Some refactors to reduce RepoPath

modules/gitrepo/fetch.go

@@ -0,0 +1,19 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package gitrepo
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/modules/git/gitcmd"
+)
+
+// FetchRemoteCommit fetches a specific commit and related commits from a remote repository into the managed repository
+// it will be checked in 2 weeks by default from git if the pull request created failure.
+// It's enough for a temporary fetch to get the merge base.
+func FetchRemoteCommit(ctx context.Context, repo, remoteRepo Repository, commitID string) error {
+	return RunCmd(ctx, repo, gitcmd.NewCommand("fetch", "--no-tags").
+		AddDynamicArguments(repoPath(remoteRepo)).
+		AddDynamicArguments(commitID))
+}

modules/gitrepo/gitrepo.go

@@ -118,3 +118,8 @@ func CreateRepoFile(ctx context.Context, repo Repository, relativeFilePath strin
 	absoluteFilePath := filepath.Join(repoPath(repo), relativeFilePath)
 	return os.Create(absoluteFilePath)
 }
+
+func MkRepoDir(ctx context.Context, repo Repository, relativeDirPath string) error {
+	absoluteDirPath := filepath.Join(repoPath(repo), relativeDirPath)
+	return os.MkdirAll(absoluteDirPath, os.ModePerm)
+}

modules/gitrepo/merge.go

@@ -0,0 +1,34 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package gitrepo
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"code.gitea.io/gitea/modules/git/gitcmd"
+)
+
+// MergeBase checks and returns merge base of two commits.
+func MergeBase(ctx context.Context, repo Repository, commit1, commit2 string) (string, error) {
+	mergeBase, err := RunCmdString(ctx, repo, gitcmd.NewCommand("merge-base").
+		AddDashesAndList(commit1, commit2))
+	if err != nil {
+		return "", fmt.Errorf("get merge-base of %s and %s failed: %w", commit1, commit2, err)
+	}
+	return strings.TrimSpace(mergeBase), nil
+}
+
+// MergeBaseFromRemote checks and returns merge base of two commits from different repositories.
+func MergeBaseFromRemote(ctx context.Context, repo, remoteRepo Repository, commit1, commit2 string) (string, error) {
+	// fetch head commit id into the current repository if the repositories are different
+	if repo.RelativePath() != remoteRepo.RelativePath() {
+		if err := FetchRemoteCommit(ctx, repo, remoteRepo, commit2); err != nil {
+			return "", fmt.Errorf("FetchRemoteCommit: %w", err)
+		}
+	}
+
+	return MergeBase(ctx, repo, commit1, commit2)
+}