src/pkg/debug/macho/file.go - go - Git at Google

 // 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 macho implements access to Mach-O object files, as defined by
 // http://developer.apple.com/mac/library/documentation/DeveloperTools/Conceptual/MachORuntime/Reference/reference.html.
 package macho

 // High level access to low level data structures.

 import (
 	"bytes";
 	"debug/dwarf";
 	"encoding/binary";
 	"fmt";
 	"io";
 	"os";
 )

 // A File represents an open Mach-O file.
 type File struct {
 	FileHeader;
 	ByteOrder	binary.ByteOrder;
 	Loads		[]Load;
 	Sections	[]*Section;

 	closer	io.Closer;
 }

 // A Load represents any Mach-O load command.
 type Load interface {
 	Raw() []byte;
 }

 // A LoadBytes is the uninterpreted bytes of a Mach-O load command.
 type LoadBytes []byte

 func (b LoadBytes) Raw() []byte	{ return b }

 // A SegmentHeader is the header for a Mach-O 32-bit or 64-bit load segment command.
 type SegmentHeader struct {
 	Cmd	LoadCmd;
 	Len	uint32;
 	Name	string;
 	Addr	uint64;
 	Memsz	uint64;
 	Offset	uint64;
 	Filesz	uint64;
 	Maxprot	uint32;
 	Prot	uint32;
 	Nsect	uint32;
 	Flag	uint32;
 }

 // A Segment represents a Mach-O 32-bit or 64-bit load segment command.
 type Segment struct {
 	LoadBytes;
 	SegmentHeader;

 	// 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 segment.
 func (s *Segment) Data() ([]byte, os.Error) {
 	dat := make([]byte, s.sr.Size());
 	n, err := s.sr.ReadAt(dat, 0);
 	return dat[0:n], err;
 }

 // Open returns a new ReadSeeker reading the segment.
 func (s *Segment) Open() io.ReadSeeker	{ return io.NewSectionReader(s.sr, 0, 1<<63-1) }

 type SectionHeader struct {
 	Name	string;
 	Seg	string;
 	Addr	uint64;
 	Size	uint64;
 	Offset	uint32;
 	Align	uint32;
 	Reloff	uint32;
 	Nreloc	uint32;
 	Flags	uint32;
 }

 type Section struct {
 	SectionHeader;

 	// 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 Mach-O section.
 func (s *Section) Data() ([]byte, os.Error) {
 	dat := make([]byte, s.sr.Size());
 	n, err := s.sr.ReadAt(dat, 0);
 	return dat[0:n], err;
 }

 // Open returns a new ReadSeeker reading the Mach-O section.
 func (s *Section) Open() io.ReadSeeker	{ return io.NewSectionReader(s.sr, 0, 1<<63-1) }


 /*
  * Mach-O reader
  */

 type FormatError struct {
 	off	int64;
 	msg	string;
 	val	interface{};
 }

 func (e *FormatError) String() string {
 	msg := e.msg;
 	if e.val != nil {
 		msg += fmt.Sprintf(" '%v' ", e.val)
 	}
 	msg += fmt.Sprintf("in record at byte %#x", e.off);
 	return msg;
 }

 // Open opens the named file using os.Open and prepares it for use as a Mach-O binary.
 func Open(name string) (*File, os.Error) {
 	f, err := os.Open(name, os.O_RDONLY, 0);
 	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() os.Error {
 	var err os.Error;
 	if f.closer != nil {
 		err = f.closer.Close();
 		f.closer = nil;
 	}
 	return err;
 }

 // NewFile creates a new File for acecssing a Mach-O binary in an underlying reader.
 // The Mach-O binary is expected to start at position 0 in the ReaderAt.
 func NewFile(r io.ReaderAt) (*File, os.Error) {
 	f := new(File);
 	sr := io.NewSectionReader(r, 0, 1<<63-1);

 	// Read and decode Mach magic to determine byte order, size.
 	// Magic32 and Magic64 differ only in the bottom bit.
 	var ident [4]uint8;
 	if _, err := r.ReadAt(&ident, 0); err != nil {
 		return nil, err
 	}
 	be := binary.BigEndian.Uint32(&ident);
 	le := binary.LittleEndian.Uint32(&ident);
 	switch Magic32 &^ 1 {
 	case be &^ 1:
 		f.ByteOrder = binary.BigEndian;
 		f.Magic = be;
 	case le &^ 1:
 		f.ByteOrder = binary.LittleEndian;
 		f.Magic = le;
 	}

 	// Read entire file header.
 	if err := binary.Read(sr, f.ByteOrder, &f.FileHeader); err != nil {
 		return nil, err
 	}

 	// Then load commands.
 	offset := int64(fileHeaderSize32);
 	if f.Magic == Magic64 {
 		offset = fileHeaderSize64
 	}
 	dat := make([]byte, f.Cmdsz);
 	if _, err := r.ReadAt(dat, offset); err != nil {
 		return nil, err
 	}
 	f.Loads = make([]Load, f.Ncmd);
 	bo := f.ByteOrder;
 	for i := range f.Loads {
 		// Each load command begins with uint32 command and length.
 		if len(dat) < 8 {
 			return nil, &FormatError{offset, "command block too small", nil}
 		}
 		cmd, siz := LoadCmd(bo.Uint32(dat[0:4])), bo.Uint32(dat[4:8]);
 		if siz < 8 || siz > uint32(len(dat)) {
 			return nil, &FormatError{offset, "invalid command block size", nil}
 		}
 		var cmddat []byte;
 		cmddat, dat = dat[0:siz], dat[siz:len(dat)];
 		offset += int64(siz);
 		var s *Segment;
 		switch cmd {
 		default:
 			f.Loads[i] = LoadBytes(cmddat)

 		case LoadCmdSegment:
 			var seg32 Segment32;
 			b := bytes.NewBuffer(cmddat);
 			if err := binary.Read(b, bo, &seg32); err != nil {
 				return nil, err
 			}
 			s = new(Segment);
 			s.LoadBytes = cmddat;
 			s.Cmd = cmd;
 			s.Len = siz;
 			s.Name = cstring(&seg32.Name);
 			s.Addr = uint64(seg32.Addr);
 			s.Memsz = uint64(seg32.Memsz);
 			s.Offset = uint64(seg32.Offset);
 			s.Filesz = uint64(seg32.Filesz);
 			s.Maxprot = seg32.Maxprot;
 			s.Prot = seg32.Prot;
 			s.Nsect = seg32.Nsect;
 			s.Flag = seg32.Flag;
 			f.Loads[i] = s;
 			for i := 0; i < int(s.Nsect); i++ {
 				var sh32 Section32;
 				if err := binary.Read(b, bo, &sh32); err != nil {
 					return nil, err
 				}
 				sh := new(Section);
 				sh.Name = cstring(&sh32.Name);
 				sh.Seg = cstring(&sh32.Seg);
 				sh.Addr = uint64(sh32.Addr);
 				sh.Size = uint64(sh32.Size);
 				sh.Offset = sh32.Offset;
 				sh.Align = sh32.Align;
 				sh.Reloff = sh32.Reloff;
 				sh.Nreloc = sh32.Nreloc;
 				sh.Flags = sh32.Flags;
 				f.pushSection(sh, r);
 			}

 		case LoadCmdSegment64:
 			var seg64 Segment64;
 			b := bytes.NewBuffer(cmddat);
 			if err := binary.Read(b, bo, &seg64); err != nil {
 				return nil, err
 			}
 			s = new(Segment);
 			s.LoadBytes = cmddat;
 			s.Cmd = cmd;
 			s.Len = siz;
 			s.Name = cstring(&seg64.Name);
 			s.Addr = seg64.Addr;
 			s.Memsz = seg64.Memsz;
 			s.Offset = seg64.Offset;
 			s.Filesz = seg64.Filesz;
 			s.Maxprot = seg64.Maxprot;
 			s.Prot = seg64.Prot;
 			s.Nsect = seg64.Nsect;
 			s.Flag = seg64.Flag;
 			f.Loads[i] = s;
 			for i := 0; i < int(s.Nsect); i++ {
 				var sh64 Section64;
 				if err := binary.Read(b, bo, &sh64); err != nil {
 					return nil, err
 				}
 				sh := new(Section);
 				sh.Name = cstring(&sh64.Name);
 				sh.Seg = cstring(&sh64.Seg);
 				sh.Addr = sh64.Addr;
 				sh.Size = sh64.Size;
 				sh.Offset = sh64.Offset;
 				sh.Align = sh64.Align;
 				sh.Reloff = sh64.Reloff;
 				sh.Nreloc = sh64.Nreloc;
 				sh.Flags = sh64.Flags;
 				f.pushSection(sh, r);
 			}
 		}
 		if s != nil {
 			s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.Filesz));
 			s.ReaderAt = s.sr;
 		}
 	}
 	return f, nil;
 }

 func (f *File) pushSection(sh *Section, r io.ReaderAt) {
 	n := len(f.Sections);
 	if n >= cap(f.Sections) {
 		m := (n + 1) * 2;
 		new := make([]*Section, n, m);
 		for i, sh := range f.Sections {
 			new[i] = sh
 		}
 		f.Sections = new;
 	}
 	f.Sections = f.Sections[0 : n+1];
 	f.Sections[n] = sh;
 	sh.sr = io.NewSectionReader(r, int64(sh.Offset), int64(sh.Size));
 	sh.ReaderAt = sh.sr;
 }

 func cstring(b []byte) string {
 	var i int;
 	for i = 0; i < len(b) && b[i] != 0; i++ {
 	}
 	return string(b[0:i]);
 }

 // Segment returns the first Segment with the given name, or nil if no such segment exists.
 func (f *File) Segment(name string) *Segment {
 	for _, l := range f.Loads {
 		if s, ok := l.(*Segment); ok && s.Name == name {
 			return s
 		}
 	}
 	return nil;
 }

 // 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;
 }

 // DWARF returns the DWARF debug information for the Mach-O file.
 func (f *File) DWARF() (*dwarf.Data, os.Error) {
 	// There are many other DWARF sections, but these
 	// are the required ones, and the debug/dwarf package
 	// does not use the others, so don't bother loading them.
 	var names = [...]string{"abbrev", "info", "str"};
 	var dat [len(names)][]byte;
 	for i, name := range names {
 		name = "__debug_" + name;
 		s := f.Section(name);
 		if s == nil {
 			return nil, os.NewError("missing Mach-O section " + name)
 		}
 		b, err := s.Data();
 		if err != nil && uint64(len(b)) < s.Size {
 			return nil, err
 		}
 		dat[i] = b;
 	}

 	abbrev, info, str := dat[0], dat[1], dat[2];
 	return dwarf.New(abbrev, nil, nil, info, nil, nil, nil, str);
 }
	// 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 macho implements access to Mach-O object files, as defined by
	// http://developer.apple.com/mac/library/documentation/DeveloperTools/Conceptual/MachORuntime/Reference/reference.html.
	package macho

	// High level access to low level data structures.

	import (
	"bytes";
	"debug/dwarf";
	"encoding/binary";
	"fmt";
	"io";
	"os";
	)

	// A File represents an open Mach-O file.
	type File struct {
	FileHeader;
	ByteOrder binary.ByteOrder;
	Loads []Load;
	Sections []*Section;

	closer io.Closer;
	}

	// A Load represents any Mach-O load command.
	type Load interface {
	Raw() []byte;
	}

	// A LoadBytes is the uninterpreted bytes of a Mach-O load command.
	type LoadBytes []byte

	func (b LoadBytes) Raw() []byte { return b }

	// A SegmentHeader is the header for a Mach-O 32-bit or 64-bit load segment command.
	type SegmentHeader struct {
	Cmd LoadCmd;
	Len uint32;
	Name string;
	Addr uint64;
	Memsz uint64;
	Offset uint64;
	Filesz uint64;
	Maxprot uint32;
	Prot uint32;
	Nsect uint32;
	Flag uint32;
	}

	// A Segment represents a Mach-O 32-bit or 64-bit load segment command.
	type Segment struct {
	LoadBytes;
	SegmentHeader;

	// 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 segment.
	func (s *Segment) Data() ([]byte, os.Error) {
	dat := make([]byte, s.sr.Size());
	n, err := s.sr.ReadAt(dat, 0);
	return dat[0:n], err;
	}

	// Open returns a new ReadSeeker reading the segment.
	func (s *Segment) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) }

	type SectionHeader struct {
	Name string;
	Seg string;
	Addr uint64;
	Size uint64;
	Offset uint32;
	Align uint32;
	Reloff uint32;
	Nreloc uint32;
	Flags uint32;
	}

	type Section struct {
	SectionHeader;

	// 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 Mach-O section.
	func (s *Section) Data() ([]byte, os.Error) {
	dat := make([]byte, s.sr.Size());
	n, err := s.sr.ReadAt(dat, 0);
	return dat[0:n], err;
	}

	// Open returns a new ReadSeeker reading the Mach-O section.
	func (s *Section) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) }


	/*
	* Mach-O reader
	*/

	type FormatError struct {
	off int64;
	msg string;
	val interface{};
	}

	func (e *FormatError) String() string {
	msg := e.msg;
	if e.val != nil {
	msg += fmt.Sprintf(" '%v' ", e.val)
	}
	msg += fmt.Sprintf("in record at byte %#x", e.off);
	return msg;
	}

	// Open opens the named file using os.Open and prepares it for use as a Mach-O binary.
	func Open(name string) (*File, os.Error) {
	f, err := os.Open(name, os.O_RDONLY, 0);
	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() os.Error {
	var err os.Error;
	if f.closer != nil {
	err = f.closer.Close();
	f.closer = nil;
	}
	return err;
	}

	// NewFile creates a new File for acecssing a Mach-O binary in an underlying reader.
	// The Mach-O binary is expected to start at position 0 in the ReaderAt.
	func NewFile(r io.ReaderAt) (*File, os.Error) {
	f := new(File);
	sr := io.NewSectionReader(r, 0, 1<<63-1);

	// Read and decode Mach magic to determine byte order, size.
	// Magic32 and Magic64 differ only in the bottom bit.
	var ident [4]uint8;
	if _, err := r.ReadAt(&ident, 0); err != nil {
	return nil, err
	}
	be := binary.BigEndian.Uint32(&ident);
	le := binary.LittleEndian.Uint32(&ident);
	switch Magic32 &^ 1 {
	case be &^ 1:
	f.ByteOrder = binary.BigEndian;
	f.Magic = be;
	case le &^ 1:
	f.ByteOrder = binary.LittleEndian;
	f.Magic = le;
	}

	// Read entire file header.
	if err := binary.Read(sr, f.ByteOrder, &f.FileHeader); err != nil {
	return nil, err
	}

	// Then load commands.
	offset := int64(fileHeaderSize32);
	if f.Magic == Magic64 {
	offset = fileHeaderSize64
	}
	dat := make([]byte, f.Cmdsz);
	if _, err := r.ReadAt(dat, offset); err != nil {
	return nil, err
	}
	f.Loads = make([]Load, f.Ncmd);
	bo := f.ByteOrder;
	for i := range f.Loads {
	// Each load command begins with uint32 command and length.
	if len(dat) < 8 {
	return nil, &FormatError{offset, "command block too small", nil}
	}
	cmd, siz := LoadCmd(bo.Uint32(dat[0:4])), bo.Uint32(dat[4:8]);
	if siz < 8 \|\| siz > uint32(len(dat)) {
	return nil, &FormatError{offset, "invalid command block size", nil}
	}
	var cmddat []byte;
	cmddat, dat = dat[0:siz], dat[siz:len(dat)];
	offset += int64(siz);
	var s *Segment;
	switch cmd {
	default:
	f.Loads[i] = LoadBytes(cmddat)

	case LoadCmdSegment:
	var seg32 Segment32;
	b := bytes.NewBuffer(cmddat);
	if err := binary.Read(b, bo, &seg32); err != nil {
	return nil, err
	}
	s = new(Segment);
	s.LoadBytes = cmddat;
	s.Cmd = cmd;
	s.Len = siz;
	s.Name = cstring(&seg32.Name);
	s.Addr = uint64(seg32.Addr);
	s.Memsz = uint64(seg32.Memsz);
	s.Offset = uint64(seg32.Offset);
	s.Filesz = uint64(seg32.Filesz);
	s.Maxprot = seg32.Maxprot;
	s.Prot = seg32.Prot;
	s.Nsect = seg32.Nsect;
	s.Flag = seg32.Flag;
	f.Loads[i] = s;
	for i := 0; i < int(s.Nsect); i++ {
	var sh32 Section32;
	if err := binary.Read(b, bo, &sh32); err != nil {
	return nil, err
	}
	sh := new(Section);
	sh.Name = cstring(&sh32.Name);
	sh.Seg = cstring(&sh32.Seg);
	sh.Addr = uint64(sh32.Addr);
	sh.Size = uint64(sh32.Size);
	sh.Offset = sh32.Offset;
	sh.Align = sh32.Align;
	sh.Reloff = sh32.Reloff;
	sh.Nreloc = sh32.Nreloc;
	sh.Flags = sh32.Flags;
	f.pushSection(sh, r);
	}

	case LoadCmdSegment64:
	var seg64 Segment64;
	b := bytes.NewBuffer(cmddat);
	if err := binary.Read(b, bo, &seg64); err != nil {
	return nil, err
	}
	s = new(Segment);
	s.LoadBytes = cmddat;
	s.Cmd = cmd;
	s.Len = siz;
	s.Name = cstring(&seg64.Name);
	s.Addr = seg64.Addr;
	s.Memsz = seg64.Memsz;
	s.Offset = seg64.Offset;
	s.Filesz = seg64.Filesz;
	s.Maxprot = seg64.Maxprot;
	s.Prot = seg64.Prot;
	s.Nsect = seg64.Nsect;
	s.Flag = seg64.Flag;
	f.Loads[i] = s;
	for i := 0; i < int(s.Nsect); i++ {
	var sh64 Section64;
	if err := binary.Read(b, bo, &sh64); err != nil {
	return nil, err
	}
	sh := new(Section);
	sh.Name = cstring(&sh64.Name);
	sh.Seg = cstring(&sh64.Seg);
	sh.Addr = sh64.Addr;
	sh.Size = sh64.Size;
	sh.Offset = sh64.Offset;
	sh.Align = sh64.Align;
	sh.Reloff = sh64.Reloff;
	sh.Nreloc = sh64.Nreloc;
	sh.Flags = sh64.Flags;
	f.pushSection(sh, r);
	}
	}
	if s != nil {
	s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.Filesz));
	s.ReaderAt = s.sr;
	}
	}
	return f, nil;
	}

	func (f File) pushSection(sh Section, r io.ReaderAt) {
	n := len(f.Sections);
	if n >= cap(f.Sections) {
	m := (n + 1) * 2;
	new := make([]*Section, n, m);
	for i, sh := range f.Sections {
	new[i] = sh
	}
	f.Sections = new;
	}
	f.Sections = f.Sections[0 : n+1];
	f.Sections[n] = sh;
	sh.sr = io.NewSectionReader(r, int64(sh.Offset), int64(sh.Size));
	sh.ReaderAt = sh.sr;
	}

	func cstring(b []byte) string {
	var i int;
	for i = 0; i < len(b) && b[i] != 0; i++ {
	}
	return string(b[0:i]);
	}

	// Segment returns the first Segment with the given name, or nil if no such segment exists.
	func (f File) Segment(name string) Segment {
	for _, l := range f.Loads {
	if s, ok := l.(*Segment); ok && s.Name == name {
	return s
	}
	}
	return nil;
	}

	// 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;
	}

	// DWARF returns the DWARF debug information for the Mach-O file.
	func (f File) DWARF() (dwarf.Data, os.Error) {
	// There are many other DWARF sections, but these
	// are the required ones, and the debug/dwarf package
	// does not use the others, so don't bother loading them.
	var names = [...]string{"abbrev", "info", "str"};
	var dat [len(names)][]byte;
	for i, name := range names {
	name = "__debug_" + name;
	s := f.Section(name);
	if s == nil {
	return nil, os.NewError("missing Mach-O section " + name)
	}
	b, err := s.Data();
	if err != nil && uint64(len(b)) < s.Size {
	return nil, err
	}
	dat[i] = b;
	}

	abbrev, info, str := dat[0], dat[1], dat[2];
	return dwarf.New(abbrev, nil, nil, info, nil, nil, nil, str);
	}