Add go fuzzer in preparation for testing. Also gofmt a few files that needed it.

Author: lavalamp

pkg/util/fuzz.go

@@ -0,0 +1,263 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"fmt"
+	"math/rand"
+	"reflect"
+)
+
+// Fuzzer knows how to fill any object with random fields.
+type Fuzzer struct {
+	customFuzz map[reflect.Type]func(reflect.Value)
+}
+
+// NewFuzzer returns a new Fuzzer with the given custom fuzzing functions.
+// Each entry in fuzzFuncs must be a function with one parameter, which will
+// be the variable we wish that function to fill with random data. For this
+// to be effective, the variable type should be either a pointer, map, slice,
+// etc. These functions are called sensibly, e.g., if you wanted custom string
+// fuzzing, the function `func(s *string)` would get called and passed the
+// address of strings.
+func NewFuzzer(fuzzFuncs ...interface{}) *Fuzzer {
+	f := &Fuzzer{
+		map[reflect.Type]func(reflect.Value){},
+	}
+	for i := range fuzzFuncs {
+		v := reflect.ValueOf(fuzzFuncs[i])
+		if v.Kind() != reflect.Func {
+			panic("Need only funcs!")
+		}
+		t := v.Type()
+		if t.NumIn() != 1 || t.NumOut() != 0 {
+			panic("Need 1 in and 0 out params!")
+		}
+		argT := t.In(0)
+		// fmt.Printf("Making entry for thing with '%v' type\n", argT)
+		f.customFuzz[argT] = func(toFuzz reflect.Value) {
+			if toFuzz.Type().AssignableTo(argT) {
+				v.Call([]reflect.Value{toFuzz})
+			} else if toFuzz.Type().ConvertibleTo(argT) {
+				v.Call([]reflect.Value{toFuzz.Convert(argT)})
+			} else {
+				panic(fmt.Errorf("%#v neither ConvertibleTo nor AssignableTo %v",
+					toFuzz.Interface(),
+					argT))
+			}
+		}
+	}
+	return f
+}
+
+// Fuzz recursively fills all of obj's fields with something random.
+// Not safe for cyclic or tree-like structs!
+// obj must be a pointer. Only exported (public) fields can be set (thanks, golang :/ )
+// Intended for tests, so will panic on bad input or unimplemented fields.
+func (f *Fuzzer) Fuzz(obj interface{}) {
+	v := reflect.ValueOf(obj)
+	if v.Kind() != reflect.Ptr {
+		panic("needed ptr!")
+	}
+	v = v.Elem()
+	f.doFuzz(v)
+}
+
+func (f *Fuzzer) doFuzz(v reflect.Value) {
+	if !v.CanSet() {
+		return
+	}
+	// Check for both pointer and non-pointer custom functions.
+	if v.CanAddr() && f.tryCustom(v.Addr()) {
+		return
+	}
+	if f.tryCustom(v) {
+		return
+	}
+	if fn, ok := fillFuncMap[v.Kind()]; ok {
+		fn(v)
+		return
+	}
+	switch v.Kind() {
+	case reflect.Map:
+		if rand.Intn(5) > 0 {
+			v.Set(reflect.MakeMap(v.Type()))
+			if f.tryCustom(v) {
+				return
+			}
+			n := 1 + rand.Intn(10)
+			for i := 0; i < n; i++ {
+				key := reflect.New(v.Type().Key()).Elem()
+				f.doFuzz(key)
+				val := reflect.New(v.Type().Elem()).Elem()
+				f.doFuzz(val)
+				v.SetMapIndex(key, val)
+			}
+			return
+		}
+		v.Set(reflect.Zero(v.Type()))
+	case reflect.Ptr:
+		if rand.Intn(5) > 0 {
+			v.Set(reflect.New(v.Type().Elem()))
+			f.doFuzz(v.Elem())
+			return
+		}
+		v.Set(reflect.Zero(v.Type()))
+	case reflect.Slice:
+		if rand.Intn(5) > 0 {
+			n := 1 + rand.Intn(10)
+			v.Set(reflect.MakeSlice(v.Type(), n, n))
+			if f.tryCustom(v) {
+				return
+			}
+			for i := 0; i < n; i++ {
+				f.doFuzz(v.Index(i))
+			}
+			return
+		}
+		v.Set(reflect.Zero(v.Type()))
+	case reflect.Struct:
+		for i := 0; i < v.NumField(); i++ {
+			f.doFuzz(v.Field(i))
+		}
+	case reflect.Array:
+		fallthrough
+	case reflect.Chan:
+		fallthrough
+	case reflect.Func:
+		fallthrough
+	case reflect.Interface:
+		fallthrough
+	default:
+		panic(fmt.Sprintf("Can't handle %#v", v.Interface()))
+	}
+}
+
+// tryCustom searches for custom handlers and Randomizer implementations, and
+// returns true if it finds a match and successfully randomizes v.
+func (f Fuzzer) tryCustom(v reflect.Value) bool {
+	// fmt.Printf("Trying thing with '%v' type\n", v.Type())
+	switch v.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Slice:
+		if v.IsNil() {
+			return false
+		}
+	case reflect.Ptr:
+		if v.IsNil() {
+			if !v.CanSet() {
+				return false
+			}
+			v.Set(reflect.New(v.Type().Elem()))
+		}
+	case reflect.Map:
+		if v.IsNil() {
+			if !v.CanSet() {
+				return false
+			}
+			v.Set(reflect.MakeMap(v.Type()))
+		}
+	}
+	if f, ok := f.customFuzz[v.Type()]; ok {
+		f(v)
+		return true
+	}
+	return false
+}
+
+func fuzzInt(v reflect.Value) {
+	v.SetInt(int64(RandUint64()))
+}
+
+func fuzzUint(v reflect.Value) {
+	v.SetUint(RandUint64())
+}
+
+var fillFuncMap = map[reflect.Kind]func(reflect.Value){
+	reflect.Bool: func(v reflect.Value) {
+		v.SetBool(RandBool())
+	},
+	reflect.Int:     fuzzInt,
+	reflect.Int8:    fuzzInt,
+	reflect.Int16:   fuzzInt,
+	reflect.Int32:   fuzzInt,
+	reflect.Int64:   fuzzInt,
+	reflect.Uint:    fuzzUint,
+	reflect.Uint8:   fuzzUint,
+	reflect.Uint16:  fuzzUint,
+	reflect.Uint32:  fuzzUint,
+	reflect.Uint64:  fuzzUint,
+	reflect.Uintptr: fuzzUint,
+	reflect.Float32: func(v reflect.Value) {
+		v.SetFloat(float64(rand.Float32()))
+	},
+	reflect.Float64: func(v reflect.Value) {
+		v.SetFloat(rand.Float64())
+	},
+	reflect.Complex64: func(v reflect.Value) {
+		panic("unimplemented")
+	},
+	reflect.Complex128: func(v reflect.Value) {
+		panic("unimplemented")
+	},
+	reflect.String: func(v reflect.Value) {
+		v.SetString(RandString())
+	},
+	reflect.UnsafePointer: func(v reflect.Value) {
+		panic("unimplemented")
+	},
+}
+
+// RandBool returns true or false randomly.
+func RandBool() bool {
+	if rand.Int()&1 == 1 {
+		return true
+	}
+	return false
+}
+
+type charRange struct {
+	first, last rune
+}
+
+// choose returns a random unicode character from the given range.
+func (r *charRange) choose() rune {
+	count := int64(r.last - r.first)
+	return r.first + rune(rand.Int63n(count))
+}
+
+var unicodeRanges = []charRange{
+	{' ', '~'},           // ASCII characters
+	{'\u00a0', '\u02af'}, // Multi-byte encoded characters
+	{'\u4e00', '\u9fff'}, // Common CJK (even longer encodings)
+}
+
+// RandString makes a random string up to 20 characters long. The returned string
+// may include a variety of (valid) UTF-8 encodings. For testing.
+func RandString() string {
+	n := rand.Intn(20)
+	runes := make([]rune, n)
+	for i := range runes {
+		runes[i] = unicodeRanges[rand.Intn(len(unicodeRanges))].choose()
+	}
+	return string(runes)
+}
+
+// RandUint64 makes random 64 bit numbers.
+// Weirdly, rand doesn't have a function that gives you 64 random bits.
+func RandUint64() uint64 {
+	return uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
+}