mirror of
https://github.com/autc04/Retro68.git
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347 lines
9.2 KiB
Go
347 lines
9.2 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package pe implements access to PE (Microsoft Windows Portable Executable) files.
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package pe
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import (
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"debug/dwarf"
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"encoding/binary"
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"fmt"
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"io"
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"os"
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)
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// Avoid use of post-Go 1.4 io features, to make safe for toolchain bootstrap.
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const seekStart = 0
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// A File represents an open PE file.
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type File struct {
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FileHeader
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OptionalHeader interface{} // of type *OptionalHeader32 or *OptionalHeader64
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Sections []*Section
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Symbols []*Symbol // COFF symbols with auxiliary symbol records removed
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COFFSymbols []COFFSymbol // all COFF symbols (including auxiliary symbol records)
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StringTable StringTable
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closer io.Closer
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}
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// Open opens the named file using os.Open and prepares it for use as a PE binary.
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func Open(name string) (*File, error) {
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f, err := os.Open(name)
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if err != nil {
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return nil, err
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}
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ff, err := NewFile(f)
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if err != nil {
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f.Close()
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return nil, err
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}
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ff.closer = f
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return ff, nil
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}
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// Close closes the File.
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// If the File was created using NewFile directly instead of Open,
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// Close has no effect.
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func (f *File) Close() error {
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var err error
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if f.closer != nil {
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err = f.closer.Close()
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f.closer = nil
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}
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return err
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}
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var (
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sizeofOptionalHeader32 = uint16(binary.Size(OptionalHeader32{}))
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sizeofOptionalHeader64 = uint16(binary.Size(OptionalHeader64{}))
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)
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// TODO(brainman): add Load function, as a replacement for NewFile, that does not call removeAuxSymbols (for performance)
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// NewFile creates a new File for accessing a PE binary in an underlying reader.
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func NewFile(r io.ReaderAt) (*File, error) {
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f := new(File)
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sr := io.NewSectionReader(r, 0, 1<<63-1)
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var dosheader [96]byte
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if _, err := r.ReadAt(dosheader[0:], 0); err != nil {
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return nil, err
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}
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var base int64
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if dosheader[0] == 'M' && dosheader[1] == 'Z' {
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signoff := int64(binary.LittleEndian.Uint32(dosheader[0x3c:]))
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var sign [4]byte
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r.ReadAt(sign[:], signoff)
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if !(sign[0] == 'P' && sign[1] == 'E' && sign[2] == 0 && sign[3] == 0) {
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return nil, fmt.Errorf("Invalid PE COFF file signature of %v.", sign)
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}
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base = signoff + 4
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} else {
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base = int64(0)
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}
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sr.Seek(base, seekStart)
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if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
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return nil, err
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}
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switch f.FileHeader.Machine {
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case IMAGE_FILE_MACHINE_UNKNOWN, IMAGE_FILE_MACHINE_AMD64, IMAGE_FILE_MACHINE_I386:
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default:
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return nil, fmt.Errorf("Unrecognised COFF file header machine value of 0x%x.", f.FileHeader.Machine)
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}
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var err error
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// Read string table.
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f.StringTable, err = readStringTable(&f.FileHeader, sr)
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if err != nil {
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return nil, err
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}
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// Read symbol table.
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f.COFFSymbols, err = readCOFFSymbols(&f.FileHeader, sr)
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if err != nil {
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return nil, err
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}
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f.Symbols, err = removeAuxSymbols(f.COFFSymbols, f.StringTable)
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if err != nil {
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return nil, err
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}
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// Read optional header.
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sr.Seek(base, seekStart)
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if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
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return nil, err
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}
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var oh32 OptionalHeader32
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var oh64 OptionalHeader64
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switch f.FileHeader.SizeOfOptionalHeader {
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case sizeofOptionalHeader32:
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if err := binary.Read(sr, binary.LittleEndian, &oh32); err != nil {
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return nil, err
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}
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if oh32.Magic != 0x10b { // PE32
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return nil, fmt.Errorf("pe32 optional header has unexpected Magic of 0x%x", oh32.Magic)
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}
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f.OptionalHeader = &oh32
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case sizeofOptionalHeader64:
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if err := binary.Read(sr, binary.LittleEndian, &oh64); err != nil {
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return nil, err
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}
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if oh64.Magic != 0x20b { // PE32+
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return nil, fmt.Errorf("pe32+ optional header has unexpected Magic of 0x%x", oh64.Magic)
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}
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f.OptionalHeader = &oh64
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}
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// Process sections.
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f.Sections = make([]*Section, f.FileHeader.NumberOfSections)
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for i := 0; i < int(f.FileHeader.NumberOfSections); i++ {
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sh := new(SectionHeader32)
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if err := binary.Read(sr, binary.LittleEndian, sh); err != nil {
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return nil, err
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}
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name, err := sh.fullName(f.StringTable)
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if err != nil {
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return nil, err
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}
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s := new(Section)
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s.SectionHeader = SectionHeader{
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Name: name,
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VirtualSize: sh.VirtualSize,
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VirtualAddress: sh.VirtualAddress,
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Size: sh.SizeOfRawData,
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Offset: sh.PointerToRawData,
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PointerToRelocations: sh.PointerToRelocations,
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PointerToLineNumbers: sh.PointerToLineNumbers,
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NumberOfRelocations: sh.NumberOfRelocations,
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NumberOfLineNumbers: sh.NumberOfLineNumbers,
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Characteristics: sh.Characteristics,
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}
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r2 := r
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if sh.PointerToRawData == 0 { // .bss must have all 0s
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r2 = zeroReaderAt{}
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}
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s.sr = io.NewSectionReader(r2, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size))
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s.ReaderAt = s.sr
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f.Sections[i] = s
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}
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for i := range f.Sections {
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var err error
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f.Sections[i].Relocs, err = readRelocs(&f.Sections[i].SectionHeader, sr)
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if err != nil {
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return nil, err
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}
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}
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return f, nil
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}
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// zeroReaderAt is ReaderAt that reads 0s.
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type zeroReaderAt struct{}
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// ReadAt writes len(p) 0s into p.
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func (w zeroReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
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for i := range p {
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p[i] = 0
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}
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return len(p), nil
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}
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// getString extracts a string from symbol string table.
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func getString(section []byte, start int) (string, bool) {
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if start < 0 || start >= len(section) {
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return "", false
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}
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for end := start; end < len(section); end++ {
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if section[end] == 0 {
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return string(section[start:end]), true
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}
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}
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return "", false
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}
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// Section returns the first section with the given name, or nil if no such
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// section exists.
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func (f *File) Section(name string) *Section {
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for _, s := range f.Sections {
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if s.Name == name {
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return s
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}
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}
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return nil
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}
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func (f *File) DWARF() (*dwarf.Data, error) {
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// There are many other DWARF sections, but these
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// are the ones the debug/dwarf package uses.
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// Don't bother loading others.
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var names = [...]string{"abbrev", "info", "line", "ranges", "str"}
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var dat [len(names)][]byte
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for i, name := range names {
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name = ".debug_" + name
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s := f.Section(name)
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if s == nil {
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continue
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}
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b, err := s.Data()
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if err != nil && uint32(len(b)) < s.Size {
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return nil, err
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}
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if 0 < s.VirtualSize && s.VirtualSize < s.Size {
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b = b[:s.VirtualSize]
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}
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dat[i] = b
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}
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abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4]
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return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
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}
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// TODO(brainman): document ImportDirectory once we decide what to do with it.
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type ImportDirectory struct {
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OriginalFirstThunk uint32
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TimeDateStamp uint32
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ForwarderChain uint32
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Name uint32
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FirstThunk uint32
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dll string
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}
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// ImportedSymbols returns the names of all symbols
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// referred to by the binary f that are expected to be
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// satisfied by other libraries at dynamic load time.
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// It does not return weak symbols.
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func (f *File) ImportedSymbols() ([]string, error) {
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pe64 := f.Machine == IMAGE_FILE_MACHINE_AMD64
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ds := f.Section(".idata")
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if ds == nil {
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// not dynamic, so no libraries
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return nil, nil
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}
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d, err := ds.Data()
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if err != nil {
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return nil, err
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}
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var ida []ImportDirectory
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for len(d) > 0 {
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var dt ImportDirectory
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dt.OriginalFirstThunk = binary.LittleEndian.Uint32(d[0:4])
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dt.Name = binary.LittleEndian.Uint32(d[12:16])
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dt.FirstThunk = binary.LittleEndian.Uint32(d[16:20])
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d = d[20:]
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if dt.OriginalFirstThunk == 0 {
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break
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}
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ida = append(ida, dt)
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}
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// TODO(brainman): this needs to be rewritten
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// ds.Data() return contets of .idata section. Why store in variable called "names"?
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// Why we are retrieving it second time? We already have it in "d", and it is not modified anywhere.
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// getString does not extracts a string from symbol string table (as getString doco says).
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// Why ds.Data() called again and again in the loop?
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// Needs test before rewrite.
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names, _ := ds.Data()
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var all []string
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for _, dt := range ida {
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dt.dll, _ = getString(names, int(dt.Name-ds.VirtualAddress))
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d, _ = ds.Data()
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// seek to OriginalFirstThunk
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d = d[dt.OriginalFirstThunk-ds.VirtualAddress:]
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for len(d) > 0 {
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if pe64 { // 64bit
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va := binary.LittleEndian.Uint64(d[0:8])
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d = d[8:]
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if va == 0 {
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break
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}
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if va&0x8000000000000000 > 0 { // is Ordinal
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// TODO add dynimport ordinal support.
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} else {
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fn, _ := getString(names, int(uint32(va)-ds.VirtualAddress+2))
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all = append(all, fn+":"+dt.dll)
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}
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} else { // 32bit
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va := binary.LittleEndian.Uint32(d[0:4])
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d = d[4:]
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if va == 0 {
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break
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}
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if va&0x80000000 > 0 { // is Ordinal
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// TODO add dynimport ordinal support.
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//ord := va&0x0000FFFF
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} else {
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fn, _ := getString(names, int(va-ds.VirtualAddress+2))
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all = append(all, fn+":"+dt.dll)
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}
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}
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}
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}
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return all, nil
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}
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// ImportedLibraries returns the names of all libraries
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// referred to by the binary f that are expected to be
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// linked with the binary at dynamic link time.
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func (f *File) ImportedLibraries() ([]string, error) {
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// TODO
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// cgo -dynimport don't use this for windows PE, so just return.
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return nil, nil
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}
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// FormatError is unused.
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// The type is retained for compatibility.
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type FormatError struct {
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}
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func (e *FormatError) Error() string {
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return "unknown error"
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}
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