// loadTxStore returns a transaction store loaded from a file.
func loadTxStore(filename string) (blockchain.TxStore, error) {
// The txstore file format is:
// <num tx data entries> <tx length> <serialized tx> <blk height>
// <num spent bits> <spent bits>
//
// All num and length fields are little-endian uint32s. The spent bits
// field is padded to a byte boundary.
filename = filepath.Join("testdata/", filename)
fi, err := os.Open(filename)
if err != nil {
return nil, err
}
// Choose read based on whether the file is compressed or not.
var r io.Reader
if strings.HasSuffix(filename, ".bz2") {
r = bzip2.NewReader(fi)
} else {
r = fi
}
defer fi.Close()
// Num of transaction store objects.
var numItems uint32
if err := binary.Read(r, binary.LittleEndian, &numItems); err != nil {
return nil, err
}
txStore := make(blockchain.TxStore)
var uintBuf uint32
for height := uint32(0); height < numItems; height++ {
txD := blockchain.TxData{}
// Serialized transaction length.
err = binary.Read(r, binary.LittleEndian, &uintBuf)
if err != nil {
return nil, err
}
serializedTxLen := uintBuf
if serializedTxLen > btcwire.MaxBlockPayload {
return nil, fmt.Errorf("Read serialized transaction "+
"length of %d is larger max allowed %d",
serializedTxLen, btcwire.MaxBlockPayload)
}
// Transaction.
var msgTx btcwire.MsgTx
err = msgTx.Deserialize(r)
if err != nil {
return nil, err
}
txD.Tx = btcutil.NewTx(&msgTx)
// Transaction hash.
txHash, err := msgTx.TxSha()
if err != nil {
return nil, err
}
txD.Hash = &txHash
// Block height the transaction came from.
err = binary.Read(r, binary.LittleEndian, &uintBuf)
if err != nil {
return nil, err
}
txD.BlockHeight = int64(uintBuf)
// Num spent bits.
err = binary.Read(r, binary.LittleEndian, &uintBuf)
if err != nil {
return nil, err
}
numSpentBits := uintBuf
numSpentBytes := numSpentBits / 8
if numSpentBits%8 != 0 {
numSpentBytes++
}
// Packed spent bytes.
spentBytes := make([]byte, numSpentBytes)
_, err = io.ReadFull(r, spentBytes)
if err != nil {
return nil, err
}
// Populate spent data based on spent bits.
txD.Spent = make([]bool, numSpentBits)
for byteNum, spentByte := range spentBytes {
for bit := 0; bit < 8; bit++ {
if uint32((byteNum*8)+bit) < numSpentBits {
if spentByte&(1<<uint(bit)) != 0 {
txD.Spent[(byteNum*8)+bit] = true
}
}
}
}
txStore[*txD.Hash] = &txD
}
return txStore, nil
}
