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cmd/go, cmd/cgo: update gofrontend mangling checks

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This is a port of two patches in the master repository.

https://golang.org/cl/259298

    cmd/cgo: split gofrontend mangling checks into cmd/internal/pkgpath

    This is a step toward porting https://golang.org/cl/219817 from the
    gofrontend repo to the main repo.

    Note that this also corrects the implementation of the v2 mangling
    scheme to use ..u and ..U where appropriate.

https://golang.org/cl/259299

    cmd/go: use cmd/internal/pkgpath for gccgo pkgpath symbol

For golang/go#37272
For golang/go#41862

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/270637
This commit is contained in:
Ian Lance Taylor 2020-10-02 16:03:37 -07:00
parent 4dabb03719
commit 397654d66a
8 changed files with 276 additions and 131 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
gcc/go/gofrontend/MERGE
View File

@ -1,4 +1,4 @@
893fa057e36ae6c9b2ac5ffdf74634c35b3489c6
c948c2d770122932a05b62f653efa2c51f72d3ae
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.

1
libgo/check-packages.txt
View File

@ -22,6 +22,7 @@ cmd/go/internal/work
cmd/internal/buildid
cmd/internal/edit
cmd/internal/objabi
cmd/internal/pkgpath
cmd/internal/test2json
compress/bzip2
compress/flate

3
libgo/go/cmd/cgo/main.go
View File

@ -244,8 +244,7 @@ var exportHeader = flag.String("exportheader", "", "where to write export header
var gccgo = flag.Bool("gccgo", false, "generate files for use with gccgo")
var gccgoprefix = flag.String("gccgoprefix", "", "-fgo-prefix option used with gccgo")
var gccgopkgpath = flag.String("gccgopkgpath", "", "-fgo-pkgpath option used with gccgo")
var gccgoMangleCheckDone bool
var gccgoNewmanglingInEffect bool
var gccgoMangler func(string) string
var importRuntimeCgo = flag.Bool("import_runtime_cgo", true, "import runtime/cgo in generated code")
var importSyscall = flag.Bool("import_syscall", true, "import syscall in generated code")
var goarch, goos string

118
libgo/go/cmd/cgo/out.go
View File

@ -6,6 +6,7 @@ package main
import (
"bytes"
"cmd/internal/pkgpath"
"debug/elf"
"debug/macho"
"debug/pe"
@ -15,7 +16,6 @@ import (
"go/token"
"internal/xcoff"
"io"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
@ -1286,112 +1286,24 @@ func (p *Package) writeExportHeader(fgcch io.Writer) {
fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
}
// gccgoUsesNewMangling reports whether gccgo uses the new collision-free
// packagepath mangling scheme (see determineGccgoManglingScheme for more
// info).
func gccgoUsesNewMangling() bool {
if !gccgoMangleCheckDone {
gccgoNewmanglingInEffect = determineGccgoManglingScheme()
gccgoMangleCheckDone = true
}
return gccgoNewmanglingInEffect
}
const mangleCheckCode = `
package läufer
func Run(x int) int {
return 1
}
`
// determineGccgoManglingScheme performs a runtime test to see which
// flavor of packagepath mangling gccgo is using. Older versions of
// gccgo use a simple mangling scheme where there can be collisions
// between packages whose paths are different but mangle to the same
// string. More recent versions of gccgo use a new mangler that avoids
// these collisions. Return value is whether gccgo uses the new mangling.
func determineGccgoManglingScheme() bool {
// Emit a small Go file for gccgo to compile.
filepat := "*_gccgo_manglecheck.go"
var f *os.File
var err error
if f, err = ioutil.TempFile(*objDir, filepat); err != nil {
fatalf("%v", err)
}
gofilename := f.Name()
defer os.Remove(gofilename)
if err = ioutil.WriteFile(gofilename, []byte(mangleCheckCode), 0666); err != nil {
fatalf("%v", err)
}
// Compile with gccgo, capturing generated assembly.
gccgocmd := os.Getenv("GCCGO")
if gccgocmd == "" {
gpath, gerr := exec.LookPath("gccgo")
if gerr != nil {
fatalf("unable to locate gccgo: %v", gerr)
}
gccgocmd = gpath
}
cmd := exec.Command(gccgocmd, "-S", "-o", "-", gofilename)
buf, cerr := cmd.CombinedOutput()
if cerr != nil {
fatalf("%s", cerr)
}
// New mangling: expect go.l..u00e4ufer.Run
// Old mangling: expect go.l__ufer.Run
return regexp.MustCompile(`go\.l\.\.u00e4ufer\.Run`).Match(buf)
}
// gccgoPkgpathToSymbolNew converts a package path to a gccgo-style
// package symbol.
func gccgoPkgpathToSymbolNew(ppath string) string {
bsl := []byte{}
changed := false
for _, c := range []byte(ppath) {
switch {
case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z',
'0' <= c && c <= '9', c == '_':
bsl = append(bsl, c)
case c == '.':
bsl = append(bsl, ".x2e"...)
default:
changed = true
encbytes := []byte(fmt.Sprintf("..z%02x", c))
bsl = append(bsl, encbytes...)
}
}
if !changed {
return ppath
}
return string(bsl)
}
// gccgoPkgpathToSymbolOld converts a package path to a gccgo-style
// package symbol using the older mangling scheme.
func gccgoPkgpathToSymbolOld(ppath string) string {
clean := func(r rune) rune {
switch {
case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
'0' <= r && r <= '9':
return r
}
return '_'
}
return strings.Map(clean, ppath)
}
// gccgoPkgpathToSymbol converts a package path to a mangled packagepath
// symbol.
func gccgoPkgpathToSymbol(ppath string) string {
if gccgoUsesNewMangling() {
return gccgoPkgpathToSymbolNew(ppath)
} else {
return gccgoPkgpathToSymbolOld(ppath)
if gccgoMangler == nil {
var err error
cmd := os.Getenv("GCCGO")
if cmd == "" {
cmd, err = exec.LookPath("gccgo")
if err != nil {
fatalf("unable to locate gccgo: %v", err)
}
}
gccgoMangler, err = pkgpath.ToSymbolFunc(cmd, *objDir)
if err != nil {
fatalf("%v", err)
}
}
return gccgoMangler(ppath)
}
// Return the package prefix when using gccgo.

47
libgo/go/cmd/go/internal/work/gccgo.go
View File

@ -11,11 +11,13 @@ import (
"os/exec"
"path/filepath"
"strings"
"sync"
"cmd/go/internal/base"
"cmd/go/internal/cfg"
"cmd/go/internal/load"
"cmd/go/internal/str"
"cmd/internal/pkgpath"
)
// The Gccgo toolchain.
@ -174,7 +176,7 @@ func (tools gccgoToolchain) asm(b *Builder, a *Action, sfiles []string) ([]strin
ofiles = append(ofiles, ofile)
sfile = mkAbs(p.Dir, sfile)
defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
if pkgpath := gccgoCleanPkgpath(p); pkgpath != "" {
if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
defs = append(defs, `-D`, `GOPKGPATH=`+pkgpath)
}
defs = tools.maybePIC(defs)
@ -556,7 +558,7 @@ func (tools gccgoToolchain) cc(b *Builder, a *Action, ofile, cfile string) error
cfile = mkAbs(p.Dir, cfile)
defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
defs = append(defs, b.gccArchArgs()...)
if pkgpath := gccgoCleanPkgpath(p); pkgpath != "" {
if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
defs = append(defs, `-D`, `GOPKGPATH="`+pkgpath+`"`)
}
compiler := envList("CC", cfg.DefaultCC(cfg.Goos, cfg.Goarch))
@ -596,28 +598,23 @@ func gccgoPkgpath(p *load.Package) string {
return p.ImportPath
}
// gccgoCleanPkgpath returns the form of p's pkgpath that gccgo uses
// for symbol names. This is like gccgoPkgpathToSymbolNew in cmd/cgo/out.go.
func gccgoCleanPkgpath(p *load.Package) string {
ppath := gccgoPkgpath(p)
bsl := []byte{}
changed := false
for _, c := range []byte(ppath) {
switch {
case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z',
'0' <= c && c <= '9', c == '_':
bsl = append(bsl, c)
case c == '.':
bsl = append(bsl, ".x2e"...)
changed = true
default:
encbytes := []byte(fmt.Sprintf("..z%02x", c))
bsl = append(bsl, encbytes...)
changed = true
var gccgoToSymbolFuncOnce sync.Once
var gccgoToSymbolFunc func(string) string
func (tools gccgoToolchain) gccgoCleanPkgpath(b *Builder, p *load.Package) string {
gccgoToSymbolFuncOnce.Do(func() {
if cfg.BuildN {
gccgoToSymbolFunc = func(s string) string { return s }
return
}
}
if !changed {
return ppath
}
return string(bsl)
fn, err := pkgpath.ToSymbolFunc(tools.compiler(), b.WorkDir)
if err != nil {
fmt.Fprintf(os.Stderr, "cmd/go: %v\n", err)
base.SetExitStatus(2)
base.Exit()
}
gccgoToSymbolFunc = fn
})
return gccgoToSymbolFunc(gccgoPkgpath(p))
}

114
libgo/go/cmd/internal/pkgpath/pkgpath.go Normal file
View File

@ -0,0 +1,114 @@
// Copyright 2020 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 pkgpath determines the package path used by gccgo/GoLLVM symbols.
// This package is not used for the gc compiler.
package pkgpath
import (
"bytes"
"errors"
"fmt"
"io/ioutil"
"os"
"os/exec"
"strings"
)
// ToSymbolFunc returns a function that may be used to convert a
// package path into a string suitable for use as a symbol.
// cmd is the gccgo/GoLLVM compiler in use, and tmpdir is a temporary
// directory to pass to ioutil.TempFile.
// For example, this returns a function that converts "net/http"
// into a string like "net..z2fhttp". The actual string varies for
// different gccgo/GoLLVM versions, which is why this returns a function
// that does the conversion appropriate for the compiler in use.
func ToSymbolFunc(cmd, tmpdir string) (func(string) string, error) {
// To determine the scheme used by cmd, we compile a small
// file and examine the assembly code. Older versions of gccgo
// use a simple mangling scheme where there can be collisions
// between packages whose paths are different but mangle to
// the same string. More recent versions use a new mangler
// that avoids these collisions.
const filepat = "*_gccgo_manglechck.go"
f, err := ioutil.TempFile(tmpdir, filepat)
if err != nil {
return nil, err
}
gofilename := f.Name()
f.Close()
defer os.Remove(gofilename)
if err := ioutil.WriteFile(gofilename, []byte(mangleCheckCode), 0644); err != nil {
return nil, err
}
command := exec.Command(cmd, "-S", "-o", "-", gofilename)
buf, err := command.Output()
if err != nil {
return nil, err
}
// New mangling: expect go.l..u00e4ufer.Run
// Old mangling: expect go.l__ufer.Run
if bytes.Contains(buf, []byte("go.l..u00e4ufer.Run")) {
return toSymbolV2, nil
} else if bytes.Contains(buf, []byte("go.l__ufer.Run")) {
return toSymbolV1, nil
} else {
return nil, errors.New(cmd + ": unrecognized mangling scheme")
}
}
// mangleCheckCode is the package we compile to determine the mangling scheme.
const mangleCheckCode = `
package läufer
func Run(x int) int {
return 1
}
`
// toSymbolV1 converts a package path using the original mangling scheme.
func toSymbolV1(ppath string) string {
clean := func(r rune) rune {
switch {
case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
'0' <= r && r <= '9':
return r
}
return '_'
}
return strings.Map(clean, ppath)
}
// toSymbolV2 converts a package path using the newer mangling scheme.
func toSymbolV2(ppath string) string {
// This has to build at boostrap time, so it has to build
// with Go 1.4, so we don't use strings.Builder.
bsl := make([]byte, 0, len(ppath))
changed := false
for _, c := range ppath {
if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_' {
bsl = append(bsl, byte(c))
continue
}
var enc string
switch {
case c == '.':
enc = ".x2e"
case c < 0x80:
enc = fmt.Sprintf("..z%02x", c)
case c < 0x10000:
enc = fmt.Sprintf("..u%04x", c)
default:
enc = fmt.Sprintf("..U%08x", c)
}
bsl = append(bsl, enc...)
changed = true
}
if !changed {
return ppath
}
return string(bsl)
}

121
libgo/go/cmd/internal/pkgpath/pkgpath_test.go Normal file
View File

@ -0,0 +1,121 @@
// Copyright 2020 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 pkgpath
import (
"os"
"testing"
)
const testEnvName = "GO_PKGPATH_TEST_COMPILER"
// This init function supports TestToSymbolFunc. For simplicity,
// we use the test binary itself as a sample gccgo driver.
// We set an environment variable to specify how it should behave.
func init() {
switch os.Getenv(testEnvName) {
case "":
return
case "v1":
os.Stdout.WriteString(`.string "go.l__ufer.Run"`)
os.Exit(0)
case "v2":
os.Stdout.WriteString(`.string "go.l..u00e4ufer.Run"`)
os.Exit(0)
case "error":
os.Stdout.WriteString(`unknown string`)
os.Exit(0)
}
}
func TestToSymbolFunc(t *testing.T) {
const input = "pä世🜃"
tests := []struct {
env string
fail bool
mangled string
}{
{
env: "v1",
mangled: "p___",
},
{
env: "v2",
mangled: "p..u00e4..u4e16..U0001f703",
},
{
env: "error",
fail: true,
},
}
cmd := os.Args[0]
tmpdir := t.TempDir()
defer os.Unsetenv(testEnvName)
for _, test := range tests {
t.Run(test.env, func(t *testing.T) {
os.Setenv(testEnvName, test.env)
fn, err := ToSymbolFunc(cmd, tmpdir)
if err != nil {
if !test.fail {
t.Errorf("ToSymbolFunc(%q, %q): unexpected error %v", cmd, tmpdir, err)
}
} else if test.fail {
t.Errorf("ToSymbolFunc(%q, %q) succeeded but expected to fail", cmd, tmpdir)
} else if got, want := fn(input), test.mangled; got != want {
t.Errorf("ToSymbolFunc(%q, %q)(%q) = %q, want %q", cmd, tmpdir, input, got, want)
}
})
}
}
var symbolTests = []struct {
input, v1, v2 string
}{
{
"",
"",
"",
},
{
"bytes",
"bytes",
"bytes",
},
{
"net/http",
"net_http",
"net..z2fhttp",
},
{
"golang.org/x/net/http",
"golang_org_x_net_http",
"golang.x2eorg..z2fx..z2fnet..z2fhttp",
},
{
"pä世.🜃",
"p____",
"p..u00e4..u4e16.x2e..U0001f703",
},
}
func TestV1(t *testing.T) {
for _, test := range symbolTests {
if got, want := toSymbolV1(test.input), test.v1; got != want {
t.Errorf("toSymbolV1(%q) = %q, want %q", test.input, got, want)
}
}
}
func TestV2(t *testing.T) {
for _, test := range symbolTests {
if got, want := toSymbolV2(test.input), test.v2; got != want {
t.Errorf("toSymbolV2(%q) = %q, want %q", test.input, got, want)
}
}
}

1
libgo/gotool-packages.txt
View File

@ -43,6 +43,7 @@ cmd/internal/buildid
cmd/internal/diff
cmd/internal/edit
cmd/internal/objabi
cmd/internal/pkgpath
cmd/internal/sys
cmd/internal/test2json
golang.org/x/crypto/ed25519