Merge branch 'sh-fix-rebase' into 'master'

Fix rebase when diff contains only deleted files

Closes gitlab#209817

See merge request gitlab-org/gitaly!2109

3 files changed, 88 insertions, 1 deletions

diff --git a/changelogs/unreleased/sh-fix-rebase.yml b/changelogs/unreleased/sh-fix-rebase.yml
new file mode 100644
index 000000000..54a81afc2
--- /dev/null
+++ b/changelogs/unreleased/sh-fix-rebase.yml
@@ -0,0 +1,5 @@
+---
+title: Fix rebase when diff contains only deleted files
+merge_request: 2109
+author:
+type: fixed
diff --git a/internal/service/operations/rebase_test.go b/internal/service/operations/rebase_test.go
index da254dced..222c723fd 100644
--- a/internal/service/operations/rebase_test.go
+++ b/internal/service/operations/rebase_test.go
@@ -404,6 +404,70 @@ func getBranchSha(t *testing.T, repoPath string, branchName string) string {
 	return strings.TrimSpace(branchSha)
 }
 
+func TestRebaseRequestWithDeletedFile(t *testing.T) {
+	ctxOuter, cancel := testhelper.Context()
+	defer cancel()
+
+	server, serverSocketPath := runFullServerWithHooks(t)
+	defer server.Stop()
+
+	client, conn := operations.NewOperationClient(t, serverSocketPath)
+	defer conn.Close()
+
+	testRepo, testRepoPath, cleanupFn := testhelper.NewTestRepoWithWorktree(t)
+	defer cleanupFn()
+
+	testRepoCopy, _, cleanup := testhelper.NewTestRepo(t)
+	defer cleanup()
+
+	cleanupSrv := operations.SetupAndStartGitlabServer(t, rebaseUser.GlId, testRepo.GlRepository)
+	defer cleanupSrv()
+
+	md := testhelper.GitalyServersMetadata(t, serverSocketPath)
+	ctx := metadata.NewOutgoingContext(ctxOuter, md)
+
+	branch := "rebase-delete-test"
+
+	testhelper.MustRunCommand(t, nil, "git", "-C", testRepoPath, "config", "user.name", string(rebaseUser.Name))
+	testhelper.MustRunCommand(t, nil, "git", "-C", testRepoPath, "config", "user.email", string(rebaseUser.Email))
+	testhelper.MustRunCommand(t, nil, "git", "-C", testRepoPath, "checkout", "-b", branch, "master~1")
+	testhelper.MustRunCommand(t, nil, "git", "-C", testRepoPath, "rm", "README")
+	testhelper.MustRunCommand(t, nil, "git", "-C", testRepoPath, "commit", "-a", "-m", "delete file")
+
+	branchSha := getBranchSha(t, testRepoPath, branch)
+
+	rebaseStream, err := client.UserRebaseConfirmable(ctx)
+	require.NoError(t, err)
+
+	headerRequest := buildHeaderRequest(testRepo, rebaseUser, "1", branch, branchSha, testRepoCopy, "master")
+	require.NoError(t, rebaseStream.Send(headerRequest), "send header")
+
+	firstResponse, err := rebaseStream.Recv()
+	require.NoError(t, err, "receive first response")
+
+	_, err = gitlog.GetCommit(ctx, testRepo, firstResponse.GetRebaseSha())
+	require.NoError(t, err, "look up git commit before rebase is applied")
+
+	applyRequest := buildApplyRequest(true)
+	require.NoError(t, rebaseStream.Send(applyRequest), "apply rebase")
+
+	secondResponse, err := rebaseStream.Recv()
+	require.NoError(t, err, "receive second response")
+
+	err = testhelper.ReceiveEOFWithTimeout(func() error {
+		_, err = rebaseStream.Recv()
+		return err
+	})
+	require.NoError(t, err, "consume EOF")
+
+	newBranchSha := getBranchSha(t, testRepoPath, branch)
+
+	require.NotEqual(t, newBranchSha, branchSha)
+	require.Equal(t, newBranchSha, firstResponse.GetRebaseSha())
+
+	require.True(t, secondResponse.GetRebaseApplied(), "the second rebase is applied")
+}
+
 // This error is used as a sentinel value
 var errRecvTimeout = errors.New("timeout waiting for response")
 
diff --git a/ruby/lib/gitlab/git/repository.rb b/ruby/lib/gitlab/git/repository.rb
index 80b4c24ef..942880482 100644
--- a/ruby/lib/gitlab/git/repository.rb
+++ b/ruby/lib/gitlab/git/repository.rb
@@ -736,6 +736,14 @@ module Gitlab
 
       private
 
+      def sparse_checkout_empty?(output)
+        output.include?("error: Sparse checkout leaves no entry on working directory")
+      end
+
+      def disable_sparse_checkout
+        run_git!(%w[config core.sparseCheckout false], include_stderr: true)
+      end
+
       def create_merge_commit(user, our_commit, their_commit, message)
         raise 'Invalid merge target' unless our_commit
         raise 'Invalid merge source' unless their_commit
@@ -884,7 +892,17 @@ module Gitlab
           configure_sparse_checkout(worktree_git_path, sparse_checkout_files)
 
           # After sparse checkout configuration, checkout `branch` in worktree
-          run_git!(%W[checkout --detach #{branch}], chdir: worktree.path, env: env, include_stderr: true)
+          output, cmd_status = run_git(%W[checkout --detach #{branch}], chdir: worktree.path, env: env, include_stderr: true)
+
+          # If sparse checkout fails, fall back to a regular checkout.
+          if cmd_status.nonzero?
+            if sparse_checkout_empty?(output)
+              disable_sparse_checkout
+              run_git!(%W[checkout --detach #{branch}], chdir: worktree.path, env: env, include_stderr: true)
+            else
+              raise GitError, output
+            end
+          end
         else
           # Create worktree and checkout `branch` in it
           run_git!(base_args + [worktree.path, branch], env: env, include_stderr: true)