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go/cmd/toolstash/main.go

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// 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.
// Toolstash provides a way to save, run, and restore a known good copy of the Go toolchain
// and to compare the object files generated by two toolchains.
//
// Usage:
//
// toolstash [-n] [-v] save [tool...]
// toolstash [-n] [-v] restore [tool...]
// toolstash [-n] [-v] [-t] go run x.go
// toolstash [-n] [-v] [-t] [-cmp] compile x.go
//
// The toolstash command manages a ``stashed'' copy of the Go toolchain
// kept in $GOROOT/pkg/toolstash. In this case, the toolchain means the
// tools available with the 'go tool' command as well as the go, godoc, and gofmt
// binaries.
//
// The command ``toolstash save'', typically run when the toolchain is known to be working,
// copies the toolchain from its installed location to the toolstash directory.
// Its inverse, ``toolchain restore'', typically run when the toolchain is known to be broken,
// copies the toolchain from the toolstash directory back to the installed locations.
// If additional arguments are given, the save or restore applies only to the named tools.
// Otherwise, it applies to all tools.
//
// Otherwise, toolstash's arguments should be a command line beginning with the
// name of a toolchain binary, which may be a short name like compile or a complete path
// to an installed binary. Toolstash runs the command line using the stashed
// copy of the binary instead of the installed one.
//
// The -n flag causes toolstash to print the commands that would be executed
// but not execute them. The combination -n -cmp shows the two commands
// that would be compared and then exits successfully. A real -cmp run might
// run additional commands for diagnosis of an output mismatch.
//
// The -v flag causes toolstash to print the commands being executed.
//
// The -t flag causes toolstash to print the time elapsed during while the
// command ran.
//
// Comparing
//
// The -cmp flag causes toolstash to run both the installed and the stashed
// copy of an assembler or compiler and check that they produce identical
// object files. If not, toolstash reports the mismatch and exits with a failure status.
// As part of reporting the mismatch, toolstash reinvokes the command with
// the -S flag and identifies the first divergence in the assembly output.
// If the command is a Go compiler, toolstash also determines whether the
// difference is triggered by optimization passes.
// On failure, toolstash leaves additional information in files named
// similarly to the default output file. If the compilation would normally
// produce a file x.6, the output from the stashed tool is left in x.6.stash
// and the debugging traces are left in x.6.log and x.6.stash.log.
//
// The -cmp flag is a no-op when the command line is not invoking an
// assembler or compiler.
//
// For example, when working on code cleanup that should not affect
// compiler output, toolstash can be used to compare the old and new
// compiler output:
//
// toolstash save
// <edit compiler sources>
// go tool dist install cmd/compile # install compiler only
// toolstash -cmp compile x.go
//
// Go Command Integration
//
// The go command accepts a -toolexec flag that specifies a program
// to use to run the build tools.
//
// To build with the stashed tools:
//
// go build -toolexec toolstash x.go
//
// To build with the stashed go command and the stashed tools:
//
// toolstash go build -toolexec toolstash x.go
//
// To verify that code cleanup in the compilers does not make any
// changes to the objects being generated for the entire tree:
//
// # Build working tree and save tools.
// ./make.bash
// toolstash save
//
// <edit compiler sources>
//
// # Install new tools, but do not rebuild the rest of tree,
// # since the compilers might generate buggy code.
// go tool dist install cmd/compile
//
// # Check that new tools behave identically to saved tools.
// go build -toolexec 'toolstash -cmp' -a std
//
// # If not, restore, in order to keep working on Go code.
// toolstash restore
//
// Version Skew
//
// The Go tools write the current Go version to object files, and (outside
// release branches) that version includes the hash and time stamp
// of the most recent Git commit. Functionally equivalent
// compilers built at different Git versions may produce object files that
// differ only in the recorded version. Toolstash ignores version mismatches
// when comparing object files, but the standard tools will refuse to compile
// or link together packages with different object versions.
//
// For the full build in the final example above to work, both the stashed
// and the installed tools must use the same version string.
// One way to ensure this is not to commit any of the changes being
// tested, so that the Git HEAD hash is the same for both builds.
// A more robust way to force the tools to have the same version string
// is to write a $GOROOT/VERSION file, which overrides the Git-based version
// computation:
//
// echo devel >$GOROOT/VERSION
//
// The version can be arbitrary text, but to pass all.bash's API check, it must
// contain the substring ``devel''. The VERSION file must be created before
// building either version of the toolchain.
//
package main // import "golang.org/x/tools/cmd/toolstash"
import (
"bufio"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"time"
)
var usageMessage = `usage: toolstash [-n] [-v] [-cmp] command line
Examples:
toolstash save
toolstash restore
toolstash go run x.go
toolstash compile x.go
toolstash -cmp compile x.go
For details, godoc golang.org/x/tools/cmd/toolstash
`
func usage() {
fmt.Fprint(os.Stderr, usageMessage)
os.Exit(2)
}
var (
goCmd = flag.String("go", "go", "path to \"go\" command")
norun = flag.Bool("n", false, "print but do not run commands")
verbose = flag.Bool("v", false, "print commands being run")
cmp = flag.Bool("cmp", false, "compare tool object files")
timing = flag.Bool("t", false, "print time commands take")
)
var (
cmd []string
tool string // name of tool: "go", "compile", etc
toolStash string // path to stashed tool
goroot string
toolDir string
stashDir string
binDir string
)
func canCmp(name string, args []string) bool {
switch name {
case "asm", "compile", "link":
if len(args) == 1 && (args[0] == "-V" || strings.HasPrefix(args[0], "-V=")) {
// cmd/go uses "compile -V=full" to query the tool's build ID.
return false
}
return true
}
return len(name) == 2 && '0' <= name[0] && name[0] <= '9' && (name[1] == 'a' || name[1] == 'g' || name[1] == 'l')
}
var binTools = []string{"go", "godoc", "gofmt"}
func isBinTool(name string) bool {
return strings.HasPrefix(name, "go")
}
func main() {
log.SetFlags(0)
log.SetPrefix("toolstash: ")
flag.Usage = usage
flag.Parse()
cmd = flag.Args()
if len(cmd) < 1 {
usage()
}
s, err := exec.Command(*goCmd, "env", "GOROOT").CombinedOutput()
if err != nil {
log.Fatalf("%s env GOROOT: %v", *goCmd, err)
}
goroot = strings.TrimSpace(string(s))
toolDir = filepath.Join(goroot, fmt.Sprintf("pkg/tool/%s_%s", runtime.GOOS, runtime.GOARCH))
stashDir = filepath.Join(goroot, "pkg/toolstash")
binDir = os.Getenv("GOBIN")
if binDir == "" {
binDir = filepath.Join(goroot, "bin")
}
switch cmd[0] {
case "save":
save()
return
case "restore":
restore()
return
}
tool = cmd[0]
if i := strings.LastIndexAny(tool, `/\`); i >= 0 {
tool = tool[i+1:]
}
if !strings.HasPrefix(tool, "a.out") {
toolStash = filepath.Join(stashDir, tool)
if _, err := os.Stat(toolStash); err != nil {
log.Print(err)
os.Exit(2)
}
if *cmp && canCmp(tool, cmd[1:]) {
compareTool()
return
}
cmd[0] = toolStash
}
if *norun {
fmt.Printf("%s\n", strings.Join(cmd, " "))
return
}
if *verbose {
log.Print(strings.Join(cmd, " "))
}
xcmd := exec.Command(cmd[0], cmd[1:]...)
xcmd.Stdin = os.Stdin
xcmd.Stdout = os.Stdout
xcmd.Stderr = os.Stderr
err = xcmd.Run()
if err != nil {
log.Fatal(err)
}
os.Exit(0)
}
func compareTool() {
if !strings.Contains(cmd[0], "/") && !strings.Contains(cmd[0], `\`) {
cmd[0] = filepath.Join(toolDir, tool)
}
outfile, ok := cmpRun(false, cmd)
if ok {
os.Remove(outfile + ".stash")
return
}
extra := "-S"
switch {
default:
log.Fatalf("unknown tool %s", tool)
case tool == "compile" || strings.HasSuffix(tool, "g"): // compiler
useDashN := true
dashcIndex := -1
for i, s := range cmd {
if s == "-+" {
// Compiling runtime. Don't use -N.
useDashN = false
}
if strings.HasPrefix(s, "-c=") {
dashcIndex = i
}
}
cmdN := injectflags(cmd, nil, useDashN)
_, ok := cmpRun(false, cmdN)
if !ok {
if useDashN {
log.Printf("compiler output differs, with optimizers disabled (-N)")
} else {
log.Printf("compiler output differs")
}
if dashcIndex >= 0 {
cmd[dashcIndex] = "-c=1"
}
cmd = injectflags(cmd, []string{"-v", "-m=2"}, useDashN)
break
}
if dashcIndex >= 0 {
cmd[dashcIndex] = "-c=1"
}
cmd = injectflags(cmd, []string{"-v", "-m=2"}, false)
log.Printf("compiler output differs, only with optimizers enabled")
case tool == "asm" || strings.HasSuffix(tool, "a"): // assembler
log.Printf("assembler output differs")
case tool == "link" || strings.HasSuffix(tool, "l"): // linker
log.Printf("linker output differs")
extra = "-v=2"
}
cmdS := injectflags(cmd, []string{extra}, false)
outfile, _ = cmpRun(true, cmdS)
fmt.Fprintf(os.Stderr, "\n%s\n", compareLogs(outfile))
os.Exit(2)
}
func injectflags(cmd []string, extra []string, addDashN bool) []string {
x := []string{cmd[0]}
if addDashN {
x = append(x, "-N")
}
x = append(x, extra...)
x = append(x, cmd[1:]...)
return x
}
func cmpRun(keepLog bool, cmd []string) (outfile string, match bool) {
cmdStash := make([]string, len(cmd))
copy(cmdStash, cmd)
cmdStash[0] = toolStash
for i, arg := range cmdStash {
if arg == "-o" {
outfile = cmdStash[i+1]
cmdStash[i+1] += ".stash"
break
}
if strings.HasSuffix(arg, ".s") || strings.HasSuffix(arg, ".go") && '0' <= tool[0] && tool[0] <= '9' {
outfile = filepath.Base(arg[:strings.LastIndex(arg, ".")] + "." + tool[:1])
cmdStash = append([]string{cmdStash[0], "-o", outfile + ".stash"}, cmdStash[1:]...)
break
}
}
if outfile == "" {
log.Fatalf("cannot determine output file for command: %s", strings.Join(cmd, " "))
}
if *norun {
fmt.Printf("%s\n", strings.Join(cmd, " "))
fmt.Printf("%s\n", strings.Join(cmdStash, " "))
os.Exit(0)
}
out, err := runCmd(cmd, keepLog, outfile+".log")
if err != nil {
log.Printf("running: %s", strings.Join(cmd, " "))
os.Stderr.Write(out)
log.Fatal(err)
}
outStash, err := runCmd(cmdStash, keepLog, outfile+".stash.log")
if err != nil {
log.Printf("running: %s", strings.Join(cmdStash, " "))
log.Printf("installed tool succeeded but stashed tool failed.\n")
if len(out) > 0 {
log.Printf("installed tool output:")
os.Stderr.Write(out)
}
if len(outStash) > 0 {
log.Printf("stashed tool output:")
os.Stderr.Write(outStash)
}
log.Fatal(err)
}
return outfile, sameObject(outfile, outfile+".stash")
}
func sameObject(file1, file2 string) bool {
f1, err := os.Open(file1)
if err != nil {
log.Fatal(err)
}
defer f1.Close()
f2, err := os.Open(file2)
if err != nil {
log.Fatal(err)
}
defer f2.Close()
b1 := bufio.NewReader(f1)
b2 := bufio.NewReader(f2)
// Go object files and archives contain lines of the form
// go object <goos> <goarch> <version>
// By default, the version on development branches includes
// the Git hash and time stamp for the most recent commit.
// We allow the versions to differ.
if !skipVersion(b1, b2, file1, file2) {
return false
}
lastByte := byte(0)
for {
c1, err1 := b1.ReadByte()
c2, err2 := b2.ReadByte()
if err1 == io.EOF && err2 == io.EOF {
return true
}
if err1 != nil {
log.Fatalf("reading %s: %v", file1, err1)
}
if err2 != nil {
log.Fatalf("reading %s: %v", file2, err1)
}
if c1 != c2 {
return false
}
if lastByte == '`' && c1 == '\n' {
if !skipVersion(b1, b2, file1, file2) {
return false
}
}
lastByte = c1
}
}
func skipVersion(b1, b2 *bufio.Reader, file1, file2 string) bool {
// Consume "go object " prefix, if there.
prefix := "go object "
for i := 0; i < len(prefix); i++ {
c1, err1 := b1.ReadByte()
c2, err2 := b2.ReadByte()
if err1 == io.EOF && err2 == io.EOF {
return true
}
if err1 != nil {
log.Fatalf("reading %s: %v", file1, err1)
}
if err2 != nil {
log.Fatalf("reading %s: %v", file2, err1)
}
if c1 != c2 {
return false
}
if c1 != prefix[i] {
return true // matching bytes, just not a version
}
}
// Keep comparing until second space.
// Must continue to match.
// If we see a \n, it's not a version string after all.
for numSpace := 0; numSpace < 2; {
c1, err1 := b1.ReadByte()
c2, err2 := b2.ReadByte()
if err1 == io.EOF && err2 == io.EOF {
return true
}
if err1 != nil {
log.Fatalf("reading %s: %v", file1, err1)
}
if err2 != nil {
log.Fatalf("reading %s: %v", file2, err1)
}
if c1 != c2 {
return false
}
if c1 == '\n' {
return true
}
if c1 == ' ' {
numSpace++
}
}
// Have now seen 'go object goos goarch ' in both files.
// Now they're allowed to diverge, until the \n, which
// must be present.
for {
c1, err1 := b1.ReadByte()
if err1 == io.EOF {
log.Fatalf("reading %s: unexpected EOF", file1)
}
if err1 != nil {
log.Fatalf("reading %s: %v", file1, err1)
}
if c1 == '\n' {
break
}
}
for {
c2, err2 := b2.ReadByte()
if err2 == io.EOF {
log.Fatalf("reading %s: unexpected EOF", file2)
}
if err2 != nil {
log.Fatalf("reading %s: %v", file2, err2)
}
if c2 == '\n' {
break
}
}
// Consumed "matching" versions from both.
return true
}
func runCmd(cmd []string, keepLog bool, logName string) (output []byte, err error) {
if *verbose {
log.Print(strings.Join(cmd, " "))
}
if *timing {
t0 := time.Now()
defer func() {
log.Printf("%.3fs elapsed # %s\n", time.Since(t0).Seconds(), strings.Join(cmd, " "))
}()
}
xcmd := exec.Command(cmd[0], cmd[1:]...)
if !keepLog {
return xcmd.CombinedOutput()
}
f, err := os.Create(logName)
if err != nil {
log.Fatal(err)
}
fmt.Fprintf(f, "GOOS=%s GOARCH=%s %s\n", os.Getenv("GOOS"), os.Getenv("GOARCH"), strings.Join(cmd, " "))
xcmd.Stdout = f
xcmd.Stderr = f
defer f.Close()
return nil, xcmd.Run()
}
func save() {
if err := os.MkdirAll(stashDir, 0777); err != nil {
log.Fatal(err)
}
toolDir := filepath.Join(goroot, fmt.Sprintf("pkg/tool/%s_%s", runtime.GOOS, runtime.GOARCH))
files, err := ioutil.ReadDir(toolDir)
if err != nil {
log.Fatal(err)
}
for _, file := range files {
if shouldSave(file.Name()) && file.Mode().IsRegular() {
cp(filepath.Join(toolDir, file.Name()), filepath.Join(stashDir, file.Name()))
}
}
for _, name := range binTools {
if !shouldSave(name) {
continue
}
src := filepath.Join(binDir, name)
if _, err := os.Stat(src); err == nil {
cp(src, filepath.Join(stashDir, name))
}
}
checkShouldSave()
}
func restore() {
files, err := ioutil.ReadDir(stashDir)
if err != nil {
log.Fatal(err)
}
for _, file := range files {
if shouldSave(file.Name()) && file.Mode().IsRegular() {
targ := toolDir
if isBinTool(file.Name()) {
targ = binDir
}
cp(filepath.Join(stashDir, file.Name()), filepath.Join(targ, file.Name()))
}
}
checkShouldSave()
}
func shouldSave(name string) bool {
if len(cmd) == 1 {
return true
}
ok := false
for i, arg := range cmd {
if i > 0 && name == arg {
ok = true
cmd[i] = "DONE"
}
}
return ok
}
func checkShouldSave() {
var missing []string
for _, arg := range cmd[1:] {
if arg != "DONE" {
missing = append(missing, arg)
}
}
if len(missing) > 0 {
log.Fatalf("%s did not find tools: %s", cmd[0], strings.Join(missing, " "))
}
}
func cp(src, dst string) {
if *verbose {
fmt.Printf("cp %s %s\n", src, dst)
}
data, err := ioutil.ReadFile(src)
if err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(dst, data, 0777); err != nil {
log.Fatal(err)
}
}