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indexIO.go
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indexIO.go
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package archiving
import (
"compress/gzip"
"encoding/binary"
"io"
"github.com/golang/glog"
"github.com/rokeller/bart/domain"
"google.golang.org/protobuf/proto"
)
func (i *Index) readIndex() error {
r, err := i.archive.storageProvider.ReadIndex()
if nil != err {
glog.Errorf("error reading index from provider: %v", err)
return err
}
defer r.Close()
// Decrypt the stream holding the index ...
cr, err := i.archive.cryptoContext.Decrypt(r)
if nil != err {
glog.Errorf("error decrypting index from provider: %v", err)
return err
}
// ... and decompress it.
gr, err := gzip.NewReader(cr)
if nil != err {
if err == gzip.ErrHeader {
return IndexDecryptionFailed
}
glog.Errorf("error decompressing index from provider: %v", err)
return err
}
defer gr.Close()
for {
entry, err := readIndexEntry(gr)
if nil != err {
return err
} else if nil == entry {
break
}
// We do this outside of the entries map message handler because it
// happens during startup and the handler doesn't need to be running
// yet.
i.entries[entry.RelPath] = indexEntry{
EntryMetadata: entry.EntryMetadata,
EntryFlags: EntryFlagsPresentInBackup,
}
}
return nil
}
// writeIndex writes the index. The caller *must* make sure that this is only
// called when message handling hasn't started, has finished, or is "paused"
// e.g. with the help of a `syncMessage` or the maintenance timer.
func (i *Index) writeIndex() error {
w, err := i.archive.storageProvider.NewIndexWriter()
if nil != err {
return err
}
defer w.Close()
// ... and then encrypt it.
cw, err := i.archive.cryptoContext.Encrypt(w)
if nil != err {
return err
}
defer cw.Close()
// Compress the data in the index ...
gw := gzip.NewWriter(cw)
defer gw.Close()
numEntries := 0
// We require the caller to take care of sync.
err = i.walkIndex(func(e domain.Entry, ef EntryFlags) error {
numEntries++
return writeIndexEntry(e, gw)
})
glog.Infof("Archive index with %d file(s) uploaded.", numEntries)
i.dirty = false
return err
}
func readIndexEntry(r io.Reader) (*domain.Entry, error) {
entrySize := make([]byte, 4)
if _, err := io.ReadFull(r, entrySize); io.EOF == err {
return nil, nil
} else if nil != err {
return nil, err
}
dataSize := binary.LittleEndian.Uint32(entrySize)
data := make([]byte, dataSize)
if _, err := io.ReadFull(r, data); nil != err {
return nil, err
}
entry := &domain.IndexEntry{}
if err := proto.Unmarshal(data, entry); nil != err {
return nil, err
}
return &domain.Entry{
RelPath: *entry.RelPath,
EntryMetadata: domain.EntryMetadata{
Timestamp: *entry.LastModified,
},
}, nil
}
func writeIndexEntry(e domain.Entry, w io.Writer) error {
buffer, err := marshalEntry(e)
if nil != err {
return err
}
entrySize := make([]byte, 4)
binary.LittleEndian.PutUint32(entrySize, uint32(len(buffer)))
if _, err := w.Write(entrySize); nil != err {
return err
}
if _, err := w.Write(buffer); nil != err {
return err
}
return nil
}
func marshalEntry(e domain.Entry) ([]byte, error) {
entry := &domain.IndexEntry{
RelPath: proto.String(e.RelPath),
LastModified: proto.Int64(e.Timestamp),
}
data, err := proto.Marshal(entry)
if nil != err {
return nil, err
}
return data, nil
}