MM-21722 - Repository synchronization tool (#86)

build/sync/plan/git/file_history.go

@@ -0,0 +1,106 @@
+package git
+
+import (
+	"crypto/sha1" //nolint
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	git "gopkg.in/src-d/go-git.v4"
+	"gopkg.in/src-d/go-git.v4/plumbing/object"
+)
+
+// ErrNotFound signifies the file was not found.
+var ErrNotFound = fmt.Errorf("not found")
+
+// FileHistory will trace all the versions of a file in the git repository
+// and return a list of sha1 hashes of that file.
+func FileHistory(path string, repo *git.Repository) ([]string, error) {
+	logOpts := git.LogOptions{
+		FileName: &path,
+	}
+	commits, err := repo.Log(&logOpts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get commits for path %q: %v", path, err)
+	}
+	defer commits.Close()
+
+	hashHistory := []string{}
+	cerr := commits.ForEach(func(c *object.Commit) error {
+		root, err := repo.TreeObject(c.TreeHash)
+		if err != nil {
+			return fmt.Errorf("failed to get commit tree: %v", err)
+		}
+		f, err := traverseTree(root, path)
+		if err == object.ErrFileNotFound || err == object.ErrDirectoryNotFound {
+			// Ignoring file not found errors.
+			return nil
+		} else if err != nil {
+			return err
+		}
+		sum, err := getReaderHash(f)
+		f.Close()
+		if err != nil {
+			return err
+		}
+		hashHistory = append(hashHistory, sum)
+		return nil
+	})
+	if cerr != nil && cerr != io.EOF {
+		return nil, cerr
+	}
+	if len(hashHistory) == 0 {
+		return nil, ErrNotFound
+	}
+	return hashHistory, nil
+}
+
+func traverseTree(root *object.Tree, path string) (io.ReadCloser, error) {
+	dirName, fileName := filepath.Split(path)
+	var err error
+	t := root
+	if dirName != "" {
+		t, err = root.Tree(filepath.Clean(dirName))
+		if err == object.ErrDirectoryNotFound {
+			return nil, err
+		} else if err != nil {
+			return nil, fmt.Errorf("failed to traverse tree to %q: %v", dirName, err)
+		}
+	}
+	f, err := t.File(fileName)
+	if err == object.ErrFileNotFound {
+		return nil, err
+	} else if err != nil {
+		return nil, fmt.Errorf("failed to lookup file %q: %v", fileName, err)
+	}
+	reader, err := f.Reader()
+	if err != nil {
+		return nil, fmt.Errorf("failed to open %q: %v", path, err)
+	}
+	return reader, nil
+}
+
+func getReaderHash(r io.Reader) (string, error) {
+	h := sha1.New() // nolint
+	_, err := io.Copy(h, r)
+	if err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+// GetFileHash calculates the sha1 hash sum of the file.
+func GetFileHash(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	sum, err := getReaderHash(f)
+	if err != nil {
+		return "", err
+	}
+	return sum, nil
+}

build/sync/plan/git/file_history_test.go

@@ -0,0 +1,27 @@
+package git_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	git "gopkg.in/src-d/go-git.v4"
+
+	gitutil "github.com/mattermost/mattermost-plugin-starter-template/build/sync/plan/git"
+)
+
+func TestFileHistory(t *testing.T) {
+	assert := assert.New(t)
+
+	repo, err := git.PlainOpenWithOptions("./", &git.PlainOpenOptions{
+		DetectDotGit: true,
+	})
+	assert.Nil(err)
+	sums, err := gitutil.FileHistory("build/sync/plan/git/testdata/testfile.txt", repo)
+	assert.Nil(err)
+	assert.Equal([]string{"ba7192052d7cf77c55d3b7bf40b350b8431b208b"}, sums)
+
+	// Calling with a non-existent file returns error.
+	sums, err = gitutil.FileHistory("build/sync/plan/git/testdata/nosuch_testfile.txt", repo)
+	assert.Equal(gitutil.ErrNotFound, err)
+	assert.Nil(sums)
+}

build/sync/plan/git/testdata/testfile.txt

@@ -0,0 +1 @@
+This file is used to test file history tracking.