// Saves Meta data from dirTree to meta File
func saveMeta(data *ReveloData) error {
var Meta *horcrux.Meta
var err error
data.lock.RLock()
Meta, err = dirTree.GetMeta(data.Root)
Meta.Config = data.Config
Meta.CurrVer = data.CurrVer
data.lock.RUnlock()
if err != nil {
log.Error("saveMeta: Cannot get Meta data")
return err
}
js, err := json.MarshalIndent(Meta, "", " ")
if err != nil {
log.WithFields(
log.Fields{"Meta": Meta, "Error": err}).Error("saveMeta: Cannot marshal meta")
return err
}
metaFile, err := os.OpenFile(data.cacheDir+"/"+data.metaName, os.O_WRONLY|os.O_SYNC, 0600)
if err != nil {
log.WithFields(log.Fields{"Meta File": data.metaName, "Error": err}).Error("saveMeta: Cannot open meta file")
return err
}
defer metaFile.Close()
// XXX Using File EX lock to avoid multiple access
for err = syscall.Flock(int(metaFile.Fd()), syscall.LOCK_EX); err == syscall.EINTR; {
}
if err != nil {
log.WithFields(log.Fields{"Error": err}).Error("saveMeta: Cannot lock meta file")
return err
}
defer syscall.Flock(int(metaFile.Fd()), syscall.LOCK_UN)
metaFile.Truncate(0) //XXX: Do Truncate(n) after write succeeds!!
n, err := metaFile.Write(js)
if err != nil {
log.WithFields(log.Fields{
"Meta file": data.metaName, "Wrote": n, "Size": len(js), "Error": err,
}).Error("saveMeta: Cannot write to meta file")
return err
}
log.Debug("saveMeta: Done")
return nil
}
