common.go

//  Copyright 2017 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 daisy

import (
	"context"
	"math/rand"
	"os"
	"os/user"
	"reflect"
	"regexp"
	"sort"
	"strings"
	"time"

	computeBeta "google.golang.org/api/compute/v0.beta"
	"google.golang.org/api/compute/v1"
)

var (
	varPattern = regexp.MustCompile(`\$\{.*\}`)
)

func getUser() string {
	if cu, err := user.Current(); err == nil {
		return cu.Username
	}
	if hn, err := os.Hostname(); err == nil {
		return hn
	}
	return "unknown"
}

// NamedSubexp extracts sub matches in the exp
func NamedSubexp(re *regexp.Regexp, s string) map[string]string {
	match := re.FindStringSubmatch(s)
	if match == nil {
		return nil
	}
	result := make(map[string]string)
	l := len(match)
	for i, name := range re.SubexpNames() {
		if i == 0 || name == "" {
			continue
		}
		result[name] = ""
		if i < l {
			result[name] = match[i]
		}
	}
	return result
}

// filter creates a copy of ss, excluding any instances of s.
func filter(ss []string, s string) []string {
	result := []string{}
	for _, element := range ss {
		if element != s {
			result = append(result, element)
		}
	}
	return result
}

func minInt(x int, ys ...int) int {
	for _, y := range ys {
		if y < x {
			x = y
		}
	}
	return x
}

func randString(n int) string {
	gen := rand.New(rand.NewSource(time.Now().UnixNano()))
	letters := "bdghjlmnpqrstvwxyz0123456789"
	b := make([]byte, n)
	for i := range b {
		b[i] = letters[gen.Int63()%int64(len(letters))]
	}
	return string(b)
}

func strIn(s string, ss []string) bool {
	for _, x := range ss {
		if s == x {
			return true
		}
	}
	return false
}

func strLitPtr(s string) *string {
	return &s
}

func strOr(s string, ss ...string) string {
	ss = append([]string{s}, ss...)
	for _, st := range ss {
		if st != "" {
			return st
		}
	}
	return ""
}

// substitute runs replacer on string elements within a complex data structure
// (except those contained in private data structure fields).
func substitute(v reflect.Value, replacer *strings.Replacer) {
	traverseData(v, func(val reflect.Value) DError {
		switch val.Interface().(type) {
		case string:
			val.SetString(replacer.Replace(val.String()))
		}
		return nil
	}, func(v reflect.Value) traverseAction {
		_, ok := v.Interface().(*Workflow)
		if ok {
			return prune
		}
		return continueTraversal
	})
}

// hasVariableDeclaration determines whether s contains a variable declaration of the style `${varname}`
func hasVariableDeclaration(s string) bool {
	return varPattern.MatchString(s)
}

func getRegionFromZone(z string) string {
	if z != "" {
		lastIndex := strings.LastIndex(z, "-")
		return z[:lastIndex]
	}
	return ""
}

// substituteSourceVars replaces source vars (${SOURCE:xxxx}) with the sources
// content.
func (w *Workflow) substituteSourceVars(ctx context.Context, v reflect.Value) DError {
	return traverseData(v, func(val reflect.Value) DError {
		switch val.Interface().(type) {
		case string:
			if matches := sourceVarRgx.FindAllStringSubmatch(val.String(), -1); matches != nil {
				futureVal := val.String()
				for _, match := range matches {
					if len(match) < 2 || !w.sourceExists(match[1]) {
						return Errf("source not found for expansion: %s", match[0])
					}
					sv, err := w.sourceContent(ctx, match[1])
					if err != nil {
						return Errf("error reading source content for %s: %v", match[1], err)
					}
					futureVal = strings.Replace(futureVal, match[0], sv, -1)
					if len(futureVal) > 1024*256 {
						return Errf("Expanded string for '%s' is too large", val.String())
					}
				}
				val.SetString(futureVal)
			}
		}
		return nil
	})
}

// traverseAction allows callers of traverseData to customize the function's traversal.
type traverseAction uint

const (
	// Continue the traversal; this is the default action of
	// traverseData, which traverses to all nodes.
	continueTraversal traverseAction = iota
	// Do not process this node or any of its children.
	prune
)

// traverseData traverses complex data structures and runs
// a function, f, on its basic data types.
// Traverses arrays, maps, slices, and public fields of structs.
// For example, f will be run on bool, int, string, etc.
// Slices, maps, and structs will not have f called on them, but will
// traverse their subelements.
// Errors returned from f will be returned by traverseDataStructure.
// actions allows the caller to determine which action to take at a node.
// The default action is 'continueTraverse'.
func traverseData(v reflect.Value, f func(reflect.Value) DError, actions ...func(reflect.Value) traverseAction) DError {

	if !v.CanSet() {
		// Don't run on private fields.
		return nil
	}

	for _, action := range actions {
		switch action(v) {
		case prune:
			return nil
		}
	}

	switch v.Kind() {
	case reflect.Chan, reflect.Func:
		return nil
	case reflect.Interface, reflect.Ptr, reflect.UnsafePointer:
		if v.IsNil() {
			return nil
		}
		// I'm a pointer, dereference me.
		return traverseData(v.Elem(), f, actions...)
	}

	switch v.Kind() {
	case reflect.Array, reflect.Slice:
		for i := 0; i < v.Len(); i++ {
			if err := traverseData(v.Index(i), f, actions...); err != nil {
				return err
			}
		}
	case reflect.Map:
		kvs := v.MapKeys()
		for _, kv := range kvs {
			vv := v.MapIndex(kv)

			// Create new mutable copies of the key and value.
			// Modify the copies.
			newKv := reflect.New(kv.Type()).Elem()
			newKv.Set(kv)
			newVv := reflect.New(vv.Type()).Elem()
			newVv.Set(vv)
			if err := traverseData(newKv, f, actions...); err != nil {
				return err
			}
			if err := traverseData(newVv, f, actions...); err != nil {
				return err
			}

			// Delete the old key-value.
			v.SetMapIndex(kv, reflect.Value{})
			// Set the new key-value.
			v.SetMapIndex(newKv, newVv)
		}
	case reflect.Struct:
		for i := 0; i < v.NumField(); i++ {
			if err := traverseData(v.Field(i), f, actions...); err != nil {
				return err
			}
		}
	default:
		// As far as I can tell, this is a basic data type. Run f on it.
		return f(v)
	}
	return nil
}

func xor(x, y bool) bool {
	return x != y
}

// CombineGuestOSFeatures merges two slices of Guest OS features and returns a
// new slice instance. Duplicates are removed.
func CombineGuestOSFeatures(features1 []*compute.GuestOsFeature,
	features2 ...string) []*compute.GuestOsFeature {

	featureSet := map[string]bool{}
	for _, feature := range features2 {
		featureSet[feature] = true
	}
	for _, feature := range features1 {
		featureSet[feature.Type] = true
	}
	ret := make([]*compute.GuestOsFeature, 0)
	for feature := range featureSet {
		ret = append(ret, &compute.GuestOsFeature{
			Type: feature,
		})
	}
	// Sort elements by type, lexically. This ensures
	// stability of output ordering for tests.
	sort.Slice(ret, func(i, j int) bool {
		return ret[i].Type < ret[j].Type
	})
	return ret
}

// CombineGuestOSFeaturesBeta merges two slices of Beta Guest OS features and
// returns a new slice instance. Duplicates are removed.
func CombineGuestOSFeaturesBeta(features1 []*computeBeta.GuestOsFeature,
	features2 ...string) []*computeBeta.GuestOsFeature {

	featureSet := map[string]bool{}
	for _, feature := range features2 {
		featureSet[feature] = true
	}
	for _, feature := range features1 {
		featureSet[feature.Type] = true
	}
	ret := make([]*computeBeta.GuestOsFeature, 0)
	for feature := range featureSet {
		ret = append(ret, &computeBeta.GuestOsFeature{
			Type: feature,
		})
	}
	// Sort elements by type, lexically. This ensures
	// stability of output ordering for tests.
	sort.Slice(ret, func(i, j int) bool {
		return ret[i].Type < ret[j].Type
	})
	return ret
}

// UpdateInstanceNoExternalIP updates Create Instance step to operate
// when no external IP access is allowed by the VPC Daisy workflow is running in.
func UpdateInstanceNoExternalIP(step *Step) {
	if step.CreateInstances != nil {
		for _, instance := range step.CreateInstances.Instances {
			if instance.Instance.NetworkInterfaces == nil {
				continue
			}
			for _, networkInterface := range instance.Instance.NetworkInterfaces {
				networkInterface.AccessConfigs = []*compute.AccessConfig{}
			}
		}
		for _, instance := range step.CreateInstances.InstancesBeta {
			if instance.Instance.NetworkInterfaces == nil {
				continue
			}
			for _, networkInterface := range instance.Instance.NetworkInterfaces {
				networkInterface.AccessConfigs = []*computeBeta.AccessConfig{}
			}
		}
	}
}