cmd/link/internal/ld: use debug/pe package to rewrite ldpe.go

This CL also includes vendored copy of debug/pe,
otherwise bootstrapping fails.

Updates #15345

Change-Id: I3a8ac990e3cb12cb4d24ec11b618b68190397fd1
Reviewed-on: https://go-review.googlesource.com/22603Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

misc/nacl/testzip.proto

@@ -36,6 +36,11 @@ go	src=..
 				gofmt_test.go
 				testdata
 					+
+			link
+				internal
+					pe
+						testdata
+							+
 			vendor
 				golang.org
 					x

src/cmd/dist/buildtool.go

@@ -55,6 +55,7 @@ var bootstrapDirs = []string{
 	"link/internal/amd64",
 	"link/internal/arm",
 	"link/internal/arm64",
+	"link/internal/pe",
 	"link/internal/ld",
 	"link/internal/mips64",
 	"link/internal/ppc64",

src/cmd/link/internal/pe/file.go

+// Copyright 2009 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 pe implements access to PE (Microsoft Windows Portable Executable) files.
+package pe
+
+import (
+	"debug/dwarf"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+)
+
+// A File represents an open PE file.
+type File struct {
+	FileHeader
+	OptionalHeader interface{} // of type *OptionalHeader32 or *OptionalHeader64
+	Sections       []*Section
+	Symbols        []*Symbol    // COFF symbols with auxiliary symbol records removed
+	COFFSymbols    []COFFSymbol // all COFF symbols (including auxiliary symbol records)
+	StringTable    StringTable
+
+	closer io.Closer
+}
+
+// Open opens the named file using os.Open and prepares it for use as a PE binary.
+func Open(name string) (*File, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	ff, err := NewFile(f)
+	if err != nil {
+		f.Close()
+		return nil, err
+	}
+	ff.closer = f
+	return ff, nil
+}
+
+// Close closes the File.
+// If the File was created using NewFile directly instead of Open,
+// Close has no effect.
+func (f *File) Close() error {
+	var err error
+	if f.closer != nil {
+		err = f.closer.Close()
+		f.closer = nil
+	}
+	return err
+}
+
+var (
+	sizeofOptionalHeader32 = uint16(binary.Size(OptionalHeader32{}))
+	sizeofOptionalHeader64 = uint16(binary.Size(OptionalHeader64{}))
+)
+
+// TODO(brainman): add Load function, as a replacement for NewFile, that does not call removeAuxSymbols (for performance)
+
+// NewFile creates a new File for accessing a PE binary in an underlying reader.
+func NewFile(r io.ReaderAt) (*File, error) {
+	f := new(File)
+	sr := io.NewSectionReader(r, 0, 1<<63-1)
+
+	var dosheader [96]byte
+	if _, err := r.ReadAt(dosheader[0:], 0); err != nil {
+		return nil, err
+	}
+	var base int64
+	if dosheader[0] == 'M' && dosheader[1] == 'Z' {
+		signoff := int64(binary.LittleEndian.Uint32(dosheader[0x3c:]))
+		var sign [4]byte
+		r.ReadAt(sign[:], signoff)
+		if !(sign[0] == 'P' && sign[1] == 'E' && sign[2] == 0 && sign[3] == 0) {
+			return nil, fmt.Errorf("Invalid PE COFF file signature of %v.", sign)
+		}
+		base = signoff + 4
+	} else {
+		base = int64(0)
+	}
+	sr.Seek(base, os.SEEK_SET)
+	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
+		return nil, err
+	}
+	switch f.FileHeader.Machine {
+	case IMAGE_FILE_MACHINE_UNKNOWN, IMAGE_FILE_MACHINE_AMD64, IMAGE_FILE_MACHINE_I386:
+	default:
+		return nil, fmt.Errorf("Unrecognised COFF file header machine value of 0x%x.", f.FileHeader.Machine)
+	}
+
+	var err error
+
+	// Read string table.
+	f.StringTable, err = readStringTable(&f.FileHeader, sr)
+	if err != nil {
+		return nil, err
+	}
+
+	// Read symbol table.
+	f.COFFSymbols, err = readCOFFSymbols(&f.FileHeader, sr)
+	if err != nil {
+		return nil, err
+	}
+	f.Symbols, err = removeAuxSymbols(f.COFFSymbols, f.StringTable)
+	if err != nil {
+		return nil, err
+	}
+
+	// Read optional header.
+	sr.Seek(base, os.SEEK_SET)
+	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
+		return nil, err
+	}
+	var oh32 OptionalHeader32
+	var oh64 OptionalHeader64
+	switch f.FileHeader.SizeOfOptionalHeader {
+	case sizeofOptionalHeader32:
+		if err := binary.Read(sr, binary.LittleEndian, &oh32); err != nil {
+			return nil, err
+		}
+		if oh32.Magic != 0x10b { // PE32
+			return nil, fmt.Errorf("pe32 optional header has unexpected Magic of 0x%x", oh32.Magic)
+		}
+		f.OptionalHeader = &oh32
+	case sizeofOptionalHeader64:
+		if err := binary.Read(sr, binary.LittleEndian, &oh64); err != nil {
+			return nil, err
+		}
+		if oh64.Magic != 0x20b { // PE32+
+			return nil, fmt.Errorf("pe32+ optional header has unexpected Magic of 0x%x", oh64.Magic)
+		}
+		f.OptionalHeader = &oh64
+	}
+
+	// Process sections.
+	f.Sections = make([]*Section, f.FileHeader.NumberOfSections)
+	for i := 0; i < int(f.FileHeader.NumberOfSections); i++ {
+		sh := new(SectionHeader32)
+		if err := binary.Read(sr, binary.LittleEndian, sh); err != nil {
+			return nil, err
+		}
+		name, err := sh.fullName(f.StringTable)
+		if err != nil {
+			return nil, err
+		}
+		s := new(Section)
+		s.SectionHeader = SectionHeader{
+			Name:                 name,
+			VirtualSize:          sh.VirtualSize,
+			VirtualAddress:       sh.VirtualAddress,
+			Size:                 sh.SizeOfRawData,
+			Offset:               sh.PointerToRawData,
+			PointerToRelocations: sh.PointerToRelocations,
+			PointerToLineNumbers: sh.PointerToLineNumbers,
+			NumberOfRelocations:  sh.NumberOfRelocations,
+			NumberOfLineNumbers:  sh.NumberOfLineNumbers,
+			Characteristics:      sh.Characteristics,
+		}
+		r2 := r
+		if sh.PointerToRawData == 0 { // .bss must have all 0s
+			r2 = zeroReaderAt{}
+		}
+		s.sr = io.NewSectionReader(r2, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size))
+		s.ReaderAt = s.sr
+		f.Sections[i] = s
+	}
+	for i := range f.Sections {
+		var err error
+		f.Sections[i].Relocs, err = readRelocs(&f.Sections[i].SectionHeader, sr)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return f, nil
+}
+
+// zeroReaderAt is ReaderAt that reads 0s.
+type zeroReaderAt struct{}
+
+// ReadAt writes len(p) 0s into p.
+func (w zeroReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
+	for i := range p {
+		p[i] = 0
+	}
+	return len(p), nil
+}
+
+// getString extracts a string from symbol string table.
+func getString(section []byte, start int) (string, bool) {
+	if start < 0 || start >= len(section) {
+		return "", false
+	}
+
+	for end := start; end < len(section); end++ {
+		if section[end] == 0 {
+			return string(section[start:end]), true
+		}
+	}
+	return "", false
+}
+
+// Section returns the first section with the given name, or nil if no such
+// section exists.
+func (f *File) Section(name string) *Section {
+	for _, s := range f.Sections {
+		if s.Name == name {
+			return s
+		}
+	}
+	return nil
+}
+
+func (f *File) DWARF() (*dwarf.Data, error) {
+	// There are many other DWARF sections, but these
+	// are the ones the debug/dwarf package uses.
+	// Don't bother loading others.
+	var names = [...]string{"abbrev", "info", "line", "ranges", "str"}
+	var dat [len(names)][]byte
+	for i, name := range names {
+		name = ".debug_" + name
+		s := f.Section(name)
+		if s == nil {
+			continue
+		}
+		b, err := s.Data()
+		if err != nil && uint32(len(b)) < s.Size {
+			return nil, err
+		}
+		if 0 < s.VirtualSize && s.VirtualSize < s.Size {
+			b = b[:s.VirtualSize]
+		}
+		dat[i] = b
+	}
+
+	abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4]
+	return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
+}
+
+// TODO(brainman): document ImportDirectory once we decide what to do with it.
+
+type ImportDirectory struct {
+	OriginalFirstThunk uint32
+	TimeDateStamp      uint32
+	ForwarderChain     uint32
+	Name               uint32
+	FirstThunk         uint32
+
+	dll string
+}
+
+// ImportedSymbols returns the names of all symbols
+// referred to by the binary f that are expected to be
+// satisfied by other libraries at dynamic load time.
+// It does not return weak symbols.
+func (f *File) ImportedSymbols() ([]string, error) {
+	pe64 := f.Machine == IMAGE_FILE_MACHINE_AMD64
+	ds := f.Section(".idata")
+	if ds == nil {
+		// not dynamic, so no libraries
+		return nil, nil
+	}
+	d, err := ds.Data()
+	if err != nil {
+		return nil, err
+	}
+	var ida []ImportDirectory
+	for len(d) > 0 {
+		var dt ImportDirectory
+		dt.OriginalFirstThunk = binary.LittleEndian.Uint32(d[0:4])
+		dt.Name = binary.LittleEndian.Uint32(d[12:16])
+		dt.FirstThunk = binary.LittleEndian.Uint32(d[16:20])
+		d = d[20:]
+		if dt.OriginalFirstThunk == 0 {
+			break
+		}
+		ida = append(ida, dt)
+	}
+	// TODO(brainman): this needs to be rewritten
+	//  ds.Data() return contets of .idata section. Why store in variable called "names"?
+	//  Why we are retrieving it second time? We already have it in "d", and it is not modified anywhere.
+	//  getString does not extracts a string from symbol string table (as getString doco says).
+	//  Why ds.Data() called again and again in the loop?
+	//  Needs test before rewrite.
+	names, _ := ds.Data()
+	var all []string
+	for _, dt := range ida {
+		dt.dll, _ = getString(names, int(dt.Name-ds.VirtualAddress))
+		d, _ = ds.Data()
+		// seek to OriginalFirstThunk
+		d = d[dt.OriginalFirstThunk-ds.VirtualAddress:]
+		for len(d) > 0 {
+			if pe64 { // 64bit
+				va := binary.LittleEndian.Uint64(d[0:8])
+				d = d[8:]
+				if va == 0 {
+					break
+				}
+				if va&0x8000000000000000 > 0 { // is Ordinal
+					// TODO add dynimport ordinal support.
+				} else {
+					fn, _ := getString(names, int(uint32(va)-ds.VirtualAddress+2))
+					all = append(all, fn+":"+dt.dll)
+				}
+			} else { // 32bit
+				va := binary.LittleEndian.Uint32(d[0:4])
+				d = d[4:]
+				if va == 0 {
+					break
+				}
+				if va&0x80000000 > 0 { // is Ordinal
+					// TODO add dynimport ordinal support.
+					//ord := va&0x0000FFFF
+				} else {
+					fn, _ := getString(names, int(va-ds.VirtualAddress+2))
+					all = append(all, fn+":"+dt.dll)
+				}
+			}
+		}
+	}
+
+	return all, nil
+}
+
+// ImportedLibraries returns the names of all libraries
+// referred to by the binary f that are expected to be
+// linked with the binary at dynamic link time.
+func (f *File) ImportedLibraries() ([]string, error) {
+	// TODO
+	// cgo -dynimport don't use this for windows PE, so just return.
+	return nil, nil
+}
+
+// FormatError is unused.
+// The type is retained for compatibility.
+type FormatError struct {
+}
+
+func (e *FormatError) Error() string {
+	return "unknown error"
+}

src/cmd/link/internal/pe/pe.go

+// Copyright 2009 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 pe
+
+type FileHeader struct {
+	Machine              uint16
+	NumberOfSections     uint16
+	TimeDateStamp        uint32
+	PointerToSymbolTable uint32
+	NumberOfSymbols      uint32
+	SizeOfOptionalHeader uint16
+	Characteristics      uint16
+}
+
+type DataDirectory struct {
+	VirtualAddress uint32
+	Size           uint32
+}
+
+type OptionalHeader32 struct {
+	Magic                       uint16
+	MajorLinkerVersion          uint8
+	MinorLinkerVersion          uint8
+	SizeOfCode                  uint32
+	SizeOfInitializedData       uint32
+	SizeOfUninitializedData     uint32
+	AddressOfEntryPoint         uint32
+	BaseOfCode                  uint32
+	BaseOfData                  uint32
+	ImageBase                   uint32
+	SectionAlignment            uint32
+	FileAlignment               uint32
+	MajorOperatingSystemVersion uint16
+	MinorOperatingSystemVersion uint16
+	MajorImageVersion           uint16
+	MinorImageVersion           uint16
+	MajorSubsystemVersion       uint16
+	MinorSubsystemVersion       uint16
+	Win32VersionValue           uint32
+	SizeOfImage                 uint32
+	SizeOfHeaders               uint32
+	CheckSum                    uint32
+	Subsystem                   uint16
+	DllCharacteristics          uint16
+	SizeOfStackReserve          uint32
+	SizeOfStackCommit           uint32
+	SizeOfHeapReserve           uint32
+	SizeOfHeapCommit            uint32
+	LoaderFlags                 uint32
+	NumberOfRvaAndSizes         uint32
+	DataDirectory               [16]DataDirectory
+}
+
+type OptionalHeader64 struct {
+	Magic                       uint16
+	MajorLinkerVersion          uint8
+	MinorLinkerVersion          uint8
+	SizeOfCode                  uint32
+	SizeOfInitializedData       uint32
+	SizeOfUninitializedData     uint32
+	AddressOfEntryPoint         uint32
+	BaseOfCode                  uint32
+	ImageBase                   uint64
+	SectionAlignment            uint32
+	FileAlignment               uint32
+	MajorOperatingSystemVersion uint16
+	MinorOperatingSystemVersion uint16
+	MajorImageVersion           uint16
+	MinorImageVersion           uint16
+	MajorSubsystemVersion       uint16
+	MinorSubsystemVersion       uint16
+	Win32VersionValue           uint32
+	SizeOfImage                 uint32
+	SizeOfHeaders               uint32
+	CheckSum                    uint32
+	Subsystem                   uint16
+	DllCharacteristics          uint16
+	SizeOfStackReserve          uint64
+	SizeOfStackCommit           uint64
+	SizeOfHeapReserve           uint64
+	SizeOfHeapCommit            uint64
+	LoaderFlags                 uint32
+	NumberOfRvaAndSizes         uint32
+	DataDirectory               [16]DataDirectory
+}
+
+const (
+	IMAGE_FILE_MACHINE_UNKNOWN   = 0x0
+	IMAGE_FILE_MACHINE_AM33      = 0x1d3
+	IMAGE_FILE_MACHINE_AMD64     = 0x8664
+	IMAGE_FILE_MACHINE_ARM       = 0x1c0
+	IMAGE_FILE_MACHINE_EBC       = 0xebc
+	IMAGE_FILE_MACHINE_I386      = 0x14c
+	IMAGE_FILE_MACHINE_IA64      = 0x200
+	IMAGE_FILE_MACHINE_M32R      = 0x9041
+	IMAGE_FILE_MACHINE_MIPS16    = 0x266
+	IMAGE_FILE_MACHINE_MIPSFPU   = 0x366
+	IMAGE_FILE_MACHINE_MIPSFPU16 = 0x466
+	IMAGE_FILE_MACHINE_POWERPC   = 0x1f0
+	IMAGE_FILE_MACHINE_POWERPCFP = 0x1f1
+	IMAGE_FILE_MACHINE_R4000     = 0x166
+	IMAGE_FILE_MACHINE_SH3       = 0x1a2
+	IMAGE_FILE_MACHINE_SH3DSP    = 0x1a3
+	IMAGE_FILE_MACHINE_SH4       = 0x1a6
+	IMAGE_FILE_MACHINE_SH5       = 0x1a8
+	IMAGE_FILE_MACHINE_THUMB     = 0x1c2
+	IMAGE_FILE_MACHINE_WCEMIPSV2 = 0x169
+)

src/cmd/link/internal/pe/section.go

+// Copyright 2016 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 pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+)
+
+// SectionHeader32 represents real PE COFF section header.
+type SectionHeader32 struct {
+	Name                 [8]uint8
+	VirtualSize          uint32
+	VirtualAddress       uint32
+	SizeOfRawData        uint32
+	PointerToRawData     uint32
+	PointerToRelocations uint32
+	PointerToLineNumbers uint32
+	NumberOfRelocations  uint16
+	NumberOfLineNumbers  uint16
+	Characteristics      uint32
+}
+
+// fullName finds real name of section sh. Normally name is stored
+// in sh.Name, but if it is longer then 8 characters, it is stored
+// in COFF string table st instead.
+func (sh *SectionHeader32) fullName(st StringTable) (string, error) {
+	if sh.Name[0] != '/' {
+		return cstring(sh.Name[:]), nil
+	}
+	i, err := strconv.Atoi(cstring(sh.Name[1:]))
+	if err != nil {
+		return "", err
+	}
+	return st.String(uint32(i))
+}
+
+// TODO(brainman): copy all IMAGE_REL_* consts from ldpe.go here
+
+// Reloc represents a PE COFF relocation.
+// Each section contains its own relocation list.
+type Reloc struct {
+	VirtualAddress   uint32
+	SymbolTableIndex uint32
+	Type             uint16
+}
+
+func readRelocs(sh *SectionHeader, r io.ReadSeeker) ([]Reloc, error) {
+	if sh.NumberOfRelocations <= 0 {
+		return nil, nil
+	}
+	_, err := r.Seek(int64(sh.PointerToRelocations), os.SEEK_SET)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to %q section relocations: %v", sh.Name, err)
+	}
+	relocs := make([]Reloc, sh.NumberOfRelocations)
+	err = binary.Read(r, binary.LittleEndian, relocs)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read section relocations: %v", err)
+	}
+	return relocs, nil
+}
+
+// SectionHeader is similar to SectionHeader32 with Name
+// field replaced by Go string.
+type SectionHeader struct {
+	Name                 string
+	VirtualSize          uint32
+	VirtualAddress       uint32
+	Size                 uint32
+	Offset               uint32
+	PointerToRelocations uint32
+	PointerToLineNumbers uint32
+	NumberOfRelocations  uint16
+	NumberOfLineNumbers  uint16
+	Characteristics      uint32
+}
+
+// Section provides access to PE COFF section.
+type Section struct {
+	SectionHeader
+	Relocs []Reloc
+
+	// Embed ReaderAt for ReadAt method.
+	// Do not embed SectionReader directly
+	// to avoid having Read and Seek.
+	// If a client wants Read and Seek it must use
+	// Open() to avoid fighting over the seek offset
+	// with other clients.
+	io.ReaderAt
+	sr *io.SectionReader
+}
+
+// Data reads and returns the contents of the PE section s.
+func (s *Section) Data() ([]byte, error) {
+	dat := make([]byte, s.sr.Size())
+	n, err := s.sr.ReadAt(dat, 0)
+	if n == len(dat) {
+		err = nil
+	}
+	return dat[0:n], err
+}
+
+// Open returns a new ReadSeeker reading the PE section s.
+func (s *Section) Open() io.ReadSeeker {
+	return io.NewSectionReader(s.sr, 0, 1<<63-1)
+}

src/cmd/link/internal/pe/string.go

+// Copyright 2016 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 pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+)
+
+// cstring converts ASCII byte sequence b to string.
+// It stops once it finds 0 or reaches end of b.
+func cstring(b []byte) string {
+	var i int
+	for i = 0; i < len(b) && b[i] != 0; i++ {
+	}
+	return string(b[:i])
+}
+
+// StringTable is a COFF string table.
+type StringTable []byte
+
+func readStringTable(fh *FileHeader, r io.ReadSeeker) (StringTable, error) {
+	// COFF string table is located right after COFF symbol table.
+	if fh.PointerToSymbolTable <= 0 {
+		return nil, nil
+	}
+	offset := fh.PointerToSymbolTable + COFFSymbolSize*fh.NumberOfSymbols
+	_, err := r.Seek(int64(offset), os.SEEK_SET)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to string table: %v", err)
+	}
+	var l uint32
+	err = binary.Read(r, binary.LittleEndian, &l)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read string table length: %v", err)
+	}
+	// string table length includes itself
+	if l <= 4 {
+		return nil, nil
+	}
+	l -= 4
+	buf := make([]byte, l)
+	_, err = io.ReadFull(r, buf)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read string table: %v", err)
+	}
+	return StringTable(buf), nil
+}
+
+// TODO(brainman): decide if start parameter should be int instead of uint32
+
+// String extracts string from COFF string table st at offset start.
+func (st StringTable) String(start uint32) (string, error) {
+	// start includes 4 bytes of string table length
+	if start < 4 {
+		return "", fmt.Errorf("offset %d is before the start of string table", start)
+	}
+	start -= 4
+	if int(start) > len(st) {
+		return "", fmt.Errorf("offset %d is beyond the end of string table", start)
+	}
+	return cstring(st[start:]), nil
+}

src/cmd/link/internal/pe/symbol.go

+// Copyright 2016 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 pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+)
+
+const COFFSymbolSize = 18
+
+// COFFSymbol represents single COFF symbol table record.
+type COFFSymbol struct {
+	Name               [8]uint8
+	Value              uint32
+	SectionNumber      int16
+	Type               uint16
+	StorageClass       uint8
+	NumberOfAuxSymbols uint8
+}
+
+func readCOFFSymbols(fh *FileHeader, r io.ReadSeeker) ([]COFFSymbol, error) {
+	if fh.NumberOfSymbols <= 0 {
+		return nil, nil
+	}
+	_, err := r.Seek(int64(fh.PointerToSymbolTable), os.SEEK_SET)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to symbol table: %v", err)
+	}
+	syms := make([]COFFSymbol, fh.NumberOfSymbols)
+	err = binary.Read(r, binary.LittleEndian, syms)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read symbol table: %v", err)
+	}
+	return syms, nil
+}
+
+// isSymNameOffset checks symbol name if it is encoded as offset into string table.
+func isSymNameOffset(name [8]byte) (bool, uint32) {
+	if name[0] == 0 && name[1] == 0 && name[2] == 0 && name[3] == 0 {
+		return true, binary.LittleEndian.Uint32(name[4:])
+	}
+	return false, 0
+}
+
+// FullName finds real name of symbol sym. Normally name is stored
+// in sym.Name, but if it is longer then 8 characters, it is stored
+// in COFF string table st instead.
+func (sym *COFFSymbol) FullName(st StringTable) (string, error) {
+	if ok, offset := isSymNameOffset(sym.Name); ok {
+		return st.String(offset)
+	}
+	return cstring(sym.Name[:]), nil
+}
+
+func removeAuxSymbols(allsyms []COFFSymbol, st StringTable) ([]*Symbol, error) {
+	if len(allsyms) == 0 {
+		return nil, nil
+	}
+	syms := make([]*Symbol, 0)
+	aux := uint8(0)
+	for _, sym := range allsyms {
+		if aux > 0 {
+			aux--
+			continue
+		}
+		name, err := sym.FullName(st)
+		if err != nil {
+			return nil, err
+		}
+		aux = sym.NumberOfAuxSymbols
+		s := &Symbol{
+			Name:          name,
+			Value:         sym.Value,
+			SectionNumber: sym.SectionNumber,
+			Type:          sym.Type,
+			StorageClass:  sym.StorageClass,
+		}
+		syms = append(syms, s)
+	}
+	return syms, nil
+}
+
+// Symbol is similar to COFFSymbol with Name field replaced
+// by Go string. Symbol also does not have NumberOfAuxSymbols.
+type Symbol struct {
+	Name          string
+	Value         uint32
+	SectionNumber int16
+	Type          uint16
+	StorageClass  uint8
+}

src/cmd/link/internal/pe/testdata/hello.c

+#include <stdio.h>
+
+int
+main(void)
+{
+	printf("hello, world\n");
+	return 0;
+}

src/cmd/link/internal/pe/vendor.bash

+#!/usr/bin/env bash
+
+# Copyright 2016 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.
+
+# Run this script to obtain an up-to-date vendored version of debug/pe
+
+PEDIR=../../../../debug/pe
+
+# Start from scratch.
+rm testdata/*
+rm *.go
+rmdir testdata
+
+# Copy all files.
+mkdir testdata
+cp $PEDIR/*.go .
+cp $PEDIR/testdata/* ./testdata
+
+# go1.4 (bootstrap) does not know what io.SeekStart is.
+sed -i 's|io.SeekStart|os.SEEK_SET|' *.go
+
+# goimports to clean up after sed
+goimports -w .
+
+# gofmt to clean up after sed
+gofmt -w .
+
+# Test that it works
+go test -short