1 files changed, 104 insertions, 0 deletions
diff --git a/cmd/gitaly-git2go/revert.go b/cmd/gitaly-git2go/revert.go
new file mode 100644
index 000000000..aaeeb00ac
--- /dev/null
+++ b/cmd/gitaly-git2go/revert.go
@@ -0,0 +1,104 @@
+//go:build static && system_libgit2
+
+package main
+
+import (
+	"context"
+	"encoding/gob"
+	"errors"
+	"flag"
+	"fmt"
+
+	git "github.com/libgit2/git2go/v33"
+	"gitlab.com/gitlab-org/gitaly/v15/cmd/gitaly-git2go/git2goutil"
+	"gitlab.com/gitlab-org/gitaly/v15/internal/git2go"
+)
+
+type revertSubcommand struct{}
+
+func (cmd *revertSubcommand) Flags() *flag.FlagSet {
+	return flag.NewFlagSet("revert", flag.ExitOnError)
+}
+
+func (cmd *revertSubcommand) Run(ctx context.Context, decoder *gob.Decoder, encoder *gob.Encoder) error {
+	var request git2go.RevertCommand
+	if err := decoder.Decode(&request); err != nil {
+		return err
+	}
+
+	commitID, err := cmd.revert(ctx, &request)
+	return encoder.Encode(git2go.Result{
+		CommitID: commitID,
+		Err:      git2go.SerializableError(err),
+	})
+}
+
+func (cmd *revertSubcommand) verify(ctx context.Context, r *git2go.RevertCommand) error {
+	if r.Repository == "" {
+		return errors.New("missing repository")
+	}
+	if r.AuthorName == "" {
+		return errors.New("missing author name")
+	}
+	if r.AuthorMail == "" {
+		return errors.New("missing author mail")
+	}
+	if r.Message == "" {
+		return errors.New("missing message")
+	}
+	if r.Ours == "" {
+		return errors.New("missing ours")
+	}
+	if r.Revert == "" {
+		return errors.New("missing revert")
+	}
+	return nil
+}
+
+func (cmd *revertSubcommand) revert(ctx context.Context, request *git2go.RevertCommand) (string, error) {
+	if err := cmd.verify(ctx, request); err != nil {
+		return "", err
+	}
+	repo, err := git2goutil.OpenRepository(request.Repository)
+	if err != nil {
+		return "", fmt.Errorf("open repository: %w", err)
+	}
+	defer repo.Free()
+
+	ours, err := lookupCommit(repo, request.Ours)
+	if err != nil {
+		return "", fmt.Errorf("ours commit lookup: %w", err)
+	}
+
+	revert, err := lookupCommit(repo, request.Revert)
+	if err != nil {
+		return "", fmt.Errorf("revert commit lookup: %w", err)
+	}
+
+	index, err := repo.RevertCommit(revert, ours, request.Mainline, nil)
+	if err != nil {
+		return "", fmt.Errorf("revert: %w", err)
+	}
+	defer index.Free()
+
+	if index.HasConflicts() {
+		return "", git2go.HasConflictsError{}
+	}
+
+	tree, err := index.WriteTreeTo(repo)
+	if err != nil {
+		return "", fmt.Errorf("write tree: %w", err)
+	}
+
+	if tree.Equal(ours.TreeId()) {
+		return "", git2go.EmptyError{}
+	}
+
+	committer := git.Signature(git2go.NewSignature(request.AuthorName, request.AuthorMail, request.AuthorDate))
+	commit, err := repo.CreateCommitFromIds("", &committer, &committer, request.Message, tree, ours.Id())
+	if err != nil {
+		return "", fmt.Errorf("create revert commit: %w", err)
+	}
+
+	return commit.String(), nil
+}