forked from saracen/go7z
/
unpack_info.go
89 lines (75 loc) · 1.74 KB
/
unpack_info.go
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package headers
import (
"errors"
"io"
)
const MaxFolderCount = 1 << 30
// ErrInvalidCountExceeded is returned when the folder count is
// < 0 || > MaxFolderCount
var ErrInvalidCountExceeded = errors.New("invalid folder count")
// UnpackInfo is a structure containing folders.
type UnpackInfo struct {
Folders []*Folder
}
// ReadUnpackInfo reads unpack info structures.
func ReadUnpackInfo(r io.Reader) (*UnpackInfo, error) {
err := ReadByteExpect(r, k7zFolder)
if err != nil {
return nil, err
}
numFolders, err := ReadNumberInt(r)
if err != nil {
return nil, err
}
if numFolders > MaxFolderCount {
return nil, ErrInvalidCountExceeded
}
unpackInfo := &UnpackInfo{}
external, err := ReadByte(r)
if err != nil {
return nil, err
}
switch external {
case 0:
unpackInfo.Folders = make([]*Folder, numFolders)
for i := range unpackInfo.Folders {
if unpackInfo.Folders[i], err = ReadFolder(r); err != nil {
return nil, err
}
}
default:
return nil, ErrAdditionalStreamsNotImplemented
}
if err = ReadByteExpect(r, k7zCodersUnpackSize); err != nil {
return nil, err
}
for _, folder := range unpackInfo.Folders {
folder.UnpackSizes = make([]uint64, folder.NumOutStreamsTotal())
for i := range folder.UnpackSizes {
if folder.UnpackSizes[i], err = ReadNumber(r); err != nil {
return nil, err
}
}
}
id, err := ReadByte(r)
if err != nil {
return nil, err
}
if id == k7zCRC {
crcs, err := ReadDigests(r, len(unpackInfo.Folders))
if err != nil {
return nil, err
}
for i := range unpackInfo.Folders {
unpackInfo.Folders[i].UnpackCRC = crcs[i]
}
id, err = ReadByte(r)
if err != nil {
return nil, err
}
}
if id != k7zEnd {
return nil, ErrUnexpectedPropertyID
}
return unpackInfo, nil
}