Update to last common bleve (#3986)

vendor/github.com/mschoch/smat/smat.go

@@ -0,0 +1,161 @@
+//  Copyright (c) 2016 Marty Schoch
+
+//  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 smat
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"math/rand"
+)
+
+// Logger is a configurable logger used by this package
+// by default output is discarded
+var Logger = log.New(ioutil.Discard, "smat ", log.LstdFlags)
+
+// Context is a container for any user state
+type Context interface{}
+
+// State is a function which describes which action to perform in the event
+// that a particular byte is seen
+type State func(next byte) ActionID
+
+// PercentAction describes the frequency with which an action should occur
+// for example: Action{Percent:10, Action:DonateMoney} means that 10% of
+// the time you should donate money.
+type PercentAction struct {
+	Percent int
+	Action  ActionID
+}
+
+// Action is any function which returns the next state to transition to
+// it can optionally mutate the provided context object
+// if any error occurs, it may return an error which will abort execution
+type Action func(Context) (State, error)
+
+// ActionID is a unique identifier for an action
+type ActionID int
+
+// NopAction does nothing and simply continues to the next input
+var NopAction ActionID = -1
+
+// ActionMap is a mapping form ActionID to Action
+type ActionMap map[ActionID]Action
+
+func (a ActionMap) findSetupTeardown(setup, teardown ActionID) (Action, Action, error) {
+	setupFunc, ok := a[setup]
+	if !ok {
+		return nil, nil, ErrSetupMissing
+	}
+	teardownFunc, ok := a[teardown]
+	if !ok {
+		return nil, nil, ErrTeardownMissing
+	}
+	return setupFunc, teardownFunc, nil
+}
+
+// Fuzz runs the fuzzing state machine with the provided context
+// first, the setup action is executed unconditionally
+// the start state is determined by this action
+// actionMap is a lookup table for all actions
+// the data byte slice determines all future state transitions
+// finally, the teardown action is executed unconditionally for cleanup
+func Fuzz(ctx Context, setup, teardown ActionID, actionMap ActionMap, data []byte) int {
+	reader := bytes.NewReader(data)
+	err := runReader(ctx, setup, teardown, actionMap, reader, nil)
+	if err != nil {
+		panic(err)
+	}
+	return 1
+}
+
+// Longevity runs the state machine with the provided context
+// first, the setup action is executed unconditionally
+// the start state is determined by this action
+// actionMap is a lookup table for all actions
+// random bytes are generated to determine all future state transitions
+// finally, the teardown action is executed unconditionally for cleanup
+func Longevity(ctx Context, setup, teardown ActionID, actionMap ActionMap, seed int64, closeChan chan struct{}) error {
+	source := rand.NewSource(seed)
+	return runReader(ctx, setup, teardown, actionMap, rand.New(source), closeChan)
+}
+
+var (
+	// ErrSetupMissing is returned when the setup action cannot be found
+	ErrSetupMissing = fmt.Errorf("setup action missing")
+	// ErrTeardownMissing is returned when the teardown action cannot be found
+	ErrTeardownMissing = fmt.Errorf("teardown action missing")
+	// ErrClosed is returned when the closeChan was closed to cancel the op
+	ErrClosed = fmt.Errorf("closed")
+	// ErrActionNotPossible is returned when an action is encountered in a
+	// FuzzCase that is not possible in the current state
+	ErrActionNotPossible = fmt.Errorf("action not possible in state")
+)
+
+func runReader(ctx Context, setup, teardown ActionID, actionMap ActionMap, r io.Reader, closeChan chan struct{}) error {
+	setupFunc, teardownFunc, err := actionMap.findSetupTeardown(setup, teardown)
+	if err != nil {
+		return err
+	}
+	Logger.Printf("invoking setup action")
+	state, err := setupFunc(ctx)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		Logger.Printf("invoking teardown action")
+		_, _ = teardownFunc(ctx)
+	}()
+
+	reader := bufio.NewReader(r)
+	for next, err := reader.ReadByte(); err == nil; next, err = reader.ReadByte() {
+		select {
+		case <-closeChan:
+			return ErrClosed
+		default:
+			actionID := state(next)
+			action, ok := actionMap[actionID]
+			if !ok {
+				Logger.Printf("no such action defined, continuing")
+				continue
+			}
+			Logger.Printf("invoking action - %d", actionID)
+			state, err = action(ctx)
+			if err != nil {
+				Logger.Printf("it was action %d that returned err %v", actionID, err)
+				return err
+			}
+		}
+	}
+	return err
+}
+
+// PercentExecute interprets the next byte as a random value and normalizes it
+// to values 0-99, it then looks to see which action should be execued based
+// on the action distributions
+func PercentExecute(next byte, pas ...PercentAction) ActionID {
+	percent := int(99 * int(next) / 255)
+
+	sofar := 0
+	for _, pa := range pas {
+		sofar = sofar + pa.Percent
+		if percent < sofar {
+			return pa.Action
+		}
+
+	}
+	return NopAction
+}