1 files changed, 123 insertions, 0 deletions
diff --git a/modules/git/blame.go b/modules/git/blame.go
new file mode 100644
index 0000000000..548236b657
--- /dev/null
+++ b/modules/git/blame.go
@@ -0,0 +1,123 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"regexp"
+
+	"code.gitea.io/gitea/modules/process"
+)
+
+// BlamePart represents block of blame - continuous lines with one sha
+type BlamePart struct {
+	Sha   string
+	Lines []string
+}
+
+// BlameReader returns part of file blame one by one
+type BlameReader struct {
+	cmd     *exec.Cmd
+	pid     int64
+	output  io.ReadCloser
+	scanner *bufio.Scanner
+	lastSha *string
+}
+
+var shaLineRegex = regexp.MustCompile("^([a-z0-9]{40})")
+
+// NextPart returns next part of blame (sequencial code lines with the same commit)
+func (r *BlameReader) NextPart() (*BlamePart, error) {
+	var blamePart *BlamePart
+
+	scanner := r.scanner
+
+	if r.lastSha != nil {
+		blamePart = &BlamePart{*r.lastSha, make([]string, 0)}
+	}
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		// Skip empty lines
+		if len(line) == 0 {
+			continue
+		}
+
+		lines := shaLineRegex.FindStringSubmatch(line)
+		if lines != nil {
+			sha1 := lines[1]
+
+			if blamePart == nil {
+				blamePart = &BlamePart{sha1, make([]string, 0)}
+			}
+
+			if blamePart.Sha != sha1 {
+				r.lastSha = &sha1
+				return blamePart, nil
+			}
+		} else if line[0] == '\t' {
+			code := line[1:]
+
+			blamePart.Lines = append(blamePart.Lines, code)
+		}
+	}
+
+	r.lastSha = nil
+
+	return blamePart, nil
+}
+
+// Close BlameReader - don't run NextPart after invoking that
+func (r *BlameReader) Close() error {
+	process.GetManager().Remove(r.pid)
+
+	if err := r.cmd.Wait(); err != nil {
+		return fmt.Errorf("Wait: %v", err)
+	}
+
+	return nil
+}
+
+// CreateBlameReader creates reader for given repository, commit and file
+func CreateBlameReader(repoPath, commitID, file string) (*BlameReader, error) {
+	_, err := OpenRepository(repoPath)
+	if err != nil {
+		return nil, err
+	}
+
+	return createBlameReader(repoPath, GitExecutable, "blame", commitID, "--porcelain", "--", file)
+}
+
+func createBlameReader(dir string, command ...string) (*BlameReader, error) {
+	cmd := exec.Command(command[0], command[1:]...)
+	cmd.Dir = dir
+	cmd.Stderr = os.Stderr
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf("StdoutPipe: %v", err)
+	}
+
+	if err = cmd.Start(); err != nil {
+		return nil, fmt.Errorf("Start: %v", err)
+	}
+
+	pid := process.GetManager().Add(fmt.Sprintf("GetBlame [repo_path: %s]", dir), cmd)
+
+	scanner := bufio.NewScanner(stdout)
+
+	return &BlameReader{
+		cmd,
+		pid,
+		stdout,
+		scanner,
+		nil,
+	}, nil
+}