devel-importer: handle history rewrite

Imports can have history rewritten because email addresses
can change in OBS and are not recorded as in git commits. This
can be handled via comparing Tree objects and rebasing
new changes ontop.

bots-common/git_utils.go

@@ -105,7 +105,7 @@ func (e *GitHandler) CloneDevel(gitDir, outName, urlString string) error {
 	params = append(params, url.String(), outName)
 
 	if err != nil {
-		return fmt.Errorf("error parsing SSH URL. %w", err);
+		return fmt.Errorf("error parsing SSH URL. %w", err)
 	}
 	out, err := e.GitExecWithOutput(gitDir, params...)
 	if err != nil {
@@ -472,6 +472,53 @@ func parseGitBlob(data <-chan byte) ([]byte, error) {
 	return d, nil
 }
 
+func (e *GitHandler) GitParseCommits(cwd string, commitIDs []string) (parsedCommits []commit, err error) {
+	var done sync.Mutex
+
+	done.Lock()
+	data_in, data_out := ChanIO{make(chan byte, 256)}, ChanIO{make(chan byte, 70)}
+	parsedCommits = make([]commit, 0, len(commitIDs))
+
+	go func() {
+		defer done.Unlock()
+		defer close(data_out.ch)
+
+		for _, id := range commitIDs {
+			data_out.Write([]byte(id))
+			data_out.ch <- '\x00'
+			c, e := parseGitCommit(data_in.ch)
+			if e != nil {
+				err = fmt.Errorf("Error parsing git commit: %w", e)
+				return
+			}
+
+			parsedCommits = append(parsedCommits, c)
+		}
+	}()
+
+	cmd := exec.Command("/usr/bin/git", "cat-file", "--batch", "-Z")
+	cmd.Env = []string{
+		"GIT_CEILING_DIRECTORIES=" + e.GitPath,
+		"GIT_CONFIG_GLOBAL=/dev/null",
+	}
+	cmd.Dir = filepath.Join(e.GitPath, cwd)
+	cmd.Stdout = &data_in
+	cmd.Stdin = &data_out
+	cmd.Stderr = writeFunc(func(data []byte) (int, error) {
+		if e.DebugLogger {
+			log.Printf(string(data))
+		}
+		return len(data), nil
+	})
+	if e.DebugLogger {
+		log.Printf("command run: %v\n", cmd.Args)
+	}
+	err = cmd.Run()
+
+	done.Lock()
+	return
+}
+
 // TODO: support sub-trees
 func (e *GitHandler) GitCatFile(cwd, commitId, filename string) (data []byte, err error) {
 	var done sync.Mutex