Fix `IsObjectExist` with gogit (#31790)

Fix #31271.

When gogit is enabled, `IsObjectExist` calls
`repo.gogitRepo.ResolveRevision`, which is not correct. It's for
checking references not objects, it could work with commit hash since
it's both a valid reference and a commit object, but it doesn't work
with blob objects.

So it causes #31271 because it reports that all blob objects do not
exist.

4 files changed, 121 insertions, 10 deletions

diff --git a/modules/git/repo_branch_gogit.go b/modules/git/repo_branch_gogit.go
index d1ec14d811..dbc4a5fedc 100644
--- a/modules/git/repo_branch_gogit.go
+++ b/modules/git/repo_branch_gogit.go
@@ -14,28 +14,33 @@ import (
 	"github.com/go-git/go-git/v5/plumbing/storer"
 )
 
-// IsObjectExist returns true if given reference exists in the repository.
+// IsObjectExist returns true if the given object exists in the repository.
+// FIXME: Inconsistent behavior with nogogit edition
+// Unlike the implementation of IsObjectExist in nogogit edition, it does not support short hashes here.
+// For example, IsObjectExist("153f451") will return false, but it will return true in nogogit edition.
+// To fix this, the solution could be adding support for short hashes in gogit edition if it's really needed.
 func (repo *Repository) IsObjectExist(name string) bool {
 	if name == "" {
 		return false
 	}
 
-	_, err := repo.gogitRepo.ResolveRevision(plumbing.Revision(name))
-
+	_, err := repo.gogitRepo.Object(plumbing.AnyObject, plumbing.NewHash(name))
 	return err == nil
 }
 
 // IsReferenceExist returns true if given reference exists in the repository.
+// FIXME: Inconsistent behavior with nogogit edition
+// Unlike the implementation of IsObjectExist in nogogit edition, it does not support blob hashes here.
+// For example, IsObjectExist([existing_blob_hash]) will return false, but it will return true in nogogit edition.
+// To fix this, the solution could be refusing to support blob hashes in nogogit edition since a blob hash is not a reference.
 func (repo *Repository) IsReferenceExist(name string) bool {
 	if name == "" {
 		return false
 	}
 
-	reference, err := repo.gogitRepo.Reference(plumbing.ReferenceName(name), true)
-	if err != nil {
-		return false
-	}
-	return reference.Type() != plumbing.InvalidReference
+	_, err := repo.gogitRepo.ResolveRevision(plumbing.Revision(name))
+
+	return err == nil
 }
 
 // IsBranchExist returns true if given branch exists in current repository.
diff --git a/modules/git/repo_branch_nogogit.go b/modules/git/repo_branch_nogogit.go
index 470faebe25..63d0f7268a 100644
--- a/modules/git/repo_branch_nogogit.go
+++ b/modules/git/repo_branch_nogogit.go
@@ -16,7 +16,7 @@ import (
 	"code.gitea.io/gitea/modules/log"
 )
 
-// IsObjectExist returns true if given reference exists in the repository.
+// IsObjectExist returns true if the given object exists in the repository.
 func (repo *Repository) IsObjectExist(name string) bool {
 	if name == "" {
 		return false
diff --git a/modules/git/repo_branch_test.go b/modules/git/repo_branch_test.go
index fe788946e5..009c545832 100644
--- a/modules/git/repo_branch_test.go
+++ b/modules/git/repo_branch_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestRepository_GetBranches(t *testing.T) {
@@ -94,3 +95,107 @@ func BenchmarkGetRefsBySha(b *testing.B) {
 	_, _ = bareRepo5.GetRefsBySha("c83380d7056593c51a699d12b9c00627bd5743e9", "")
 	_, _ = bareRepo5.GetRefsBySha("58a4bcc53ac13e7ff76127e0fb518b5262bf09af", "")
 }
+
+func TestRepository_IsObjectExist(t *testing.T) {
+	repo, err := openRepositoryWithDefaultContext(filepath.Join(testReposDir, "repo1_bare"))
+	require.NoError(t, err)
+	defer repo.Close()
+
+	// FIXME: Inconsistent behavior between gogit and nogogit editions
+	// See the comment of IsObjectExist in gogit edition for more details.
+	supportShortHash := !isGogit
+
+	tests := []struct {
+		name string
+		arg  string
+		want bool
+	}{
+		{
+			name: "empty",
+			arg:  "",
+			want: false,
+		},
+		{
+			name: "branch",
+			arg:  "master",
+			want: false,
+		},
+		{
+			name: "commit hash",
+			arg:  "ce064814f4a0d337b333e646ece456cd39fab612",
+			want: true,
+		},
+		{
+			name: "short commit hash",
+			arg:  "ce06481",
+			want: supportShortHash,
+		},
+		{
+			name: "blob hash",
+			arg:  "153f451b9ee7fa1da317ab17a127e9fd9d384310",
+			want: true,
+		},
+		{
+			name: "short blob hash",
+			arg:  "153f451",
+			want: supportShortHash,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, repo.IsObjectExist(tt.arg))
+		})
+	}
+}
+
+func TestRepository_IsReferenceExist(t *testing.T) {
+	repo, err := openRepositoryWithDefaultContext(filepath.Join(testReposDir, "repo1_bare"))
+	require.NoError(t, err)
+	defer repo.Close()
+
+	// FIXME: Inconsistent behavior between gogit and nogogit editions
+	// See the comment of IsReferenceExist in gogit edition for more details.
+	supportBlobHash := !isGogit
+
+	tests := []struct {
+		name string
+		arg  string
+		want bool
+	}{
+		{
+			name: "empty",
+			arg:  "",
+			want: false,
+		},
+		{
+			name: "branch",
+			arg:  "master",
+			want: true,
+		},
+		{
+			name: "commit hash",
+			arg:  "ce064814f4a0d337b333e646ece456cd39fab612",
+			want: true,
+		},
+		{
+			name: "short commit hash",
+			arg:  "ce06481",
+			want: true,
+		},
+		{
+			name: "blob hash",
+			arg:  "153f451b9ee7fa1da317ab17a127e9fd9d384310",
+			want: supportBlobHash,
+		},
+		{
+			name: "short blob hash",
+			arg:  "153f451",
+			want: supportBlobHash,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, repo.IsReferenceExist(tt.arg))
+		})
+	}
+}
diff --git a/modules/markup/html.go b/modules/markup/html.go
index b8069d459a..8d3327c49e 100644
--- a/modules/markup/html.go
+++ b/modules/markup/html.go
@@ -1144,7 +1144,8 @@ func hashCurrentPatternProcessor(ctx *RenderContext, node *html.Node) {
 				})
 			}
 
-			exist = ctx.GitRepo.IsObjectExist(hash)
+			// Don't use IsObjectExist since it doesn't support short hashs with gogit edition.
+			exist = ctx.GitRepo.IsReferenceExist(hash)
 			ctx.ShaExistCache[hash] = exist
 		}