feat: initial tracing support (#1623)

vendor/golang.org/x/net/internal/timeseries/timeseries.go

@@ -0,0 +1,525 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package timeseries implements a time series structure for stats collection.
+package timeseries // import "golang.org/x/net/internal/timeseries"
+
+import (
+	"fmt"
+	"log"
+	"time"
+)
+
+const (
+	timeSeriesNumBuckets       = 64
+	minuteHourSeriesNumBuckets = 60
+)
+
+var timeSeriesResolutions = []time.Duration{
+	1 * time.Second,
+	10 * time.Second,
+	1 * time.Minute,
+	10 * time.Minute,
+	1 * time.Hour,
+	6 * time.Hour,
+	24 * time.Hour,          // 1 day
+	7 * 24 * time.Hour,      // 1 week
+	4 * 7 * 24 * time.Hour,  // 4 weeks
+	16 * 7 * 24 * time.Hour, // 16 weeks
+}
+
+var minuteHourSeriesResolutions = []time.Duration{
+	1 * time.Second,
+	1 * time.Minute,
+}
+
+// An Observable is a kind of data that can be aggregated in a time series.
+type Observable interface {
+	Multiply(ratio float64)    // Multiplies the data in self by a given ratio
+	Add(other Observable)      // Adds the data from a different observation to self
+	Clear()                    // Clears the observation so it can be reused.
+	CopyFrom(other Observable) // Copies the contents of a given observation to self
+}
+
+// Float attaches the methods of Observable to a float64.
+type Float float64
+
+// NewFloat returns a Float.
+func NewFloat() Observable {
+	f := Float(0)
+	return &f
+}
+
+// String returns the float as a string.
+func (f *Float) String() string { return fmt.Sprintf("%g", f.Value()) }
+
+// Value returns the float's value.
+func (f *Float) Value() float64 { return float64(*f) }
+
+func (f *Float) Multiply(ratio float64) { *f *= Float(ratio) }
+
+func (f *Float) Add(other Observable) {
+	o := other.(*Float)
+	*f += *o
+}
+
+func (f *Float) Clear() { *f = 0 }
+
+func (f *Float) CopyFrom(other Observable) {
+	o := other.(*Float)
+	*f = *o
+}
+
+// A Clock tells the current time.
+type Clock interface {
+	Time() time.Time
+}
+
+type defaultClock int
+
+var defaultClockInstance defaultClock
+
+func (defaultClock) Time() time.Time { return time.Now() }
+
+// Information kept per level. Each level consists of a circular list of
+// observations. The start of the level may be derived from end and the
+// len(buckets) * sizeInMillis.
+type tsLevel struct {
+	oldest   int               // index to oldest bucketed Observable
+	newest   int               // index to newest bucketed Observable
+	end      time.Time         // end timestamp for this level
+	size     time.Duration     // duration of the bucketed Observable
+	buckets  []Observable      // collections of observations
+	provider func() Observable // used for creating new Observable
+}
+
+func (l *tsLevel) Clear() {
+	l.oldest = 0
+	l.newest = len(l.buckets) - 1
+	l.end = time.Time{}
+	for i := range l.buckets {
+		if l.buckets[i] != nil {
+			l.buckets[i].Clear()
+			l.buckets[i] = nil
+		}
+	}
+}
+
+func (l *tsLevel) InitLevel(size time.Duration, numBuckets int, f func() Observable) {
+	l.size = size
+	l.provider = f
+	l.buckets = make([]Observable, numBuckets)
+}
+
+// Keeps a sequence of levels. Each level is responsible for storing data at
+// a given resolution. For example, the first level stores data at a one
+// minute resolution while the second level stores data at a one hour
+// resolution.
+
+// Each level is represented by a sequence of buckets. Each bucket spans an
+// interval equal to the resolution of the level. New observations are added
+// to the last bucket.
+type timeSeries struct {
+	provider    func() Observable // make more Observable
+	numBuckets  int               // number of buckets in each level
+	levels      []*tsLevel        // levels of bucketed Observable
+	lastAdd     time.Time         // time of last Observable tracked
+	total       Observable        // convenient aggregation of all Observable
+	clock       Clock             // Clock for getting current time
+	pending     Observable        // observations not yet bucketed
+	pendingTime time.Time         // what time are we keeping in pending
+	dirty       bool              // if there are pending observations
+}
+
+// init initializes a level according to the supplied criteria.
+func (ts *timeSeries) init(resolutions []time.Duration, f func() Observable, numBuckets int, clock Clock) {
+	ts.provider = f
+	ts.numBuckets = numBuckets
+	ts.clock = clock
+	ts.levels = make([]*tsLevel, len(resolutions))
+
+	for i := range resolutions {
+		if i > 0 && resolutions[i-1] >= resolutions[i] {
+			log.Print("timeseries: resolutions must be monotonically increasing")
+			break
+		}
+		newLevel := new(tsLevel)
+		newLevel.InitLevel(resolutions[i], ts.numBuckets, ts.provider)
+		ts.levels[i] = newLevel
+	}
+
+	ts.Clear()
+}
+
+// Clear removes all observations from the time series.
+func (ts *timeSeries) Clear() {
+	ts.lastAdd = time.Time{}
+	ts.total = ts.resetObservation(ts.total)
+	ts.pending = ts.resetObservation(ts.pending)
+	ts.pendingTime = time.Time{}
+	ts.dirty = false
+
+	for i := range ts.levels {
+		ts.levels[i].Clear()
+	}
+}
+
+// Add records an observation at the current time.
+func (ts *timeSeries) Add(observation Observable) {
+	ts.AddWithTime(observation, ts.clock.Time())
+}
+
+// AddWithTime records an observation at the specified time.
+func (ts *timeSeries) AddWithTime(observation Observable, t time.Time) {
+
+	smallBucketDuration := ts.levels[0].size
+
+	if t.After(ts.lastAdd) {
+		ts.lastAdd = t
+	}
+
+	if t.After(ts.pendingTime) {
+		ts.advance(t)
+		ts.mergePendingUpdates()
+		ts.pendingTime = ts.levels[0].end
+		ts.pending.CopyFrom(observation)
+		ts.dirty = true
+	} else if t.After(ts.pendingTime.Add(-1 * smallBucketDuration)) {
+		// The observation is close enough to go into the pending bucket.
+		// This compensates for clock skewing and small scheduling delays
+		// by letting the update stay in the fast path.
+		ts.pending.Add(observation)
+		ts.dirty = true
+	} else {
+		ts.mergeValue(observation, t)
+	}
+}
+
+// mergeValue inserts the observation at the specified time in the past into all levels.
+func (ts *timeSeries) mergeValue(observation Observable, t time.Time) {
+	for _, level := range ts.levels {
+		index := (ts.numBuckets - 1) - int(level.end.Sub(t)/level.size)
+		if 0 <= index && index < ts.numBuckets {
+			bucketNumber := (level.oldest + index) % ts.numBuckets
+			if level.buckets[bucketNumber] == nil {
+				level.buckets[bucketNumber] = level.provider()
+			}
+			level.buckets[bucketNumber].Add(observation)
+		}
+	}
+	ts.total.Add(observation)
+}
+
+// mergePendingUpdates applies the pending updates into all levels.
+func (ts *timeSeries) mergePendingUpdates() {
+	if ts.dirty {
+		ts.mergeValue(ts.pending, ts.pendingTime)
+		ts.pending = ts.resetObservation(ts.pending)
+		ts.dirty = false
+	}
+}
+
+// advance cycles the buckets at each level until the latest bucket in
+// each level can hold the time specified.
+func (ts *timeSeries) advance(t time.Time) {
+	if !t.After(ts.levels[0].end) {
+		return
+	}
+	for i := 0; i < len(ts.levels); i++ {
+		level := ts.levels[i]
+		if !level.end.Before(t) {
+			break
+		}
+
+		// If the time is sufficiently far, just clear the level and advance
+		// directly.
+		if !t.Before(level.end.Add(level.size * time.Duration(ts.numBuckets))) {
+			for _, b := range level.buckets {
+				ts.resetObservation(b)
+			}
+			level.end = time.Unix(0, (t.UnixNano()/level.size.Nanoseconds())*level.size.Nanoseconds())
+		}
+
+		for t.After(level.end) {
+			level.end = level.end.Add(level.size)
+			level.newest = level.oldest
+			level.oldest = (level.oldest + 1) % ts.numBuckets
+			ts.resetObservation(level.buckets[level.newest])
+		}
+
+		t = level.end
+	}
+}
+
+// Latest returns the sum of the num latest buckets from the level.
+func (ts *timeSeries) Latest(level, num int) Observable {
+	now := ts.clock.Time()
+	if ts.levels[0].end.Before(now) {
+		ts.advance(now)
+	}
+
+	ts.mergePendingUpdates()
+
+	result := ts.provider()
+	l := ts.levels[level]
+	index := l.newest
+
+	for i := 0; i < num; i++ {
+		if l.buckets[index] != nil {
+			result.Add(l.buckets[index])
+		}
+		if index == 0 {
+			index = ts.numBuckets
+		}
+		index--
+	}
+
+	return result
+}
+
+// LatestBuckets returns a copy of the num latest buckets from level.
+func (ts *timeSeries) LatestBuckets(level, num int) []Observable {
+	if level < 0 || level > len(ts.levels) {
+		log.Print("timeseries: bad level argument: ", level)
+		return nil
+	}
+	if num < 0 || num >= ts.numBuckets {
+		log.Print("timeseries: bad num argument: ", num)
+		return nil
+	}
+
+	results := make([]Observable, num)
+	now := ts.clock.Time()
+	if ts.levels[0].end.Before(now) {
+		ts.advance(now)
+	}
+
+	ts.mergePendingUpdates()
+
+	l := ts.levels[level]
+	index := l.newest
+
+	for i := 0; i < num; i++ {
+		result := ts.provider()
+		results[i] = result
+		if l.buckets[index] != nil {
+			result.CopyFrom(l.buckets[index])
+		}
+
+		if index == 0 {
+			index = ts.numBuckets
+		}
+		index -= 1
+	}
+	return results
+}
+
+// ScaleBy updates observations by scaling by factor.
+func (ts *timeSeries) ScaleBy(factor float64) {
+	for _, l := range ts.levels {
+		for i := 0; i < ts.numBuckets; i++ {
+			l.buckets[i].Multiply(factor)
+		}
+	}
+
+	ts.total.Multiply(factor)
+	ts.pending.Multiply(factor)
+}
+
+// Range returns the sum of observations added over the specified time range.
+// If start or finish times don't fall on bucket boundaries of the same
+// level, then return values are approximate answers.
+func (ts *timeSeries) Range(start, finish time.Time) Observable {
+	return ts.ComputeRange(start, finish, 1)[0]
+}
+
+// Recent returns the sum of observations from the last delta.
+func (ts *timeSeries) Recent(delta time.Duration) Observable {
+	now := ts.clock.Time()
+	return ts.Range(now.Add(-delta), now)
+}
+
+// Total returns the total of all observations.
+func (ts *timeSeries) Total() Observable {
+	ts.mergePendingUpdates()
+	return ts.total
+}
+
+// ComputeRange computes a specified number of values into a slice using
+// the observations recorded over the specified time period. The return
+// values are approximate if the start or finish times don't fall on the
+// bucket boundaries at the same level or if the number of buckets spanning
+// the range is not an integral multiple of num.
+func (ts *timeSeries) ComputeRange(start, finish time.Time, num int) []Observable {
+	if start.After(finish) {
+		log.Printf("timeseries: start > finish, %v>%v", start, finish)
+		return nil
+	}
+
+	if num < 0 {
+		log.Printf("timeseries: num < 0, %v", num)
+		return nil
+	}
+
+	results := make([]Observable, num)
+
+	for _, l := range ts.levels {
+		if !start.Before(l.end.Add(-l.size * time.Duration(ts.numBuckets))) {
+			ts.extract(l, start, finish, num, results)
+			return results
+		}
+	}
+
+	// Failed to find a level that covers the desired range. So just
+	// extract from the last level, even if it doesn't cover the entire
+	// desired range.
+	ts.extract(ts.levels[len(ts.levels)-1], start, finish, num, results)
+
+	return results
+}
+
+// RecentList returns the specified number of values in slice over the most
+// recent time period of the specified range.
+func (ts *timeSeries) RecentList(delta time.Duration, num int) []Observable {
+	if delta < 0 {
+		return nil
+	}
+	now := ts.clock.Time()
+	return ts.ComputeRange(now.Add(-delta), now, num)
+}
+
+// extract returns a slice of specified number of observations from a given
+// level over a given range.
+func (ts *timeSeries) extract(l *tsLevel, start, finish time.Time, num int, results []Observable) {
+	ts.mergePendingUpdates()
+
+	srcInterval := l.size
+	dstInterval := finish.Sub(start) / time.Duration(num)
+	dstStart := start
+	srcStart := l.end.Add(-srcInterval * time.Duration(ts.numBuckets))
+
+	srcIndex := 0
+
+	// Where should scanning start?
+	if dstStart.After(srcStart) {
+		advance := int(dstStart.Sub(srcStart) / srcInterval)
+		srcIndex += advance
+		srcStart = srcStart.Add(time.Duration(advance) * srcInterval)
+	}
+
+	// The i'th value is computed as show below.
+	// interval = (finish/start)/num
+	// i'th value = sum of observation in range
+	//   [ start + i       * interval,
+	//     start + (i + 1) * interval )
+	for i := 0; i < num; i++ {
+		results[i] = ts.resetObservation(results[i])
+		dstEnd := dstStart.Add(dstInterval)
+		for srcIndex < ts.numBuckets && srcStart.Before(dstEnd) {
+			srcEnd := srcStart.Add(srcInterval)
+			if srcEnd.After(ts.lastAdd) {
+				srcEnd = ts.lastAdd
+			}
+
+			if !srcEnd.Before(dstStart) {
+				srcValue := l.buckets[(srcIndex+l.oldest)%ts.numBuckets]
+				if !srcStart.Before(dstStart) && !srcEnd.After(dstEnd) {
+					// dst completely contains src.
+					if srcValue != nil {
+						results[i].Add(srcValue)
+					}
+				} else {
+					// dst partially overlaps src.
+					overlapStart := maxTime(srcStart, dstStart)
+					overlapEnd := minTime(srcEnd, dstEnd)
+					base := srcEnd.Sub(srcStart)
+					fraction := overlapEnd.Sub(overlapStart).Seconds() / base.Seconds()
+
+					used := ts.provider()
+					if srcValue != nil {
+						used.CopyFrom(srcValue)
+					}
+					used.Multiply(fraction)
+					results[i].Add(used)
+				}
+
+				if srcEnd.After(dstEnd) {
+					break
+				}
+			}
+			srcIndex++
+			srcStart = srcStart.Add(srcInterval)
+		}
+		dstStart = dstStart.Add(dstInterval)
+	}
+}
+
+// resetObservation clears the content so the struct may be reused.
+func (ts *timeSeries) resetObservation(observation Observable) Observable {
+	if observation == nil {
+		observation = ts.provider()
+	} else {
+		observation.Clear()
+	}
+	return observation
+}
+
+// TimeSeries tracks data at granularities from 1 second to 16 weeks.
+type TimeSeries struct {
+	timeSeries
+}
+
+// NewTimeSeries creates a new TimeSeries using the function provided for creating new Observable.
+func NewTimeSeries(f func() Observable) *TimeSeries {
+	return NewTimeSeriesWithClock(f, defaultClockInstance)
+}
+
+// NewTimeSeriesWithClock creates a new TimeSeries using the function provided for creating new Observable and the clock for
+// assigning timestamps.
+func NewTimeSeriesWithClock(f func() Observable, clock Clock) *TimeSeries {
+	ts := new(TimeSeries)
+	ts.timeSeries.init(timeSeriesResolutions, f, timeSeriesNumBuckets, clock)
+	return ts
+}
+
+// MinuteHourSeries tracks data at granularities of 1 minute and 1 hour.
+type MinuteHourSeries struct {
+	timeSeries
+}
+
+// NewMinuteHourSeries creates a new MinuteHourSeries using the function provided for creating new Observable.
+func NewMinuteHourSeries(f func() Observable) *MinuteHourSeries {
+	return NewMinuteHourSeriesWithClock(f, defaultClockInstance)
+}
+
+// NewMinuteHourSeriesWithClock creates a new MinuteHourSeries using the function provided for creating new Observable and the clock for
+// assigning timestamps.
+func NewMinuteHourSeriesWithClock(f func() Observable, clock Clock) *MinuteHourSeries {
+	ts := new(MinuteHourSeries)
+	ts.timeSeries.init(minuteHourSeriesResolutions, f,
+		minuteHourSeriesNumBuckets, clock)
+	return ts
+}
+
+func (ts *MinuteHourSeries) Minute() Observable {
+	return ts.timeSeries.Latest(0, 60)
+}
+
+func (ts *MinuteHourSeries) Hour() Observable {
+	return ts.timeSeries.Latest(1, 60)
+}
+
+func minTime(a, b time.Time) time.Time {
+	if a.Before(b) {
+		return a
+	}
+	return b
+}
+
+func maxTime(a, b time.Time) time.Time {
+	if a.After(b) {
+		return a
+	}
+	return b
+}

vendor/golang.org/x/net/trace/events.go

@@ -0,0 +1,532 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package trace
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+	"io"
+	"log"
+	"net/http"
+	"runtime"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"text/tabwriter"
+	"time"
+)
+
+const maxEventsPerLog = 100
+
+type bucket struct {
+	MaxErrAge time.Duration
+	String    string
+}
+
+var buckets = []bucket{
+	{0, "total"},
+	{10 * time.Second, "errs<10s"},
+	{1 * time.Minute, "errs<1m"},
+	{10 * time.Minute, "errs<10m"},
+	{1 * time.Hour, "errs<1h"},
+	{10 * time.Hour, "errs<10h"},
+	{24000 * time.Hour, "errors"},
+}
+
+// RenderEvents renders the HTML page typically served at /debug/events.
+// It does not do any auth checking. The request may be nil.
+//
+// Most users will use the Events handler.
+func RenderEvents(w http.ResponseWriter, req *http.Request, sensitive bool) {
+	now := time.Now()
+	data := &struct {
+		Families []string // family names
+		Buckets  []bucket
+		Counts   [][]int // eventLog count per family/bucket
+
+		// Set when a bucket has been selected.
+		Family    string
+		Bucket    int
+		EventLogs eventLogs
+		Expanded  bool
+	}{
+		Buckets: buckets,
+	}
+
+	data.Families = make([]string, 0, len(families))
+	famMu.RLock()
+	for name := range families {
+		data.Families = append(data.Families, name)
+	}
+	famMu.RUnlock()
+	sort.Strings(data.Families)
+
+	// Count the number of eventLogs in each family for each error age.
+	data.Counts = make([][]int, len(data.Families))
+	for i, name := range data.Families {
+		// TODO(sameer): move this loop under the family lock.
+		f := getEventFamily(name)
+		data.Counts[i] = make([]int, len(data.Buckets))
+		for j, b := range data.Buckets {
+			data.Counts[i][j] = f.Count(now, b.MaxErrAge)
+		}
+	}
+
+	if req != nil {
+		var ok bool
+		data.Family, data.Bucket, ok = parseEventsArgs(req)
+		if !ok {
+			// No-op
+		} else {
+			data.EventLogs = getEventFamily(data.Family).Copy(now, buckets[data.Bucket].MaxErrAge)
+		}
+		if data.EventLogs != nil {
+			defer data.EventLogs.Free()
+			sort.Sort(data.EventLogs)
+		}
+		if exp, err := strconv.ParseBool(req.FormValue("exp")); err == nil {
+			data.Expanded = exp
+		}
+	}
+
+	famMu.RLock()
+	defer famMu.RUnlock()
+	if err := eventsTmpl().Execute(w, data); err != nil {
+		log.Printf("net/trace: Failed executing template: %v", err)
+	}
+}
+
+func parseEventsArgs(req *http.Request) (fam string, b int, ok bool) {
+	fam, bStr := req.FormValue("fam"), req.FormValue("b")
+	if fam == "" || bStr == "" {
+		return "", 0, false
+	}
+	b, err := strconv.Atoi(bStr)
+	if err != nil || b < 0 || b >= len(buckets) {
+		return "", 0, false
+	}
+	return fam, b, true
+}
+
+// An EventLog provides a log of events associated with a specific object.
+type EventLog interface {
+	// Printf formats its arguments with fmt.Sprintf and adds the
+	// result to the event log.
+	Printf(format string, a ...interface{})
+
+	// Errorf is like Printf, but it marks this event as an error.
+	Errorf(format string, a ...interface{})
+
+	// Finish declares that this event log is complete.
+	// The event log should not be used after calling this method.
+	Finish()
+}
+
+// NewEventLog returns a new EventLog with the specified family name
+// and title.
+func NewEventLog(family, title string) EventLog {
+	el := newEventLog()
+	el.ref()
+	el.Family, el.Title = family, title
+	el.Start = time.Now()
+	el.events = make([]logEntry, 0, maxEventsPerLog)
+	el.stack = make([]uintptr, 32)
+	n := runtime.Callers(2, el.stack)
+	el.stack = el.stack[:n]
+
+	getEventFamily(family).add(el)
+	return el
+}
+
+func (el *eventLog) Finish() {
+	getEventFamily(el.Family).remove(el)
+	el.unref() // matches ref in New
+}
+
+var (
+	famMu    sync.RWMutex
+	families = make(map[string]*eventFamily) // family name => family
+)
+
+func getEventFamily(fam string) *eventFamily {
+	famMu.Lock()
+	defer famMu.Unlock()
+	f := families[fam]
+	if f == nil {
+		f = &eventFamily{}
+		families[fam] = f
+	}
+	return f
+}
+
+type eventFamily struct {
+	mu        sync.RWMutex
+	eventLogs eventLogs
+}
+
+func (f *eventFamily) add(el *eventLog) {
+	f.mu.Lock()
+	f.eventLogs = append(f.eventLogs, el)
+	f.mu.Unlock()
+}
+
+func (f *eventFamily) remove(el *eventLog) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	for i, el0 := range f.eventLogs {
+		if el == el0 {
+			copy(f.eventLogs[i:], f.eventLogs[i+1:])
+			f.eventLogs = f.eventLogs[:len(f.eventLogs)-1]
+			return
+		}
+	}
+}
+
+func (f *eventFamily) Count(now time.Time, maxErrAge time.Duration) (n int) {
+	f.mu.RLock()
+	defer f.mu.RUnlock()
+	for _, el := range f.eventLogs {
+		if el.hasRecentError(now, maxErrAge) {
+			n++
+		}
+	}
+	return
+}
+
+func (f *eventFamily) Copy(now time.Time, maxErrAge time.Duration) (els eventLogs) {
+	f.mu.RLock()
+	defer f.mu.RUnlock()
+	els = make(eventLogs, 0, len(f.eventLogs))
+	for _, el := range f.eventLogs {
+		if el.hasRecentError(now, maxErrAge) {
+			el.ref()
+			els = append(els, el)
+		}
+	}
+	return
+}
+
+type eventLogs []*eventLog
+
+// Free calls unref on each element of the list.
+func (els eventLogs) Free() {
+	for _, el := range els {
+		el.unref()
+	}
+}
+
+// eventLogs may be sorted in reverse chronological order.
+func (els eventLogs) Len() int           { return len(els) }
+func (els eventLogs) Less(i, j int) bool { return els[i].Start.After(els[j].Start) }
+func (els eventLogs) Swap(i, j int)      { els[i], els[j] = els[j], els[i] }
+
+// A logEntry is a timestamped log entry in an event log.
+type logEntry struct {
+	When    time.Time
+	Elapsed time.Duration // since previous event in log
+	NewDay  bool          // whether this event is on a different day to the previous event
+	What    string
+	IsErr   bool
+}
+
+// WhenString returns a string representation of the elapsed time of the event.
+// It will include the date if midnight was crossed.
+func (e logEntry) WhenString() string {
+	if e.NewDay {
+		return e.When.Format("2006/01/02 15:04:05.000000")
+	}
+	return e.When.Format("15:04:05.000000")
+}
+
+// An eventLog represents an active event log.
+type eventLog struct {
+	// Family is the top-level grouping of event logs to which this belongs.
+	Family string
+
+	// Title is the title of this event log.
+	Title string
+
+	// Timing information.
+	Start time.Time
+
+	// Call stack where this event log was created.
+	stack []uintptr
+
+	// Append-only sequence of events.
+	//
+	// TODO(sameer): change this to a ring buffer to avoid the array copy
+	// when we hit maxEventsPerLog.
+	mu            sync.RWMutex
+	events        []logEntry
+	LastErrorTime time.Time
+	discarded     int
+
+	refs int32 // how many buckets this is in
+}
+
+func (el *eventLog) reset() {
+	// Clear all but the mutex. Mutexes may not be copied, even when unlocked.
+	el.Family = ""
+	el.Title = ""
+	el.Start = time.Time{}
+	el.stack = nil
+	el.events = nil
+	el.LastErrorTime = time.Time{}
+	el.discarded = 0
+	el.refs = 0
+}
+
+func (el *eventLog) hasRecentError(now time.Time, maxErrAge time.Duration) bool {
+	if maxErrAge == 0 {
+		return true
+	}
+	el.mu.RLock()
+	defer el.mu.RUnlock()
+	return now.Sub(el.LastErrorTime) < maxErrAge
+}
+
+// delta returns the elapsed time since the last event or the log start,
+// and whether it spans midnight.
+// L >= el.mu
+func (el *eventLog) delta(t time.Time) (time.Duration, bool) {
+	if len(el.events) == 0 {
+		return t.Sub(el.Start), false
+	}
+	prev := el.events[len(el.events)-1].When
+	return t.Sub(prev), prev.Day() != t.Day()
+
+}
+
+func (el *eventLog) Printf(format string, a ...interface{}) {
+	el.printf(false, format, a...)
+}
+
+func (el *eventLog) Errorf(format string, a ...interface{}) {
+	el.printf(true, format, a...)
+}
+
+func (el *eventLog) printf(isErr bool, format string, a ...interface{}) {
+	e := logEntry{When: time.Now(), IsErr: isErr, What: fmt.Sprintf(format, a...)}
+	el.mu.Lock()
+	e.Elapsed, e.NewDay = el.delta(e.When)
+	if len(el.events) < maxEventsPerLog {
+		el.events = append(el.events, e)
+	} else {
+		// Discard the oldest event.
+		if el.discarded == 0 {
+			// el.discarded starts at two to count for the event it
+			// is replacing, plus the next one that we are about to
+			// drop.
+			el.discarded = 2
+		} else {
+			el.discarded++
+		}
+		// TODO(sameer): if this causes allocations on a critical path,
+		// change eventLog.What to be a fmt.Stringer, as in trace.go.
+		el.events[0].What = fmt.Sprintf("(%d events discarded)", el.discarded)
+		// The timestamp of the discarded meta-event should be
+		// the time of the last event it is representing.
+		el.events[0].When = el.events[1].When
+		copy(el.events[1:], el.events[2:])
+		el.events[maxEventsPerLog-1] = e
+	}
+	if e.IsErr {
+		el.LastErrorTime = e.When
+	}
+	el.mu.Unlock()
+}
+
+func (el *eventLog) ref() {
+	atomic.AddInt32(&el.refs, 1)
+}
+
+func (el *eventLog) unref() {
+	if atomic.AddInt32(&el.refs, -1) == 0 {
+		freeEventLog(el)
+	}
+}
+
+func (el *eventLog) When() string {
+	return el.Start.Format("2006/01/02 15:04:05.000000")
+}
+
+func (el *eventLog) ElapsedTime() string {
+	elapsed := time.Since(el.Start)
+	return fmt.Sprintf("%.6f", elapsed.Seconds())
+}
+
+func (el *eventLog) Stack() string {
+	buf := new(bytes.Buffer)
+	tw := tabwriter.NewWriter(buf, 1, 8, 1, '\t', 0)
+	printStackRecord(tw, el.stack)
+	tw.Flush()
+	return buf.String()
+}
+
+// printStackRecord prints the function + source line information
+// for a single stack trace.
+// Adapted from runtime/pprof/pprof.go.
+func printStackRecord(w io.Writer, stk []uintptr) {
+	for _, pc := range stk {
+		f := runtime.FuncForPC(pc)
+		if f == nil {
+			continue
+		}
+		file, line := f.FileLine(pc)
+		name := f.Name()
+		// Hide runtime.goexit and any runtime functions at the beginning.
+		if strings.HasPrefix(name, "runtime.") {
+			continue
+		}
+		fmt.Fprintf(w, "#   %s\t%s:%d\n", name, file, line)
+	}
+}
+
+func (el *eventLog) Events() []logEntry {
+	el.mu.RLock()
+	defer el.mu.RUnlock()
+	return el.events
+}
+
+// freeEventLogs is a freelist of *eventLog
+var freeEventLogs = make(chan *eventLog, 1000)
+
+// newEventLog returns a event log ready to use.
+func newEventLog() *eventLog {
+	select {
+	case el := <-freeEventLogs:
+		return el
+	default:
+		return new(eventLog)
+	}
+}
+
+// freeEventLog adds el to freeEventLogs if there's room.
+// This is non-blocking.
+func freeEventLog(el *eventLog) {
+	el.reset()
+	select {
+	case freeEventLogs <- el:
+	default:
+	}
+}
+
+var eventsTmplCache *template.Template
+var eventsTmplOnce sync.Once
+
+func eventsTmpl() *template.Template {
+	eventsTmplOnce.Do(func() {
+		eventsTmplCache = template.Must(template.New("events").Funcs(template.FuncMap{
+			"elapsed":   elapsed,
+			"trimSpace": strings.TrimSpace,
+		}).Parse(eventsHTML))
+	})
+	return eventsTmplCache
+}
+
+const eventsHTML = `
+<html>
+	<head>
+		<title>events</title>
+	</head>
+	<style type="text/css">
+		body {
+			font-family: sans-serif;
+		}
+		table#req-status td.family {
+			padding-right: 2em;
+		}
+		table#req-status td.active {
+			padding-right: 1em;
+		}
+		table#req-status td.empty {
+			color: #aaa;
+		}
+		table#reqs {
+			margin-top: 1em;
+		}
+		table#reqs tr.first {
+			{{if $.Expanded}}font-weight: bold;{{end}}
+		}
+		table#reqs td {
+			font-family: monospace;
+		}
+		table#reqs td.when {
+			text-align: right;
+			white-space: nowrap;
+		}
+		table#reqs td.elapsed {
+			padding: 0 0.5em;
+			text-align: right;
+			white-space: pre;
+			width: 10em;
+		}
+		address {
+			font-size: smaller;
+			margin-top: 5em;
+		}
+	</style>
+	<body>
+
+<h1>/debug/events</h1>
+
+<table id="req-status">
+	{{range $i, $fam := .Families}}
+	<tr>
+		<td class="family">{{$fam}}</td>
+
+	        {{range $j, $bucket := $.Buckets}}
+	        {{$n := index $.Counts $i $j}}
+		<td class="{{if not $bucket.MaxErrAge}}active{{end}}{{if not $n}}empty{{end}}">
+	                {{if $n}}<a href="?fam={{$fam}}&b={{$j}}{{if $.Expanded}}&exp=1{{end}}">{{end}}
+		        [{{$n}} {{$bucket.String}}]
+			{{if $n}}</a>{{end}}
+		</td>
+                {{end}}
+
+	</tr>{{end}}
+</table>
+
+{{if $.EventLogs}}
+<hr />
+<h3>Family: {{$.Family}}</h3>
+
+{{if $.Expanded}}<a href="?fam={{$.Family}}&b={{$.Bucket}}">{{end}}
+[Summary]{{if $.Expanded}}</a>{{end}}
+
+{{if not $.Expanded}}<a href="?fam={{$.Family}}&b={{$.Bucket}}&exp=1">{{end}}
+[Expanded]{{if not $.Expanded}}</a>{{end}}
+
+<table id="reqs">
+	<tr><th>When</th><th>Elapsed</th></tr>
+	{{range $el := $.EventLogs}}
+	<tr class="first">
+		<td class="when">{{$el.When}}</td>
+		<td class="elapsed">{{$el.ElapsedTime}}</td>
+		<td>{{$el.Title}}
+	</tr>
+	{{if $.Expanded}}
+	<tr>
+		<td class="when"></td>
+		<td class="elapsed"></td>
+		<td><pre>{{$el.Stack|trimSpace}}</pre></td>
+	</tr>
+	{{range $el.Events}}
+	<tr>
+		<td class="when">{{.WhenString}}</td>
+		<td class="elapsed">{{elapsed .Elapsed}}</td>
+		<td>.{{if .IsErr}}E{{else}}.{{end}}. {{.What}}</td>
+	</tr>
+	{{end}}
+	{{end}}
+	{{end}}
+</table>
+{{end}}
+	</body>
+</html>
+`

vendor/golang.org/x/net/trace/histogram.go

@@ -0,0 +1,365 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package trace
+
+// This file implements histogramming for RPC statistics collection.
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+	"log"
+	"math"
+	"sync"
+
+	"golang.org/x/net/internal/timeseries"
+)
+
+const (
+	bucketCount = 38
+)
+
+// histogram keeps counts of values in buckets that are spaced
+// out in powers of 2: 0-1, 2-3, 4-7...
+// histogram implements timeseries.Observable
+type histogram struct {
+	sum          int64   // running total of measurements
+	sumOfSquares float64 // square of running total
+	buckets      []int64 // bucketed values for histogram
+	value        int     // holds a single value as an optimization
+	valueCount   int64   // number of values recorded for single value
+}
+
+// addMeasurement records a value measurement observation to the histogram.
+func (h *histogram) addMeasurement(value int64) {
+	// TODO: assert invariant
+	h.sum += value
+	h.sumOfSquares += float64(value) * float64(value)
+
+	bucketIndex := getBucket(value)
+
+	if h.valueCount == 0 || (h.valueCount > 0 && h.value == bucketIndex) {
+		h.value = bucketIndex
+		h.valueCount++
+	} else {
+		h.allocateBuckets()
+		h.buckets[bucketIndex]++
+	}
+}
+
+func (h *histogram) allocateBuckets() {
+	if h.buckets == nil {
+		h.buckets = make([]int64, bucketCount)
+		h.buckets[h.value] = h.valueCount
+		h.value = 0
+		h.valueCount = -1
+	}
+}
+
+func log2(i int64) int {
+	n := 0
+	for ; i >= 0x100; i >>= 8 {
+		n += 8
+	}
+	for ; i > 0; i >>= 1 {
+		n += 1
+	}
+	return n
+}
+
+func getBucket(i int64) (index int) {
+	index = log2(i) - 1
+	if index < 0 {
+		index = 0
+	}
+	if index >= bucketCount {
+		index = bucketCount - 1
+	}
+	return
+}
+
+// Total returns the number of recorded observations.
+func (h *histogram) total() (total int64) {
+	if h.valueCount >= 0 {
+		total = h.valueCount
+	}
+	for _, val := range h.buckets {
+		total += int64(val)
+	}
+	return
+}
+
+// Average returns the average value of recorded observations.
+func (h *histogram) average() float64 {
+	t := h.total()
+	if t == 0 {
+		return 0
+	}
+	return float64(h.sum) / float64(t)
+}
+
+// Variance returns the variance of recorded observations.
+func (h *histogram) variance() float64 {
+	t := float64(h.total())
+	if t == 0 {
+		return 0
+	}
+	s := float64(h.sum) / t
+	return h.sumOfSquares/t - s*s
+}
+
+// StandardDeviation returns the standard deviation of recorded observations.
+func (h *histogram) standardDeviation() float64 {
+	return math.Sqrt(h.variance())
+}
+
+// PercentileBoundary estimates the value that the given fraction of recorded
+// observations are less than.
+func (h *histogram) percentileBoundary(percentile float64) int64 {
+	total := h.total()
+
+	// Corner cases (make sure result is strictly less than Total())
+	if total == 0 {
+		return 0
+	} else if total == 1 {
+		return int64(h.average())
+	}
+
+	percentOfTotal := round(float64(total) * percentile)
+	var runningTotal int64
+
+	for i := range h.buckets {
+		value := h.buckets[i]
+		runningTotal += value
+		if runningTotal == percentOfTotal {
+			// We hit an exact bucket boundary. If the next bucket has data, it is a
+			// good estimate of the value. If the bucket is empty, we interpolate the
+			// midpoint between the next bucket's boundary and the next non-zero
+			// bucket. If the remaining buckets are all empty, then we use the
+			// boundary for the next bucket as the estimate.
+			j := uint8(i + 1)
+			min := bucketBoundary(j)
+			if runningTotal < total {
+				for h.buckets[j] == 0 {
+					j++
+				}
+			}
+			max := bucketBoundary(j)
+			return min + round(float64(max-min)/2)
+		} else if runningTotal > percentOfTotal {
+			// The value is in this bucket. Interpolate the value.
+			delta := runningTotal - percentOfTotal
+			percentBucket := float64(value-delta) / float64(value)
+			bucketMin := bucketBoundary(uint8(i))
+			nextBucketMin := bucketBoundary(uint8(i + 1))
+			bucketSize := nextBucketMin - bucketMin
+			return bucketMin + round(percentBucket*float64(bucketSize))
+		}
+	}
+	return bucketBoundary(bucketCount - 1)
+}
+
+// Median returns the estimated median of the observed values.
+func (h *histogram) median() int64 {
+	return h.percentileBoundary(0.5)
+}
+
+// Add adds other to h.
+func (h *histogram) Add(other timeseries.Observable) {
+	o := other.(*histogram)
+	if o.valueCount == 0 {
+		// Other histogram is empty
+	} else if h.valueCount >= 0 && o.valueCount > 0 && h.value == o.value {
+		// Both have a single bucketed value, aggregate them
+		h.valueCount += o.valueCount
+	} else {
+		// Two different values necessitate buckets in this histogram
+		h.allocateBuckets()
+		if o.valueCount >= 0 {
+			h.buckets[o.value] += o.valueCount
+		} else {
+			for i := range h.buckets {
+				h.buckets[i] += o.buckets[i]
+			}
+		}
+	}
+	h.sumOfSquares += o.sumOfSquares
+	h.sum += o.sum
+}
+
+// Clear resets the histogram to an empty state, removing all observed values.
+func (h *histogram) Clear() {
+	h.buckets = nil
+	h.value = 0
+	h.valueCount = 0
+	h.sum = 0
+	h.sumOfSquares = 0
+}
+
+// CopyFrom copies from other, which must be a *histogram, into h.
+func (h *histogram) CopyFrom(other timeseries.Observable) {
+	o := other.(*histogram)
+	if o.valueCount == -1 {
+		h.allocateBuckets()
+		copy(h.buckets, o.buckets)
+	}
+	h.sum = o.sum
+	h.sumOfSquares = o.sumOfSquares
+	h.value = o.value
+	h.valueCount = o.valueCount
+}
+
+// Multiply scales the histogram by the specified ratio.
+func (h *histogram) Multiply(ratio float64) {
+	if h.valueCount == -1 {
+		for i := range h.buckets {
+			h.buckets[i] = int64(float64(h.buckets[i]) * ratio)
+		}
+	} else {
+		h.valueCount = int64(float64(h.valueCount) * ratio)
+	}
+	h.sum = int64(float64(h.sum) * ratio)
+	h.sumOfSquares = h.sumOfSquares * ratio
+}
+
+// New creates a new histogram.
+func (h *histogram) New() timeseries.Observable {
+	r := new(histogram)
+	r.Clear()
+	return r
+}
+
+func (h *histogram) String() string {
+	return fmt.Sprintf("%d, %f, %d, %d, %v",
+		h.sum, h.sumOfSquares, h.value, h.valueCount, h.buckets)
+}
+
+// round returns the closest int64 to the argument
+func round(in float64) int64 {
+	return int64(math.Floor(in + 0.5))
+}
+
+// bucketBoundary returns the first value in the bucket.
+func bucketBoundary(bucket uint8) int64 {
+	if bucket == 0 {
+		return 0
+	}
+	return 1 << bucket
+}
+
+// bucketData holds data about a specific bucket for use in distTmpl.
+type bucketData struct {
+	Lower, Upper       int64
+	N                  int64
+	Pct, CumulativePct float64
+	GraphWidth         int
+}
+
+// data holds data about a Distribution for use in distTmpl.
+type data struct {
+	Buckets                 []*bucketData
+	Count, Median           int64
+	Mean, StandardDeviation float64
+}
+
+// maxHTMLBarWidth is the maximum width of the HTML bar for visualizing buckets.
+const maxHTMLBarWidth = 350.0
+
+// newData returns data representing h for use in distTmpl.
+func (h *histogram) newData() *data {
+	// Force the allocation of buckets to simplify the rendering implementation
+	h.allocateBuckets()
+	// We scale the bars on the right so that the largest bar is
+	// maxHTMLBarWidth pixels in width.
+	maxBucket := int64(0)
+	for _, n := range h.buckets {
+		if n > maxBucket {
+			maxBucket = n
+		}
+	}
+	total := h.total()
+	barsizeMult := maxHTMLBarWidth / float64(maxBucket)
+	var pctMult float64
+	if total == 0 {
+		pctMult = 1.0
+	} else {
+		pctMult = 100.0 / float64(total)
+	}
+
+	buckets := make([]*bucketData, len(h.buckets))
+	runningTotal := int64(0)
+	for i, n := range h.buckets {
+		if n == 0 {
+			continue
+		}
+		runningTotal += n
+		var upperBound int64
+		if i < bucketCount-1 {
+			upperBound = bucketBoundary(uint8(i + 1))
+		} else {
+			upperBound = math.MaxInt64
+		}
+		buckets[i] = &bucketData{
+			Lower:         bucketBoundary(uint8(i)),
+			Upper:         upperBound,
+			N:             n,
+			Pct:           float64(n) * pctMult,
+			CumulativePct: float64(runningTotal) * pctMult,
+			GraphWidth:    int(float64(n) * barsizeMult),
+		}
+	}
+	return &data{
+		Buckets:           buckets,
+		Count:             total,
+		Median:            h.median(),
+		Mean:              h.average(),
+		StandardDeviation: h.standardDeviation(),
+	}
+}
+
+func (h *histogram) html() template.HTML {
+	buf := new(bytes.Buffer)
+	if err := distTmpl().Execute(buf, h.newData()); err != nil {
+		buf.Reset()
+		log.Printf("net/trace: couldn't execute template: %v", err)
+	}
+	return template.HTML(buf.String())
+}
+
+var distTmplCache *template.Template
+var distTmplOnce sync.Once
+
+func distTmpl() *template.Template {
+	distTmplOnce.Do(func() {
+		// Input: data
+		distTmplCache = template.Must(template.New("distTmpl").Parse(`
+<table>
+<tr>
+    <td style="padding:0.25em">Count: {{.Count}}</td>
+    <td style="padding:0.25em">Mean: {{printf "%.0f" .Mean}}</td>
+    <td style="padding:0.25em">StdDev: {{printf "%.0f" .StandardDeviation}}</td>
+    <td style="padding:0.25em">Median: {{.Median}}</td>
+</tr>
+</table>
+<hr>
+<table>
+{{range $b := .Buckets}}
+{{if $b}}
+  <tr>
+    <td style="padding:0 0 0 0.25em">[</td>
+    <td style="text-align:right;padding:0 0.25em">{{.Lower}},</td>
+    <td style="text-align:right;padding:0 0.25em">{{.Upper}})</td>
+    <td style="text-align:right;padding:0 0.25em">{{.N}}</td>
+    <td style="text-align:right;padding:0 0.25em">{{printf "%#.3f" .Pct}}%</td>
+    <td style="text-align:right;padding:0 0.25em">{{printf "%#.3f" .CumulativePct}}%</td>
+    <td><div style="background-color: blue; height: 1em; width: {{.GraphWidth}};"></div></td>
+  </tr>
+{{end}}
+{{end}}
+</table>
+`))
+	})
+	return distTmplCache
+}

vendor/golang.org/x/sys/windows/registry/key.go

@@ -0,0 +1,206 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+// +build windows
+
+// Package registry provides access to the Windows registry.
+//
+// Here is a simple example, opening a registry key and reading a string value from it.
+//
+//	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//	defer k.Close()
+//
+//	s, _, err := k.GetStringValue("SystemRoot")
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//	fmt.Printf("Windows system root is %q\n", s)
+package registry
+
+import (
+	"io"
+	"runtime"
+	"syscall"
+	"time"
+)
+
+const (
+	// Registry key security and access rights.
+	// See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724878.aspx
+	// for details.
+	ALL_ACCESS         = 0xf003f
+	CREATE_LINK        = 0x00020
+	CREATE_SUB_KEY     = 0x00004
+	ENUMERATE_SUB_KEYS = 0x00008
+	EXECUTE            = 0x20019
+	NOTIFY             = 0x00010
+	QUERY_VALUE        = 0x00001
+	READ               = 0x20019
+	SET_VALUE          = 0x00002
+	WOW64_32KEY        = 0x00200
+	WOW64_64KEY        = 0x00100
+	WRITE              = 0x20006
+)
+
+// Key is a handle to an open Windows registry key.
+// Keys can be obtained by calling OpenKey; there are
+// also some predefined root keys such as CURRENT_USER.
+// Keys can be used directly in the Windows API.
+type Key syscall.Handle
+
+const (
+	// Windows defines some predefined root keys that are always open.
+	// An application can use these keys as entry points to the registry.
+	// Normally these keys are used in OpenKey to open new keys,
+	// but they can also be used anywhere a Key is required.
+	CLASSES_ROOT     = Key(syscall.HKEY_CLASSES_ROOT)
+	CURRENT_USER     = Key(syscall.HKEY_CURRENT_USER)
+	LOCAL_MACHINE    = Key(syscall.HKEY_LOCAL_MACHINE)
+	USERS            = Key(syscall.HKEY_USERS)
+	CURRENT_CONFIG   = Key(syscall.HKEY_CURRENT_CONFIG)
+	PERFORMANCE_DATA = Key(syscall.HKEY_PERFORMANCE_DATA)
+)
+
+// Close closes open key k.
+func (k Key) Close() error {
+	return syscall.RegCloseKey(syscall.Handle(k))
+}
+
+// OpenKey opens a new key with path name relative to key k.
+// It accepts any open key, including CURRENT_USER and others,
+// and returns the new key and an error.
+// The access parameter specifies desired access rights to the
+// key to be opened.
+func OpenKey(k Key, path string, access uint32) (Key, error) {
+	p, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return 0, err
+	}
+	var subkey syscall.Handle
+	err = syscall.RegOpenKeyEx(syscall.Handle(k), p, 0, access, &subkey)
+	if err != nil {
+		return 0, err
+	}
+	return Key(subkey), nil
+}
+
+// OpenRemoteKey opens a predefined registry key on another
+// computer pcname. The key to be opened is specified by k, but
+// can only be one of LOCAL_MACHINE, PERFORMANCE_DATA or USERS.
+// If pcname is "", OpenRemoteKey returns local computer key.
+func OpenRemoteKey(pcname string, k Key) (Key, error) {
+	var err error
+	var p *uint16
+	if pcname != "" {
+		p, err = syscall.UTF16PtrFromString(`\\` + pcname)
+		if err != nil {
+			return 0, err
+		}
+	}
+	var remoteKey syscall.Handle
+	err = regConnectRegistry(p, syscall.Handle(k), &remoteKey)
+	if err != nil {
+		return 0, err
+	}
+	return Key(remoteKey), nil
+}
+
+// ReadSubKeyNames returns the names of subkeys of key k.
+// The parameter n controls the number of returned names,
+// analogous to the way os.File.Readdirnames works.
+func (k Key) ReadSubKeyNames(n int) ([]string, error) {
+	// RegEnumKeyEx must be called repeatedly and to completion.
+	// During this time, this goroutine cannot migrate away from
+	// its current thread. See https://golang.org/issue/49320 and
+	// https://golang.org/issue/49466.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	names := make([]string, 0)
+	// Registry key size limit is 255 bytes and described there:
+	// https://msdn.microsoft.com/library/windows/desktop/ms724872.aspx
+	buf := make([]uint16, 256) //plus extra room for terminating zero byte
+loopItems:
+	for i := uint32(0); ; i++ {
+		if n > 0 {
+			if len(names) == n {
+				return names, nil
+			}
+		}
+		l := uint32(len(buf))
+		for {
+			err := syscall.RegEnumKeyEx(syscall.Handle(k), i, &buf[0], &l, nil, nil, nil, nil)
+			if err == nil {
+				break
+			}
+			if err == syscall.ERROR_MORE_DATA {
+				// Double buffer size and try again.
+				l = uint32(2 * len(buf))
+				buf = make([]uint16, l)
+				continue
+			}
+			if err == _ERROR_NO_MORE_ITEMS {
+				break loopItems
+			}
+			return names, err
+		}
+		names = append(names, syscall.UTF16ToString(buf[:l]))
+	}
+	if n > len(names) {
+		return names, io.EOF
+	}
+	return names, nil
+}
+
+// CreateKey creates a key named path under open key k.
+// CreateKey returns the new key and a boolean flag that reports
+// whether the key already existed.
+// The access parameter specifies the access rights for the key
+// to be created.
+func CreateKey(k Key, path string, access uint32) (newk Key, openedExisting bool, err error) {
+	var h syscall.Handle
+	var d uint32
+	err = regCreateKeyEx(syscall.Handle(k), syscall.StringToUTF16Ptr(path),
+		0, nil, _REG_OPTION_NON_VOLATILE, access, nil, &h, &d)
+	if err != nil {
+		return 0, false, err
+	}
+	return Key(h), d == _REG_OPENED_EXISTING_KEY, nil
+}
+
+// DeleteKey deletes the subkey path of key k and its values.
+func DeleteKey(k Key, path string) error {
+	return regDeleteKey(syscall.Handle(k), syscall.StringToUTF16Ptr(path))
+}
+
+// A KeyInfo describes the statistics of a key. It is returned by Stat.
+type KeyInfo struct {
+	SubKeyCount     uint32
+	MaxSubKeyLen    uint32 // size of the key's subkey with the longest name, in Unicode characters, not including the terminating zero byte
+	ValueCount      uint32
+	MaxValueNameLen uint32 // size of the key's longest value name, in Unicode characters, not including the terminating zero byte
+	MaxValueLen     uint32 // longest data component among the key's values, in bytes
+	lastWriteTime   syscall.Filetime
+}
+
+// ModTime returns the key's last write time.
+func (ki *KeyInfo) ModTime() time.Time {
+	return time.Unix(0, ki.lastWriteTime.Nanoseconds())
+}
+
+// Stat retrieves information about the open key k.
+func (k Key) Stat() (*KeyInfo, error) {
+	var ki KeyInfo
+	err := syscall.RegQueryInfoKey(syscall.Handle(k), nil, nil, nil,
+		&ki.SubKeyCount, &ki.MaxSubKeyLen, nil, &ki.ValueCount,
+		&ki.MaxValueNameLen, &ki.MaxValueLen, nil, &ki.lastWriteTime)
+	if err != nil {
+		return nil, err
+	}
+	return &ki, nil
+}

vendor/golang.org/x/sys/windows/registry/mksyscall.go

@@ -0,0 +1,10 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build generate
+// +build generate
+
+package registry
+
+//go:generate go run golang.org/x/sys/windows/mkwinsyscall -output zsyscall_windows.go syscall.go

vendor/golang.org/x/sys/windows/registry/syscall.go

@@ -0,0 +1,33 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+// +build windows
+
+package registry
+
+import "syscall"
+
+const (
+	_REG_OPTION_NON_VOLATILE = 0
+
+	_REG_CREATED_NEW_KEY     = 1
+	_REG_OPENED_EXISTING_KEY = 2
+
+	_ERROR_NO_MORE_ITEMS syscall.Errno = 259
+)
+
+func LoadRegLoadMUIString() error {
+	return procRegLoadMUIStringW.Find()
+}
+
+//sys	regCreateKeyEx(key syscall.Handle, subkey *uint16, reserved uint32, class *uint16, options uint32, desired uint32, sa *syscall.SecurityAttributes, result *syscall.Handle, disposition *uint32) (regerrno error) = advapi32.RegCreateKeyExW
+//sys	regDeleteKey(key syscall.Handle, subkey *uint16) (regerrno error) = advapi32.RegDeleteKeyW
+//sys	regSetValueEx(key syscall.Handle, valueName *uint16, reserved uint32, vtype uint32, buf *byte, bufsize uint32) (regerrno error) = advapi32.RegSetValueExW
+//sys	regEnumValue(key syscall.Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, valtype *uint32, buf *byte, buflen *uint32) (regerrno error) = advapi32.RegEnumValueW
+//sys	regDeleteValue(key syscall.Handle, name *uint16) (regerrno error) = advapi32.RegDeleteValueW
+//sys   regLoadMUIString(key syscall.Handle, name *uint16, buf *uint16, buflen uint32, buflenCopied *uint32, flags uint32, dir *uint16) (regerrno error) = advapi32.RegLoadMUIStringW
+//sys	regConnectRegistry(machinename *uint16, key syscall.Handle, result *syscall.Handle) (regerrno error) = advapi32.RegConnectRegistryW
+
+//sys	expandEnvironmentStrings(src *uint16, dst *uint16, size uint32) (n uint32, err error) = kernel32.ExpandEnvironmentStringsW

vendor/golang.org/x/sys/windows/registry/value.go

@@ -0,0 +1,387 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+// +build windows
+
+package registry
+
+import (
+	"errors"
+	"io"
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+)
+
+const (
+	// Registry value types.
+	NONE                       = 0
+	SZ                         = 1
+	EXPAND_SZ                  = 2
+	BINARY                     = 3
+	DWORD                      = 4
+	DWORD_BIG_ENDIAN           = 5
+	LINK                       = 6
+	MULTI_SZ                   = 7
+	RESOURCE_LIST              = 8
+	FULL_RESOURCE_DESCRIPTOR   = 9
+	RESOURCE_REQUIREMENTS_LIST = 10
+	QWORD                      = 11
+)
+
+var (
+	// ErrShortBuffer is returned when the buffer was too short for the operation.
+	ErrShortBuffer = syscall.ERROR_MORE_DATA
+
+	// ErrNotExist is returned when a registry key or value does not exist.
+	ErrNotExist = syscall.ERROR_FILE_NOT_FOUND
+
+	// ErrUnexpectedType is returned by Get*Value when the value's type was unexpected.
+	ErrUnexpectedType = errors.New("unexpected key value type")
+)
+
+// GetValue retrieves the type and data for the specified value associated
+// with an open key k. It fills up buffer buf and returns the retrieved
+// byte count n. If buf is too small to fit the stored value it returns
+// ErrShortBuffer error along with the required buffer size n.
+// If no buffer is provided, it returns true and actual buffer size n.
+// If no buffer is provided, GetValue returns the value's type only.
+// If the value does not exist, the error returned is ErrNotExist.
+//
+// GetValue is a low level function. If value's type is known, use the appropriate
+// Get*Value function instead.
+func (k Key) GetValue(name string, buf []byte) (n int, valtype uint32, err error) {
+	pname, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return 0, 0, err
+	}
+	var pbuf *byte
+	if len(buf) > 0 {
+		pbuf = (*byte)(unsafe.Pointer(&buf[0]))
+	}
+	l := uint32(len(buf))
+	err = syscall.RegQueryValueEx(syscall.Handle(k), pname, nil, &valtype, pbuf, &l)
+	if err != nil {
+		return int(l), valtype, err
+	}
+	return int(l), valtype, nil
+}
+
+func (k Key) getValue(name string, buf []byte) (data []byte, valtype uint32, err error) {
+	p, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return nil, 0, err
+	}
+	var t uint32
+	n := uint32(len(buf))
+	for {
+		err = syscall.RegQueryValueEx(syscall.Handle(k), p, nil, &t, (*byte)(unsafe.Pointer(&buf[0])), &n)
+		if err == nil {
+			return buf[:n], t, nil
+		}
+		if err != syscall.ERROR_MORE_DATA {
+			return nil, 0, err
+		}
+		if n <= uint32(len(buf)) {
+			return nil, 0, err
+		}
+		buf = make([]byte, n)
+	}
+}
+
+// GetStringValue retrieves the string value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetStringValue returns ErrNotExist.
+// If value is not SZ or EXPAND_SZ, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetStringValue(name string) (val string, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 64))
+	if err2 != nil {
+		return "", typ, err2
+	}
+	switch typ {
+	case SZ, EXPAND_SZ:
+	default:
+		return "", typ, ErrUnexpectedType
+	}
+	if len(data) == 0 {
+		return "", typ, nil
+	}
+	u := (*[1 << 29]uint16)(unsafe.Pointer(&data[0]))[: len(data)/2 : len(data)/2]
+	return syscall.UTF16ToString(u), typ, nil
+}
+
+// GetMUIStringValue retrieves the localized string value for
+// the specified value name associated with an open key k.
+// If the value name doesn't exist or the localized string value
+// can't be resolved, GetMUIStringValue returns ErrNotExist.
+// GetMUIStringValue panics if the system doesn't support
+// regLoadMUIString; use LoadRegLoadMUIString to check if
+// regLoadMUIString is supported before calling this function.
+func (k Key) GetMUIStringValue(name string) (string, error) {
+	pname, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return "", err
+	}
+
+	buf := make([]uint16, 1024)
+	var buflen uint32
+	var pdir *uint16
+
+	err = regLoadMUIString(syscall.Handle(k), pname, &buf[0], uint32(len(buf)), &buflen, 0, pdir)
+	if err == syscall.ERROR_FILE_NOT_FOUND { // Try fallback path
+
+		// Try to resolve the string value using the system directory as
+		// a DLL search path; this assumes the string value is of the form
+		// @[path]\dllname,-strID but with no path given, e.g. @tzres.dll,-320.
+
+		// This approach works with tzres.dll but may have to be revised
+		// in the future to allow callers to provide custom search paths.
+
+		var s string
+		s, err = ExpandString("%SystemRoot%\\system32\\")
+		if err != nil {
+			return "", err
+		}
+		pdir, err = syscall.UTF16PtrFromString(s)
+		if err != nil {
+			return "", err
+		}
+
+		err = regLoadMUIString(syscall.Handle(k), pname, &buf[0], uint32(len(buf)), &buflen, 0, pdir)
+	}
+
+	for err == syscall.ERROR_MORE_DATA { // Grow buffer if needed
+		if buflen <= uint32(len(buf)) {
+			break // Buffer not growing, assume race; break
+		}
+		buf = make([]uint16, buflen)
+		err = regLoadMUIString(syscall.Handle(k), pname, &buf[0], uint32(len(buf)), &buflen, 0, pdir)
+	}
+
+	if err != nil {
+		return "", err
+	}
+
+	return syscall.UTF16ToString(buf), nil
+}
+
+// ExpandString expands environment-variable strings and replaces
+// them with the values defined for the current user.
+// Use ExpandString to expand EXPAND_SZ strings.
+func ExpandString(value string) (string, error) {
+	if value == "" {
+		return "", nil
+	}
+	p, err := syscall.UTF16PtrFromString(value)
+	if err != nil {
+		return "", err
+	}
+	r := make([]uint16, 100)
+	for {
+		n, err := expandEnvironmentStrings(p, &r[0], uint32(len(r)))
+		if err != nil {
+			return "", err
+		}
+		if n <= uint32(len(r)) {
+			return syscall.UTF16ToString(r[:n]), nil
+		}
+		r = make([]uint16, n)
+	}
+}
+
+// GetStringsValue retrieves the []string value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetStringsValue returns ErrNotExist.
+// If value is not MULTI_SZ, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetStringsValue(name string) (val []string, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 64))
+	if err2 != nil {
+		return nil, typ, err2
+	}
+	if typ != MULTI_SZ {
+		return nil, typ, ErrUnexpectedType
+	}
+	if len(data) == 0 {
+		return nil, typ, nil
+	}
+	p := (*[1 << 29]uint16)(unsafe.Pointer(&data[0]))[: len(data)/2 : len(data)/2]
+	if len(p) == 0 {
+		return nil, typ, nil
+	}
+	if p[len(p)-1] == 0 {
+		p = p[:len(p)-1] // remove terminating null
+	}
+	val = make([]string, 0, 5)
+	from := 0
+	for i, c := range p {
+		if c == 0 {
+			val = append(val, string(utf16.Decode(p[from:i])))
+			from = i + 1
+		}
+	}
+	return val, typ, nil
+}
+
+// GetIntegerValue retrieves the integer value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetIntegerValue returns ErrNotExist.
+// If value is not DWORD or QWORD, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetIntegerValue(name string) (val uint64, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 8))
+	if err2 != nil {
+		return 0, typ, err2
+	}
+	switch typ {
+	case DWORD:
+		if len(data) != 4 {
+			return 0, typ, errors.New("DWORD value is not 4 bytes long")
+		}
+		var val32 uint32
+		copy((*[4]byte)(unsafe.Pointer(&val32))[:], data)
+		return uint64(val32), DWORD, nil
+	case QWORD:
+		if len(data) != 8 {
+			return 0, typ, errors.New("QWORD value is not 8 bytes long")
+		}
+		copy((*[8]byte)(unsafe.Pointer(&val))[:], data)
+		return val, QWORD, nil
+	default:
+		return 0, typ, ErrUnexpectedType
+	}
+}
+
+// GetBinaryValue retrieves the binary value for the specified
+// value name associated with an open key k. It also returns the value's type.
+// If value does not exist, GetBinaryValue returns ErrNotExist.
+// If value is not BINARY, it will return the correct value
+// type and ErrUnexpectedType.
+func (k Key) GetBinaryValue(name string) (val []byte, valtype uint32, err error) {
+	data, typ, err2 := k.getValue(name, make([]byte, 64))
+	if err2 != nil {
+		return nil, typ, err2
+	}
+	if typ != BINARY {
+		return nil, typ, ErrUnexpectedType
+	}
+	return data, typ, nil
+}
+
+func (k Key) setValue(name string, valtype uint32, data []byte) error {
+	p, err := syscall.UTF16PtrFromString(name)
+	if err != nil {
+		return err
+	}
+	if len(data) == 0 {
+		return regSetValueEx(syscall.Handle(k), p, 0, valtype, nil, 0)
+	}
+	return regSetValueEx(syscall.Handle(k), p, 0, valtype, &data[0], uint32(len(data)))
+}
+
+// SetDWordValue sets the data and type of a name value
+// under key k to value and DWORD.
+func (k Key) SetDWordValue(name string, value uint32) error {
+	return k.setValue(name, DWORD, (*[4]byte)(unsafe.Pointer(&value))[:])
+}
+
+// SetQWordValue sets the data and type of a name value
+// under key k to value and QWORD.
+func (k Key) SetQWordValue(name string, value uint64) error {
+	return k.setValue(name, QWORD, (*[8]byte)(unsafe.Pointer(&value))[:])
+}
+
+func (k Key) setStringValue(name string, valtype uint32, value string) error {
+	v, err := syscall.UTF16FromString(value)
+	if err != nil {
+		return err
+	}
+	buf := (*[1 << 29]byte)(unsafe.Pointer(&v[0]))[: len(v)*2 : len(v)*2]
+	return k.setValue(name, valtype, buf)
+}
+
+// SetStringValue sets the data and type of a name value
+// under key k to value and SZ. The value must not contain a zero byte.
+func (k Key) SetStringValue(name, value string) error {
+	return k.setStringValue(name, SZ, value)
+}
+
+// SetExpandStringValue sets the data and type of a name value
+// under key k to value and EXPAND_SZ. The value must not contain a zero byte.
+func (k Key) SetExpandStringValue(name, value string) error {
+	return k.setStringValue(name, EXPAND_SZ, value)
+}
+
+// SetStringsValue sets the data and type of a name value
+// under key k to value and MULTI_SZ. The value strings
+// must not contain a zero byte.
+func (k Key) SetStringsValue(name string, value []string) error {
+	ss := ""
+	for _, s := range value {
+		for i := 0; i < len(s); i++ {
+			if s[i] == 0 {
+				return errors.New("string cannot have 0 inside")
+			}
+		}
+		ss += s + "\x00"
+	}
+	v := utf16.Encode([]rune(ss + "\x00"))
+	buf := (*[1 << 29]byte)(unsafe.Pointer(&v[0]))[: len(v)*2 : len(v)*2]
+	return k.setValue(name, MULTI_SZ, buf)
+}
+
+// SetBinaryValue sets the data and type of a name value
+// under key k to value and BINARY.
+func (k Key) SetBinaryValue(name string, value []byte) error {
+	return k.setValue(name, BINARY, value)
+}
+
+// DeleteValue removes a named value from the key k.
+func (k Key) DeleteValue(name string) error {
+	return regDeleteValue(syscall.Handle(k), syscall.StringToUTF16Ptr(name))
+}
+
+// ReadValueNames returns the value names of key k.
+// The parameter n controls the number of returned names,
+// analogous to the way os.File.Readdirnames works.
+func (k Key) ReadValueNames(n int) ([]string, error) {
+	ki, err := k.Stat()
+	if err != nil {
+		return nil, err
+	}
+	names := make([]string, 0, ki.ValueCount)
+	buf := make([]uint16, ki.MaxValueNameLen+1) // extra room for terminating null character
+loopItems:
+	for i := uint32(0); ; i++ {
+		if n > 0 {
+			if len(names) == n {
+				return names, nil
+			}
+		}
+		l := uint32(len(buf))
+		for {
+			err := regEnumValue(syscall.Handle(k), i, &buf[0], &l, nil, nil, nil, nil)
+			if err == nil {
+				break
+			}
+			if err == syscall.ERROR_MORE_DATA {
+				// Double buffer size and try again.
+				l = uint32(2 * len(buf))
+				buf = make([]uint16, l)
+				continue
+			}
+			if err == _ERROR_NO_MORE_ITEMS {
+				break loopItems
+			}
+			return names, err
+		}
+		names = append(names, syscall.UTF16ToString(buf[:l]))
+	}
+	if n > len(names) {
+		return names, io.EOF
+	}
+	return names, nil
+}

vendor/golang.org/x/sys/windows/registry/zsyscall_windows.go

@@ -0,0 +1,117 @@
+// Code generated by 'go generate'; DO NOT EDIT.
+
+package registry
+
+import (
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var _ unsafe.Pointer
+
+// Do the interface allocations only once for common
+// Errno values.
+const (
+	errnoERROR_IO_PENDING = 997
+)
+
+var (
+	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+	errERROR_EINVAL     error = syscall.EINVAL
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return errERROR_EINVAL
+	case errnoERROR_IO_PENDING:
+		return errERROR_IO_PENDING
+	}
+	// TODO: add more here, after collecting data on the common
+	// error values see on Windows. (perhaps when running
+	// all.bat?)
+	return e
+}
+
+var (
+	modadvapi32 = windows.NewLazySystemDLL("advapi32.dll")
+	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
+
+	procRegConnectRegistryW       = modadvapi32.NewProc("RegConnectRegistryW")
+	procRegCreateKeyExW           = modadvapi32.NewProc("RegCreateKeyExW")
+	procRegDeleteKeyW             = modadvapi32.NewProc("RegDeleteKeyW")
+	procRegDeleteValueW           = modadvapi32.NewProc("RegDeleteValueW")
+	procRegEnumValueW             = modadvapi32.NewProc("RegEnumValueW")
+	procRegLoadMUIStringW         = modadvapi32.NewProc("RegLoadMUIStringW")
+	procRegSetValueExW            = modadvapi32.NewProc("RegSetValueExW")
+	procExpandEnvironmentStringsW = modkernel32.NewProc("ExpandEnvironmentStringsW")
+)
+
+func regConnectRegistry(machinename *uint16, key syscall.Handle, result *syscall.Handle) (regerrno error) {
+	r0, _, _ := syscall.Syscall(procRegConnectRegistryW.Addr(), 3, uintptr(unsafe.Pointer(machinename)), uintptr(key), uintptr(unsafe.Pointer(result)))
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regCreateKeyEx(key syscall.Handle, subkey *uint16, reserved uint32, class *uint16, options uint32, desired uint32, sa *syscall.SecurityAttributes, result *syscall.Handle, disposition *uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(procRegCreateKeyExW.Addr(), 9, uintptr(key), uintptr(unsafe.Pointer(subkey)), uintptr(reserved), uintptr(unsafe.Pointer(class)), uintptr(options), uintptr(desired), uintptr(unsafe.Pointer(sa)), uintptr(unsafe.Pointer(result)), uintptr(unsafe.Pointer(disposition)))
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regDeleteKey(key syscall.Handle, subkey *uint16) (regerrno error) {
+	r0, _, _ := syscall.Syscall(procRegDeleteKeyW.Addr(), 2, uintptr(key), uintptr(unsafe.Pointer(subkey)), 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regDeleteValue(key syscall.Handle, name *uint16) (regerrno error) {
+	r0, _, _ := syscall.Syscall(procRegDeleteValueW.Addr(), 2, uintptr(key), uintptr(unsafe.Pointer(name)), 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regEnumValue(key syscall.Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, valtype *uint32, buf *byte, buflen *uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(procRegEnumValueW.Addr(), 8, uintptr(key), uintptr(index), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(nameLen)), uintptr(unsafe.Pointer(reserved)), uintptr(unsafe.Pointer(valtype)), uintptr(unsafe.Pointer(buf)), uintptr(unsafe.Pointer(buflen)), 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regLoadMUIString(key syscall.Handle, name *uint16, buf *uint16, buflen uint32, buflenCopied *uint32, flags uint32, dir *uint16) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(procRegLoadMUIStringW.Addr(), 7, uintptr(key), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(buf)), uintptr(buflen), uintptr(unsafe.Pointer(buflenCopied)), uintptr(flags), uintptr(unsafe.Pointer(dir)), 0, 0)
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func regSetValueEx(key syscall.Handle, valueName *uint16, reserved uint32, vtype uint32, buf *byte, bufsize uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall6(procRegSetValueExW.Addr(), 6, uintptr(key), uintptr(unsafe.Pointer(valueName)), uintptr(reserved), uintptr(vtype), uintptr(unsafe.Pointer(buf)), uintptr(bufsize))
+	if r0 != 0 {
+		regerrno = syscall.Errno(r0)
+	}
+	return
+}
+
+func expandEnvironmentStrings(src *uint16, dst *uint16, size uint32) (n uint32, err error) {
+	r0, _, e1 := syscall.Syscall(procExpandEnvironmentStringsW.Addr(), 3, uintptr(unsafe.Pointer(src)), uintptr(unsafe.Pointer(dst)), uintptr(size))
+	n = uint32(r0)
+	if n == 0 {
+		err = errnoErr(e1)
+	}
+	return
+}