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package ingest
import (
"fmt"
"codeberg.org/lindenii/furgit/internal/intconv"
objectid "codeberg.org/lindenii/furgit/object/id"
objecttype "codeberg.org/lindenii/furgit/object/type"
)
// parseEntryPrefix parses one entry prefix from stream.
func parseEntryPrefix(state *ingestState, startOffset uint64) (objectRecord, error) {
var record objectRecord
record.offset = startOffset
first, err := state.stream.ReadByte()
if err != nil {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: fmt.Sprintf("read first header byte: %v", err)}
}
record.packedType = objecttype.Type((first >> 4) & 0x07)
size := int64(first & 0x0f)
headerLen := uint32(1)
shift := uint(4)
b := first
for b&0x80 != 0 {
b, err = state.stream.ReadByte()
if err != nil {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: fmt.Sprintf("read size continuation: %v", err)}
}
headerLen++
size |= int64(b&0x7f) << shift
shift += 7
}
if size < 0 {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: "negative declared size"}
}
record.declaredSize = size
switch record.packedType {
case objecttype.TypeCommit, objecttype.TypeTree, objecttype.TypeBlob, objecttype.TypeTag:
case objecttype.TypeRefDelta:
baseRaw := make([]byte, state.algo.Size())
err := state.stream.readFull(baseRaw)
if err != nil {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: fmt.Sprintf("read ref base: %v", err)}
}
baseID, err := objectid.FromBytes(state.algo, baseRaw)
if err != nil {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: fmt.Sprintf("parse ref base: %v", err)}
}
record.baseObject = baseID
baseRawLen, err := intconv.IntToUint32(len(baseRaw))
if err != nil {
return record, err
}
headerLen += baseRawLen
case objecttype.TypeOfsDelta:
dist, consumed, err := readOfsDistanceFromStream(state.stream)
if err != nil {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: err.Error()}
}
if startOffset <= dist {
return record, &MalformedPackEntryError{Offset: startOffset, Reason: "ofs base offset out of bounds"}
}
record.baseOffset = startOffset - dist
consumedUint32, err := intconv.IntToUint32(consumed)
if err != nil {
return record, err
}
headerLen += consumedUint32
case objecttype.TypeInvalid, objecttype.TypeFuture:
return record, &MalformedPackEntryError{Offset: startOffset, Reason: fmt.Sprintf("unsupported object type %d", record.packedType)}
default:
return record, &MalformedPackEntryError{Offset: startOffset, Reason: fmt.Sprintf("unsupported object type %d", record.packedType)}
}
record.headerLen = headerLen
return record, nil
}
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