

modules/git/notes_test.go

@@ -22,3 +22,17 @@ func TestGetNotes(t *testing.T) {
 	assert.Equal(t, []byte("Note contents\n"), note.Message)
 	assert.Equal(t, "Vladimir Panteleev", note.Commit.Author.Name)
 }
+
+func TestGetNestedNotes(t *testing.T) {
+	repoPath := filepath.Join(testReposDir, "repo3_notes")
+	repo, err := OpenRepository(repoPath)
+	assert.NoError(t, err)
+
+	note := Note{}
+	err = GetNote(repo, "3e668dbfac39cbc80a9ff9c61eb565d944453ba4", &note)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("Note 2"), note.Message)
+	err = GetNote(repo, "ba0a96fa63532d6c5087ecef070b0250ed72fa47", &note)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("Note 1"), note.Message)
+}

modules/git/tests/repos/repo3_notes/COMMIT_EDITMSG

@@ -0,0 +1 @@
+2

modules/git/tests/repos/repo3_notes/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

modules/git/tests/repos/repo3_notes/config

@@ -0,0 +1,7 @@
+[core]
+	repositoryformatversion = 0
+	filemode = false
+	bare = false
+	logallrefupdates = true
+	symlinks = false
+	ignorecase = true

modules/git/tests/repos/repo3_notes/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

modules/git/tests/repos/repo3_notes/logs/HEAD

@@ -0,0 +1,2 @@
+0000000000000000000000000000000000000000 ba0a96fa63532d6c5087ecef070b0250ed72fa47 Filip Navara <filip.navara@gmail.com> 1567767895 +0200	commit (initial): 1
+ba0a96fa63532d6c5087ecef070b0250ed72fa47 3e668dbfac39cbc80a9ff9c61eb565d944453ba4 Filip Navara <filip.navara@gmail.com> 1567767909 +0200	commit: 2

modules/git/tests/repos/repo3_notes/logs/refs/heads/master

@@ -0,0 +1,2 @@
+0000000000000000000000000000000000000000 ba0a96fa63532d6c5087ecef070b0250ed72fa47 Filip Navara <filip.navara@gmail.com> 1567767895 +0200	commit (initial): 1
+ba0a96fa63532d6c5087ecef070b0250ed72fa47 3e668dbfac39cbc80a9ff9c61eb565d944453ba4 Filip Navara <filip.navara@gmail.com> 1567767909 +0200	commit: 2

modules/git/tests/repos/repo3_notes/objects/3e/668dbfac39cbc80a9ff9c61eb565d944453ba4

@@ -0,0 +1,3 @@
+x
ťŽ;Â0@™s
+ďH•ă&v*!ÄÄČś4<EFBFBD>JôŁ(p~
+G`|oxziťç©
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modules/git/tests/repos/repo3_notes/objects/65/4c8b6b63c08bf37f638d3f521626b7fbbd4d37

@@ -0,0 +1 @@
+x
ќЌ;В0©}Љн‘"Зїu$„RQr‡•ЩK1F–Йщ1ЃnfЉчR-%w<EFBFBD>Сzcбґ{д%7Аўh#Сx¶€ЙQ¤айfXС»?jѓKЮт®ґS#8ЙЧ¦зПЦ{ЎјM©–3М> †Ёќ…Ј6Z«QЗmзїФя8В

modules/git/tests/repos/repo3_notes/refs/heads/master

@@ -0,0 +1 @@
+3e668dbfac39cbc80a9ff9c61eb565d944453ba4

modules/git/tests/repos/repo3_notes/refs/notes/commits

@@ -0,0 +1 @@
+654c8b6b63c08bf37f638d3f521626b7fbbd4d37