Golang obj.Boffset函數代碼示例

func ldobjfile(ctxt *Link, f *obj.Biobuf, pkg string, length int64, pn string) {
	start := obj.Boffset(f)
	ctxt.IncVersion()
	var buf [8]uint8
	obj.Bread(f, buf[:])
	if string(buf[:]) != startmagic {
		log.Fatalf("%s: invalid file start %x %x %x %x %x %x %x %x", pn, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7])
	}
	c := obj.Bgetc(f)
	if c != 1 {
		log.Fatalf("%s: invalid file version number %d", pn, c)
	}

	var lib string
	for {
		lib = rdstring(f)
		if lib == "" {
			break
		}
		addlib(ctxt, pkg, pn, lib)
	}

	ctxt.CurRefs = []*LSym{nil} // zeroth ref is nil
	for {
		c, err := f.Peek(1)
		if err != nil {
			log.Fatalf("%s: peeking: %v", pn, err)
		}
		if c[0] == 0xff {
			obj.Bgetc(f)
			break
		}
		readref(ctxt, f, pkg, pn)
	}

	dataLength := rdint64(f)
	data := make([]byte, dataLength)
	obj.Bread(f, data)

	for {
		c, err := f.Peek(1)
		if err != nil {
			log.Fatalf("%s: peeking: %v", pn, err)
		}
		if c[0] == 0xff {
			break
		}
		readsym(ctxt, f, &data, pkg, pn)
	}

	buf = [8]uint8{}
	obj.Bread(f, buf[:])
	if string(buf[:]) != endmagic {
		log.Fatalf("%s: invalid file end", pn)
	}

	if obj.Boffset(f) != start+length {
		log.Fatalf("%s: unexpected end at %d, want %d", pn, int64(obj.Boffset(f)), int64(start+length))
	}
}

func ldhostobj(ld func(*obj.Biobuf, string, int64, string), f *obj.Biobuf, pkg string, length int64, pn string, file string) {
	isinternal := false
	for i := 0; i < len(internalpkg); i++ {
		if pkg == internalpkg[i] {
			isinternal = true
			break
		}
	}

	// DragonFly declares errno with __thread, which results in a symbol
	// type of R_386_TLS_GD or R_X86_64_TLSGD. The Go linker does not
	// currently know how to handle TLS relocations, hence we have to
	// force external linking for any libraries that link in code that
	// uses errno. This can be removed if the Go linker ever supports
	// these relocation types.
	if HEADTYPE == obj.Hdragonfly {
		if pkg == "net" || pkg == "os/user" {
			isinternal = false
		}
	}

	if !isinternal {
		externalobj = true
	}

	hostobj = append(hostobj, Hostobj{})
	h := &hostobj[len(hostobj)-1]
	h.ld = ld
	h.pkg = pkg
	h.pn = pn
	h.file = file
	h.off = obj.Boffset(f)
	h.length = length
}

// hostArchive reads an archive file holding host objects and links in
// required objects.  The general format is the same as a Go archive
// file, but it has an armap listing symbols and the objects that
// define them.  This is used for the compiler support library
// libgcc.a.
func hostArchive(name string) {
	f, err := obj.Bopenr(name)
	if err != nil {
		if os.IsNotExist(err) {
			// It's OK if we don't have a libgcc file at all.
			return
		}
		Exitf("cannot open file %s: %v", name, err)
	}
	defer obj.Bterm(f)

	magbuf := make([]byte, len(ARMAG))
	if obj.Bread(f, magbuf) != len(magbuf) {
		Exitf("file %s too short", name)
	}

	var arhdr ArHdr
	l := nextar(f, obj.Boffset(f), &arhdr)
	if l <= 0 {
		Exitf("%s missing armap", name)
	}

	var armap archiveMap
	if arhdr.name == "/" || arhdr.name == "/SYM64/" {
		armap = readArmap(name, f, arhdr)
	} else {
		Exitf("%s missing armap", name)
	}

	loaded := make(map[uint64]bool)
	any := true
	for any {
		var load []uint64
		for s := Ctxt.Allsym; s != nil; s = s.Allsym {
			for _, r := range s.R {
				if r.Sym != nil && r.Sym.Type&obj.SMASK == obj.SXREF {
					if off := armap[r.Sym.Name]; off != 0 && !loaded[off] {
						load = append(load, off)
						loaded[off] = true
					}
				}
			}
		}

		for _, off := range load {
			l := nextar(f, int64(off), &arhdr)
			if l <= 0 {
				Exitf("%s missing archive entry at offset %d", name, off)
			}
			pname := fmt.Sprintf("%s(%s)", name, arhdr.name)
			l = atolwhex(arhdr.size)

			h := ldobj(f, "libgcc", l, pname, name, ArchiveObj)
			obj.Bseek(f, h.off, 0)
			h.ld(f, h.pkg, h.length, h.pn)
		}

		any = len(load) > 0
	}
}

func ldobjfile(ctxt *Link, f *obj.Biobuf, pkg string, length int64, pn string) {
	start := obj.Boffset(f)
	ctxt.Version++
	var buf [8]uint8
	obj.Bread(f, buf[:])
	if string(buf[:]) != startmagic {
		log.Fatalf("%s: invalid file start %x %x %x %x %x %x %x %x", pn, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7])
	}
	c := obj.Bgetc(f)
	if c != 1 {
		log.Fatalf("%s: invalid file version number %d", pn, c)
	}

	var lib string
	for {
		lib = rdstring(f)
		if lib == "" {
			break
		}
		addlib(ctxt, pkg, pn, lib)
	}

	for {
		c, err := f.Peek(1)
		if err != nil {
			log.Fatalf("%s: peeking: %v", pn, err)
		}
		if c[0] == 0xff {
			break
		}
		readsym(ctxt, f, pkg, pn)
	}

	buf = [8]uint8{}
	obj.Bread(f, buf[:])
	if string(buf[:]) != endmagic {
		log.Fatalf("%s: invalid file end", pn)
	}

	if obj.Boffset(f) != start+length {
		log.Fatalf("%s: unexpected end at %d, want %d", pn, int64(obj.Boffset(f)), int64(start+length))
	}
}

func dumpobj() {
	var err error
	bout, err = obj.Bopenw(outfile)
	if err != nil {
		Flusherrors()
		fmt.Printf("can't create %s: %v\n", outfile, err)
		errorexit()
	}

	startobj := int64(0)
	var arhdr [ArhdrSize]byte
	if writearchive != 0 {
		obj.Bwritestring(bout, "!<arch>\n")
		arhdr = [ArhdrSize]byte{}
		bout.Write(arhdr[:])
		startobj = obj.Boffset(bout)
	}

	fmt.Fprintf(bout, "go object %s %s %s %s\n", obj.Getgoos(), obj.Getgoarch(), obj.Getgoversion(), obj.Expstring())
	dumpexport()

	if writearchive != 0 {
		bout.Flush()
		size := obj.Boffset(bout) - startobj
		if size&1 != 0 {
			obj.Bputc(bout, 0)
		}
		obj.Bseek(bout, startobj-ArhdrSize, 0)
		formathdr(arhdr[:], "__.PKGDEF", size)
		bout.Write(arhdr[:])
		bout.Flush()

		obj.Bseek(bout, startobj+size+(size&1), 0)
		arhdr = [ArhdrSize]byte{}
		bout.Write(arhdr[:])
		startobj = obj.Boffset(bout)
		fmt.Fprintf(bout, "go object %s %s %s %s\n", obj.Getgoos(), obj.Getgoarch(), obj.Getgoversion(), obj.Expstring())
	}

	if pragcgobuf != "" {
		if writearchive != 0 {
			// write empty export section; must be before cgo section
			fmt.Fprintf(bout, "\n$$\n\n$$\n\n")
		}

		fmt.Fprintf(bout, "\n$$  // cgo\n")
		fmt.Fprintf(bout, "%s\n$$\n\n", pragcgobuf)
	}

	fmt.Fprintf(bout, "\n!\n")

	externs := len(externdcl)

	dumpglobls()
	dumptypestructs()

	// Dump extra globals.
	tmp := externdcl

	if externdcl != nil {
		externdcl = externdcl[externs:]
	}
	dumpglobls()
	externdcl = tmp

	dumpdata()
	obj.Writeobjdirect(Ctxt, bout)

	if writearchive != 0 {
		bout.Flush()
		size := obj.Boffset(bout) - startobj
		if size&1 != 0 {
			obj.Bputc(bout, 0)
		}
		obj.Bseek(bout, startobj-ArhdrSize, 0)
		formathdr(arhdr[:], "_go_.o", size)
		bout.Write(arhdr[:])
	}

	obj.Bterm(bout)
}

func objfile(lib *Library) {
	pkg := pathtoprefix(lib.Pkg)

	if Debug['v'] > 1 {
		fmt.Fprintf(&Bso, "%5.2f ldobj: %s (%s)\n", obj.Cputime(), lib.File, pkg)
	}
	Bso.Flush()
	var err error
	var f *obj.Biobuf
	f, err = obj.Bopenr(lib.File)
	if err != nil {
		Exitf("cannot open file %s: %v", lib.File, err)
	}

	magbuf := make([]byte, len(ARMAG))
	if obj.Bread(f, magbuf) != len(magbuf) || !strings.HasPrefix(string(magbuf), ARMAG) {
		/* load it as a regular file */
		l := obj.Bseek(f, 0, 2)

		obj.Bseek(f, 0, 0)
		ldobj(f, pkg, l, lib.File, lib.File, FileObj)
		obj.Bterm(f)

		return
	}

	/* skip over optional __.GOSYMDEF and process __.PKGDEF */
	off := obj.Boffset(f)

	var arhdr ArHdr
	l := nextar(f, off, &arhdr)
	var pname string
	if l <= 0 {
		Diag("%s: short read on archive file symbol header", lib.File)
		goto out
	}

	if strings.HasPrefix(arhdr.name, symname) {
		off += l
		l = nextar(f, off, &arhdr)
		if l <= 0 {
			Diag("%s: short read on archive file symbol header", lib.File)
			goto out
		}
	}

	if !strings.HasPrefix(arhdr.name, pkgname) {
		Diag("%s: cannot find package header", lib.File)
		goto out
	}

	if Buildmode == BuildmodeShared {
		before := obj.Boffset(f)
		pkgdefBytes := make([]byte, atolwhex(arhdr.size))
		obj.Bread(f, pkgdefBytes)
		hash := sha1.Sum(pkgdefBytes)
		lib.hash = hash[:]
		obj.Bseek(f, before, 0)
	}

	off += l

	if Debug['u'] != 0 {
		ldpkg(f, pkg, atolwhex(arhdr.size), lib.File, Pkgdef)
	}

	/*
	 * load all the object files from the archive now.
	 * this gives us sequential file access and keeps us
	 * from needing to come back later to pick up more
	 * objects.  it breaks the usual C archive model, but
	 * this is Go, not C.  the common case in Go is that
	 * we need to load all the objects, and then we throw away
	 * the individual symbols that are unused.
	 *
	 * loading every object will also make it possible to
	 * load foreign objects not referenced by __.GOSYMDEF.
	 */
	for {
		l = nextar(f, off, &arhdr)
		if l == 0 {
			break
		}
		if l < 0 {
			Exitf("%s: malformed archive", lib.File)
		}

		off += l

		pname = fmt.Sprintf("%s(%s)", lib.File, arhdr.name)
		l = atolwhex(arhdr.size)
		ldobj(f, pkg, l, pname, lib.File, ArchiveObj)
	}

out:
	obj.Bterm(f)
}

func ldobj(f *obj.Biobuf, pkg string, length int64, pn string, file string, whence int) {
	eof := obj.Boffset(f) + length

	start := obj.Boffset(f)
	c1 := obj.Bgetc(f)
	c2 := obj.Bgetc(f)
	c3 := obj.Bgetc(f)
	c4 := obj.Bgetc(f)
	obj.Bseek(f, start, 0)

	magic := uint32(c1)<<24 | uint32(c2)<<16 | uint32(c3)<<8 | uint32(c4)
	if magic == 0x7f454c46 { // \x7F E L F
		ldhostobj(ldelf, f, pkg, length, pn, file)
		return
	}

	if magic&^1 == 0xfeedface || magic&^0x01000000 == 0xcefaedfe {
		ldhostobj(ldmacho, f, pkg, length, pn, file)
		return
	}

	if c1 == 0x4c && c2 == 0x01 || c1 == 0x64 && c2 == 0x86 {
		ldhostobj(ldpe, f, pkg, length, pn, file)
		return
	}

	/* check the header */
	line := obj.Brdline(f, '\n')
	if line == "" {
		if obj.Blinelen(f) > 0 {
			Diag("%s: not an object file", pn)
			return
		}
		Diag("truncated object file: %s", pn)
		return
	}

	if !strings.HasPrefix(line, "go object ") {
		if strings.HasSuffix(pn, ".go") {
			Exitf("%cl: input %s is not .%c file (use %cg to compile .go files)", Thearch.Thechar, pn, Thearch.Thechar, Thearch.Thechar)
		}

		if line == Thestring {
			// old header format: just $GOOS
			Diag("%s: stale object file", pn)
			return
		}

		Diag("%s: not an object file", pn)
		return
	}

	// First, check that the basic goos, goarch, and version match.
	t := fmt.Sprintf("%s %s %s ", goos, obj.Getgoarch(), obj.Getgoversion())

	line = strings.TrimRight(line, "\n")
	if !strings.HasPrefix(line[10:]+" ", t) && Debug['f'] == 0 {
		Diag("%s: object is [%s] expected [%s]", pn, line[10:], t)
		return
	}

	// Second, check that longer lines match each other exactly,
	// so that the Go compiler and write additional information
	// that must be the same from run to run.
	if len(line) >= len(t)+10 {
		if theline == "" {
			theline = line[10:]
		} else if theline != line[10:] {
			Diag("%s: object is [%s] expected [%s]", pn, line[10:], theline)
			return
		}
	}

	/* skip over exports and other info -- ends with \n!\n */
	import0 := obj.Boffset(f)

	c1 = '\n' // the last line ended in \n
	c2 = obj.Bgetc(f)
	c3 = obj.Bgetc(f)
	for c1 != '\n' || c2 != '!' || c3 != '\n' {
		c1 = c2
		c2 = c3
		c3 = obj.Bgetc(f)
		if c3 == obj.Beof {
			Diag("truncated object file: %s", pn)
			return
		}
	}

	import1 := obj.Boffset(f)

	obj.Bseek(f, import0, 0)
	ldpkg(f, pkg, import1-import0-2, pn, whence) // -2 for !\n
	obj.Bseek(f, import1, 0)

	ldobjfile(Ctxt, f, pkg, eof-obj.Boffset(f), pn)
}

func ldelf(f *obj.Biobuf, pkg string, length int64, pn string) {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f ldelf %s\n", obj.Cputime(), pn)
	}

	Ctxt.Version++
	base := int32(obj.Boffset(f))

	var add uint64
	var e binary.ByteOrder
	var elfobj *ElfObj
	var err error
	var flag int
	var hdr *ElfHdrBytes
	var hdrbuf [64]uint8
	var info uint64
	var is64 int
	var j int
	var n int
	var name string
	var p []byte
	var r []Reloc
	var rela int
	var rp *Reloc
	var rsect *ElfSect
	var s *LSym
	var sect *ElfSect
	var sym ElfSym
	var symbols []*LSym
	if obj.Bread(f, hdrbuf[:]) != len(hdrbuf) {
		goto bad
	}
	hdr = new(ElfHdrBytes)
	binary.Read(bytes.NewReader(hdrbuf[:]), binary.BigEndian, hdr) // only byte arrays; byte order doesn't matter
	if string(hdr.Ident[:4]) != "\x7FELF" {
		goto bad
	}
	switch hdr.Ident[5] {
	case ElfDataLsb:
		e = binary.LittleEndian

	case ElfDataMsb:
		e = binary.BigEndian

	default:
		goto bad
	}

	// read header
	elfobj = new(ElfObj)

	elfobj.e = e
	elfobj.f = f
	elfobj.base = int64(base)
	elfobj.length = length
	elfobj.name = pn

	is64 = 0
	if hdr.Ident[4] == ElfClass64 {
		is64 = 1
		hdr := new(ElfHdrBytes64)
		binary.Read(bytes.NewReader(hdrbuf[:]), binary.BigEndian, hdr) // only byte arrays; byte order doesn't matter
		elfobj.type_ = uint32(e.Uint16(hdr.Type[:]))
		elfobj.machine = uint32(e.Uint16(hdr.Machine[:]))
		elfobj.version = e.Uint32(hdr.Version[:])
		elfobj.phoff = e.Uint64(hdr.Phoff[:])
		elfobj.shoff = e.Uint64(hdr.Shoff[:])
		elfobj.flags = e.Uint32(hdr.Flags[:])
		elfobj.ehsize = uint32(e.Uint16(hdr.Ehsize[:]))
		elfobj.phentsize = uint32(e.Uint16(hdr.Phentsize[:]))
		elfobj.phnum = uint32(e.Uint16(hdr.Phnum[:]))
		elfobj.shentsize = uint32(e.Uint16(hdr.Shentsize[:]))
		elfobj.shnum = uint32(e.Uint16(hdr.Shnum[:]))
		elfobj.shstrndx = uint32(e.Uint16(hdr.Shstrndx[:]))
	} else {
		elfobj.type_ = uint32(e.Uint16(hdr.Type[:]))
		elfobj.machine = uint32(e.Uint16(hdr.Machine[:]))
		elfobj.version = e.Uint32(hdr.Version[:])
		elfobj.entry = uint64(e.Uint32(hdr.Entry[:]))
		elfobj.phoff = uint64(e.Uint32(hdr.Phoff[:]))
		elfobj.shoff = uint64(e.Uint32(hdr.Shoff[:]))
		elfobj.flags = e.Uint32(hdr.Flags[:])
		elfobj.ehsize = uint32(e.Uint16(hdr.Ehsize[:]))
		elfobj.phentsize = uint32(e.Uint16(hdr.Phentsize[:]))
		elfobj.phnum = uint32(e.Uint16(hdr.Phnum[:]))
		elfobj.shentsize = uint32(e.Uint16(hdr.Shentsize[:]))
		elfobj.shnum = uint32(e.Uint16(hdr.Shnum[:]))
		elfobj.shstrndx = uint32(e.Uint16(hdr.Shstrndx[:]))
	}

	elfobj.is64 = is64

	if uint32(hdr.Ident[6]) != elfobj.version {
		goto bad
	}

	if e.Uint16(hdr.Type[:]) != ElfTypeRelocatable {
		Diag("%s: elf but not elf relocatable object", pn)
		return
	}
//.........這裏部分代碼省略.........

func ldpe(f *obj.Biobuf, pkg string, length int64, pn string) {
	if Debug['v'] != 0 {
		fmt.Fprintf(&Bso, "%5.2f ldpe %s\n", obj.Cputime(), pn)
	}

	var sect *PeSect
	Ctxt.Version++
	base := int32(obj.Boffset(f))

	peobj := new(PeObj)
	peobj.f = f
	peobj.base = uint32(base)
	peobj.name = pn

	// read header
	var err error
	var j int
	var l uint32
	var name string
	var numaux int
	var r []Reloc
	var rp *Reloc
	var rsect *PeSect
	var s *LSym
	var sym *PeSym
	var symbuf [18]uint8
	if err = binary.Read(f, binary.LittleEndian, &peobj.fh); err != nil {
		goto bad
	}

	// load section list
	peobj.sect = make([]PeSect, peobj.fh.NumberOfSections)

	peobj.nsect = uint(peobj.fh.NumberOfSections)
	for i := 0; i < int(peobj.fh.NumberOfSections); i++ {
		if err = binary.Read(f, binary.LittleEndian, &peobj.sect[i].sh); err != nil {
			goto bad
		}
		peobj.sect[i].size = uint64(peobj.sect[i].sh.SizeOfRawData)
		peobj.sect[i].name = cstring(peobj.sect[i].sh.Name[:])
	}

	// TODO return error if found .cormeta

	// load string table
	obj.Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(peobj.fh.NumberOfSymbols), 0)

	if obj.Bread(f, symbuf[:4]) != 4 {
		goto bad
	}
	l = Le32(symbuf[:])
	peobj.snames = make([]byte, l)
	obj.Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(peobj.fh.NumberOfSymbols), 0)
	if obj.Bread(f, peobj.snames) != len(peobj.snames) {
		goto bad
	}

	// rewrite section names if they start with /
	for i := 0; i < int(peobj.fh.NumberOfSections); i++ {
		if peobj.sect[i].name == "" {
			continue
		}
		if peobj.sect[i].name[0] != '/' {
			continue
		}
		n, _ := strconv.Atoi(peobj.sect[i].name[1:])
		peobj.sect[i].name = cstring(peobj.snames[n:])
	}

	// read symbols
	peobj.pesym = make([]PeSym, peobj.fh.NumberOfSymbols)

	peobj.npesym = uint(peobj.fh.NumberOfSymbols)
	obj.Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable), 0)
	for i := 0; uint32(i) < peobj.fh.NumberOfSymbols; i += numaux + 1 {
		obj.Bseek(f, int64(base)+int64(peobj.fh.PointerToSymbolTable)+int64(len(symbuf))*int64(i), 0)
		if obj.Bread(f, symbuf[:]) != len(symbuf) {
			goto bad
		}

		if (symbuf[0] == 0) && (symbuf[1] == 0) && (symbuf[2] == 0) && (symbuf[3] == 0) {
			l = Le32(symbuf[4:])
			peobj.pesym[i].name = cstring(peobj.snames[l:]) // sym name length <= 8
		} else {
			peobj.pesym[i].name = cstring(symbuf[:8])
		}

		peobj.pesym[i].value = Le32(symbuf[8:])
		peobj.pesym[i].sectnum = Le16(symbuf[12:])
		peobj.pesym[i].sclass = symbuf[16]
		peobj.pesym[i].aux = symbuf[17]
		peobj.pesym[i].type_ = Le16(symbuf[14:])
		numaux = int(peobj.pesym[i].aux)
		if numaux < 0 {
			numaux = 0
		}
	}

	// create symbols for mapped sections
	for i := 0; uint(i) < peobj.nsect; i++ {
//.........這裏部分代碼省略.........

func ldmacho(f *obj.Biobuf, pkg string, length int64, pn string) {
	var err error
	var j int
	var is64 bool
	var secaddr uint64
	var hdr [7 * 4]uint8
	var cmdp []byte
	var dat []byte
	var ncmd uint32
	var cmdsz uint32
	var ty uint32
	var sz uint32
	var off uint32
	var m *LdMachoObj
	var e binary.ByteOrder
	var sect *LdMachoSect
	var rel *LdMachoRel
	var rpi int
	var s *LSym
	var s1 *LSym
	var outer *LSym
	var c *LdMachoCmd
	var symtab *LdMachoSymtab
	var dsymtab *LdMachoDysymtab
	var sym *LdMachoSym
	var r []Reloc
	var rp *Reloc
	var name string

	Ctxt.Version++
	base := obj.Boffset(f)
	if obj.Bread(f, hdr[:]) != len(hdr) {
		goto bad
	}

	if binary.BigEndian.Uint32(hdr[:])&^1 == 0xFEEDFACE {
		e = binary.BigEndian
	} else if binary.LittleEndian.Uint32(hdr[:])&^1 == 0xFEEDFACE {
		e = binary.LittleEndian
	} else {
		err = fmt.Errorf("bad magic - not mach-o file")
		goto bad
	}

	is64 = e.Uint32(hdr[:]) == 0xFEEDFACF
	ncmd = e.Uint32([]byte(hdr[4*4:]))
	cmdsz = e.Uint32([]byte(hdr[5*4:]))
	if ncmd > 0x10000 || cmdsz >= 0x01000000 {
		err = fmt.Errorf("implausible mach-o header ncmd=%d cmdsz=%d", ncmd, cmdsz)
		goto bad
	}

	if is64 {
		var tmp [4]uint8
		obj.Bread(f, tmp[:4]) // skip reserved word in header
	}

	m = new(LdMachoObj)

	m.f = f
	m.e = e
	m.cputype = uint(e.Uint32([]byte(hdr[1*4:])))
	m.subcputype = uint(e.Uint32([]byte(hdr[2*4:])))
	m.filetype = e.Uint32([]byte(hdr[3*4:]))
	m.ncmd = uint(ncmd)
	m.flags = e.Uint32([]byte(hdr[6*4:]))
	m.is64 = is64
	m.base = base
	m.length = length
	m.name = pn

	switch Thearch.Thechar {
	default:
		Diag("%s: mach-o %s unimplemented", pn, Thestring)
		return

	case '6':
		if e != binary.LittleEndian || m.cputype != LdMachoCpuAmd64 {
			Diag("%s: mach-o object but not amd64", pn)
			return
		}

	case '8':
		if e != binary.LittleEndian || m.cputype != LdMachoCpu386 {
			Diag("%s: mach-o object but not 386", pn)
			return
		}
	}

	m.cmd = make([]LdMachoCmd, ncmd)
	off = uint32(len(hdr))
	cmdp = make([]byte, cmdsz)
	if obj.Bread(f, cmdp) != len(cmdp) {
		err = fmt.Errorf("reading cmds: %v", err)
		goto bad
	}

	// read and parse load commands
	c = nil

//.........這裏部分代碼省略.........

func dumpobj() {
	var err error
	bout, err = obj.Bopenw(outfile)
	if err != nil {
		Flusherrors()
		fmt.Printf("can't create %s: %v\n", outfile, err)
		errorexit()
	}

	startobj := int64(0)
	var arhdr [ArhdrSize]byte
	if writearchive != 0 {
		obj.Bwritestring(bout, "!<arch>\n")
		arhdr = [ArhdrSize]byte{}
		obj.Bwrite(bout, arhdr[:])
		startobj = obj.Boffset(bout)
	}

	fmt.Fprintf(bout, "go object %s %s %s %s\n", obj.Getgoos(), obj.Getgoarch(), obj.Getgoversion(), obj.Expstring())
	dumpexport()

	if writearchive != 0 {
		obj.Bflush(bout)
		size := obj.Boffset(bout) - startobj
		if size&1 != 0 {
			obj.Bputc(bout, 0)
		}
		obj.Bseek(bout, startobj-ArhdrSize, 0)
		formathdr(arhdr[:], "__.PKGDEF", size)
		obj.Bwrite(bout, arhdr[:])
		obj.Bflush(bout)

		obj.Bseek(bout, startobj+size+(size&1), 0)
		arhdr = [ArhdrSize]byte{}
		obj.Bwrite(bout, arhdr[:])
		startobj = obj.Boffset(bout)
		fmt.Fprintf(bout, "go object %s %s %s %s\n", obj.Getgoos(), obj.Getgoarch(), obj.Getgoversion(), obj.Expstring())
	}

	if pragcgobuf != "" {
		if writearchive != 0 {
			// write empty export section; must be before cgo section
			fmt.Fprintf(bout, "\n$$\n\n$$\n\n")
		}

		fmt.Fprintf(bout, "\n$$  // cgo\n")
		fmt.Fprintf(bout, "%s\n$$\n\n", pragcgobuf)
	}

	fmt.Fprintf(bout, "\n!\n")

	var externs *NodeList
	if externdcl != nil {
		externs = externdcl.End
	}

	dumpglobls()
	dumptypestructs()

	// Dump extra globals.
	tmp := externdcl

	if externs != nil {
		externdcl = externs.Next
	}
	dumpglobls()
	externdcl = tmp

	zero := Pkglookup("zerovalue", Runtimepkg)
	ggloblsym(zero, int32(zerosize), obj.DUPOK|obj.RODATA)

	dumpdata()
	obj.Writeobjdirect(Ctxt, bout)

	if writearchive != 0 {
		obj.Bflush(bout)
		size := obj.Boffset(bout) - startobj
		if size&1 != 0 {
			obj.Bputc(bout, 0)
		}
		obj.Bseek(bout, startobj-ArhdrSize, 0)
		name := fmt.Sprintf("_go_.%c", Thearch.Thechar)
		formathdr(arhdr[:], name, size)
		obj.Bwrite(bout, arhdr[:])
	}

	obj.Bterm(bout)
}