src/cmd/link/internal/ld/dwarf_test.go

// Copyright 2017 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 ld

import (
	objfilepkg "cmd/internal/objfile" // renamed to avoid conflict with objfile function
	"debug/dwarf"
	"internal/testenv"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"runtime"
	"testing"
)

func TestRuntimeTypeDIEs(t *testing.T) {
	testenv.MustHaveGoBuild(t)

	if runtime.GOOS == "plan9" {
		t.Skip("skipping on plan9; no DWARF symbol table in executables")
	}

	dir, err := ioutil.TempDir("", "TestRuntimeTypeDIEs")
	if err != nil {
		t.Fatalf("could not create directory: %v", err)
	}
	defer os.RemoveAll(dir)

	f := gobuild(t, dir, `package main; func main() { }`)
	defer f.Close()

	dwarf, err := f.DWARF()
	if err != nil {
		t.Fatalf("error reading DWARF: %v", err)
	}

	want := map[string]bool{
		"runtime._type":         true,
		"runtime.arraytype":     true,
		"runtime.chantype":      true,
		"runtime.functype":      true,
		"runtime.maptype":       true,
		"runtime.ptrtype":       true,
		"runtime.slicetype":     true,
		"runtime.structtype":    true,
		"runtime.interfacetype": true,
		"runtime.itab":          true,
		"runtime.imethod":       true,
	}

	found := findTypes(t, dwarf, want)
	if len(found) != len(want) {
		t.Errorf("found %v, want %v", found, want)
	}
}

func findTypes(t *testing.T, dw *dwarf.Data, want map[string]bool) (found map[string]bool) {
	found = make(map[string]bool)
	rdr := dw.Reader()
	for entry, err := rdr.Next(); entry != nil; entry, err = rdr.Next() {
		if err != nil {
			t.Fatalf("error reading DWARF: %v", err)
		}
		switch entry.Tag {
		case dwarf.TagTypedef:
			if name, ok := entry.Val(dwarf.AttrName).(string); ok && want[name] {
				found[name] = true
			}
		}
	}
	return
}

func gobuild(t *testing.T, dir string, testfile string) *objfilepkg.File {
	src := filepath.Join(dir, "test.go")
	dst := filepath.Join(dir, "out")

	if err := ioutil.WriteFile(src, []byte(testfile), 0666); err != nil {
		t.Fatal(err)
	}

	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", dst, src)
	if b, err := cmd.CombinedOutput(); err != nil {
		t.Logf("build: %s\n", b)
		t.Fatalf("build error: %v", err)
	}

	f, err := objfilepkg.Open(dst)
	if err != nil {
		t.Fatal(err)
	}
	return f
}

func TestEmbeddedStructMarker(t *testing.T) {
	testenv.MustHaveGoBuild(t)

	if runtime.GOOS == "plan9" {
		t.Skip("skipping on plan9; no DWARF symbol table in executables")
	}

	const prog = `
package main

import "fmt"

type Foo struct { v int }
type Bar struct {
	Foo
	name string
}
type Baz struct {
	*Foo
	name string
}

func main() {
	bar := Bar{ Foo: Foo{v: 123}, name: "onetwothree"}
	baz := Baz{ Foo: &bar.Foo, name: "123" }
	fmt.Println(bar, baz)
}`

	want := map[string]map[string]bool{
		"main.Foo": map[string]bool{"v": false},
		"main.Bar": map[string]bool{"Foo": true, "name": false},
		"main.Baz": map[string]bool{"Foo": true, "name": false},
	}

	dir, err := ioutil.TempDir("", "TestEmbeddedStructMarker")
	if err != nil {
		t.Fatalf("could not create directory: %v", err)
	}
	defer os.RemoveAll(dir)

	f := gobuild(t, dir, prog)

	defer f.Close()

	d, err := f.DWARF()
	if err != nil {
		t.Fatalf("error reading DWARF: %v", err)
	}

	rdr := d.Reader()
	for entry, err := rdr.Next(); entry != nil; entry, err = rdr.Next() {
		if err != nil {
			t.Fatalf("error reading DWARF: %v", err)
		}
		switch entry.Tag {
		case dwarf.TagStructType:
			name := entry.Val(dwarf.AttrName).(string)
			wantMembers := want[name]
			if wantMembers == nil {
				continue
			}
			gotMembers, err := findMembers(rdr)
			if err != nil {
				t.Fatalf("error reading DWARF: %v", err)
			}

			if !reflect.DeepEqual(gotMembers, wantMembers) {
				t.Errorf("type %v: got map[member]embedded = %+v, want %+v", name, wantMembers, gotMembers)
			}
			delete(want, name)
		}
	}
	if len(want) != 0 {
		t.Errorf("failed to check all expected types: missing types = %+v", want)
	}
}

func findMembers(rdr *dwarf.Reader) (map[string]bool, error) {
	memberEmbedded := map[string]bool{}
	// TODO(hyangah): define in debug/dwarf package
	const goEmbeddedStruct = dwarf.Attr(0x2903)
	for entry, err := rdr.Next(); entry != nil; entry, err = rdr.Next() {
		if err != nil {
			return nil, err
		}
		switch entry.Tag {
		case dwarf.TagMember:
			name := entry.Val(dwarf.AttrName).(string)
			embedded := entry.Val(goEmbeddedStruct).(bool)
			memberEmbedded[name] = embedded
		case 0:
			return memberEmbedded, nil
		}
	}
	return memberEmbedded, nil
}