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|
package ingest
import (
"encoding/binary"
"fmt"
"io"
"codeberg.org/lindenii/furgit/format/packfile"
)
const packHeaderSize = 12
type packHeader struct {
Version uint32
ObjectCount uint32
}
// readAndValidatePackHeader reads one PACK header from src and validates it.
func readAndValidatePackHeader(src io.Reader) (packHeader, [packHeaderSize]byte, error) {
var hdr [packHeaderSize]byte
_, err := io.ReadFull(src, hdr[:])
if err != nil {
return packHeader{}, [packHeaderSize]byte{}, &InvalidPackHeaderError{
Reason: fmt.Sprintf("read header: %v", err),
}
}
header, err := parseAndValidatePackHeader(hdr)
if err != nil {
return packHeader{}, [packHeaderSize]byte{}, err
}
return header, hdr, nil
}
// parseAndValidatePackHeader validates one already-read PACK header.
func parseAndValidatePackHeader(hdr [packHeaderSize]byte) (packHeader, error) {
if binary.BigEndian.Uint32(hdr[:4]) != packfile.Signature {
return packHeader{}, &InvalidPackHeaderError{Reason: "signature mismatch"}
}
version := binary.BigEndian.Uint32(hdr[4:8])
if !packfile.SupportedVersion(version) {
return packHeader{}, &InvalidPackHeaderError{
Reason: fmt.Sprintf("unsupported version %d", version),
}
}
return packHeader{
Version: version,
ObjectCount: binary.BigEndian.Uint32(hdr[8:12]),
}, nil
}
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