92 lines
1.7 KiB
Go
92 lines
1.7 KiB
Go
// Copyright 2014 The zappy Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Copyright 2011 The Snappy-Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the SNAPPY-GO-LICENSE file.
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// +build !cgo purego
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package zappy
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import (
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"encoding/binary"
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"github.com/cznic/internal/buffer"
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)
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func puregoDecode() bool { return true }
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// Decode returns the decoded form of src. The returned slice may be a sub-
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// slice of buf if buf was large enough to hold the entire decoded block.
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// Otherwise, a newly allocated slice will be returned.
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// It is valid to pass a nil buf.
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func Decode(buf, src []byte) ([]byte, error) {
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dLen, s, err := decodedLen(src)
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if err != nil {
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return nil, err
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}
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if dLen == 0 {
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if len(src) == 1 {
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return nil, nil
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}
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return nil, ErrCorrupt
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}
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if len(buf) < dLen {
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buf = *buffer.Get(dLen)
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}
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var d, offset, length int
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for s < len(src) {
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n, i := binary.Varint(src[s:])
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if i <= 0 {
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return nil, ErrCorrupt
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}
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s += i
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if n >= 0 {
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length = int(n + 1)
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if length > len(buf)-d || length > len(src)-s {
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return nil, ErrCorrupt
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}
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copy(buf[d:], src[s:s+length])
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d += length
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s += length
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continue
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}
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length = int(-n)
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off64, i := binary.Uvarint(src[s:])
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if i <= 0 {
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return nil, ErrCorrupt
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}
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offset = int(off64)
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s += i
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if s > len(src) {
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return nil, ErrCorrupt
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}
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end := d + length
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if offset > d || end > len(buf) {
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return nil, ErrCorrupt
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}
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for s, v := range buf[d-offset : end-offset] {
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buf[d+s] = v
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}
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d = end
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}
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if d != dLen {
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return nil, ErrCorrupt
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}
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return buf[:d], nil
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}
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