95 lines
2.3 KiB
Go
95 lines
2.3 KiB
Go
// Copyright 2021 The 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 LICENSE file.
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package fuzz
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import (
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"reflect"
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)
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func isMinimizable(t reflect.Type) bool {
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return t == reflect.TypeOf("") || t == reflect.TypeOf([]byte(nil))
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}
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func minimizeBytes(v []byte, try func([]byte) bool, shouldStop func() bool) {
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tmp := make([]byte, len(v))
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// If minimization was successful at any point during minimizeBytes,
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// then the vals slice in (*workerServer).minimizeInput will point to
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// tmp. Since tmp is altered while making new candidates, we need to
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// make sure that it is equal to the correct value, v, before exiting
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// this function.
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defer copy(tmp, v)
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// First, try to cut the tail.
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for n := 1024; n != 0; n /= 2 {
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for len(v) > n {
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if shouldStop() {
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return
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}
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candidate := v[:len(v)-n]
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if !try(candidate) {
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break
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}
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// Set v to the new value to continue iterating.
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v = candidate
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}
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}
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// Then, try to remove each individual byte.
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for i := 0; i < len(v)-1; i++ {
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if shouldStop() {
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return
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}
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candidate := tmp[:len(v)-1]
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copy(candidate[:i], v[:i])
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copy(candidate[i:], v[i+1:])
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if !try(candidate) {
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continue
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}
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// Update v to delete the value at index i.
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copy(v[i:], v[i+1:])
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v = v[:len(candidate)]
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// v[i] is now different, so decrement i to redo this iteration
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// of the loop with the new value.
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i--
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}
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// Then, try to remove each possible subset of bytes.
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for i := 0; i < len(v)-1; i++ {
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copy(tmp, v[:i])
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for j := len(v); j > i+1; j-- {
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if shouldStop() {
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return
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}
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candidate := tmp[:len(v)-j+i]
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copy(candidate[i:], v[j:])
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if !try(candidate) {
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continue
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}
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// Update v and reset the loop with the new length.
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copy(v[i:], v[j:])
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v = v[:len(candidate)]
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j = len(v)
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}
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}
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// Then, try to make it more simplified and human-readable by trying to replace each
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// byte with a printable character.
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printableChars := []byte("012789ABCXYZabcxyz !\"#$%&'()*+,.")
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for i, b := range v {
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if shouldStop() {
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return
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}
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for _, pc := range printableChars {
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v[i] = pc
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if try(v) {
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// Successful. Move on to the next byte in v.
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break
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}
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// Unsuccessful. Revert v[i] back to original value.
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v[i] = b
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}
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}
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}
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