cmd/objdump: works with windows pe executables now

Most code is copy from addr2line change 01dd67e5827f

Update #7406
Fixes #7937

LGTM=iant
R=golang-codereviews, iant, 0intro
CC=golang-codereviews
https://golang.org/cl/95090044

src/cmd/objdump/main.go

@@ -170,18 +170,50 @@ func loadTables(f *os.File) (textStart uint64, textData, symtab, pclntab []byte,
 			textStart = uint64(sect.VirtualAddress)
 			textData, _ = sect.Data()
 		}
-		if sect := obj.Section(".gosymtab"); sect != nil {
-			if symtab, err = sect.Data(); err != nil {
-				return 0, nil, nil, nil, err
-			}
+		if pclntab, err = loadPETable(obj, "pclntab", "epclntab"); err != nil {
+			return 0, nil, nil, nil, err
 		}
-		if sect := obj.Section(".gopclntab"); sect != nil {
-			if pclntab, err = sect.Data(); err != nil {
-				return 0, nil, nil, nil, err
-			}
+		if symtab, err = loadPETable(obj, "symtab", "esymtab"); err != nil {
+			return 0, nil, nil, nil, err
 		}
 		return textStart, textData, symtab, pclntab, nil
 	}
 
 	return 0, nil, nil, nil, fmt.Errorf("unrecognized binary format")
 }
+
+func findPESymbol(f *pe.File, name string) (*pe.Symbol, error) {
+	for _, s := range f.Symbols {
+		if s.Name != name {
+			continue
+		}
+		if s.SectionNumber <= 0 {
+			return nil, fmt.Errorf("symbol %s: invalid section number %d", name, s.SectionNumber)
+		}
+		if len(f.Sections) < int(s.SectionNumber) {
+			return nil, fmt.Errorf("symbol %s: section number %d is larger than max %d", name, s.SectionNumber, len(f.Sections))
+		}
+		return s, nil
+	}
+	return nil, fmt.Errorf("no %s symbol found", name)
+}
+
+func loadPETable(f *pe.File, sname, ename string) ([]byte, error) {
+	ssym, err := findPESymbol(f, sname)
+	if err != nil {
+		return nil, err
+	}
+	esym, err := findPESymbol(f, ename)
+	if err != nil {
+		return nil, err
+	}
+	if ssym.SectionNumber != esym.SectionNumber {
+		return nil, fmt.Errorf("%s and %s symbols must be in the same section", sname, ename)
+	}
+	sect := f.Sections[ssym.SectionNumber-1]
+	data, err := sect.Data()
+	if err != nil {
+		return nil, err
+	}
+	return data[ssym.Value:esym.Value], nil
+}

src/cmd/objdump/objdump_test.go

+// Copyright 2014 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 main
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func loadSyms(t *testing.T) map[string]string {
+	cmd := exec.Command("go", "tool", "nm", os.Args[0])
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("go tool nm %v: %v\n%s", os.Args[0], err, string(out))
+	}
+	syms := make(map[string]string)
+	scanner := bufio.NewScanner(bytes.NewReader(out))
+	for scanner.Scan() {
+		f := strings.Fields(scanner.Text())
+		if len(f) < 3 {
+			continue
+		}
+		syms[f[2]] = f[0]
+	}
+	if err := scanner.Err(); err != nil {
+		t.Fatalf("error reading symbols: %v", err)
+	}
+	return syms
+}
+
+func runObjDump(t *testing.T, exepath, startaddr string) (path, lineno string) {
+	addr, err := strconv.ParseUint(startaddr, 16, 64)
+	if err != nil {
+		t.Fatalf("invalid start address %v: %v", startaddr, err)
+	}
+	endaddr := fmt.Sprintf("%x", addr+10)
+	cmd := exec.Command(exepath, os.Args[0], "0x"+startaddr, "0x"+endaddr)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("go tool objdump %v: %v\n%s", os.Args[0], err, string(out))
+	}
+	f := strings.Split(string(out), "\n")
+	if len(f) < 1 {
+		t.Fatal("objdump output must have at least one line")
+	}
+	pathAndLineNo := f[0]
+	f = strings.Split(pathAndLineNo, ":")
+	if runtime.GOOS == "windows" {
+		switch len(f) {
+		case 2:
+			return f[0], f[1]
+		case 3:
+			return f[0] + ":" + f[1], f[2]
+		default:
+			t.Fatalf("no line number found in %q", pathAndLineNo)
+		}
+	}
+	if len(f) != 2 {
+		t.Fatalf("no line number found in %q", pathAndLineNo)
+	}
+	return f[0], f[1]
+}
+
+// This is line 75.  The test depends on that.
+func TestObjDump(t *testing.T) {
+	if runtime.GOOS == "plan9" {
+		t.Skip("skipping test; see http://golang.org/issue/7947")
+	}
+	syms := loadSyms(t)
+
+	tmpDir, err := ioutil.TempDir("", "TestObjDump")
+	if err != nil {
+		t.Fatal("TempDir failed: ", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	exepath := filepath.Join(tmpDir, "testobjdump.exe")
+	out, err := exec.Command("go", "build", "-o", exepath, "cmd/objdump").CombinedOutput()
+	if err != nil {
+		t.Fatalf("go build -o %v cmd/objdump: %v\n%s", exepath, err, string(out))
+	}
+
+	srcPath, srcLineNo := runObjDump(t, exepath, syms["cmd/objdump.TestObjDump"])
+	fi1, err := os.Stat("objdump_test.go")
+	if err != nil {
+		t.Fatalf("Stat failed: %v", err)
+	}
+	fi2, err := os.Stat(srcPath)
+	if err != nil {
+		t.Fatalf("Stat failed: %v", err)
+	}
+	if !os.SameFile(fi1, fi2) {
+		t.Fatalf("objdump_test.go and %s are not same file", srcPath)
+	}
+	if srcLineNo != "76" {
+		t.Fatalf("line number = %v; want 76", srcLineNo)
+	}
+}