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package read
import (
"encoding/binary"
"codeberg.org/lindenii/furgit/commitgraph"
"codeberg.org/lindenii/furgit/commitgraph/bloom"
"codeberg.org/lindenii/furgit/internal/intconv"
objectid "codeberg.org/lindenii/furgit/object/id"
)
func parseLayer(layer *layer, algo objectid.Algorithm) error { //nolint:maintidx
if len(layer.data) < commitgraph.HeaderSize {
return &MalformedError{Path: layer.path, Reason: "file too short"}
}
header := layer.data[:commitgraph.HeaderSize]
signature := binary.BigEndian.Uint32(header[:4])
if signature != commitgraph.FileSignature {
return &MalformedError{Path: layer.path, Reason: "invalid signature"}
}
version := header[4]
if version != commitgraph.FileVersion {
return &UnsupportedVersionError{Version: version}
}
expectedHashVersion, err := intconv.Uint32ToUint8(algo.PackHashID())
if err != nil {
return err
}
hashVersion := header[5]
if hashVersion != expectedHashVersion {
return &MalformedError{Path: layer.path, Reason: "hash version does not match object format"}
}
numChunks := int(header[6])
baseCount := uint32(header[7])
tocLen := (numChunks + 1) * commitgraph.ChunkEntrySize
tocStart := commitgraph.HeaderSize
tocEnd := tocStart + tocLen
if tocEnd > len(layer.data) {
return &MalformedError{Path: layer.path, Reason: "truncated chunk table"}
}
type tocEntry struct {
id uint32
offset uint64
}
entries := make([]tocEntry, 0, numChunks+1)
for i := range numChunks + 1 {
entryOff := tocStart + i*commitgraph.ChunkEntrySize
entryData := layer.data[entryOff : entryOff+commitgraph.ChunkEntrySize]
entry := tocEntry{
id: binary.BigEndian.Uint32(entryData[:4]),
offset: binary.BigEndian.Uint64(entryData[4:]),
}
entries = append(entries, entry)
}
if entries[len(entries)-1].id != 0 {
return &MalformedError{Path: layer.path, Reason: "missing chunk table terminator"}
}
trailerStart := len(layer.data) - algo.Size()
chunks := make(map[uint32][]byte, numChunks)
for i := range numChunks {
entry := entries[i]
if entry.id == 0 {
return &MalformedError{Path: layer.path, Reason: "early chunk table terminator"}
}
next := entries[i+1]
start, err := intconv.Uint64ToInt(entry.offset)
if err != nil {
return err
}
end, err := intconv.Uint64ToInt(next.offset)
if err != nil {
return err
}
if start < tocEnd || end < start || end > trailerStart {
return &MalformedError{Path: layer.path, Reason: "invalid chunk offsets"}
}
if _, exists := chunks[entry.id]; exists {
return &MalformedError{Path: layer.path, Reason: "duplicate chunk id"}
}
chunks[entry.id] = layer.data[start:end]
}
oidf := chunks[commitgraph.ChunkOIDF]
if len(oidf) != commitgraph.FanoutSize {
return &MalformedError{Path: layer.path, Reason: "invalid OIDF length"}
}
layer.chunkOIDFanout = oidf
layer.numCommits = binary.BigEndian.Uint32(oidf[commitgraph.FanoutSize-4:])
for i := range 255 {
cur := binary.BigEndian.Uint32(oidf[i*4 : (i+1)*4])
next := binary.BigEndian.Uint32(oidf[(i+1)*4 : (i+2)*4])
if cur > next {
return &MalformedError{Path: layer.path, Reason: "non-monotonic OIDF fanout"}
}
}
hashSize := algo.Size()
hashSizeU64, err := intconv.IntToUint64(hashSize)
if err != nil {
return err
}
oidl := chunks[commitgraph.ChunkOIDL]
oidlWantLen64 := uint64(layer.numCommits) * hashSizeU64
oidlWantLen, err := intconv.Uint64ToInt(oidlWantLen64)
if err != nil {
return err
}
if len(oidl) != oidlWantLen {
return &MalformedError{Path: layer.path, Reason: "invalid OIDL length"}
}
layer.chunkOIDLookup = oidl
stride := hashSize + 16
strideU64, err := intconv.IntToUint64(stride)
if err != nil {
return err
}
cdat := chunks[commitgraph.ChunkCDAT]
cdatWantLen64 := uint64(layer.numCommits) * strideU64
cdatWantLen, err := intconv.Uint64ToInt(cdatWantLen64)
if err != nil {
return err
}
if len(cdat) != cdatWantLen {
return &MalformedError{Path: layer.path, Reason: "invalid CDAT length"}
}
layer.chunkCommit = cdat
gda2 := chunks[commitgraph.ChunkGDA2]
if len(gda2) != 0 {
wantLen64 := uint64(layer.numCommits) * 4
wantLen, err := intconv.Uint64ToInt(wantLen64)
if err != nil {
return err
}
if len(gda2) != wantLen {
return &MalformedError{Path: layer.path, Reason: "invalid GDA2 length"}
}
layer.chunkGeneration = gda2
}
gdo2 := chunks[commitgraph.ChunkGDO2]
if len(gdo2) != 0 {
if len(gdo2)%8 != 0 {
return &MalformedError{Path: layer.path, Reason: "invalid GDO2 length"}
}
layer.chunkGenerationOv = gdo2
}
edge := chunks[commitgraph.ChunkEDGE]
if len(edge) != 0 {
if len(edge)%4 != 0 {
return &MalformedError{Path: layer.path, Reason: "invalid EDGE length"}
}
layer.chunkExtraEdges = edge
}
base := chunks[commitgraph.ChunkBASE]
if baseCount == 0 {
if len(base) != 0 {
return &MalformedError{Path: layer.path, Reason: "unexpected BASE chunk"}
}
} else {
wantLen64 := uint64(baseCount) * hashSizeU64
wantLen, err := intconv.Uint64ToInt(wantLen64)
if err != nil {
return err
}
if len(base) != wantLen {
return &MalformedError{Path: layer.path, Reason: "invalid BASE length"}
}
layer.chunkBaseGraphs = base
}
layer.baseCount = baseCount
bidx := chunks[commitgraph.ChunkBIDX]
bdat := chunks[commitgraph.ChunkBDAT]
if len(bidx) != 0 || len(bdat) != 0 { //nolint:nestif
if len(bidx) == 0 || len(bdat) == 0 {
return &MalformedError{Path: layer.path, Reason: "BIDX/BDAT must both be present"}
}
bidxWantLen64 := uint64(layer.numCommits) * 4
bidxWantLen, err := intconv.Uint64ToInt(bidxWantLen64)
if err != nil {
return err
}
if len(bidx) != bidxWantLen {
return &MalformedError{Path: layer.path, Reason: "invalid BIDX length"}
}
if len(bdat) < bloom.DataHeaderSize {
return &MalformedError{Path: layer.path, Reason: "invalid BDAT length"}
}
settings, err := bloom.ParseSettings(bdat)
if err != nil {
return err
}
prev := uint32(0)
for i := range layer.numCommits {
off := int(i) * 4
cur := binary.BigEndian.Uint32(bidx[off : off+4])
if i > 0 && cur < prev {
return &MalformedError{Path: layer.path, Reason: "non-monotonic BIDX"}
}
bdatDataLen := len(bdat) - bloom.DataHeaderSize
bdatDataLenU32, err := intconv.IntToUint32(bdatDataLen)
if err != nil {
return err
}
if cur > bdatDataLenU32 {
return &MalformedError{Path: layer.path, Reason: "BIDX offset out of range"}
}
prev = cur
}
layer.chunkBloomIndex = bidx
layer.chunkBloomData = bdat
layer.bloomSettings = settings
}
return nil
}
|
