Bump version to 5.11.0

vendor/github.com/golang/glog/README

@@ -1,44 +0,0 @@
-glog
-====
-
-Leveled execution logs for Go.
-
-This is an efficient pure Go implementation of leveled logs in the
-manner of the open source C++ package
-	https://github.com/google/glog
-
-By binding methods to booleans it is possible to use the log package
-without paying the expense of evaluating the arguments to the log.
-Through the -vmodule flag, the package also provides fine-grained
-control over logging at the file level.
-
-The comment from glog.go introduces the ideas:
-
-	Package glog implements logging analogous to the Google-internal
-	C++ INFO/ERROR/V setup.  It provides functions Info, Warning,
-	Error, Fatal, plus formatting variants such as Infof. It
-	also provides V-style logging controlled by the -v and
-	-vmodule=file=2 flags.
-	
-	Basic examples:
-	
-		glog.Info("Prepare to repel boarders")
-	
-		glog.Fatalf("Initialization failed: %s", err)
-	
-	See the documentation for the V function for an explanation
-	of these examples:
-	
-		if glog.V(2) {
-			glog.Info("Starting transaction...")
-		}
-	
-		glog.V(2).Infoln("Processed", nItems, "elements")
-
-
-The repository contains an open source version of the log package
-used inside Google. The master copy of the source lives inside
-Google, not here. The code in this repo is for export only and is not itself
-under development. Feature requests will be ignored.
-
-Send bug reports to golang-nuts@googlegroups.com.

vendor/github.com/golang/glog/README.md

@@ -0,0 +1,36 @@
+# glog
+
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/golang/glog)](https://pkg.go.dev/github.com/golang/glog)
+
+Leveled execution logs for Go.
+
+This is an efficient pure Go implementation of leveled logs in the
+manner of the open source C++ package [_glog_](https://github.com/google/glog).
+
+By binding methods to booleans it is possible to use the log package without paying the expense of evaluating the arguments to the log. Through the `-vmodule` flag, the package also provides fine-grained
+control over logging at the file level.
+
+The comment from `glog.go` introduces the ideas:
+
+Package _glog_ implements logging analogous to the Google-internal C++ INFO/ERROR/V setup.  It provides the functions Info, Warning, Error, Fatal, plus formatting variants such as Infof. It also provides V-style loggingcontrolled by the `-v` and `-vmodule=file=2` flags.
+	
+Basic examples:
+
+```go
+glog.Info("Prepare to repel boarders")
+	
+glog.Fatalf("Initialization failed: %s", err)
+```
+	
+See the documentation for the V function for an explanation of these examples:
+
+```go
+if glog.V(2) {
+	glog.Info("Starting transaction...")
+}
+glog.V(2).Infoln("Processed", nItems, "elements")
+```
+
+The repository contains an open source version of the log package used inside Google. The master copy of the source lives inside Google, not here. The code in this repo is for export only and is not itself under development. Feature requests will be ignored.
+
+Send bug reports to golang-nuts@googlegroups.com.

vendor/github.com/golang/glog/glog_file.go

@@ -1,6 +1,6 @@
-// Go support for leveled logs, analogous to https://code.google.com/p/google-glog/
+// Go support for leveled logs, analogous to https://github.com/google/glog.
 //
-// Copyright 2013 Google Inc. All Rights Reserved.
+// Copyright 2023 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.
@@ -19,26 +19,34 @@
 package glog
 
 import (
+	"bufio"
+	"bytes"
 	"errors"
 	"flag"
 	"fmt"
+	"io"
 	"os"
 	"os/user"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
-)
 
-// MaxSize is the maximum size of a log file in bytes.
-var MaxSize uint64 = 1024 * 1024 * 1800
+	"github.com/golang/glog/internal/logsink"
+)
 
 // logDirs lists the candidate directories for new log files.
 var logDirs []string
 
-// If non-empty, overrides the choice of directory in which to write logs.
-// See createLogDirs for the full list of possible destinations.
-var logDir = flag.String("log_dir", "", "If non-empty, write log files in this directory")
+var (
+	// If non-empty, overrides the choice of directory in which to write logs.
+	// See createLogDirs for the full list of possible destinations.
+	logDir      = flag.String("log_dir", "", "If non-empty, write log files in this directory")
+	logLink     = flag.String("log_link", "", "If non-empty, add symbolic links in this directory to the log files")
+	logBufLevel = flag.Int("logbuflevel", int(logsink.Info), "Buffer log messages logged at this level or lower"+
+		" (-1 means don't buffer; 0 means buffer INFO only; ...). Has limited applicability on non-prod platforms.")
+)
 
 func createLogDirs() {
 	if *logDir != "" {
@@ -64,9 +72,17 @@ func init() {
 	if err == nil {
 		userName = current.Username
 	}
-
-	// Sanitize userName since it may contain filepath separators on Windows.
-	userName = strings.Replace(userName, `\`, "_", -1)
+	// Sanitize userName since it is used to construct file paths.
+	userName = strings.Map(func(r rune) rune {
+		switch {
+		case r >= 'a' && r <= 'z':
+		case r >= 'A' && r <= 'Z':
+		case r >= '0' && r <= '9':
+		default:
+			return '_'
+		}
+		return r
+	}, userName)
 }
 
 // shortHostname returns its argument, truncating at the first period.
@@ -116,9 +132,282 @@ func create(tag string, t time.Time) (f *os.File, filename string, err error) {
 			symlink := filepath.Join(dir, link)
 			os.Remove(symlink)        // ignore err
 			os.Symlink(name, symlink) // ignore err
+			if *logLink != "" {
+				lsymlink := filepath.Join(*logLink, link)
+				os.Remove(lsymlink)         // ignore err
+				os.Symlink(fname, lsymlink) // ignore err
+			}
 			return f, fname, nil
 		}
 		lastErr = err
 	}
 	return nil, "", fmt.Errorf("log: cannot create log: %v", lastErr)
 }
+
+// flushSyncWriter is the interface satisfied by logging destinations.
+type flushSyncWriter interface {
+	Flush() error
+	Sync() error
+	io.Writer
+	filenames() []string
+}
+
+var sinks struct {
+	stderr stderrSink
+	file   fileSink
+}
+
+func init() {
+	// Register stderr first: that way if we crash during file-writing at least
+	// the log will have gone somewhere.
+	logsink.TextSinks = append(logsink.TextSinks, &sinks.stderr, &sinks.file)
+
+	sinks.file.flushChan = make(chan logsink.Severity, 1)
+	go sinks.file.flushDaemon()
+}
+
+// stderrSink is a logsink.Text that writes log entries to stderr
+// if they meet certain conditions.
+type stderrSink struct {
+	mu sync.Mutex
+	w  io.Writer // if nil Emit uses os.Stderr directly
+}
+
+// Enabled implements logsink.Text.Enabled.  It returns true if any of the
+// various stderr flags are enabled for logs of the given severity, if the log
+// message is from the standard "log" package, or if google.Init has not yet run
+// (and hence file logging is not yet initialized).
+func (s *stderrSink) Enabled(m *logsink.Meta) bool {
+	return toStderr || alsoToStderr || m.Severity >= stderrThreshold.get()
+}
+
+// Emit implements logsink.Text.Emit.
+func (s *stderrSink) Emit(m *logsink.Meta, data []byte) (n int, err error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	w := s.w
+	if w == nil {
+		w = os.Stderr
+	}
+	dn, err := w.Write(data)
+	n += dn
+	return n, err
+}
+
+// severityWriters is an array of flushSyncWriter with a value for each
+// logsink.Severity.
+type severityWriters [4]flushSyncWriter
+
+// fileSink is a logsink.Text that prints to a set of Google log files.
+type fileSink struct {
+	mu sync.Mutex
+	// file holds writer for each of the log types.
+	file      severityWriters
+	flushChan chan logsink.Severity
+}
+
+// Enabled implements logsink.Text.Enabled.  It returns true if google.Init
+// has run and both --disable_log_to_disk and --logtostderr are false.
+func (s *fileSink) Enabled(m *logsink.Meta) bool {
+	return !toStderr
+}
+
+// Emit implements logsink.Text.Emit
+func (s *fileSink) Emit(m *logsink.Meta, data []byte) (n int, err error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if err = s.createMissingFiles(m.Severity); err != nil {
+		return 0, err
+	}
+	for sev := m.Severity; sev >= logsink.Info; sev-- {
+		if _, fErr := s.file[sev].Write(data); fErr != nil && err == nil {
+			err = fErr // Take the first error.
+		}
+	}
+	n = len(data)
+	if int(m.Severity) > *logBufLevel {
+		select {
+		case s.flushChan <- m.Severity:
+		default:
+		}
+	}
+
+	return n, err
+}
+
+// syncBuffer joins a bufio.Writer to its underlying file, providing access to the
+// file's Sync method and providing a wrapper for the Write method that provides log
+// file rotation. There are conflicting methods, so the file cannot be embedded.
+// s.mu is held for all its methods.
+type syncBuffer struct {
+	sink *fileSink
+	*bufio.Writer
+	file   *os.File
+	names  []string
+	sev    logsink.Severity
+	nbytes uint64 // The number of bytes written to this file
+}
+
+func (sb *syncBuffer) Sync() error {
+	return sb.file.Sync()
+}
+
+func (sb *syncBuffer) Write(p []byte) (n int, err error) {
+	if sb.nbytes+uint64(len(p)) >= MaxSize {
+		if err := sb.rotateFile(time.Now()); err != nil {
+			return 0, err
+		}
+	}
+	n, err = sb.Writer.Write(p)
+	sb.nbytes += uint64(n)
+	return n, err
+}
+
+func (sb *syncBuffer) filenames() []string {
+	return sb.names
+}
+
+const footer = "\nCONTINUED IN NEXT FILE\n"
+
+// rotateFile closes the syncBuffer's file and starts a new one.
+func (sb *syncBuffer) rotateFile(now time.Time) error {
+	var err error
+	pn := "<none>"
+	file, name, err := create(sb.sev.String(), now)
+
+	if sb.file != nil {
+		// The current log file becomes the previous log at the end of
+		// this block, so save its name for use in the header of the next
+		// file.
+		pn = sb.file.Name()
+		sb.Flush()
+		// If there's an existing file, write a footer with the name of
+		// the next file in the chain, followed by the constant string
+		// \nCONTINUED IN NEXT FILE\n to make continuation detection simple.
+		sb.file.Write([]byte("Next log: "))
+		sb.file.Write([]byte(name))
+		sb.file.Write([]byte(footer))
+		sb.file.Close()
+	}
+
+	sb.file = file
+	sb.names = append(sb.names, name)
+	sb.nbytes = 0
+	if err != nil {
+		return err
+	}
+
+	sb.Writer = bufio.NewWriterSize(sb.file, bufferSize)
+
+	// Write header.
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "Log file created at: %s\n", now.Format("2006/01/02 15:04:05"))
+	fmt.Fprintf(&buf, "Running on machine: %s\n", host)
+	fmt.Fprintf(&buf, "Binary: Built with %s %s for %s/%s\n", runtime.Compiler, runtime.Version(), runtime.GOOS, runtime.GOARCH)
+	fmt.Fprintf(&buf, "Previous log: %s\n", pn)
+	fmt.Fprintf(&buf, "Log line format: [IWEF]mmdd hh:mm:ss.uuuuuu threadid file:line] msg\n")
+	n, err := sb.file.Write(buf.Bytes())
+	sb.nbytes += uint64(n)
+	return err
+}
+
+// bufferSize sizes the buffer associated with each log file. It's large
+// so that log records can accumulate without the logging thread blocking
+// on disk I/O. The flushDaemon will block instead.
+const bufferSize = 256 * 1024
+
+// createMissingFiles creates all the log files for severity from infoLog up to
+// upTo that have not already been created.
+// s.mu is held.
+func (s *fileSink) createMissingFiles(upTo logsink.Severity) error {
+	if s.file[upTo] != nil {
+		return nil
+	}
+	now := time.Now()
+	// Files are created in increasing severity order, so we can be assured that
+	// if a high severity logfile exists, then so do all of lower severity.
+	for sev := logsink.Info; sev <= upTo; sev++ {
+		if s.file[sev] != nil {
+			continue
+		}
+		sb := &syncBuffer{
+			sink: s,
+			sev:  sev,
+		}
+		if err := sb.rotateFile(now); err != nil {
+			return err
+		}
+		s.file[sev] = sb
+	}
+	return nil
+}
+
+// flushDaemon periodically flushes the log file buffers.
+func (s *fileSink) flushDaemon() {
+	tick := time.NewTicker(30 * time.Second)
+	defer tick.Stop()
+	for {
+		select {
+		case <-tick.C:
+			s.Flush()
+		case sev := <-s.flushChan:
+			s.flush(sev)
+		}
+	}
+}
+
+// Flush flushes all pending log I/O.
+func Flush() {
+	sinks.file.Flush()
+}
+
+// Flush flushes all the logs and attempts to "sync" their data to disk.
+func (s *fileSink) Flush() error {
+	return s.flush(logsink.Info)
+}
+
+// flush flushes all logs of severity threshold or greater.
+func (s *fileSink) flush(threshold logsink.Severity) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	var firstErr error
+	updateErr := func(err error) {
+		if err != nil && firstErr == nil {
+			firstErr = err
+		}
+	}
+
+	// Flush from fatal down, in case there's trouble flushing.
+	for sev := logsink.Fatal; sev >= threshold; sev-- {
+		file := s.file[sev]
+		if file != nil {
+			updateErr(file.Flush())
+			updateErr(file.Sync())
+		}
+	}
+
+	return firstErr
+}
+
+// Names returns the names of the log files holding the FATAL, ERROR,
+// WARNING, or INFO logs. Returns ErrNoLog if the log for the given
+// level doesn't exist (e.g. because no messages of that level have been
+// written). This may return multiple names if the log type requested
+// has rolled over.
+func Names(s string) ([]string, error) {
+	severity, err := logsink.ParseSeverity(s)
+	if err != nil {
+		return nil, err
+	}
+
+	sinks.file.mu.Lock()
+	defer sinks.file.mu.Unlock()
+	f := sinks.file.file[severity]
+	if f == nil {
+		return nil, ErrNoLog
+	}
+
+	return f.filenames(), nil
+}

vendor/github.com/golang/glog/glog_file_linux.go

@@ -0,0 +1,39 @@
+// Go support for leveled logs, analogous to https://github.com/google/glog.
+//
+// Copyright 2023 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.
+
+//go:build linux
+
+package glog
+
+import (
+	"errors"
+	"runtime"
+	"syscall"
+)
+
+// abortProcess attempts to kill the current process in a way that will dump the
+// currently-running goroutines someplace useful (like stderr).
+//
+// It does this by sending SIGABRT to the current thread.
+//
+// If successful, abortProcess does not return.
+func abortProcess() error {
+	runtime.LockOSThread()
+	if err := syscall.Tgkill(syscall.Getpid(), syscall.Gettid(), syscall.SIGABRT); err != nil {
+		return err
+	}
+	return errors.New("log: killed current thread with SIGABRT, but still running")
+}

vendor/github.com/golang/glog/glog_file_other.go

@@ -0,0 +1,30 @@
+// Go support for leveled logs, analogous to https://github.com/google/glog.
+//
+// Copyright 2023 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.
+
+//go:build !(unix || windows)
+
+package glog
+
+import (
+	"fmt"
+	"runtime"
+)
+
+// abortProcess returns an error on platforms that presumably don't support signals.
+func abortProcess() error {
+	return fmt.Errorf("not sending SIGABRT (%s/%s does not support signals), falling back", runtime.GOOS, runtime.GOARCH)
+
+}

vendor/github.com/golang/glog/glog_file_posix.go

@@ -0,0 +1,53 @@
+// Go support for leveled logs, analogous to https://github.com/google/glog.
+//
+// Copyright 2023 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.
+
+//go:build (unix || windows) && !linux
+
+package glog
+
+import (
+	"os"
+	"syscall"
+	"time"
+)
+
+// abortProcess attempts to kill the current process in a way that will dump the
+// currently-running goroutines someplace useful (like stderr).
+//
+// It does this by sending SIGABRT to the current process. Unfortunately, the
+// signal may or may not be delivered to the current thread; in order to do that
+// portably, we would need to add a cgo dependency and call pthread_kill.
+//
+// If successful, abortProcess does not return.
+func abortProcess() error {
+	p, err := os.FindProcess(os.Getpid())
+	if err != nil {
+		return err
+	}
+	if err := p.Signal(syscall.SIGABRT); err != nil {
+		return err
+	}
+
+	// Sent the signal.  Now we wait for it to arrive and any SIGABRT handlers to
+	// run (and eventually terminate the process themselves).
+	//
+	// We could just "select{}" here, but there's an outside chance that would
+	// trigger the runtime's deadlock detector if there happen not to be any
+	// background goroutines running.  So we'll sleep a while first to give
+	// the signal some time.
+	time.Sleep(10 * time.Second)
+	select {}
+}

vendor/github.com/golang/glog/glog_flags.go

@@ -0,0 +1,398 @@
+// Go support for leveled logs, analogous to https://github.com/google/glog.
+//
+// Copyright 2023 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 glog
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"github.com/golang/glog/internal/logsink"
+)
+
+// modulePat contains a filter for the -vmodule flag.
+// It holds a verbosity level and a file pattern to match.
+type modulePat struct {
+	pattern string
+	literal bool // The pattern is a literal string
+	full    bool // The pattern wants to match the full path
+	level   Level
+}
+
+// match reports whether the file matches the pattern. It uses a string
+// comparison if the pattern contains no metacharacters.
+func (m *modulePat) match(full, file string) bool {
+	if m.literal {
+		if m.full {
+			return full == m.pattern
+		}
+		return file == m.pattern
+	}
+	if m.full {
+		match, _ := filepath.Match(m.pattern, full)
+		return match
+	}
+	match, _ := filepath.Match(m.pattern, file)
+	return match
+}
+
+// isLiteral reports whether the pattern is a literal string, that is, has no metacharacters
+// that require filepath.Match to be called to match the pattern.
+func isLiteral(pattern string) bool {
+	return !strings.ContainsAny(pattern, `\*?[]`)
+}
+
+// isFull reports whether the pattern matches the full file path, that is,
+// whether it contains /.
+func isFull(pattern string) bool {
+	return strings.ContainsRune(pattern, '/')
+}
+
+// verboseFlags represents the setting of the -v and -vmodule flags.
+type verboseFlags struct {
+	// moduleLevelCache is a sync.Map storing the -vmodule Level for each V()
+	// call site, identified by PC. If there is no matching -vmodule filter,
+	// the cached value is exactly v. moduleLevelCache is replaced with a new
+	// Map whenever the -vmodule or -v flag changes state.
+	moduleLevelCache atomic.Value
+
+	// mu guards all fields below.
+	mu sync.Mutex
+
+	// v stores the value of the -v flag.  It may be read safely using
+	// sync.LoadInt32, but is only modified under mu.
+	v Level
+
+	// module stores the parsed -vmodule flag.
+	module []modulePat
+
+	// moduleLength caches len(module).  If greater than zero, it
+	// means vmodule is enabled. It may be read safely using sync.LoadInt32, but
+	// is only modified under mu.
+	moduleLength int32
+}
+
+// NOTE: For compatibility with the open-sourced v1 version of this
+// package (github.com/golang/glog) we need to retain that flag.Level
+// implements the flag.Value interface. See also go/log-vs-glog.
+
+// String is part of the flag.Value interface.
+func (l *Level) String() string {
+	return strconv.FormatInt(int64(l.Get().(Level)), 10)
+}
+
+// Get is part of the flag.Value interface.
+func (l *Level) Get() any {
+	if l == &vflags.v {
+		// l is the value registered for the -v flag.
+		return Level(atomic.LoadInt32((*int32)(l)))
+	}
+	return *l
+}
+
+// Set is part of the flag.Value interface.
+func (l *Level) Set(value string) error {
+	v, err := strconv.Atoi(value)
+	if err != nil {
+		return err
+	}
+	if l == &vflags.v {
+		// l is the value registered for the -v flag.
+		vflags.mu.Lock()
+		defer vflags.mu.Unlock()
+		vflags.moduleLevelCache.Store(&sync.Map{})
+		atomic.StoreInt32((*int32)(l), int32(v))
+		return nil
+	}
+	*l = Level(v)
+	return nil
+}
+
+// vModuleFlag is the flag.Value for the --vmodule flag.
+type vModuleFlag struct{ *verboseFlags }
+
+func (f vModuleFlag) String() string {
+	// Do not panic on the zero value.
+	// https://groups.google.com/g/golang-nuts/c/Atlr8uAjn6U/m/iId17Td5BQAJ.
+	if f.verboseFlags == nil {
+		return ""
+	}
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	var b bytes.Buffer
+	for i, f := range f.module {
+		if i > 0 {
+			b.WriteRune(',')
+		}
+		fmt.Fprintf(&b, "%s=%d", f.pattern, f.level)
+	}
+	return b.String()
+}
+
+// Get returns nil for this flag type since the struct is not exported.
+func (f vModuleFlag) Get() any { return nil }
+
+var errVmoduleSyntax = errors.New("syntax error: expect comma-separated list of filename=N")
+
+// Syntax: -vmodule=recordio=2,foo/bar/baz=1,gfs*=3
+func (f vModuleFlag) Set(value string) error {
+	var filter []modulePat
+	for _, pat := range strings.Split(value, ",") {
+		if len(pat) == 0 {
+			// Empty strings such as from a trailing comma can be ignored.
+			continue
+		}
+		patLev := strings.Split(pat, "=")
+		if len(patLev) != 2 || len(patLev[0]) == 0 || len(patLev[1]) == 0 {
+			return errVmoduleSyntax
+		}
+		pattern := patLev[0]
+		v, err := strconv.Atoi(patLev[1])
+		if err != nil {
+			return errors.New("syntax error: expect comma-separated list of filename=N")
+		}
+		// TODO: check syntax of filter?
+		filter = append(filter, modulePat{pattern, isLiteral(pattern), isFull(pattern), Level(v)})
+	}
+
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.module = filter
+	atomic.StoreInt32((*int32)(&f.moduleLength), int32(len(f.module)))
+	f.moduleLevelCache.Store(&sync.Map{})
+	return nil
+}
+
+func (f *verboseFlags) levelForPC(pc uintptr) Level {
+	if level, ok := f.moduleLevelCache.Load().(*sync.Map).Load(pc); ok {
+		return level.(Level)
+	}
+
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	level := Level(f.v)
+	fn := runtime.FuncForPC(pc)
+	file, _ := fn.FileLine(pc)
+	// The file is something like /a/b/c/d.go. We want just the d for
+	// regular matches, /a/b/c/d for full matches.
+	file = strings.TrimSuffix(file, ".go")
+	full := file
+	if slash := strings.LastIndex(file, "/"); slash >= 0 {
+		file = file[slash+1:]
+	}
+	for _, filter := range f.module {
+		if filter.match(full, file) {
+			level = filter.level
+			break // Use the first matching level.
+		}
+	}
+	f.moduleLevelCache.Load().(*sync.Map).Store(pc, level)
+	return level
+}
+
+func (f *verboseFlags) enabled(callerDepth int, level Level) bool {
+	if atomic.LoadInt32(&f.moduleLength) == 0 {
+		// No vmodule values specified, so compare against v level.
+		return Level(atomic.LoadInt32((*int32)(&f.v))) >= level
+	}
+
+	pcs := [1]uintptr{}
+	if runtime.Callers(callerDepth+2, pcs[:]) < 1 {
+		return false
+	}
+	frame, _ := runtime.CallersFrames(pcs[:]).Next()
+	return f.levelForPC(frame.Entry) >= level
+}
+
+// traceLocation represents an entry in the -log_backtrace_at flag.
+type traceLocation struct {
+	file string
+	line int
+}
+
+var errTraceSyntax = errors.New("syntax error: expect file.go:234")
+
+func parseTraceLocation(value string) (traceLocation, error) {
+	fields := strings.Split(value, ":")
+	if len(fields) != 2 {
+		return traceLocation{}, errTraceSyntax
+	}
+	file, lineStr := fields[0], fields[1]
+	if !strings.Contains(file, ".") {
+		return traceLocation{}, errTraceSyntax
+	}
+	line, err := strconv.Atoi(lineStr)
+	if err != nil {
+		return traceLocation{}, errTraceSyntax
+	}
+	if line < 0 {
+		return traceLocation{}, errors.New("negative value for line")
+	}
+	return traceLocation{file, line}, nil
+}
+
+// match reports whether the specified file and line matches the trace location.
+// The argument file name is the full path, not the basename specified in the flag.
+func (t traceLocation) match(file string, line int) bool {
+	if t.line != line {
+		return false
+	}
+	if i := strings.LastIndex(file, "/"); i >= 0 {
+		file = file[i+1:]
+	}
+	return t.file == file
+}
+
+func (t traceLocation) String() string {
+	return fmt.Sprintf("%s:%d", t.file, t.line)
+}
+
+// traceLocations represents the -log_backtrace_at flag.
+// Syntax: -log_backtrace_at=recordio.go:234,sstable.go:456
+// Note that unlike vmodule the file extension is included here.
+type traceLocations struct {
+	mu      sync.Mutex
+	locsLen int32 // Safe for atomic read without mu.
+	locs    []traceLocation
+}
+
+func (t *traceLocations) String() string {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	var buf bytes.Buffer
+	for i, tl := range t.locs {
+		if i > 0 {
+			buf.WriteString(",")
+		}
+		buf.WriteString(tl.String())
+	}
+	return buf.String()
+}
+
+// Get always returns nil for this flag type since the struct is not exported
+func (t *traceLocations) Get() any { return nil }
+
+func (t *traceLocations) Set(value string) error {
+	var locs []traceLocation
+	for _, s := range strings.Split(value, ",") {
+		if s == "" {
+			continue
+		}
+		loc, err := parseTraceLocation(s)
+		if err != nil {
+			return err
+		}
+		locs = append(locs, loc)
+	}
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	atomic.StoreInt32(&t.locsLen, int32(len(locs)))
+	t.locs = locs
+	return nil
+}
+
+func (t *traceLocations) match(file string, line int) bool {
+	if atomic.LoadInt32(&t.locsLen) == 0 {
+		return false
+	}
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	for _, tl := range t.locs {
+		if tl.match(file, line) {
+			return true
+		}
+	}
+	return false
+}
+
+// severityFlag is an atomic flag.Value implementation for logsink.Severity.
+type severityFlag int32
+
+func (s *severityFlag) get() logsink.Severity {
+	return logsink.Severity(atomic.LoadInt32((*int32)(s)))
+}
+func (s *severityFlag) String() string { return strconv.FormatInt(int64(*s), 10) }
+func (s *severityFlag) Get() any       { return s.get() }
+func (s *severityFlag) Set(value string) error {
+	threshold, err := logsink.ParseSeverity(value)
+	if err != nil {
+		// Not a severity name.  Try a raw number.
+		v, err := strconv.Atoi(value)
+		if err != nil {
+			return err
+		}
+		threshold = logsink.Severity(v)
+		if threshold < logsink.Info || threshold > logsink.Fatal {
+			return fmt.Errorf("Severity %d out of range (min %d, max %d).", v, logsink.Info, logsink.Fatal)
+		}
+	}
+	atomic.StoreInt32((*int32)(s), int32(threshold))
+	return nil
+}
+
+var (
+	vflags verboseFlags // The -v and -vmodule flags.
+
+	logBacktraceAt traceLocations // The -log_backtrace_at flag.
+
+	// Boolean flags. Not handled atomically because the flag.Value interface
+	// does not let us avoid the =true, and that shorthand is necessary for
+	// compatibility. TODO: does this matter enough to fix? Seems unlikely.
+	toStderr     bool // The -logtostderr flag.
+	alsoToStderr bool // The -alsologtostderr flag.
+
+	stderrThreshold severityFlag // The -stderrthreshold flag.
+)
+
+// verboseEnabled returns whether the caller at the given depth should emit
+// verbose logs at the given level, with depth 0 identifying the caller of
+// verboseEnabled.
+func verboseEnabled(callerDepth int, level Level) bool {
+	return vflags.enabled(callerDepth+1, level)
+}
+
+// backtraceAt returns whether the logging call at the given function and line
+// should also emit a backtrace of the current call stack.
+func backtraceAt(file string, line int) bool {
+	return logBacktraceAt.match(file, line)
+}
+
+func init() {
+	vflags.moduleLevelCache.Store(&sync.Map{})
+
+	flag.Var(&vflags.v, "v", "log level for V logs")
+	flag.Var(vModuleFlag{&vflags}, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
+
+	flag.Var(&logBacktraceAt, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
+
+	stderrThreshold = severityFlag(logsink.Error)
+
+	flag.BoolVar(&toStderr, "logtostderr", false, "log to standard error instead of files")
+	flag.BoolVar(&alsoToStderr, "alsologtostderr", false, "log to standard error as well as files")
+	flag.Var(&stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr")
+}

vendor/github.com/golang/glog/internal/logsink/logsink.go

@@ -0,0 +1,393 @@
+// Copyright 2023 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 logsink
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/golang/glog/internal/stackdump"
+)
+
+// MaxLogMessageLen is the limit on length of a formatted log message, including
+// the standard line prefix and trailing newline.
+//
+// Chosen to match C++ glog.
+const MaxLogMessageLen = 15000
+
+// A Severity is a severity at which a message can be logged.
+type Severity int8
+
+// These constants identify the log levels in order of increasing severity.
+// A message written to a high-severity log file is also written to each
+// lower-severity log file.
+const (
+	Info Severity = iota
+	Warning
+	Error
+
+	// Fatal contains logs written immediately before the process terminates.
+	//
+	// Sink implementations should not terminate the process themselves: the log
+	// package will perform any necessary cleanup and terminate the process as
+	// appropriate.
+	Fatal
+)
+
+func (s Severity) String() string {
+	switch s {
+	case Info:
+		return "INFO"
+	case Warning:
+		return "WARNING"
+	case Error:
+		return "ERROR"
+	case Fatal:
+		return "FATAL"
+	}
+	return fmt.Sprintf("%T(%d)", s, s)
+}
+
+// ParseSeverity returns the case-insensitive Severity value for the given string.
+func ParseSeverity(name string) (Severity, error) {
+	name = strings.ToUpper(name)
+	for s := Info; s <= Fatal; s++ {
+		if s.String() == name {
+			return s, nil
+		}
+	}
+	return -1, fmt.Errorf("logsink: invalid severity %q", name)
+}
+
+// Meta is metadata about a logging call.
+type Meta struct {
+	// The context with which the log call was made (or nil). If set, the context
+	// is only valid during the logsink.Structured.Printf call, it should not be
+	// retained.
+	Context context.Context
+
+	// Time is the time at which the log call was made.
+	Time time.Time
+
+	// File is the source file from which the log entry originates.
+	File string
+	// Line is the line offset within the source file.
+	Line int
+	// Depth is the number of stack frames between the logsink and the log call.
+	Depth int
+
+	Severity Severity
+
+	// Verbose indicates whether the call was made via "log.V".  Log entries below
+	// the current verbosity threshold are not sent to the sink.
+	Verbose bool
+
+	// Thread ID. This can be populated with a thread ID from another source,
+	// such as a system we are importing logs from. In the normal case, this
+	// will be set to the process ID (PID), since Go doesn't have threads.
+	Thread int64
+
+	// Stack trace starting in the logging function. May be nil.
+	// A logsink should implement the StackWanter interface to request this.
+	//
+	// Even if WantStack returns false, this field may be set (e.g. if another
+	// sink wants a stack trace).
+	Stack *stackdump.Stack
+}
+
+// Structured is a logging destination that accepts structured data as input.
+type Structured interface {
+	// Printf formats according to a fmt.Printf format specifier and writes a log
+	// entry.  The precise result of formatting depends on the sink, but should
+	// aim for consistency with fmt.Printf.
+	//
+	// Printf returns the number of bytes occupied by the log entry, which
+	// may not be equal to the total number of bytes written.
+	//
+	// Printf returns any error encountered *if* it is severe enough that the log
+	// package should terminate the process.
+	//
+	// The sink must not modify the *Meta parameter, nor reference it after
+	// Printf has returned: it may be reused in subsequent calls.
+	Printf(meta *Meta, format string, a ...any) (n int, err error)
+}
+
+// StackWanter can be implemented by a logsink.Structured to indicate that it
+// wants a stack trace to accompany at least some of the log messages it receives.
+type StackWanter interface {
+	// WantStack returns true if the sink requires a stack trace for a log message
+	// with this metadata.
+	//
+	// NOTE: Returning true implies that meta.Stack will be non-nil. Returning
+	// false does NOT imply that meta.Stack will be nil.
+	WantStack(meta *Meta) bool
+}
+
+// Text is a logging destination that accepts pre-formatted log lines (instead of
+// structured data).
+type Text interface {
+	// Enabled returns whether this sink should output messages for the given
+	// Meta.  If the sink returns false for a given Meta, the Printf function will
+	// not call Emit on it for the corresponding log message.
+	Enabled(*Meta) bool
+
+	// Emit writes a pre-formatted text log entry (including any applicable
+	// header) to the log.  It returns the number of bytes occupied by the entry
+	// (which may differ from the length of the passed-in slice).
+	//
+	// Emit returns any error encountered *if* it is severe enough that the log
+	// package should terminate the process.
+	//
+	// The sink must not modify the *Meta parameter, nor reference it after
+	// Printf has returned: it may be reused in subsequent calls.
+	//
+	// NOTE: When developing a text sink, keep in mind the surface in which the
+	// logs will be displayed, and whether it's important that the sink be
+	// resistent to tampering in the style of b/211428300. Standard text sinks
+	// (like `stderrSink`) do not protect against this (e.g. by escaping
+	// characters) because the cases where they would show user-influenced bytes
+	// are vanishingly small.
+	Emit(*Meta, []byte) (n int, err error)
+}
+
+// bufs is a pool of *bytes.Buffer used in formatting log entries.
+var bufs sync.Pool // Pool of *bytes.Buffer.
+
+// textPrintf formats a text log entry and emits it to all specified Text sinks.
+//
+// The returned n is the maximum across all Emit calls.
+// The returned err is the first non-nil error encountered.
+// Sinks that are disabled by configuration should return (0, nil).
+func textPrintf(m *Meta, textSinks []Text, format string, args ...any) (n int, err error) {
+	// We expect at most file, stderr, and perhaps syslog.  If there are more,
+	// we'll end up allocating - no big deal.
+	const maxExpectedTextSinks = 3
+	var noAllocSinks [maxExpectedTextSinks]Text
+
+	sinks := noAllocSinks[:0]
+	for _, s := range textSinks {
+		if s.Enabled(m) {
+			sinks = append(sinks, s)
+		}
+	}
+	if len(sinks) == 0 && m.Severity != Fatal {
+		return 0, nil // No TextSinks specified; don't bother formatting.
+	}
+
+	bufi := bufs.Get()
+	var buf *bytes.Buffer
+	if bufi == nil {
+		buf = bytes.NewBuffer(nil)
+		bufi = buf
+	} else {
+		buf = bufi.(*bytes.Buffer)
+		buf.Reset()
+	}
+
+	// Lmmdd hh:mm:ss.uuuuuu PID/GID file:line]
+	//
+	// The "PID" entry arguably ought to be TID for consistency with other
+	// environments, but TID is not meaningful in a Go program due to the
+	// multiplexing of goroutines across threads.
+	//
+	// Avoid Fprintf, for speed. The format is so simple that we can do it quickly by hand.
+	// It's worth about 3X. Fprintf is hard.
+	const severityChar = "IWEF"
+	buf.WriteByte(severityChar[m.Severity])
+
+	_, month, day := m.Time.Date()
+	hour, minute, second := m.Time.Clock()
+	twoDigits(buf, int(month))
+	twoDigits(buf, day)
+	buf.WriteByte(' ')
+	twoDigits(buf, hour)
+	buf.WriteByte(':')
+	twoDigits(buf, minute)
+	buf.WriteByte(':')
+	twoDigits(buf, second)
+	buf.WriteByte('.')
+	nDigits(buf, 6, uint64(m.Time.Nanosecond()/1000), '0')
+	buf.WriteByte(' ')
+
+	nDigits(buf, 7, uint64(m.Thread), ' ')
+	buf.WriteByte(' ')
+
+	{
+		file := m.File
+		if i := strings.LastIndex(file, "/"); i >= 0 {
+			file = file[i+1:]
+		}
+		buf.WriteString(file)
+	}
+
+	buf.WriteByte(':')
+	{
+		var tmp [19]byte
+		buf.Write(strconv.AppendInt(tmp[:0], int64(m.Line), 10))
+	}
+	buf.WriteString("] ")
+
+	msgStart := buf.Len()
+	fmt.Fprintf(buf, format, args...)
+	if buf.Len() > MaxLogMessageLen-1 {
+		buf.Truncate(MaxLogMessageLen - 1)
+	}
+	msgEnd := buf.Len()
+	if b := buf.Bytes(); b[len(b)-1] != '\n' {
+		buf.WriteByte('\n')
+	}
+
+	for _, s := range sinks {
+		sn, sErr := s.Emit(m, buf.Bytes())
+		if sn > n {
+			n = sn
+		}
+		if sErr != nil && err == nil {
+			err = sErr
+		}
+	}
+
+	if m.Severity == Fatal {
+		savedM := *m
+		fatalMessageStore(savedEntry{
+			meta: &savedM,
+			msg:  buf.Bytes()[msgStart:msgEnd],
+		})
+	} else {
+		bufs.Put(bufi)
+	}
+	return n, err
+}
+
+const digits = "0123456789"
+
+// twoDigits formats a zero-prefixed two-digit integer to buf.
+func twoDigits(buf *bytes.Buffer, d int) {
+	buf.WriteByte(digits[(d/10)%10])
+	buf.WriteByte(digits[d%10])
+}
+
+// nDigits formats an n-digit integer to buf, padding with pad on the left. It
+// assumes d != 0.
+func nDigits(buf *bytes.Buffer, n int, d uint64, pad byte) {
+	var tmp [20]byte
+
+	cutoff := len(tmp) - n
+	j := len(tmp) - 1
+	for ; d > 0; j-- {
+		tmp[j] = digits[d%10]
+		d /= 10
+	}
+	for ; j >= cutoff; j-- {
+		tmp[j] = pad
+	}
+	j++
+	buf.Write(tmp[j:])
+}
+
+// Printf writes a log entry to all registered TextSinks in this package, then
+// to all registered StructuredSinks.
+//
+// The returned n is the maximum across all Emit and Printf calls.
+// The returned err is the first non-nil error encountered.
+// Sinks that are disabled by configuration should return (0, nil).
+func Printf(m *Meta, format string, args ...any) (n int, err error) {
+	m.Depth++
+	n, err = textPrintf(m, TextSinks, format, args...)
+
+	for _, sink := range StructuredSinks {
+		// TODO: Support TextSinks that implement StackWanter?
+		if sw, ok := sink.(StackWanter); ok && sw.WantStack(m) {
+			if m.Stack == nil {
+				// First, try to find a stacktrace in args, otherwise generate one.
+				for _, arg := range args {
+					if stack, ok := arg.(stackdump.Stack); ok {
+						m.Stack = &stack
+						break
+					}
+				}
+				if m.Stack == nil {
+					stack := stackdump.Caller( /* skipDepth = */ m.Depth)
+					m.Stack = &stack
+				}
+			}
+		}
+		sn, sErr := sink.Printf(m, format, args...)
+		if sn > n {
+			n = sn
+		}
+		if sErr != nil && err == nil {
+			err = sErr
+		}
+	}
+	return n, err
+}
+
+// The sets of sinks to which logs should be written.
+//
+// These must only be modified during package init, and are read-only thereafter.
+var (
+	// StructuredSinks is the set of Structured sink instances to which logs
+	// should be written.
+	StructuredSinks []Structured
+
+	// TextSinks is the set of Text sink instances to which logs should be
+	// written.
+	//
+	// These are registered separately from Structured sink implementations to
+	// avoid the need to repeat the work of formatting a message for each Text
+	// sink that writes it.  The package-level Printf function writes to both sets
+	// independenty, so a given log destination should only register a Structured
+	// *or* a Text sink (not both).
+	TextSinks []Text
+)
+
+type savedEntry struct {
+	meta *Meta
+	msg  []byte
+}
+
+// StructuredTextWrapper is a Structured sink which forwards logs to a set of Text sinks.
+//
+// The purpose of this sink is to allow applications to intercept logging calls before they are
+// serialized and sent to Text sinks. For example, if one needs to redact PII from logging
+// arguments before they reach STDERR, one solution would be to do the redacting in a Structured
+// sink that forwards logs to a StructuredTextWrapper instance, and make STDERR a child of that
+// StructuredTextWrapper instance. This is how one could set this up in their application:
+//
+// func init() {
+//
+//	wrapper := logsink.StructuredTextWrapper{TextSinks: logsink.TextSinks}
+//	// sanitizersink will intercept logs and remove PII
+//	sanitizer := sanitizersink{Sink: &wrapper}
+//	logsink.StructuredSinks = append(logsink.StructuredSinks, &sanitizer)
+//	logsink.TextSinks = nil
+//
+// }
+type StructuredTextWrapper struct {
+	// TextSinks is the set of Text sinks that should receive logs from this
+	// StructuredTextWrapper instance.
+	TextSinks []Text
+}
+
+// Printf forwards logs to all Text sinks registered in the StructuredTextWrapper.
+func (w *StructuredTextWrapper) Printf(meta *Meta, format string, args ...any) (n int, err error) {
+	return textPrintf(meta, w.TextSinks, format, args...)
+}

vendor/github.com/golang/glog/internal/logsink/logsink_fatal.go

@@ -0,0 +1,35 @@
+package logsink
+
+import (
+	"sync/atomic"
+	"unsafe"
+)
+
+func fatalMessageStore(e savedEntry) {
+	// Only put a new one in if we haven't assigned before.
+	atomic.CompareAndSwapPointer(&fatalMessage, nil, unsafe.Pointer(&e))
+}
+
+var fatalMessage unsafe.Pointer // savedEntry stored with CompareAndSwapPointer
+
+// FatalMessage returns the Meta and message contents of the first message
+// logged with Fatal severity, or false if none has occurred.
+func FatalMessage() (*Meta, []byte, bool) {
+	e := (*savedEntry)(atomic.LoadPointer(&fatalMessage))
+	if e == nil {
+		return nil, nil, false
+	}
+	return e.meta, e.msg, true
+}
+
+// DoNotUseRacyFatalMessage is FatalMessage, but worse.
+//
+//go:norace
+//go:nosplit
+func DoNotUseRacyFatalMessage() (*Meta, []byte, bool) {
+	e := (*savedEntry)(fatalMessage)
+	if e == nil {
+		return nil, nil, false
+	}
+	return e.meta, e.msg, true
+}

vendor/github.com/golang/glog/internal/stackdump/stackdump.go

@@ -0,0 +1,127 @@
+// Copyright 2023 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 stackdump provides wrappers for runtime.Stack and runtime.Callers
+// with uniform support for skipping caller frames.
+//
+// ⚠ Unlike the functions in the runtime package, these may allocate a
+// non-trivial quantity of memory: use them with care. ⚠
+package stackdump
+
+import (
+	"bytes"
+	"runtime"
+)
+
+// runtimeStackSelfFrames is 1 if runtime.Stack includes the call to
+// runtime.Stack itself or 0 if it does not.
+//
+// As of 2016-04-27, the gccgo compiler includes runtime.Stack but the gc
+// compiler does not.
+var runtimeStackSelfFrames = func() int {
+	for n := 1 << 10; n < 1<<20; n *= 2 {
+		buf := make([]byte, n)
+		n := runtime.Stack(buf, false)
+		if bytes.Contains(buf[:n], []byte("runtime.Stack")) {
+			return 1
+		} else if n < len(buf) || bytes.Count(buf, []byte("\n")) >= 3 {
+			return 0
+		}
+	}
+	return 0
+}()
+
+// Stack is a stack dump for a single goroutine.
+type Stack struct {
+	// Text is a representation of the stack dump in a human-readable format.
+	Text []byte
+
+	// PC is a representation of the stack dump using raw program counter values.
+	PC []uintptr
+}
+
+func (s Stack) String() string { return string(s.Text) }
+
+// Caller returns the Stack dump for the calling goroutine, starting skipDepth
+// frames before the caller of Caller.  (Caller(0) provides a dump starting at
+// the caller of this function.)
+func Caller(skipDepth int) Stack {
+	return Stack{
+		Text: CallerText(skipDepth + 1),
+		PC:   CallerPC(skipDepth + 1),
+	}
+}
+
+// CallerText returns a textual dump of the stack starting skipDepth frames before
+// the caller.  (CallerText(0) provides a dump starting at the caller of this
+// function.)
+func CallerText(skipDepth int) []byte {
+	for n := 1 << 10; ; n *= 2 {
+		buf := make([]byte, n)
+		n := runtime.Stack(buf, false)
+		if n < len(buf) {
+			return pruneFrames(skipDepth+1+runtimeStackSelfFrames, buf[:n])
+		}
+	}
+}
+
+// CallerPC returns a dump of the program counters of the stack starting
+// skipDepth frames before the caller.  (CallerPC(0) provides a dump starting at
+// the caller of this function.)
+func CallerPC(skipDepth int) []uintptr {
+	for n := 1 << 8; ; n *= 2 {
+		buf := make([]uintptr, n)
+		n := runtime.Callers(skipDepth+2, buf)
+		if n < len(buf) {
+			return buf[:n]
+		}
+	}
+}
+
+// pruneFrames removes the topmost skipDepth frames of the first goroutine in a
+// textual stack dump.  It overwrites the passed-in slice.
+//
+// If there are fewer than skipDepth frames in the first goroutine's stack,
+// pruneFrames prunes it to an empty stack and leaves the remaining contents
+// intact.
+func pruneFrames(skipDepth int, stack []byte) []byte {
+	headerLen := 0
+	for i, c := range stack {
+		if c == '\n' {
+			headerLen = i + 1
+			break
+		}
+	}
+	if headerLen == 0 {
+		return stack // No header line - not a well-formed stack trace.
+	}
+
+	skipLen := headerLen
+	skipNewlines := skipDepth * 2
+	for ; skipLen < len(stack) && skipNewlines > 0; skipLen++ {
+		c := stack[skipLen]
+		if c != '\n' {
+			continue
+		}
+		skipNewlines--
+		skipLen++
+		if skipNewlines == 0 || skipLen == len(stack) || stack[skipLen] == '\n' {
+			break
+		}
+	}
+
+	pruned := stack[skipLen-headerLen:]
+	copy(pruned, stack[:headerLen])
+	return pruned
+}