depot/go/nix/nixwire/nixwire.go

105 lines
2.2 KiB
Go

package nixwire
import (
"encoding/binary"
"fmt"
"io"
)
type Serializer struct {
io.Writer
}
func (w Serializer) WritePadding(n int64) (int64, error) {
if n%8 > 0 {
n, err := w.Write(make([]byte, 8-(n%8)))
return int64(n), err
}
return 0, nil
}
func (w Serializer) WriteUint64(n uint64) (int64, error) {
buf := make([]byte, 8)
binary.LittleEndian.PutUint64(buf, n)
wrote, err := w.Write(buf)
return int64(wrote), err
}
func (w Serializer) WriteString(s string) (int64, error) {
nSize, err := w.WriteUint64(uint64(len(s)))
if err != nil {
return int64(nSize), err
}
nData, err := w.Write([]byte(s))
if err != nil {
return int64(nSize) + int64(nData), err
}
nPad, err := w.WritePadding(int64(len(s)))
return int64(nSize) + int64(nData) + int64(nPad), err
}
type Deserializer struct {
io.Reader
}
func (r Deserializer) ReadPadding(n uint64) error {
if n%8 == 0 {
return nil
}
buf := make([]byte, 8-(int(n)%8))
if _, err := io.ReadFull(r, buf); err != nil {
return fmt.Errorf("reading padding: %w", err)
}
for _, n := range buf {
if n != 0 {
return fmt.Errorf("padding was not all 0")
}
}
return nil
}
func (r Deserializer) ReadUint64() (uint64, error) {
buf := make([]byte, 8)
if _, err := io.ReadFull(r, buf); err != nil {
return 0, fmt.Errorf("reading uint64: %w", err)
}
return binary.LittleEndian.Uint64(buf), nil
}
func (r Deserializer) ReadString() (string, error) {
strLen, err := r.ReadUint64()
if err != nil {
return "", fmt.Errorf("reading length: %w", err)
}
strBuf := make([]byte, int(strLen))
if _, err := io.ReadFull(r, strBuf); err != nil {
return "", fmt.Errorf("reading string buffer: %w", err)
}
if err := r.ReadPadding(strLen); err != nil {
return "", fmt.Errorf("reading string padding: %w", err)
}
return string(strBuf), nil
}
func (r Deserializer) ReadStrings() ([]string, error) {
setLen, err := r.ReadUint64()
if err != nil {
return nil, fmt.Errorf("reading string set length: %w", err)
}
xs := make([]string, int(setLen))
for n := uint64(0); n < setLen; n++ {
xs[n], err = r.ReadString()
if err != nil {
return nil, fmt.Errorf("reading string %d of %d: %w", n, setLen, err)
}
}
return xs, nil
}