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// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
//
// Copyright 2013 Julien Schmidt. All rights reserved.
// http://www.julienschmidt.com
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
package mysql
import (
"io"
)
const (
defaultBufSize = 4096
)
type buffer struct {
buf []byte
rd io.Reader
idx int
length int
}
func newBuffer(rd io.Reader) *buffer {
return &buffer{
buf: make([]byte, defaultBufSize),
rd: rd,
}
}
// fill reads at least _need_ bytes in the buffer
// existing data in the buffer gets lost
func (b *buffer) fill(need int) (err error) {
b.idx = 0
b.length = 0
n := 0
for b.length < need {
n, err = b.rd.Read(b.buf[b.length:])
b.length += n
if err == nil {
continue
}
return // err
}
return
}
// read len(p) bytes
func (b *buffer) read(p []byte) (err error) {
need := len(p)
if b.length < need {
if b.length > 0 {
copy(p[0:b.length], b.buf[b.idx:])
need -= b.length
p = p[b.length:]
b.idx = 0
b.length = 0
}
if need >= len(b.buf) {
var n int
has := 0
for err == nil && need > has {
n, err = b.rd.Read(p[has:])
has += n
}
return
}
err = b.fill(need) // err deferred
}
copy(p, b.buf[b.idx:])
b.idx += need
b.length -= need
return
}