gitattributes: Implement the use of --source

Since Git 2.40 git-check-attr(1) learned to accept a --source argument
to specify the tree-ish to read the file from. This makes it unnecessary
to copy the contents of that file to info/attributes.

This change makes CheckAttr() accept a git revision to read the
.gitattributes straight from the given revision.

Label: maintenance::refactor

5 files changed, 29 insertions, 27 deletions

diff --git a/internal/git/gitattributes/check_attr.go b/internal/git/gitattributes/check_attr.go
index 474bd3bc5..35b9c9538 100644
--- a/internal/git/gitattributes/check_attr.go
+++ b/internal/git/gitattributes/check_attr.go
@@ -29,12 +29,13 @@ type CheckAttrCmd struct {
 }
 
 // CheckAttr creates a CheckAttrCmd that checks the given list of attribute names.
-func CheckAttr(ctx context.Context, repo git.RepositoryExecutor, names []string) (*CheckAttrCmd, func(), error) {
+func CheckAttr(ctx context.Context, repo git.RepositoryExecutor, revision git.Revision, names []string) (*CheckAttrCmd, func(), error) {
 	cmd, err := repo.Exec(ctx, git.Command{
 		Name: "check-attr",
 		Flags: []git.Option{
 			git.Flag{Name: "--stdin"},
 			git.Flag{Name: "-z"},
+			git.ValueFlag{Name: "--source", Value: revision.String()},
 		},
 		Args: append(names, endOfAttributes),
 	},
diff --git a/internal/git/gitattributes/check_attr_test.go b/internal/git/gitattributes/check_attr_test.go
index 98ef1bb2b..dcd7e4e0a 100644
--- a/internal/git/gitattributes/check_attr_test.go
+++ b/internal/git/gitattributes/check_attr_test.go
@@ -1,21 +1,17 @@
 package gitattributes
 
 import (
-	"os"
-	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/git"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/git/gittest"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/git/localrepo"
-	"gitlab.com/gitlab-org/gitaly/v16/internal/helper/perm"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/testhelper"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/testhelper/testcfg"
 )
 
 func TestCheckAttrCmd_Check(t *testing.T) {
-	t.Parallel()
-
 	ctx := testhelper.Context(t)
 	cfg := testcfg.Build(t)
 
@@ -24,14 +20,9 @@ func TestCheckAttrCmd_Check(t *testing.T) {
 	})
 	repo := localrepo.NewTestRepo(t, cfg, repoProto)
 
-	// Until https://gitlab.com/groups/gitlab-org/-/epics/9006 is completed
-	// we rely on info/attributes.
-	infoPath := filepath.Join(repoPath, "info")
-	require.NoError(t, os.MkdirAll(infoPath, perm.SharedDir))
-	attrPath := filepath.Join(infoPath, "attributes")
-
 	for _, tc := range []struct {
 		desc         string
+		treeOID      git.ObjectID
 		attrContent  string
 		path         string
 		expectedAttr Attributes
@@ -39,6 +30,12 @@ func TestCheckAttrCmd_Check(t *testing.T) {
 		{
 			desc:         "no attributes",
 			path:         "README.md",
+			treeOID:      gittest.DefaultObjectHash.EmptyTreeOID,
+			expectedAttr: Attributes{},
+		},
+		{
+			desc:         "empty attributes",
+			path:         "README.md",
 			expectedAttr: Attributes{},
 		},
 		{
@@ -138,10 +135,25 @@ func TestCheckAttrCmd_Check(t *testing.T) {
 			expectedAttr: Attributes{Attribute{Name: "foo", State: "bar"}},
 		},
 	} {
+		tc := tc
+
 		t.Run(tc.desc, func(t *testing.T) {
-			require.NoError(t, os.WriteFile(attrPath, []byte(tc.attrContent), perm.SharedFile))
+			t.Parallel()
+
+			treeOID := tc.treeOID
+			if treeOID == "" {
+				treeOID = gittest.WriteTree(t, cfg, repoPath, []gittest.TreeEntry{
+					{Path: ".gitattributes", Mode: "100644", Content: tc.attrContent},
+				})
+			} else {
+				require.Empty(t, tc.attrContent, "cannot specify both attrContent & treeOID")
+			}
+
+			commitID := gittest.WriteCommit(t, cfg, repoPath,
+				gittest.WithMessage(tc.desc),
+				gittest.WithTree(treeOID))
 
-			checkCmd, finish, err := CheckAttr(ctx, repo, []string{"foo", "bar"})
+			checkCmd, finish, err := CheckAttr(ctx, repo, commitID.Revision(), []string{"foo", "bar"})
 			require.NoError(t, err)
 			t.Cleanup(finish)
 
diff --git a/internal/git/gittest/tree.go b/internal/git/gittest/tree.go
index 58db5e888..7237d32b7 100644
--- a/internal/git/gittest/tree.go
+++ b/internal/git/gittest/tree.go
@@ -98,11 +98,9 @@ func WriteTree(tb testing.TB, cfg config.Cfg, repoPath string, entries []TreeEnt
 
 		require.False(tb, len(entry.OID) > 0 && len(entry.Content) > 0,
 			"entry cannot have both OID and content")
-		require.False(tb, len(entry.OID) == 0 && len(entry.Content) == 0,
-			"entry must have either an OID or content")
 
 		oid := entry.OID
-		if len(entry.Content) > 0 {
+		if oid == "" {
 			oid = WriteBlob(tb, cfg, repoPath, []byte(entry.Content))
 		}
 
diff --git a/internal/gitaly/linguist/linguist.go b/internal/gitaly/linguist/linguist.go
index db2847b67..32c8b06e0 100644
--- a/internal/gitaly/linguist/linguist.go
+++ b/internal/gitaly/linguist/linguist.go
@@ -63,7 +63,7 @@ func (inst *Instance) Stats(ctx context.Context, commitID git.ObjectID) (ByteCou
 	}
 	defer cancel()
 
-	checkAttr, finishAttr, err := gitattributes.CheckAttr(ctx, inst.repo, linguistAttrs)
+	checkAttr, finishAttr, err := gitattributes.CheckAttr(ctx, inst.repo, commitID.Revision(), linguistAttrs)
 	if err != nil {
 		return nil, fmt.Errorf("linguist create check attr: %w", err)
 	}
diff --git a/internal/gitaly/linguist/linguist_test.go b/internal/gitaly/linguist/linguist_test.go
index fe3d6c2b1..cd8df0dfd 100644
--- a/internal/gitaly/linguist/linguist_test.go
+++ b/internal/gitaly/linguist/linguist_test.go
@@ -523,15 +523,6 @@ func TestInstance_Stats(t *testing.T) {
 		t.Run(tc.desc, func(t *testing.T) {
 			repoProto, repoPath, objectID := tc.setup(t)
 
-			// Apply the gitattributes
-			// We should get rid of this with https://gitlab.com/groups/gitlab-org/-/epics/9006
-			infoPath := filepath.Join(repoPath, "info")
-			require.NoError(t, os.MkdirAll(infoPath, perm.SharedDir))
-			attrData, err := gittest.NewCommand(t, cfg, "-C", repoPath, "cat-file", "blob", objectID.String()+":.gitattributes").Output()
-			if err == nil {
-				require.NoError(t, os.WriteFile(filepath.Join(infoPath, "attributes"), attrData, perm.SharedFile))
-			}
-
 			repo := localrepo.NewTestRepo(t, cfg, repoProto)
 			linguist := New(cfg, catfileCache, repo)
 			stats, err := linguist.Stats(ctx, objectID)