Fix reverting a merge commit failing (#28794) (#28825)

Backport #28794

Fixes #22236

---
Error occurring currently while trying to revert commit using read-tree
-m approach:
> 2022/12/26 16:04:43 ...rvices/pull/patch.go:240:AttemptThreeWayMerge()
[E] [63a9c61a] Unable to run read-tree -m! Error: exit status 128 -
fatal: this operation must be run in a work tree
> 	 - fatal: this operation must be run in a work tree

We need to clone a non-bare repository for `git read-tree -m` to work.


bb371ae
adds support to create a non-bare cloned temporary upload repository.

After cloning a non-bare temporary upload repository, we [set default
index](https://github.com/go-gitea/gitea/blob/main/services/repository/files/cherry_pick.go#L37)
(`git read-tree HEAD`).
This operation ends up resetting the git index file (see investigation
details below), due to which, we need to call `git update-index
--refresh` afterward.

Here's the diff of the index file before and after we execute
SetDefaultIndex: https://www.diffchecker.com/hyOP3eJy/

Notice the **ctime**, **mtime** are set to 0 after SetDefaultIndex.

You can reproduce the same behavior using these steps:
```bash
$ git clone https://try.gitea.io/me-heer/test.git -s -b main
$ cd test
$ git read-tree HEAD
$ git read-tree -m 1f085d7ed8 1f085d7ed8 9933caed00
error: Entry '1' not uptodate. Cannot merge.
```

After which, we can fix like this:
```bash
$ git update-index --refresh
$ git read-tree -m 1f085d7ed8 1f085d7ed8 9933caed00
```

models/fixtures/repo_unit.yml

@@ -649,3 +649,10 @@
  repo_id: 49
  type: 2
  created_unix: 946684810
+
+-
+ id: 98
+ repo_id: 59
+ type: 1
+ config: "{}"
+ created_unix: 946684810

models/fixtures/repository.yml

@@ -1693,3 +1693,16 @@
  size: 0
  is_fsck_enabled: true
  close_issues_via_commit_in_any_branch: false
+
+-
+ id: 59
+ owner_id: 2
+ owner_name: user2
+ lower_name: test_commit_revert
+ name: test_commit_revert
+ default_branch: main
+ is_empty: false
+ is_archived: false
+ is_private: true
+ status: 0
+ num_issues: 0

models/fixtures/user.yml

@@ -66,7 +66,7 @@
  num_followers: 2
  num_following: 1
  num_stars: 2
- num_repos: 14
+ num_repos: 15
  num_teams: 0
  num_members: 0
  visibility: 0

services/packages/cargo/index.go

@@ -267,7 +267,7 @@ func alterRepositoryContent(ctx context.Context, doer *user_model.User, repo *re
  defer t.Close()
 
  var lastCommitID string
- if err := t.Clone(repo.DefaultBranch); err != nil {
+ if err := t.Clone(repo.DefaultBranch, true); err != nil {
  if !git.IsErrBranchNotExist(err) || !repo.IsEmpty {
  return err
  }

services/repository/files/cherry_pick.go

@@ -31,12 +31,15 @@ func CherryPick(ctx context.Context, repo *repo_model.Repository, doer *user_mod
  log.Error("%v", err)
  }
  defer t.Close()
- if err := t.Clone(opts.OldBranch); err != nil {
+ if err := t.Clone(opts.OldBranch, false); err != nil {
  return nil, err
  }
  if err := t.SetDefaultIndex(); err != nil {
  return nil, err
  }
+ if err := t.RefreshIndex(); err != nil {
+ return nil, err
+ }
 
  // Get the commit of the original branch
  commit, err := t.GetBranchCommit(opts.OldBranch)

services/repository/files/diff.go

@@ -21,7 +21,7 @@ func GetDiffPreview(ctx context.Context, repo *repo_model.Repository, branch, tr
  return nil, err
  }
  defer t.Close()
- if err := t.Clone(branch); err != nil {
+ if err := t.Clone(branch, true); err != nil {
  return nil, err
  }
  if err := t.SetDefaultIndex(); err != nil {

services/repository/files/patch.go

@@ -108,7 +108,7 @@ func ApplyDiffPatch(ctx context.Context, repo *repo_model.Repository, doer *user
  log.Error("%v", err)
  }
  defer t.Close()
- if err := t.Clone(opts.OldBranch); err != nil {
+ if err := t.Clone(opts.OldBranch, true); err != nil {
  return nil, err
  }
  if err := t.SetDefaultIndex(); err != nil {

services/repository/files/temp_repo.go

@@ -51,8 +51,13 @@ func (t *TemporaryUploadRepository) Close() {
 }
 
 // Clone the base repository to our path and set branch as the HEAD
-func (t *TemporaryUploadRepository) Clone(branch string) error {
- if _, _, err := git.NewCommand(t.ctx, "clone", "-s", "--bare", "-b").AddDynamicArguments(branch, t.repo.RepoPath(), t.basePath).RunStdString(nil); err != nil {
+func (t *TemporaryUploadRepository) Clone(branch string, bare bool) error {
+ cmd := git.NewCommand(t.ctx, "clone", "-s", "-b").AddDynamicArguments(branch, t.repo.RepoPath(), t.basePath)
+ if bare {
+ cmd.AddArguments("--bare")
+ }
+
+ if _, _, err := cmd.RunStdString(nil); err != nil {
  stderr := err.Error()
  if matched, _ := regexp.MatchString(".*Remote branch .* not found in upstream origin.*", stderr); matched {
  return git.ErrBranchNotExist{
@@ -98,6 +103,14 @@ func (t *TemporaryUploadRepository) SetDefaultIndex() error {
  return nil
 }
 
+// RefreshIndex looks at the current index and checks to see if merges or updates are needed by checking stat() information.
+func (t *TemporaryUploadRepository) RefreshIndex() error {
+ if _, _, err := git.NewCommand(t.ctx, "update-index", "--refresh").RunStdString(&git.RunOpts{Dir: t.basePath}); err != nil {
+ return fmt.Errorf("RefreshIndex: %w", err)
+ }
+ return nil
+}
+
 // LsFiles checks if the given filename arguments are in the index
 func (t *TemporaryUploadRepository) LsFiles(filenames ...string) ([]string, error) {
  stdOut := new(bytes.Buffer)

services/repository/files/update.go

@@ -141,7 +141,7 @@ func ChangeRepoFiles(ctx context.Context, repo *repo_model.Repository, doer *use
  }
  defer t.Close()
  hasOldBranch := true
- if err := t.Clone(opts.OldBranch); err != nil {
+ if err := t.Clone(opts.OldBranch, true); err != nil {
  for _, file := range opts.Files {
  if file.Operation == "delete" {
  return nil, err

services/repository/files/upload.go

@@ -87,7 +87,7 @@ func UploadRepoFiles(ctx context.Context, repo *repo_model.Repository, doer *use
  defer t.Close()
 
  hasOldBranch := true
- if err = t.Clone(opts.OldBranch); err != nil {
+ if err = t.Clone(opts.OldBranch, true); err != nil {
  if !git.IsErrBranchNotExist(err) || !repo.IsEmpty {
  return err
  }

tests/gitea-repositories-meta/user2/test_commit_revert.git/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/main

tests/gitea-repositories-meta/user2/test_commit_revert.git/config

@@ -0,0 +1,8 @@
+[core]
+ repositoryformatversion = 0
+ filemode = true
+ bare = true
+ ignorecase = true
+ precomposeunicode = true
+[remote "origin"]
+ url = https://try.gitea.io/me-heer/test_commit_revert.git

tests/gitea-repositories-meta/user2/test_commit_revert.git/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

tests/gitea-repositories-meta/user2/test_commit_revert.git/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

tests/gitea-repositories-meta/user2/test_commit_revert.git/packed-refs

@@ -0,0 +1,3 @@
+# pack-refs with: peeled fully-peeled sorted 
+46aa6ab2c881ae90e15d9ccfc947d1625c892ce5 refs/heads/develop
+deebcbc752e540bab4ce3ee713d3fc8fdc35b2f7 refs/heads/main

tests/integration/repo_mergecommit_revert_test.go

@@ -0,0 +1,34 @@
+package integration
+
+import (
+ "net/http"
+ "testing"
+
+ "code.gitea.io/gitea/tests"
+
+ "github.com/stretchr/testify/assert"
+)
+
+func TestRepoMergeCommitRevert(t *testing.T) {
+ defer tests.PrepareTestEnv(t)()
+ session := loginUser(t, "user2")
+
+ req := NewRequest(t, "GET", "/user2/test_commit_revert/_cherrypick/deebcbc752e540bab4ce3ee713d3fc8fdc35b2f7/main?ref=main&refType=branch&cherry-pick-type=revert")
+ resp := session.MakeRequest(t, req, http.StatusOK)
+
+ htmlDoc := NewHTMLParser(t, resp.Body)
+ req = NewRequestWithValues(t, "POST", "/user2/test_commit_revert/_cherrypick/deebcbc752e540bab4ce3ee713d3fc8fdc35b2f7/main", map[string]string{
+ "_csrf": htmlDoc.GetCSRF(),
+ "last_commit": "deebcbc752e540bab4ce3ee713d3fc8fdc35b2f7",
+ "page_has_posted": "true",
+ "revert": "true",
+ "commit_summary": "reverting test commit",
+ "commit_message": "test message",
+ "commit_choice": "direct",
+ "new_branch_name": "test-revert-branch-1",
+ })
+ resp = session.MakeRequest(t, req, http.StatusSeeOther)
+
+ // A successful revert redirects to the main branch
+ assert.EqualValues(t, "/user2/test_commit_revert/src/branch/main", resp.Header().Get("Location"))
+}