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package loose
import (
"bufio"
"bytes"
"errors"
"io"
"os"
"codeberg.org/lindenii/furgit/internal/compress/zlib"
"codeberg.org/lindenii/furgit/internal/iolimit"
"codeberg.org/lindenii/furgit/objectid"
"codeberg.org/lindenii/furgit/objecttype"
)
type objectReader struct {
// reader is the stream exposed by Read.
reader io.Reader
// file is the underlying loose object file and is closed by Close.
file *os.File
// zr is the zlib decoder and is closed by Close.
zr io.ReadCloser
}
func (reader *objectReader) Read(dst []byte) (int, error) {
return reader.reader.Read(dst)
}
func (reader *objectReader) Close() error {
errZlib := reader.zr.Close()
errFile := reader.file.Close()
return errors.Join(errZlib, errFile)
}
// openInflated opens and zlib-decodes a loose object file.
// The caller owns both returned closers and must close them.
func (store *Store) openInflated(id objectid.ObjectID) (*os.File, io.ReadCloser, error) {
file, err := store.openObject(id)
if err != nil {
return nil, nil, err
}
zr, err := zlib.NewReader(file)
if err != nil {
_ = file.Close()
return nil, nil, err
}
return file, zr, nil
}
// ReadReaderFull reads a full serialized object stream as "type size\0content".
//
// The caller must close the returned reader.
//
// Close releases resources only. It does not drain unread data for additional
// validation. In particular, malformed trailing compressed data, trailing bytes
// past the declared object size, and the zlib Adler-32 trailer may go
// unverified unless the caller reads to io.EOF.
func (store *Store) ReadReaderFull(id objectid.ObjectID) (io.ReadCloser, error) {
file, zr, err := store.openInflated(id)
if err != nil {
return nil, err
}
br := bufio.NewReader(zr)
header, _, size, err := readHeader(br)
if err != nil {
_ = zr.Close()
_ = file.Close()
return nil, err
}
return &objectReader{
reader: io.MultiReader(
bytes.NewReader(header),
iolimit.ExpectLengthReader(br, size),
),
file: file,
zr: zr,
}, nil
}
// ReadReaderContent reads an object's type, declared content length, and
// content stream.
//
// The caller must close the returned reader.
//
// Close releases resources only. It does not drain unread data for additional
// validation. In particular, malformed trailing compressed data, trailing bytes
// past the declared object size, and the zlib Adler-32 trailer may go
// unverified unless the caller reads to io.EOF.
func (store *Store) ReadReaderContent(id objectid.ObjectID) (objecttype.Type, int64, io.ReadCloser, error) {
file, zr, err := store.openInflated(id)
if err != nil {
return objecttype.TypeInvalid, 0, nil, err
}
br := bufio.NewReader(zr)
_, ty, size, err := readHeader(br)
if err != nil {
_ = zr.Close()
_ = file.Close()
return objecttype.TypeInvalid, 0, nil, err
}
return ty, size, &objectReader{
reader: iolimit.ExpectLengthReader(br, size),
file: file,
zr: zr,
}, nil
}
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