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cmd/go: add -trimpath build flag
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"go build -trimpath" trims the recorded file paths in the
resulting packages and executables to avoid recording
the names of any local directories. Instead, the files appear
to be stored in directories named either "go/src/..." (for the
standard library) or named after the module or package
in which the files appear.

Fixes #16860.

Change-Id: I433afeeb1fdeea641286b21693fee5e0a66d607e
Reviewed-on: https://go-review.googlesource.com/c/go/+/173345
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
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rsc committed Apr 24, 2019
1 parent 8a20fde commit 7469564
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Showing 8 changed files with 85 additions and 15 deletions.
6 changes: 6 additions & 0 deletions src/cmd/go/alldocs.go

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1 change: 1 addition & 0 deletions src/cmd/go/internal/cfg/cfg.go
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ var (
BuildToolchainName string
BuildToolchainCompiler func() string
BuildToolchainLinker func() string
BuildTrimpath bool // -trimpath flag
BuildV bool // -v flag
BuildWork bool // -work flag
BuildX bool // -x flag
Expand Down
7 changes: 7 additions & 0 deletions src/cmd/go/internal/work/build.go
Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,12 @@ and test commands:
a space-separated list of build tags to consider satisfied during the
build. For more information about build tags, see the description of
build constraints in the documentation for the go/build package.
-trimpath
remove all file system paths from the resulting executable.
Instead of absolute file system paths, the recorded file names
will begin with either "go" (for the standard library),
or a module path@version (when using modules),
or a plain import path (when using GOPATH).
-toolexec 'cmd args'
a program to use to invoke toolchain programs like vet and asm.
For example, instead of running asm, the go command will run
Expand Down Expand Up @@ -229,6 +235,7 @@ func AddBuildFlags(cmd *base.Command) {
cmd.Flag.BoolVar(&cfg.BuildMSan, "msan", false, "")
cmd.Flag.Var((*base.StringsFlag)(&cfg.BuildContext.BuildTags), "tags", "")
cmd.Flag.Var((*base.StringsFlag)(&cfg.BuildToolexec), "toolexec", "")
cmd.Flag.BoolVar(&cfg.BuildTrimpath, "trimpath", false, "")
cmd.Flag.BoolVar(&cfg.BuildWork, "work", false, "")

// Undocumented, unstable debugging flags.
Expand Down
3 changes: 2 additions & 1 deletion src/cmd/go/internal/work/exec.go
Original file line number Diff line number Diff line change
Expand Up @@ -1930,7 +1930,8 @@ func joinUnambiguously(a []string) string {
q := strconv.Quote(s)
// A gccgo command line can contain -( and -).
// Make sure we quote them since they are special to the shell.
if s == "" || strings.ContainsAny(s, " ()") || len(q) > len(s)+2 {
// The trimpath argument can also contain > (part of =>) and ;. Quote those too.
if s == "" || strings.ContainsAny(s, " ()>;") || len(q) > len(s)+2 {
buf.WriteString(q)
} else {
buf.WriteString(s)
Expand Down
34 changes: 27 additions & 7 deletions src/cmd/go/internal/work/gc.go
Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ func (gcToolchain) gc(b *Builder, a *Action, archive string, importcfg []byte, s
}
}

args := []interface{}{cfg.BuildToolexec, base.Tool("compile"), "-o", ofile, "-trimpath", trimDir(a.Objdir), gcflags, gcargs, "-D", p.Internal.LocalPrefix}
args := []interface{}{cfg.BuildToolexec, base.Tool("compile"), "-o", ofile, "-trimpath", a.trimpath(), gcflags, gcargs, "-D", p.Internal.LocalPrefix}
if importcfg != nil {
if err := b.writeFile(objdir+"importcfg", importcfg); err != nil {
return "", nil, err
Expand Down Expand Up @@ -215,17 +215,33 @@ CheckFlags:
return c
}

func trimDir(dir string) string {
if len(dir) > 1 && dir[len(dir)-1] == filepath.Separator {
dir = dir[:len(dir)-1]
// trimpath returns the -trimpath argument to use
// when compiling the action.
func (a *Action) trimpath() string {
// Strip the object directory entirely.
objdir := a.Objdir
if len(objdir) > 1 && objdir[len(objdir)-1] == filepath.Separator {
objdir = objdir[:len(objdir)-1]
}
return dir
rewrite := objdir + "=>"

// For "go build -trimpath", rewrite package source directory
// to a file system-independent path (just the import path).
if cfg.BuildTrimpath {
if m := a.Package.Module; m != nil {
rewrite += ";" + m.Dir + "=>" + m.Path + "@" + m.Version
} else {
rewrite += ";" + a.Package.Dir + "=>" + a.Package.ImportPath
}
}

return rewrite
}

func asmArgs(a *Action, p *load.Package) []interface{} {
// Add -I pkg/GOOS_GOARCH so #include "textflag.h" works in .s files.
inc := filepath.Join(cfg.GOROOT, "pkg", "include")
args := []interface{}{cfg.BuildToolexec, base.Tool("asm"), "-trimpath", trimDir(a.Objdir), "-I", a.Objdir, "-I", inc, "-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch, forcedAsmflags, p.Internal.Asmflags}
args := []interface{}{cfg.BuildToolexec, base.Tool("asm"), "-trimpath", a.trimpath(), "-I", a.Objdir, "-I", inc, "-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch, forcedAsmflags, p.Internal.Asmflags}
if p.ImportPath == "runtime" && cfg.Goarch == "386" {
for _, arg := range forcedAsmflags {
if arg == "-dynlink" {
Expand Down Expand Up @@ -567,7 +583,11 @@ func (gcToolchain) ld(b *Builder, root *Action, out, importcfg, mainpkg string)
dir, out = filepath.Split(out)
}

return b.run(root, dir, root.Package.ImportPath, nil, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags, mainpkg)
env := []string{}
if cfg.BuildTrimpath {
env = append(env, "GOROOT_FINAL=go")
}
return b.run(root, dir, root.Package.ImportPath, env, cfg.BuildToolexec, base.Tool("link"), "-o", out, "-importcfg", importcfg, ldflags, mainpkg)
}

func (gcToolchain) ldShared(b *Builder, root *Action, toplevelactions []*Action, out, importcfg string, allactions []*Action) error {
Expand Down
23 changes: 18 additions & 5 deletions src/cmd/go/script_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -539,6 +539,13 @@ func (ts *testScript) cmdEnv(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! env")
}

conv := func(s string) string { return s }
if len(args) > 0 && args[0] == "-r" {
conv = regexp.QuoteMeta
args = args[1:]
}

if len(args) == 0 {
printed := make(map[string]bool) // env list can have duplicates; only print effective value (from envMap) once
for _, kv := range ts.env {
Expand All @@ -556,8 +563,9 @@ func (ts *testScript) cmdEnv(neg bool, args []string) {
fmt.Fprintf(&ts.log, "%s=%s\n", env, ts.envMap[env])
continue
}
ts.env = append(ts.env, env)
ts.envMap[env[:i]] = env[i+1:]
key, val := env[:i], conv(env[i+1:])
ts.env = append(ts.env, key+"="+val)
ts.envMap[key] = val
}
}

Expand Down Expand Up @@ -743,6 +751,11 @@ func scriptMatch(ts *testScript, neg bool, args []string, text, name string) {
}
args = args[1:]
}
quiet := false
if len(args) >= 1 && args[0] == "-q" {
quiet = true
args = args[1:]
}

extraUsage := ""
want := 1
Expand Down Expand Up @@ -773,22 +786,22 @@ func scriptMatch(ts *testScript, neg bool, args []string, text, name string) {

if neg {
if re.MatchString(text) {
if isGrep {
if isGrep && !quiet {
fmt.Fprintf(&ts.log, "[%s]\n%s\n", name, text)
}
ts.fatalf("unexpected match for %#q found in %s: %s", pattern, name, re.FindString(text))
}
} else {
if !re.MatchString(text) {
if isGrep {
if isGrep && !quiet {
fmt.Fprintf(&ts.log, "[%s]\n%s\n", name, text)
}
ts.fatalf("no match for %#q found in %s", pattern, name)
}
if n > 0 {
count := len(re.FindAllString(text, -1))
if count != n {
if isGrep {
if isGrep && !quiet {
fmt.Fprintf(&ts.log, "[%s]\n%s\n", name, text)
}
ts.fatalf("have %d matches for %#q, want %d", count, pattern, n)
Expand Down
7 changes: 5 additions & 2 deletions src/cmd/go/testdata/script/README
Original file line number Diff line number Diff line change
Expand Up @@ -111,9 +111,11 @@ The commands are:
src can include "stdout" or "stderr" to use the standard output or standard error
from the most recent exec or go command.

- env [key=value...]
- env [-r] [key=value...]
With no arguments, print the environment (useful for debugging).
Otherwise add the listed key=value pairs to the environment.
The -r flag causes the values to be escaped using regexp.QuoteMeta
before being recorded.

- [!] exec program [args...] [&]
Run the given executable program with the arguments.
Expand All @@ -135,9 +137,10 @@ The commands are:
Run the (test copy of the) go command with the given arguments.
It must (or must not) succeed.

- [!] grep [-count=N] pattern file
- [!] grep [-count=N] [-q] pattern file
The file's content must (or must not) match the regular expression pattern.
For positive matches, -count=N specifies an exact number of matches to require.
The -q flag disables printing the file content on a mismatch.

- mkdir path...
Create the listed directories, if they do not already exists.
Expand Down
19 changes: 19 additions & 0 deletions src/cmd/go/testdata/script/build_trimpath.txt
Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
env -r GOROOT_REGEXP=$GOROOT
env -r WORK_REGEXP=$WORK
env GOROOT GOROOT_REGEXP WORK WORK_REGEXP

go build -trimpath -o hello.exe hello.go
! grep -q $GOROOT_REGEXP hello.exe
! grep -q $WORK_REGEXP hello.exe

env GO111MODULE=on
go build -trimpath -o fortune.exe rsc.io/fortune
! grep -q $GOROOT_REGEXP fortune.exe
! grep -q $WORK_REGEXP fortune.exe

-- hello.go --
package main
func main() { println("hello") }

-- go.mod --
module m

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