Fix sync fork for consistency (#33147) (#33192)

Backport #33147 by changchaishi

Fixes #33145

An integration test could be added.

---------

Co-authored-by: Chai-Shi <changchaishi@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/structs/repo_branch.go

@@ -133,3 +133,11 @@ type EditBranchProtectionOption struct {
 type UpdateBranchProtectionPriories struct {
 	IDs []int64 `json:"ids"`
 }
+
+type MergeUpstreamRequest struct {
+	Branch string `json:"branch"`
+}
+
+type MergeUpstreamResponse struct {
+	MergeStyle string `json:"merge_type"`
+}

routers/api/v1/api.go

@@ -1190,6 +1190,7 @@ func Routes() *web.Router {
 				m.Get("/archive/*", reqRepoReader(unit.TypeCode), repo.GetArchive)
 				m.Combo("/forks").Get(repo.ListForks).
 					Post(reqToken(), reqRepoReader(unit.TypeCode), bind(api.CreateForkOption{}), repo.CreateFork)
+				m.Post("/merge-upstream", reqToken(), mustNotBeArchived, reqRepoWriter(unit.TypeCode), bind(api.MergeUpstreamRequest{}), repo.MergeUpstream)
 				m.Group("/branches", func() {
 					m.Get("", repo.ListBranches)
 					m.Get("/*", repo.GetBranch)

routers/api/v1/repo/branch.go

@@ -19,6 +19,7 @@ import (
 	"code.gitea.io/gitea/modules/optional"
 	repo_module "code.gitea.io/gitea/modules/repository"
 	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers/api/v1/utils"
 	"code.gitea.io/gitea/services/context"
@@ -1194,3 +1195,47 @@ func UpdateBranchProtectionPriories(ctx *context.APIContext) {
 
 	ctx.Status(http.StatusNoContent)
 }
+
+func MergeUpstream(ctx *context.APIContext) {
+	// swagger:operation POST /repos/{owner}/{repo}/merge-upstream repository repoMergeUpstream
+	// ---
+	// summary: Merge a branch from upstream
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: owner
+	//   in: path
+	//   description: owner of the repo
+	//   type: string
+	//   required: true
+	// - name: repo
+	//   in: path
+	//   description: name of the repo
+	//   type: string
+	//   required: true
+	// - name: body
+	//   in: body
+	//   schema:
+	//     "$ref": "#/definitions/MergeUpstreamRequest"
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/MergeUpstreamResponse"
+	//   "400":
+	//     "$ref": "#/responses/error"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	form := web.GetForm(ctx).(*api.MergeUpstreamRequest)
+	mergeStyle, err := repo_service.MergeUpstream(ctx, ctx.Doer, ctx.Repo.Repository, form.Branch)
+	if err != nil {
+		if errors.Is(err, util.ErrInvalidArgument) {
+			ctx.Error(http.StatusBadRequest, "MergeUpstream", err)
+			return
+		} else if errors.Is(err, util.ErrNotExist) {
+			ctx.Error(http.StatusNotFound, "MergeUpstream", err)
+			return
+		}
+		ctx.Error(http.StatusInternalServerError, "MergeUpstream", err)
+		return
+	}
+	ctx.JSON(http.StatusOK, &api.MergeUpstreamResponse{MergeStyle: mergeStyle})
+}

routers/api/v1/swagger/repo.go

@@ -448,3 +448,15 @@ type swaggerCompare struct {
 	// in:body
 	Body api.Compare `json:"body"`
 }
+
+// swagger:response MergeUpstreamRequest
+type swaggerMergeUpstreamRequest struct {
+	// in:body
+	Body api.MergeUpstreamRequest `json:"body"`
+}
+
+// swagger:response MergeUpstreamResponse
+type swaggerMergeUpstreamResponse struct {
+	// in:body
+	Body api.MergeUpstreamResponse `json:"body"`
+}

services/repository/merge_upstream.go

@@ -12,17 +12,19 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
 	repo_module "code.gitea.io/gitea/modules/repository"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/pull"
 )
 
 type UpstreamDivergingInfo struct {
-	BaseIsNewer   bool
-	CommitsBehind int
-	CommitsAhead  int
+	BaseHasNewCommits bool
+	CommitsBehind     int
+	CommitsAhead      int
 }
 
+// MergeUpstream merges the base repository's default branch into the fork repository's current branch.
 func MergeUpstream(ctx context.Context, doer *user_model.User, repo *repo_model.Repository, branch string) (mergeStyle string, err error) {
 	if err = repo.MustNotBeArchived(); err != nil {
 		return "", err
@@ -32,7 +34,7 @@ func MergeUpstream(ctx context.Context, doer *user_model.User, repo *repo_model.
 	}
 	err = git.Push(ctx, repo.BaseRepo.RepoPath(), git.PushOptions{
 		Remote: repo.RepoPath(),
-		Branch: fmt.Sprintf("%s:%s", branch, branch),
+		Branch: fmt.Sprintf("%s:%s", repo.BaseRepo.DefaultBranch, branch),
 		Env:    repo_module.PushingEnvironment(doer, repo),
 	})
 	if err == nil {
@@ -64,7 +66,7 @@ func MergeUpstream(ctx context.Context, doer *user_model.User, repo *repo_model.
 		BaseRepoID: repo.BaseRepo.ID,
 		BaseRepo:   repo.BaseRepo,
 		HeadBranch: branch, // maybe HeadCommitID is not needed
-		BaseBranch: branch,
+		BaseBranch: repo.BaseRepo.DefaultBranch,
 	}
 	fakeIssue.PullRequest = fakePR
 	err = pull.Update(ctx, fakePR, doer, "merge upstream", false)
@@ -74,6 +76,7 @@ func MergeUpstream(ctx context.Context, doer *user_model.User, repo *repo_model.
 	return "merge", nil
 }
 
+// GetUpstreamDivergingInfo returns the information about the divergence between the fork repository's branch and the base repository's default branch.
 func GetUpstreamDivergingInfo(ctx context.Context, repo *repo_model.Repository, branch string) (*UpstreamDivergingInfo, error) {
 	if !repo.IsFork {
 		return nil, util.NewInvalidArgumentErrorf("repo is not a fork")
@@ -92,7 +95,7 @@ func GetUpstreamDivergingInfo(ctx context.Context, repo *repo_model.Repository,
 		return nil, err
 	}
 
-	baseBranch, err := git_model.GetBranch(ctx, repo.BaseRepo.ID, branch)
+	baseBranch, err := git_model.GetBranch(ctx, repo.BaseRepo.ID, repo.BaseRepo.DefaultBranch)
 	if err != nil {
 		return nil, err
 	}
@@ -102,14 +105,42 @@ func GetUpstreamDivergingInfo(ctx context.Context, repo *repo_model.Repository,
 		return info, nil
 	}
 
-	// TODO: if the fork repo has new commits, this call will fail:
+	// if the fork repo has new commits, this call will fail because they are not in the base repo
 	// exit status 128 - fatal: Invalid symmetric difference expression aaaaaaaaaaaa...bbbbbbbbbbbb
-	// so at the moment, we are not able to handle this case, should be improved in the future
+	// so at the moment, we first check the update time, then check whether the fork branch has base's head
 	diff, err := git.GetDivergingCommits(ctx, repo.BaseRepo.RepoPath(), baseBranch.CommitID, forkBranch.CommitID)
 	if err != nil {
-		info.BaseIsNewer = baseBranch.UpdatedUnix > forkBranch.UpdatedUnix
+		info.BaseHasNewCommits = baseBranch.UpdatedUnix > forkBranch.UpdatedUnix
+		if info.BaseHasNewCommits {
+			return info, nil
+		}
+
+		// if the base's update time is before the fork, check whether the base's head is in the fork
+		baseGitRepo, baseGitRepoCloser, err := gitrepo.RepositoryFromContextOrOpen(ctx, repo.BaseRepo)
+		if err != nil {
+			return nil, err
+		}
+		defer baseGitRepoCloser.Close()
+
+		headGitRepo, headGitRepoCloser, err := gitrepo.RepositoryFromContextOrOpen(ctx, repo)
+		if err != nil {
+			return nil, err
+		}
+		defer headGitRepoCloser.Close()
+
+		baseCommitID, err := baseGitRepo.ConvertToGitID(baseBranch.CommitID)
+		if err != nil {
+			return nil, err
+		}
+		headCommit, err := headGitRepo.GetCommit(forkBranch.CommitID)
+		if err != nil {
+			return nil, err
+		}
+		hasPreviousCommit, _ := headCommit.HasPreviousCommit(baseCommitID)
+		info.BaseHasNewCommits = !hasPreviousCommit
 		return info, nil
 	}
+
 	info.CommitsBehind, info.CommitsAhead = diff.Behind, diff.Ahead
 	return info, nil
 }

templates/repo/code/upstream_diverging_info.tmpl

@@ -1,8 +1,8 @@
-{{if and .UpstreamDivergingInfo (or .UpstreamDivergingInfo.BaseIsNewer .UpstreamDivergingInfo.CommitsBehind)}}
+{{if and .UpstreamDivergingInfo (or .UpstreamDivergingInfo.BaseHasNewCommits .UpstreamDivergingInfo.CommitsBehind)}}
 <div class="ui message flex-text-block">
 	<div class="tw-flex-1">
-		{{$upstreamLink := printf "%s/src/branch/%s" .Repository.BaseRepo.Link (.BranchName|PathEscapeSegments)}}
-		{{$upstreamHtml := HTMLFormat `<a href="%s">%s:%s</a>` $upstreamLink .Repository.BaseRepo.FullName .BranchName}}
+		{{$upstreamLink := printf "%s/src/branch/%s" .Repository.BaseRepo.Link (.Repository.BaseRepo.DefaultBranch|PathEscapeSegments)}}
+		{{$upstreamHtml := HTMLFormat `<a href="%s">%s:%s</a>` $upstreamLink .Repository.BaseRepo.FullName .Repository.BaseRepo.DefaultBranch}}
 		{{if .UpstreamDivergingInfo.CommitsBehind}}
 			{{ctx.Locale.TrN .UpstreamDivergingInfo.CommitsBehind "repo.pulls.upstream_diverging_prompt_behind_1" "repo.pulls.upstream_diverging_prompt_behind_n" .UpstreamDivergingInfo.CommitsBehind $upstreamHtml}}
 		{{else}}