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package furgit
import (
"bytes"
"fmt"
"io"
"os"
"path/filepath"
"strconv"
"git.sr.ht/~runxiyu/furgit/internal/bufpool"
"git.sr.ht/~runxiyu/furgit/internal/zlib"
"git.sr.ht/~runxiyu/furgit/internal/zlibx"
)
const looseHeaderLimit = 4096
// loosePath returns the path for a loose object, validating hash size.
func (repo *Repository) loosePath(id Hash) (string, error) {
if id.algo != repo.hashAlgo {
return "", fmt.Errorf("furgit: hash algorithm mismatch: got %s, expected %s", id.algo.String(), repo.hashAlgo.String())
}
hex := id.String()
return filepath.Join("objects", hex[:2], hex[2:]), nil
}
func (repo *Repository) looseRead(id Hash) (ObjectType, bufpool.Buffer, error) {
ty, body, err := repo.looseReadTyped(id)
if err != nil {
return ObjectTypeInvalid, bufpool.Buffer{}, err
}
return ty, body, nil
}
func (repo *Repository) looseReadTyped(id Hash) (ObjectType, bufpool.Buffer, error) {
path, err := repo.loosePath(id)
if err != nil {
return ObjectTypeInvalid, bufpool.Buffer{}, err
}
path = repo.repoPath(path)
f, err := os.Open(path)
if err != nil {
if os.IsNotExist(err) {
return ObjectTypeInvalid, bufpool.Buffer{}, ErrNotFound
}
return ObjectTypeInvalid, bufpool.Buffer{}, err
}
defer func() { _ = f.Close() }()
compressed, err := io.ReadAll(f)
if err != nil {
return ObjectTypeInvalid, bufpool.Buffer{}, err
}
raw, err := zlibx.Decompress(compressed)
if err != nil {
return ObjectTypeInvalid, bufpool.Buffer{}, err
}
rawBytes := raw.Bytes()
nul := bytes.IndexByte(rawBytes, 0)
if nul < 0 {
raw.Release()
return ObjectTypeInvalid, bufpool.Buffer{}, ErrInvalidObject
}
header := rawBytes[:nul]
body := rawBytes[nul+1:]
ty, declaredSize, err := parseLooseHeader(header)
if err != nil {
raw.Release()
return ObjectTypeInvalid, bufpool.Buffer{}, err
}
if declaredSize != int64(len(body)) {
raw.Release()
return ObjectTypeInvalid, bufpool.Buffer{}, ErrInvalidObject
}
copy(rawBytes, body)
raw.Resize(len(body))
return ty, raw, nil
}
func (repo *Repository) looseTypeSize(id Hash) (ObjectType, int64, error) {
path, err := repo.loosePath(id)
if err != nil {
return ObjectTypeInvalid, 0, err
}
path = repo.repoPath(path)
// #nosec G304
f, err := os.Open(path)
if err != nil {
if os.IsNotExist(err) {
return ObjectTypeInvalid, 0, ErrNotFound
}
return ObjectTypeInvalid, 0, err
}
defer func() { _ = f.Close() }()
zr, err := zlib.NewReader(f)
if err != nil {
return ObjectTypeInvalid, 0, err
}
defer func() { _ = zr.Close() }()
header := make([]byte, 0, 64)
chunk := make([]byte, 128)
for {
n, readErr := zr.Read(chunk)
if n > 0 {
data := chunk[:n]
if nul := bytes.IndexByte(data, 0); nul >= 0 {
header = append(header, data[:nul]...)
if len(header) > looseHeaderLimit {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
break
}
header = append(header, data...)
if len(header) > looseHeaderLimit {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
}
if readErr != nil {
if readErr == io.EOF {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
return ObjectTypeInvalid, 0, readErr
}
}
return parseLooseHeader(header)
}
func parseLooseHeader(header []byte) (ObjectType, int64, error) {
space := bytes.IndexByte(header, ' ')
if space < 0 {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
ty, err := objTypeFromName(string(header[:space]))
if err != nil {
return ObjectTypeInvalid, 0, err
}
expect := header[space+1:]
if len(expect) == 0 {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
size, err := strconv.ParseInt(string(expect), 10, 64)
if err != nil {
return ObjectTypeInvalid, 0, fmt.Errorf("furgit: loose: size parse: %w", err)
}
if size < 0 {
return ObjectTypeInvalid, 0, ErrInvalidObject
}
return ty, size, nil
}
func objTypeFromName(name string) (ObjectType, error) {
switch name {
case objectTypeNameBlob:
return ObjectTypeBlob, nil
case objectTypeNameTree:
return ObjectTypeTree, nil
case objectTypeNameCommit:
return ObjectTypeCommit, nil
case objectTypeNameTag:
return ObjectTypeTag, nil
default:
return ObjectTypeInvalid, ErrInvalidObject
}
}
// WriteLooseObject writes an object to the repository as a loose object.
func (repo *Repository) WriteLooseObject(obj Object) (Hash, error) {
var raw []byte
var err error
switch o := obj.(type) {
case *Blob:
raw, err = o.Serialize()
case *Tree:
raw, err = o.Serialize()
case *Commit:
raw, err = o.Serialize()
case *Tag:
raw, err = o.Serialize()
default:
return Hash{}, fmt.Errorf("furgit: unsupported object type for writing: %T", obj)
}
// TODO: Consider adding serialize to the interface?
if err != nil {
return Hash{}, err
}
id := repo.computeRawHash(raw)
path, err := repo.loosePath(id)
if err != nil {
return Hash{}, err
}
path = repo.repoPath(path)
if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
return Hash{}, err
}
var buf bytes.Buffer
zw := zlib.NewWriter(&buf)
if _, err := zw.Write(raw); err != nil {
return Hash{}, err
}
if err := zw.Close(); err != nil {
return Hash{}, err
}
if err := os.WriteFile(path, buf.Bytes(), 0o644); err != nil {
return Hash{}, err
}
return id, nil
}
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