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forgejo/vendor/github.com/djherbis/buffer/mem.go

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package buffer
import (
"bytes"
"encoding/gob"
"fmt"
"io"
"github.com/djherbis/buffer/limio"
)
type memory struct {
N int64
*bytes.Buffer
}
// New returns a new in memory BufferAt with max size N.
// It's backed by a bytes.Buffer.
func New(n int64) BufferAt {
return &memory{
N: n,
Buffer: bytes.NewBuffer(nil),
}
}
func (buf *memory) Cap() int64 {
return buf.N
}
func (buf *memory) Len() int64 {
return int64(buf.Buffer.Len())
}
func (buf *memory) Write(p []byte) (n int, err error) {
return limio.LimitWriter(buf.Buffer, Gap(buf)).Write(p)
}
func (buf *memory) WriteAt(p []byte, off int64) (n int, err error) {
if off > buf.Len() {
return 0, io.ErrShortWrite
} else if len64(p)+off <= buf.Len() {
d := buf.Bytes()[off:]
return copy(d, p), nil
} else {
d := buf.Bytes()[off:]
n = copy(d, p)
m, err := buf.Write(p[n:])
return n + m, err
}
}
func (buf *memory) ReadAt(p []byte, off int64) (n int, err error) {
return bytes.NewReader(buf.Bytes()).ReadAt(p, off)
}
func (buf *memory) Read(p []byte) (n int, err error) {
return io.LimitReader(buf.Buffer, buf.Len()).Read(p)
}
func (buf *memory) ReadFrom(r io.Reader) (n int64, err error) {
return buf.Buffer.ReadFrom(io.LimitReader(r, Gap(buf)))
}
func init() {
gob.Register(&memory{})
}
func (buf *memory) MarshalBinary() ([]byte, error) {
var b bytes.Buffer
fmt.Fprintln(&b, buf.N)
b.Write(buf.Bytes())
return b.Bytes(), nil
}
func (buf *memory) UnmarshalBinary(bindata []byte) error {
data := make([]byte, len(bindata))
copy(data, bindata)
b := bytes.NewBuffer(data)
_, err := fmt.Fscanln(b, &buf.N)
buf.Buffer = bytes.NewBuffer(b.Bytes())
return err
}