package gitimport (	"fmt"	"io"	"os"	"os/exec"	"strconv"	"strings"	"github.com/go-git/go-git/v6/plumbing"	"github.com/go-git/go-git/v6/plumbing/object")// returns the tree entry for a file path without loading the blob contents. low RAM usage.func FindFileEntry(tree *object.Tree, path string) (*object.TreeEntry, error) {	path = strings.TrimPrefix(path, "/")	if path == "" {		return nil, fmt.Errorf("git: empty path")	}	entry, err := tree.FindEntry(path)	if err != nil {		return nil, err	}	if !entry.Mode.IsFile() {		return nil, fmt.Errorf("git: %s is not a file", path)	}	return entry, nil}// returns the size in bytes of a blob using git. only reads the object header. low RAM usage.func BlobSize(repoPath string, hash plumbing.Hash) (int64, error) {	cmd := exec.Command("git", "-C", repoPath, "cat-file", "-s", hash.String())	out, err := cmd.Output()	if err != nil {		return 0, fmt.Errorf("git cat-file -s: %w", err)	}	size, err := strconv.ParseInt(strings.TrimSpace(string(out)), 10, 64)	if err != nil {		return 0, fmt.Errorf("git cat-file -s: %w", err)	}	return size, nil}// streams the contents of a blob to w using git. low RAM usage.func StreamBlob(repoPath string, hash plumbing.Hash, w io.Writer) error {	cmd := exec.Command("git", "-C", repoPath, "cat-file", "blob", hash.String())	cmd.Stderr = os.Stderr	stdout, err := cmd.StdoutPipe()	if err != nil {		return fmt.Errorf("git cat-file: %w", err)	}	if err := cmd.Start(); err != nil {		return fmt.Errorf("git cat-file: %w", err)	}	_, err = io.Copy(w, stdout)	if err != nil {		cmd.Process.Kill()		cmd.Wait()		return fmt.Errorf("stream blob: %w", err)	}	if err := cmd.Wait(); err != nil {		return fmt.Errorf("git cat-file: %w", err)	}	return nil}// reads n bytes from the start of a blob. used for mimetypes.func ReadBlobPrefix(repoPath string, hash plumbing.Hash, n int64) ([]byte, error) {	cmd := exec.Command("git", "-C", repoPath, "cat-file", "blob", hash.String())	cmd.Stderr = os.Stderr	stdout, err := cmd.StdoutPipe()	if err != nil {		return nil, fmt.Errorf("git cat-file: %w", err)	}	if err := cmd.Start(); err != nil {		return nil, fmt.Errorf("git cat-file: %w", err)	}	data, err := io.ReadAll(io.LimitReader(stdout, n))	if err != nil {		cmd.Process.Kill()		cmd.Wait()		return nil, fmt.Errorf("read blob prefix: %w", err)	}	// for big blobs git may still be writing to the pipe; don't leave it hanging.	cmd.Process.Kill()	cmd.Wait()	return data, nil}