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78 lines
1.8 KiB
78 lines
1.8 KiB
// Copyright 2016, Joe Tsai. 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.md file.
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// +build gofuzz
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// This file exists to export internal implementation details for fuzz testing.
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package bzip2
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func ForwardBWT(buf []byte) (ptr int) {
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var bwt burrowsWheelerTransform
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return bwt.Encode(buf)
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}
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func ReverseBWT(buf []byte, ptr int) {
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var bwt burrowsWheelerTransform
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bwt.Decode(buf, ptr)
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}
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type fuzzReader struct {
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Checksums Checksums
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}
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// updateChecksum updates Checksums.
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//
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// If a valid pos is provided, it appends the (pos, val) pair to the slice.
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// Otherwise, it will update the last record with the new value.
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func (fr *fuzzReader) updateChecksum(pos int64, val uint32) {
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if pos >= 0 {
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fr.Checksums = append(fr.Checksums, Checksum{pos, val})
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} else {
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fr.Checksums[len(fr.Checksums)-1].Value = val
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}
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}
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type Checksum struct {
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Offset int64 // Bit offset of the checksum
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Value uint32 // Checksum value
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}
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type Checksums []Checksum
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// Apply overwrites all checksum fields in d with the ones in cs.
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func (cs Checksums) Apply(d []byte) []byte {
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d = append([]byte(nil), d...)
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for _, c := range cs {
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setU32(d, c.Offset, c.Value)
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}
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return d
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}
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func setU32(d []byte, pos int64, val uint32) {
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for i := uint(0); i < 32; i++ {
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bpos := uint64(pos) + uint64(i)
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d[bpos/8] &= ^byte(1 << (7 - bpos%8))
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d[bpos/8] |= byte(val>>(31-i)) << (7 - bpos%8)
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}
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}
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// Verify checks that all checksum fields in d matches those in cs.
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func (cs Checksums) Verify(d []byte) bool {
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for _, c := range cs {
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if getU32(d, c.Offset) != c.Value {
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return false
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}
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}
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return true
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}
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func getU32(d []byte, pos int64) (val uint32) {
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for i := uint(0); i < 32; i++ {
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bpos := uint64(pos) + uint64(i)
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val |= (uint32(d[bpos/8] >> (7 - bpos%8))) << (31 - i)
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}
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return val
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}
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