Add finalizers to ensure that repos are closed and blobreaders are closed

It may be prudent to add runtime finalizers to the git.Repository and
git.blobReader objects to absolutely ensure that these are both properly
cancelled, cleaned and closed out.

This commit is a backport of an extract from go-gitea#19448

Signed-off-by: Andrew Thornton <art27@cantab.net>

Author: zeripath

modules/git/blob_nogogit.go

@@ -12,6 +12,7 @@ import (
 	"bytes"
 	"io"
 	"math"
+	"runtime"
 
 	"code.gitea.io/gitea/modules/log"
 )
@@ -54,11 +55,14 @@ func (b *Blob) DataAsync() (io.ReadCloser, error) {
 		return io.NopCloser(bytes.NewReader(bs)), err
 	}
 
-	return &blobReader{
+	br := &blobReader{
 		rd:     rd,
 		n:      size,
 		cancel: cancel,
-	}, nil
+	}
+	runtime.SetFinalizer(br, func(br *blobReader) { br.Close() })
+
+	return br, nil
 }
 
 // Size returns the uncompressed size of the blob

modules/git/repo_base_gogit.go

@@ -63,13 +63,17 @@ func OpenRepositoryCtx(ctx context.Context, repoPath string) (*Repository, error
 		return nil, err
 	}
 
-	return &Repository{
+	repo := &Repository{
 		Path:         repoPath,
 		gogitRepo:    gogitRepo,
 		gogitStorage: storage,
 		tagCache:     newObjectCache(),
 		Ctx:          ctx,
-	}, nil
+	}
+
+	runtime.SetFinalizer(repo, func(repo *Repository) { repo.Close() })
+
+	return repo, nil
 }
 
 // Close this repository, in particular close the underlying gogitStorage if this is not nil

modules/git/repo_base_nogogit.go

@@ -13,6 +13,7 @@ import (
 	"context"
 	"errors"
 	"path/filepath"
+	"runtime"
 
 	"code.gitea.io/gitea/modules/log"
 )
@@ -64,6 +65,8 @@ func OpenRepositoryCtx(ctx context.Context, repoPath string) (*Repository, error
 	repo.batchWriter, repo.batchReader, repo.batchCancel = CatFileBatch(ctx, repoPath)
 	repo.checkWriter, repo.checkReader, repo.checkCancel = CatFileBatchCheck(ctx, repo.Path)
 
+	runtime.SetFinalizer(repo, func(repo *Repository) { repo.Close() })
+
 	return repo, nil
 }