// Inferno utils/8l/asm.c
// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/8l/asm.c
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package ld
import (
"bufio"
"bytes"
"cmd/internal/bio"
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/loadelf"
"cmd/link/internal/loadmacho"
"cmd/link/internal/loadpe"
"cmd/link/internal/objfile"
"cmd/link/internal/sym"
"crypto/sha1"
"debug/elf"
"encoding/base64"
"encoding/binary"
"encoding/hex"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"sync"
)
// Data layout and relocation.
// Derived from Inferno utils/6l/l.h
// https://bitbucket.org/inferno-os/inferno-os/src/default/utils/6l/l.h
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
type Arch struct {
Funcalign int
Maxalign int
Minalign int
Dwarfregsp int
Dwarfreglr int
Linuxdynld string
Freebsddynld string
Netbsddynld string
Openbsddynld string
Dragonflydynld string
Solarisdynld string
Adddynrel func(*Link, *sym.Symbol, *sym.Reloc) bool
Archinit func(*Link)
Archreloc func(*Link, *sym.Reloc, *sym.Symbol, *int64) bool
Archrelocvariant func(*Link, *sym.Reloc, *sym.Symbol, int64) int64
Trampoline func(*Link, *sym.Reloc, *sym.Symbol)
Asmb func(*Link)
Elfreloc1 func(*Link, *sym.Reloc, int64) bool
Elfsetupplt func(*Link)
Gentext func(*Link)
Machoreloc1 func(*sys.Arch, *OutBuf, *sym.Symbol, *sym.Reloc, int64) bool
PEreloc1 func(*sys.Arch, *OutBuf, *sym.Symbol, *sym.Reloc, int64) bool
// TLSIEtoLE converts a TLS Initial Executable relocation to
// a TLS Local Executable relocation.
//
// This is possible when a TLS IE relocation refers to a local
// symbol in an executable, which is typical when internally
// linking PIE binaries.
TLSIEtoLE func(s *sym.Symbol, off, size int)
}
var (
Thearch Arch
Lcsize int32
rpath Rpath
Spsize int32
Symsize int32
)
const (
MINFUNC = 16 // minimum size for a function
)
// DynlinkingGo returns whether we are producing Go code that can live
// in separate shared libraries linked together at runtime.
func (ctxt *Link) DynlinkingGo() bool {
if !ctxt.Loaded {
panic("DynlinkingGo called before all symbols loaded")
}
return ctxt.BuildMode == BuildModeShared || ctxt.linkShared || ctxt.BuildMode == BuildModePlugin || ctxt.CanUsePlugins()
}
// CanUsePlugins returns whether a plugins can be used
func (ctxt *Link) CanUsePlugins() bool {
return ctxt.Syms.ROLookup("plugin.Open", 0) != nil
}
// UseRelro returns whether to make use of "read only relocations" aka
// relro.
func (ctxt *Link) UseRelro() bool {
switch ctxt.BuildMode {
case BuildModeCArchive, BuildModeCShared, BuildModeShared, BuildModePIE, BuildModePlugin:
return ctxt.IsELF
default:
return ctxt.linkShared
}
}
var (
dynexp []*sym.Symbol
dynlib []string
ldflag []string
havedynamic int
Funcalign int
iscgo bool
elfglobalsymndx int
interpreter string
debug_s bool // backup old value of debug['s']
HEADR int32
nerrors int
liveness int64
)
var (
Segtext sym.Segment
Segrodata sym.Segment
Segrelrodata sym.Segment
Segdata sym.Segment
Segdwarf sym.Segment
)
/* whence for ldpkg */
const (
FileObj = 0 + iota
ArchiveObj
Pkgdef
)
const pkgdef = "__.PKGDEF"
var (
// Set if we see an object compiled by the host compiler that is not
// from a package that is known to support internal linking mode.
externalobj = false
theline string
)
func Lflag(ctxt *Link, arg string) {
ctxt.Libdir = append(ctxt.Libdir, arg)
}
/*
* Unix doesn't like it when we write to a running (or, sometimes,
* recently run) binary, so remove the output file before writing it.
* On Windows 7, remove() can force a subsequent create() to fail.
* S_ISREG() does not exist on Plan 9.
*/
func mayberemoveoutfile() {
if fi, err := os.Lstat(*flagOutfile); err == nil && !fi.Mode().IsRegular() {
return
}
os.Remove(*flagOutfile)
}
func libinit(ctxt *Link) {
Funcalign = Thearch.Funcalign
// add goroot to the end of the libdir list.
suffix := ""
suffixsep := ""
if *flagInstallSuffix != "" {
suffixsep = "_"
suffix = *flagInstallSuffix
} else if *flagRace {
suffixsep = "_"
suffix = "race"
} else if *flagMsan {
suffixsep = "_"
suffix = "msan"
}
Lflag(ctxt, filepath.Join(objabi.GOROOT, "pkg", fmt.Sprintf("%s_%s%s%s", objabi.GOOS, objabi.GOARCH, suffixsep, suffix)))
mayberemoveoutfile()
f, err := os.OpenFile(*flagOutfile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0775)
if err != nil {
Exitf("cannot create %s: %v", *flagOutfile, err)
}
ctxt.Out.w = bufio.NewWriter(f)
ctxt.Out.f = f
if *flagEntrySymbol == "" {
switch ctxt.BuildMode {
case BuildModeCShared, BuildModeCArchive:
*flagEntrySymbol = fmt.Sprintf("_rt0_%s_%s_lib", objabi.GOARCH, objabi.GOOS)
case BuildModeExe, BuildModePIE:
*flagEntrySymbol = fmt.Sprintf("_rt0_%s_%s", objabi.GOARCH, objabi.GOOS)
case BuildModeShared, BuildModePlugin:
// No *flagEntrySymbol for -buildmode=shared and plugin
default:
Errorf(nil, "unknown *flagEntrySymbol for buildmode %v", ctxt.BuildMode)
}
}
}
func errorexit() {
if nerrors != 0 {
Exit(2)
}
Exit(0)
}
func loadinternal(ctxt *Link, name string) *sym.Library {
if ctxt.linkShared && ctxt.PackageShlib != nil {
if shlib := ctxt.PackageShlib[name]; shlib != "" {
return addlibpath(ctxt, "internal", "internal", "", name, shlib)
}
}
if ctxt.PackageFile != nil {
if pname := ctxt.PackageFile[name]; pname != "" {
return addlibpath(ctxt, "internal", "internal", pname, name, "")
}
ctxt.Logf("loadinternal: cannot find %s\n", name)
return nil
}
for i := 0; i < len(ctxt.Libdir); i++ {
if ctxt.linkShared {
shlibname := filepath.Join(ctxt.Libdir[i], name+".shlibname")
if ctxt.Debugvlog != 0 {
ctxt.Logf("searching for %s.a in %s\n", name, shlibname)
}
if _, err := os.Stat(shlibname); err == nil {
return addlibpath(ctxt, "internal", "internal", "", name, shlibname)
}
}
pname := filepath.Join(ctxt.Libdir[i], name+".a")
if ctxt.Debugvlog != 0 {
ctxt.Logf("searching for %s.a in %s\n", name, pname)
}
if _, err := os.Stat(pname); err == nil {
return addlibpath(ctxt, "internal", "internal", pname, name, "")
}
}
ctxt.Logf("warning: unable to find %s.a\n", name)
return nil
}
// findLibPathCmd uses cmd command to find gcc library libname.
// It returns library full path if found, or "none" if not found.
func (ctxt *Link) findLibPathCmd(cmd, libname string) string {
if *flagExtld == "" {
*flagExtld = "gcc"
}
args := hostlinkArchArgs(ctxt.Arch)
args = append(args, cmd)
if ctxt.Debugvlog != 0 {
ctxt.Logf("%s %v\n", *flagExtld, args)
}
out, err := exec.Command(*flagExtld, args...).Output()
if err != nil {
if ctxt.Debugvlog != 0 {
ctxt.Logf("not using a %s file because compiler failed\n%v\n%s\n", libname, err, out)
}
return "none"
}
return strings.TrimSpace(string(out))
}
// findLibPath searches for library libname.
// It returns library full path if found, or "none" if not found.
func (ctxt *Link) findLibPath(libname string) string {
return ctxt.findLibPathCmd("--print-file-name="+libname, libname)
}
func (ctxt *Link) loadlib() {
switch ctxt.BuildMode {
case BuildModeCShared, BuildModePlugin:
s := ctxt.Syms.Lookup("runtime.islibrary", 0)
s.Attr |= sym.AttrDuplicateOK
s.AddUint8(1)
case BuildModeCArchive:
s := ctxt.Syms.Lookup("runtime.isarchive", 0)
s.Attr |= sym.AttrDuplicateOK
s.AddUint8(1)
}
loadinternal(ctxt, "runtime")
if ctxt.Arch.Family == sys.ARM {
loadinternal(ctxt, "math")
}
if *flagRace {
loadinternal(ctxt, "runtime/race")
}
if *flagMsan {
loadinternal(ctxt, "runtime/msan")
}
// ctxt.Library grows during the loop, so not a range loop.
for i := 0; i < len(ctxt.Library); i++ {
lib := ctxt.Library[i]
if lib.Shlib == "" {
if ctxt.Debugvlog > 1 {
ctxt.Logf("%5.2f autolib: %s (from %s)\n", Cputime(), lib.File, lib.Objref)
}
loadobjfile(ctxt, lib)
}
}
for _, lib := range ctxt.Library {
if lib.Shlib != "" {
if ctxt.Debugvlog > 1 {
ctxt.Logf("%5.2f autolib: %s (from %s)\n", Cputime(), lib.Shlib, lib.Objref)
}
ldshlibsyms(ctxt, lib.Shlib)
}
}
iscgo = ctxt.Syms.ROLookup("x_cgo_init", 0) != nil
// We now have enough information to determine the link mode.
determineLinkMode(ctxt)
// Recalculate pe parameters now that we have ctxt.LinkMode set.
if ctxt.HeadType == objabi.Hwindows {
Peinit(ctxt)
}
if ctxt.HeadType == objabi.Hdarwin && ctxt.LinkMode == LinkExternal {
*FlagTextAddr = 0
}
if ctxt.LinkMode == LinkExternal && ctxt.Arch.Family == sys.PPC64 {
toc := ctxt.Syms.Lookup(".TOC.", 0)
toc.Type = sym.SDYNIMPORT
}
if ctxt.LinkMode == LinkExternal && !iscgo && ctxt.LibraryByPkg["runtime/cgo"] == nil {
// This indicates a user requested -linkmode=external.
// The startup code uses an import of runtime/cgo to decide
// whether to initialize the TLS. So give it one. This could
// be handled differently but it's an unusual case.
if lib := loadinternal(ctxt, "runtime/cgo"); lib != nil {
if lib.Shlib != "" {
ldshlibsyms(ctxt, lib.Shlib)
} else {
if ctxt.BuildMode == BuildModeShared || ctxt.linkShared {
Exitf("cannot implicitly include runtime/cgo in a shared library")
}
loadobjfile(ctxt, lib)
}
}
}
if ctxt.LinkMode == LinkInternal {
// Drop all the cgo_import_static declarations.
// Turns out we won't be needing them.
for _, s := range ctxt.Syms.Allsym {
if s.Type == sym.SHOSTOBJ {
// If a symbol was marked both
// cgo_import_static and cgo_import_dynamic,
// then we want to make it cgo_import_dynamic
// now.
if s.Extname != "" && s.Dynimplib != "" && !s.Attr.CgoExport() {
s.Type = sym.SDYNIMPORT
} else {
s.Type = 0
}
}
}
}
tlsg := ctxt.Syms.Lookup("runtime.tlsg", 0)
// runtime.tlsg is used for external linking on platforms that do not define
// a variable to hold g in assembly (currently only intel).
if tlsg.Type == 0 {
tlsg.Type = sym.STLSBSS
tlsg.Size = int64(ctxt.Arch.PtrSize)
} else if tlsg.Type != sym.SDYNIMPORT {
Errorf(nil, "runtime declared tlsg variable %v", tlsg.Type)
}
tlsg.Attr |= sym.AttrReachable
ctxt.Tlsg = tlsg
var moduledata *sym.Symbol
if ctxt.BuildMode == BuildModePlugin {
moduledata = ctxt.Syms.Lookup("local.pluginmoduledata", 0)
moduledata.Attr |= sym.AttrLocal
} else {
moduledata = ctxt.Syms.Lookup("runtime.firstmoduledata", 0)
}
if moduledata.Type != 0 && moduledata.Type != sym.SDYNIMPORT {
// If the module (toolchain-speak for "executable or shared
// library") we are linking contains the runtime package, it
// will define the runtime.firstmoduledata symbol and we
// truncate it back to 0 bytes so we can define its entire
// contents in symtab.go:symtab().
moduledata.Size = 0
// In addition, on ARM, the runtime depends on the linker
// recording the value of GOARM.
if ctxt.Arch.Family == sys.ARM {
s := ctxt.Syms.Lookup("runtime.goarm", 0)
s.Type = sym.SRODATA
s.Size = 0
s.AddUint8(uint8(objabi.GOARM))
}
if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
s := ctxt.Syms.Lookup("runtime.framepointer_enabled", 0)
s.Type = sym.SRODATA
s.Size = 0
s.AddUint8(1)
}
} else {
// If OTOH the module does not contain the runtime package,
// create a local symbol for the moduledata.
moduledata = ctxt.Syms.Lookup("local.moduledata", 0)
moduledata.Attr |= sym.AttrLocal
}
// In all cases way we mark the moduledata as noptrdata to hide it from
// the GC.
moduledata.Type = sym.SNOPTRDATA
moduledata.Attr |= sym.AttrReachable
ctxt.Moduledata = moduledata
// Now that we know the link mode, trim the dynexp list.
x := sym.AttrCgoExportDynamic
if ctxt.LinkMode == LinkExternal {
x = sym.AttrCgoExportStatic
}
w := 0
for i := 0; i < len(dynexp); i++ {
if dynexp[i].Attr&x != 0 {
dynexp[w] = dynexp[i]
w++
}
}
dynexp = dynexp[:w]
// In internal link mode, read the host object files.
if ctxt.LinkMode == LinkInternal {
hostobjs(ctxt)
// If we have any undefined symbols in external
// objects, try to read them from the libgcc file.
any := false
for _, s := range ctxt.Syms.Allsym {
for _, r := range s.R {
if r.Sym != nil && r.Sym.Type == sym.SXREF && r.Sym.Name != ".got" {
any = true
break
}
}
}
if any {
if *flagLibGCC == "" {
*flagLibGCC = ctxt.findLibPathCmd("--print-libgcc-file-name", "libgcc")
}
if *flagLibGCC != "none" {
hostArchive(ctxt, *flagLibGCC)
}
if ctxt.HeadType == objabi.Hwindows {
if p := ctxt.findLibPath("libmingwex.a"); p != "none" {
hostArchive(ctxt, p)
}
if p := ctxt.findLibPath("libmingw32.a"); p != "none" {
hostArchive(ctxt, p)
}
// TODO: maybe do something similar to peimporteddlls to collect all lib names
// and try link them all to final exe just like libmingwex.a and libmingw32.a:
/*
for:
#cgo windows LDFLAGS: -lmsvcrt -lm
import:
libmsvcrt.a libm.a
*/
}
}
} else {
hostlinksetup(ctxt)
}
// We've loaded all the code now.
ctxt.Loaded = true
// If there are no dynamic libraries needed, gcc disables dynamic linking.
// Because of this, glibc's dynamic ELF loader occasionally (like in version 2.13)
// assumes that a dynamic binary always refers to at least one dynamic library.
// Rather than be a source of test cases for glibc, disable dynamic linking
// the same way that gcc would.
//
// Exception: on OS X, programs such as Shark only work with dynamic
// binaries, so leave it enabled on OS X (Mach-O) binaries.
// Also leave it enabled on Solaris which doesn't support
// statically linked binaries.
if ctxt.BuildMode == BuildModeExe {
if havedynamic == 0 && ctxt.HeadType != objabi.Hdarwin && ctxt.HeadType != objabi.Hsolaris {
*FlagD = true
}
}
// If type. symbols are visible in the symbol table, rename them
// using a SHA-1 prefix. This reduces binary size (the full
// string of a type symbol can be multiple kilobytes) and removes
// characters that upset external linkers.
//
// Keep the type.. prefix, which parts of the linker (like the
// DWARF generator) know means the symbol is not decodable.
//
// Leave type.runtime. symbols alone, because other parts of
// the linker manipulates them, and also symbols whose names
// would not be shortened by this process.
if typeSymbolMangling(ctxt) {
*FlagW = true // disable DWARF generation
for _, s := range ctxt.Syms.Allsym {
newName := typeSymbolMangle(s.Name)
if newName != s.Name {
ctxt.Syms.Rename(s.Name, newName, int(s.Version))
}
}
}
// If package versioning is required, generate a hash of the
// the packages used in the link.
if ctxt.BuildMode == BuildModeShared || ctxt.BuildMode == BuildModePlugin || ctxt.CanUsePlugins() {
for _, lib := range ctxt.Library {
if lib.Shlib == "" {
genhash(ctxt, lib)
}
}
}
if ctxt.Arch == sys.Arch386 {
if (ctxt.BuildMode == BuildModeCArchive && ctxt.IsELF) || (ctxt.BuildMode == BuildModeCShared && ctxt.HeadType != objabi.Hwindows) || ctxt.BuildMode == BuildModePIE || ctxt.DynlinkingGo() {
got := ctxt.Syms.Lookup("_GLOBAL_OFFSET_TABLE_", 0)
got.Type = sym.SDYNIMPORT
got.Attr |= sym.AttrReachable
}
}
importcycles()
// put symbols into Textp
// do it in postorder so that packages are laid down in dependency order
// internal first, then everything else
ctxt.Library = postorder(ctxt.Library)
for _, doInternal := range [2]bool{true, false} {
for _, lib := range ctxt.Library {
if isRuntimeDepPkg(lib.Pkg) != doInternal {
continue
}
ctxt.Textp = append(ctxt.Textp, lib.Textp...)
for _, s := range lib.DupTextSyms {
if !s.Attr.OnList() {
ctxt.Textp = append(ctxt.Textp, s)
s.Attr |= sym.AttrOnList
// dupok symbols may be defined in multiple packages. its
// associated package is chosen sort of arbitrarily (the
// first containing package that the linker loads). canonicalize
// it here to the package with which it will be laid down
// in text.
s.File = objabi.PathToPrefix(lib.Pkg)
}
}
}
}
if len(ctxt.Shlibs) > 0 {
// We might have overwritten some functions above (this tends to happen for the
// autogenerated type equality/hashing functions) and we don't want to generated
// pcln table entries for these any more so remove them from Textp.
textp := make([]*sym.Symbol, 0, len(ctxt.Textp))
for _, s := range ctxt.Textp {
if s.Type != sym.SDYNIMPORT {
textp = append(textp, s)
}
}
ctxt.Textp = textp
}
}
// typeSymbolMangling reports whether the linker should shorten the
// names of symbols that represent Go types.
//
// As the names of these symbols are derived from the string of
// the type, they can run to many kilobytes long. So we shorten
// them using a SHA-1 when the name appears in the final binary.
//
// These are the symbols that begin with the prefix 'type.' and
// contain run-time type information used by the runtime and reflect
// packages. All Go binaries contain these symbols, but only only
// those programs loaded dynamically in multiple parts need these
// symbols to have entries in the symbol table.
func typeSymbolMangling(ctxt *Link) bool {
return ctxt.BuildMode == BuildModeShared || ctxt.linkShared || ctxt.BuildMode == BuildModePlugin || ctxt.Syms.ROLookup("plugin.Open", 0) != nil
}
// typeSymbolMangle mangles the given symbol name into something shorter.
func typeSymbolMangle(name string) string {
if !strings.HasPrefix(name, "type.") {
return name
}
if strings.HasPrefix(name, "type.runtime.") {
return name
}
if len(name) <= 14 && !strings.Contains(name, "@") { // Issue 19529
return name
}
hash := sha1.Sum([]byte(name))
prefix := "type."
if name[5] == '.' {
prefix = "type.."
}
return prefix + base64.StdEncoding.EncodeToString(hash[:6])
}
/*
* look for the next file in an archive.
* adapted from libmach.
*/
func nextar(bp *bio.Reader, off int64, a *ArHdr) int64 {
if off&1 != 0 {
off++
}
bp.Seek(off, 0)
var buf [SAR_HDR]byte
if n, err := io.ReadFull(bp, buf[:]); err != nil {
if n == 0 && err != io.EOF {
return -1
}
return 0
}
a.name = artrim(buf[0:16])
a.date = artrim(buf[16:28])
a.uid = artrim(buf[28:34])
a.gid = artrim(buf[34:40])
a.mode = artrim(buf[40:48])
a.size = artrim(buf[48:58])
a.fmag = artrim(buf[58:60])
arsize := atolwhex(a.size)
if arsize&1 != 0 {
arsize++
}
return arsize + SAR_HDR
}
func genhash(ctxt *Link, lib *sym.Library) {
f, err := bio.Open(lib.File)
if err != nil {
Errorf(nil, "cannot open file %s for hash generation: %v", lib.File, err)
return
}
defer f.Close()
var magbuf [len(ARMAG)]byte
if _, err := io.ReadFull(f, magbuf[:]); err != nil {
Exitf("file %s too short", lib.File)
}
if string(magbuf[:]) != ARMAG {
Exitf("%s is not an archive file", lib.File)
}
var arhdr ArHdr
l := nextar(f, f.Offset(), &arhdr)
if l <= 0 {
Errorf(nil, "%s: short read on archive file symbol header", lib.File)
return
}
h := sha1.New()
// To compute the hash of a package, we hash the first line of
// __.PKGDEF (which contains the toolchain version and any
// GOEXPERIMENT flags) and the export data (which is between
// the first two occurrences of "\n$$").
pkgDefBytes := make([]byte, atolwhex(arhdr.size))
_, err = io.ReadFull(f, pkgDefBytes)
if err != nil {
Errorf(nil, "%s: error reading package data: %v", lib.File, err)
return
}
firstEOL := bytes.IndexByte(pkgDefBytes, '\n')
if firstEOL < 0 {
Errorf(nil, "cannot parse package data of %s for hash generation, no newline found", lib.File)
return
}
firstDoubleDollar := bytes.Index(pkgDefBytes, []byte("\n$$"))
if firstDoubleDollar < 0 {
Errorf(nil, "cannot parse package data of %s for hash generation, no \\n$$ found", lib.File)
return
}
secondDoubleDollar := bytes.Index(pkgDefBytes[firstDoubleDollar+1:], []byte("\n$$"))
if secondDoubleDollar < 0 {
Errorf(nil, "cannot parse package data of %s for hash generation, only one \\n$$ found", lib.File)
return
}
h.Write(pkgDefBytes[0:firstEOL])
h.Write(pkgDefBytes[firstDoubleDollar : firstDoubleDollar+secondDoubleDollar])
lib.Hash = hex.EncodeToString(h.Sum(nil))
}
func loadobjfile(ctxt *Link, lib *sym.Library) {
pkg := objabi.PathToPrefix(lib.Pkg)
if ctxt.Debugvlog > 1 {
ctxt.Logf("%5.2f ldobj: %s (%s)\n", Cputime(), lib.File, pkg)
}
f, err := bio.Open(lib.File)
if err != nil {
Exitf("cannot open file %s: %v", lib.File, err)
}
for i := 0; i < len(ARMAG); i++ {
if c, err := f.ReadByte(); err == nil && c == ARMAG[i] {
continue
}
/* load it as a regular file */
l := f.Seek(0, 2)
f.Seek(0, 0)
ldobj(ctxt, f, lib, l, lib.File, lib.File, FileObj)
f.Close()
return
}
/* process __.PKGDEF */
off := f.Offset()
var arhdr ArHdr
l := nextar(f, off, &arhdr)
var pname string
if l <= 0 {
Errorf(nil, "%s: short read on archive file symbol header", lib.File)
goto out
}
if !strings.HasPrefix(arhdr.name, pkgdef) {
Errorf(nil, "%s: cannot find package header", lib.File)
goto out
}
off += l
ldpkg(ctxt, 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 __.PKGDEF.
*/
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(ctxt, f, lib, l, pname, lib.File, ArchiveObj)
}
out:
f.Close()
}
type Hostobj struct {
ld func(*Link, *bio.Reader, string, int64, string)
pkg string
pn string
file string
off int64
length int64
}
var hostobj []Hostobj
// These packages can use internal linking mode.
// Others trigger external mode.
var internalpkg = []string{
"crypto/x509",
"net",
"os/user",
"runtime/cgo",
"runtime/race",
"runtime/msan",
}
func ldhostobj(ld func(*Link, *bio.Reader, string, int64, string), headType objabi.HeadType, f *bio.Reader, pkg string, length int64, pn string, file string) *Hostobj {
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 == objabi.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 = f.Offset()
h.length = length
return h
}
func hostobjs(ctxt *Link) {
var h *Hostobj
for i := 0; i < len(hostobj); i++ {
h = &hostobj[i]
f, err := bio.Open(h.file)
if err != nil {
Exitf("cannot reopen %s: %v", h.pn, err)
}
f.Seek(h.off, 0)
h.ld(ctxt, f, h.pkg, h.length, h.pn)
f.Close()
}
}
// provided by lib9
func rmtemp() {
os.RemoveAll(*flagTmpdir)
}
func hostlinksetup(ctxt *Link) {
if ctxt.LinkMode != LinkExternal {
return
}
// For external link, record that we need to tell the external linker -s,
// and turn off -s internally: the external linker needs the symbol
// information for its final link.
debug_s = *FlagS
*FlagS = false
// create temporary directory and arrange cleanup
if *flagTmpdir == "" {
dir, err := ioutil.TempDir("", "go-link-")
if err != nil {
log.Fatal(err)
}
*flagTmpdir = dir
AtExit(rmtemp)
}
// change our output to temporary object file
ctxt.Out.f.Close()
mayberemoveoutfile()
p := filepath.Join(*flagTmpdir, "go.o")
var err error
f, err := os.OpenFile(p, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0775)
if err != nil {
Exitf("cannot create %s: %v", p, err)
}
ctxt.Out.w = bufio.NewWriter(f)
ctxt.Out.f = f
ctxt.Out.off = 0
}
// hostobjCopy creates a copy of the object files in hostobj in a
// temporary directory.
func hostobjCopy() (paths []string) {
var wg sync.WaitGroup
sema := make(chan struct{}, runtime.NumCPU()) // limit open file descriptors
for i, h := range hostobj {
h := h
dst := filepath.Join(*flagTmpdir, fmt.Sprintf("%06d.o", i))
paths = append(paths, dst)
wg.Add(1)
go func() {
sema <- struct{}{}
defer func() {
<-sema
wg.Done()
}()
f, err := os.Open(h.file)
if err != nil {
Exitf("cannot reopen %s: %v", h.pn, err)
}
if _, err := f.Seek(h.off, 0); err != nil {
Exitf("cannot seek %s: %v", h.pn, err)
}
w, err := os.Create(dst)
if err != nil {
Exitf("cannot create %s: %v", dst, err)
}
if _, err := io.CopyN(w, f, h.length); err != nil {
Exitf("cannot write %s: %v", dst, err)
}
if err := w.Close(); err != nil {
Exitf("cannot close %s: %v", dst, err)
}
}()
}
wg.Wait()
return paths
}
// writeGDBLinkerScript creates gcc linker script file in temp
// directory. writeGDBLinkerScript returns created file path.
// The script is used to work around gcc bug
// (see https://golang.org/issue/20183 for details).
func writeGDBLinkerScript() string {
name := "fix_debug_gdb_scripts.ld"
path := filepath.Join(*flagTmpdir, name)
src := `SECTIONS
{
.debug_gdb_scripts BLOCK(__section_alignment__) (NOLOAD) :
{
*(.debug_gdb_scripts)
}
}
INSERT AFTER .debug_types;
`
err := ioutil.WriteFile(path, []byte(src), 0666)
if err != nil {
Errorf(nil, "WriteFile %s failed: %v", name, err)
}
return path
}
// archive builds a .a archive from the hostobj object files.
func (ctxt *Link) archive() {
if ctxt.BuildMode != BuildModeCArchive {
return
}
if *flagExtar == "" {
*flagExtar = "ar"
}
mayberemoveoutfile()
// Force the buffer to flush here so that external
// tools will see a complete file.
ctxt.Out.Flush()
if err := ctxt.Out.f.Close(); err != nil {
Exitf("close: %v", err)
}
ctxt.Out.f = nil
argv := []string{*flagExtar, "-q", "-c", "-s", *flagOutfile}
argv = append(argv, filepath.Join(*flagTmpdir, "go.o"))
argv = append(argv, hostobjCopy()...)
if ctxt.Debugvlog != 0 {
ctxt.Logf("archive: %s\n", strings.Join(argv, " "))
}
if out, err := exec.Command(argv[0], argv[1:]...).CombinedOutput(); err != nil {
Exitf("running %s failed: %v\n%s", argv[0], err, out)
}
}
func (ctxt *Link) hostlink() {
if ctxt.LinkMode != LinkExternal || nerrors > 0 {
return
}
if ctxt.BuildMode == BuildModeCArchive {
return
}
if *flagExtld == "" {
*flagExtld = "gcc"
}
var argv []string
argv = append(argv, *flagExtld)
argv = append(argv, hostlinkArchArgs(ctxt.Arch)...)
if *FlagS || debug_s {
if ctxt.HeadType == objabi.Hdarwin {
// Recent versions of macOS print
// ld: warning: option -s is obsolete and being ignored
// so do not pass any arguments.
} else {
argv = append(argv, "-s")
}
}
switch ctxt.HeadType {
case objabi.Hdarwin:
argv = append(argv, "-Wl,-headerpad,1144")
if ctxt.DynlinkingGo() {
argv = append(argv, "-Wl,-flat_namespace")
}
if ctxt.BuildMode == BuildModeExe && !ctxt.Arch.InFamily(sys.ARM64) {
argv = append(argv, "-Wl,-no_pie")
}
case objabi.Hopenbsd:
argv = append(argv, "-Wl,-nopie")
case objabi.Hwindows:
if windowsgui {
argv = append(argv, "-mwindows")
} else {
argv = append(argv, "-mconsole")
}
}
switch ctxt.BuildMode {
case BuildModeExe:
if ctxt.HeadType == objabi.Hdarwin {
if ctxt.Arch.Family == sys.ARM64 {
// __PAGEZERO segment size determined empirically.
// XCode 9.0.1 successfully uploads an iOS app with this value.
argv = append(argv, "-Wl,-pagezero_size,100000000")
} else {
argv = append(argv, "-Wl,-pagezero_size,4000000")
}
}
case BuildModePIE:
// ELF.
if ctxt.HeadType != objabi.Hdarwin {
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-pie")
}
case BuildModeCShared:
if ctxt.HeadType == objabi.Hdarwin {
argv = append(argv, "-dynamiclib")
if ctxt.Arch.Family != sys.AMD64 {
argv = append(argv, "-Wl,-read_only_relocs,suppress")
}
} else {
// ELF.
argv = append(argv, "-Wl,-Bsymbolic")
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-shared")
if ctxt.HeadType != objabi.Hwindows {
// Pass -z nodelete to mark the shared library as
// non-closeable: a dlclose will do nothing.
argv = append(argv, "-Wl,-z,nodelete")
}
}
case BuildModeShared:
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-shared")
case BuildModePlugin:
if ctxt.HeadType == objabi.Hdarwin {
argv = append(argv, "-dynamiclib")
} else {
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
}
argv = append(argv, "-shared")
}
}
if ctxt.IsELF && ctxt.DynlinkingGo() {
// We force all symbol resolution to be done at program startup
// because lazy PLT resolution can use large amounts of stack at
// times we cannot allow it to do so.
argv = append(argv, "-Wl,-znow")
// Do not let the host linker generate COPY relocations. These
// can move symbols out of sections that rely on stable offsets
// from the beginning of the section (like sym.STYPE).
argv = append(argv, "-Wl,-znocopyreloc")
if ctxt.Arch.InFamily(sys.ARM, sys.ARM64) {
// On ARM, the GNU linker will generate COPY relocations
// even with -znocopyreloc set.
// https://sourceware.org/bugzilla/show_bug.cgi?id=19962
//
// On ARM64, the GNU linker will fail instead of
// generating COPY relocations.
//
// In both cases, switch to gold.
argv = append(argv, "-fuse-ld=gold")
// If gold is not installed, gcc will silently switch
// back to ld.bfd. So we parse the version information
// and provide a useful error if gold is missing.
cmd := exec.Command(*flagExtld, "-fuse-ld=gold", "-Wl,--version")
if out, err := cmd.CombinedOutput(); err == nil {
if !bytes.Contains(out, []byte("GNU gold")) {
log.Fatalf("ARM external linker must be gold (issue #15696), but is not: %s", out)
}
}
}
}
if ctxt.IsELF && len(buildinfo) > 0 {
argv = append(argv, fmt.Sprintf("-Wl,--build-id=0x%x", buildinfo))
}
// On Windows, given -o foo, GCC will append ".exe" to produce
// "foo.exe". We have decided that we want to honor the -o
// option. To make this work, we append a '.' so that GCC
// will decide that the file already has an extension. We
// only want to do this when producing a Windows output file
// on a Windows host.
outopt := *flagOutfile
if objabi.GOOS == "windows" && runtime.GOOS == "windows" && filepath.Ext(outopt) == "" {
outopt += "."
}
argv = append(argv, "-o")
argv = append(argv, outopt)
if rpath.val != "" {
argv = append(argv, fmt.Sprintf("-Wl,-rpath,%s", rpath.val))
}
// Force global symbols to be exported for dlopen, etc.
if ctxt.IsELF {
argv = append(argv, "-rdynamic")
}
if strings.Contains(argv[0], "clang") {
argv = append(argv, "-Qunused-arguments")
}
argv = append(argv, filepath.Join(*flagTmpdir, "go.o"))
argv = append(argv, hostobjCopy()...)
if ctxt.linkShared {
seenDirs := make(map[string]bool)
seenLibs := make(map[string]bool)
addshlib := func(path string) {
dir, base := filepath.Split(path)
if !seenDirs[dir] {
argv = append(argv, "-L"+dir)
if !rpath.set {
argv = append(argv, "-Wl,-rpath="+dir)
}
seenDirs[dir] = true
}
base = strings.TrimSuffix(base, ".so")
base = strings.TrimPrefix(base, "lib")
if !seenLibs[base] {
argv = append(argv, "-l"+base)
seenLibs[base] = true
}
}
for _, shlib := range ctxt.Shlibs {
addshlib(shlib.Path)
for _, dep := range shlib.Deps {
if dep == "" {
continue
}
libpath := findshlib(ctxt, dep)
if libpath != "" {
addshlib(libpath)
}
}
}
}
argv = append(argv, ldflag...)
// When building a program with the default -buildmode=exe the
// gc compiler generates code requires DT_TEXTREL in a
// position independent executable (PIE). On systems where the
// toolchain creates PIEs by default, and where DT_TEXTREL
// does not work, the resulting programs will not run. See
// issue #17847. To avoid this problem pass -no-pie to the
// toolchain if it is supported.
if ctxt.BuildMode == BuildModeExe {
src := filepath.Join(*flagTmpdir, "trivial.c")
if err := ioutil.WriteFile(src, []byte("int main() { return 0; }"), 0666); err != nil {
Errorf(nil, "WriteFile trivial.c failed: %v", err)
}
// GCC uses -no-pie, clang uses -nopie.
for _, nopie := range []string{"-no-pie", "-nopie"} {
cmd := exec.Command(argv[0], nopie, "trivial.c")
cmd.Dir = *flagTmpdir
cmd.Env = append([]string{"LC_ALL=C"}, os.Environ()...)
out, err := cmd.CombinedOutput()
// GCC says "unrecognized command line option ‘-no-pie’"
// clang says "unknown argument: '-no-pie'"
supported := err == nil && !bytes.Contains(out, []byte("unrecognized")) && !bytes.Contains(out, []byte("unknown"))
if supported {
argv = append(argv, nopie)
break
}
}
}
for _, p := range strings.Fields(*flagExtldflags) {
argv = append(argv, p)
// clang, unlike GCC, passes -rdynamic to the linker
// even when linking with -static, causing a linker
// error when using GNU ld. So take out -rdynamic if
// we added it. We do it in this order, rather than
// only adding -rdynamic later, so that -*extldflags
// can override -rdynamic without using -static.
if ctxt.IsELF && p == "-static" {
for i := range argv {
if argv[i] == "-rdynamic" {
argv[i] = "-static"
}
}
}
}
if ctxt.HeadType == objabi.Hwindows {
// use gcc linker script to work around gcc bug
// (see https://golang.org/issue/20183 for details).
p := writeGDBLinkerScript()
argv = append(argv, "-Wl,-T,"+p)
// libmingw32 and libmingwex have some inter-dependencies,
// so must use linker groups.
argv = append(argv, "-Wl,--start-group", "-lmingwex", "-lmingw32", "-Wl,--end-group")
argv = append(argv, peimporteddlls()...)
}
if ctxt.Debugvlog != 0 {
ctxt.Logf("%5.2f host link:", Cputime())
for _, v := range argv {
ctxt.Logf(" %q", v)
}
ctxt.Logf("\n")
}
if out, err := exec.Command(argv[0], argv[1:]...).CombinedOutput(); err != nil {
Exitf("running %s failed: %v\n%s", argv[0], err, out)
} else if len(out) > 0 {
// always print external output even if the command is successful, so that we don't
// swallow linker warnings (see https://golang.org/issue/17935).
ctxt.Logf("%s", out)
}
if !*FlagS && !*FlagW && !debug_s && ctxt.HeadType == objabi.Hdarwin {
// Skip combining dwarf on arm.
if !ctxt.Arch.InFamily(sys.ARM, sys.ARM64) {
dsym := filepath.Join(*flagTmpdir, "go.dwarf")
if out, err := exec.Command("dsymutil", "-f", *flagOutfile, "-o", dsym).CombinedOutput(); err != nil {
Exitf("%s: running dsymutil failed: %v\n%s", os.Args[0], err, out)
}
// Skip combining if `dsymutil` didn't generate a file. See #11994.
if _, err := os.Stat(dsym); os.IsNotExist(err) {
return
}
// For os.Rename to work reliably, must be in same directory as outfile.
combinedOutput := *flagOutfile + "~"
if err := machoCombineDwarf(*flagOutfile, dsym, combinedOutput, ctxt.BuildMode); err != nil {
Exitf("%s: combining dwarf failed: %v", os.Args[0], err)
}
os.Remove(*flagOutfile)
if err := os.Rename(combinedOutput, *flagOutfile); err != nil {
Exitf("%s: %v", os.Args[0], err)
}
}
}
}
// hostlinkArchArgs returns arguments to pass to the external linker
// based on the architecture.
func hostlinkArchArgs(arch *sys.Arch) []string {
switch arch.Family {
case sys.I386:
return []string{"-m32"}
case sys.AMD64, sys.PPC64, sys.S390X:
return []string{"-m64"}
case sys.ARM:
return []string{"-marm"}
case sys.ARM64:
// nothing needed
case sys.MIPS64:
return []string{"-mabi=64"}
case sys.MIPS:
return []string{"-mabi=32"}
}
return nil
}
// ldobj loads an input object. If it is a host object (an object
// compiled by a non-Go compiler) it returns the Hostobj pointer. If
// it is a Go object, it returns nil.
func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string, file string, whence int) *Hostobj {
pkg := objabi.PathToPrefix(lib.Pkg)
eof := f.Offset() + length
start := f.Offset()
c1 := bgetc(f)
c2 := bgetc(f)
c3 := bgetc(f)
c4 := bgetc(f)
f.Seek(start, 0)
magic := uint32(c1)<<24 | uint32(c2)<<16 | uint32(c3)<<8 | uint32(c4)
if magic == 0x7f454c46 { // \x7F E L F
ldelf := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, flags, err := loadelf.Load(ctxt.Arch, ctxt.Syms, f, pkg, length, pn, ehdr.flags)
if err != nil {
Errorf(nil, "%v", err)
return
}
ehdr.flags = flags
ctxt.Textp = append(ctxt.Textp, textp...)
}
return ldhostobj(ldelf, ctxt.HeadType, f, pkg, length, pn, file)
}
if magic&^1 == 0xfeedface || magic&^0x01000000 == 0xcefaedfe {
ldmacho := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, err := loadmacho.Load(ctxt.Arch, ctxt.Syms, f, pkg, length, pn)
if err != nil {
Errorf(nil, "%v", err)
return
}
ctxt.Textp = append(ctxt.Textp, textp...)
}
return ldhostobj(ldmacho, ctxt.HeadType, f, pkg, length, pn, file)
}
if c1 == 0x4c && c2 == 0x01 || c1 == 0x64 && c2 == 0x86 {
ldpe := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
textp, rsrc, err := loadpe.Load(ctxt.Arch, ctxt.Syms, f, pkg, length, pn)
if err != nil {
Errorf(nil, "%v", err)
return
}
if rsrc != nil {
setpersrc(ctxt, rsrc)
}
ctxt.Textp = append(ctxt.Textp, textp...)
}
return ldhostobj(ldpe, ctxt.HeadType, f, pkg, length, pn, file)
}
/* check the header */
line, err := f.ReadString('\n')
if err != nil {
Errorf(nil, "truncated object file: %s: %v", pn, err)
return nil
}
if !strings.HasPrefix(line, "go object ") {
if strings.HasSuffix(pn, ".go") {
Exitf("%s: uncompiled .go source file", pn)
return nil
}
if line == ctxt.Arch.Name {
// old header format: just $GOOS
Errorf(nil, "%s: stale object file", pn)
return nil
}
Errorf(nil, "%s: not an object file", pn)
return nil
}
// First, check that the basic GOOS, GOARCH, and Version match.
t := fmt.Sprintf("%s %s %s ", objabi.GOOS, objabi.GOARCH, objabi.Version)
line = strings.TrimRight(line, "\n")
if !strings.HasPrefix(line[10:]+" ", t) && !*flagF {
Errorf(nil, "%s: object is [%s] expected [%s]", pn, line[10:], t)
return nil
}
// 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:] {
Errorf(nil, "%s: object is [%s] expected [%s]", pn, line[10:], theline)
return nil
}
}
// Skip over exports and other info -- ends with \n!\n.
//
// Note: It's possible for "\n!\n" to appear within the binary
// package export data format. To avoid truncating the package
// definition prematurely (issue 21703), we keep keep track of
// how many "$$" delimiters we've seen.
import0 := f.Offset()
c1 = '\n' // the last line ended in \n
c2 = bgetc(f)
c3 = bgetc(f)
markers := 0
for {
if c1 == '\n' {
if markers%2 == 0 && c2 == '!' && c3 == '\n' {
break
}
if c2 == '$' && c3 == '$' {
markers++
}
}
c1 = c2
c2 = c3
c3 = bgetc(f)
if c3 == -1 {
Errorf(nil, "truncated object file: %s", pn)
return nil
}
}
import1 := f.Offset()
f.Seek(import0, 0)
ldpkg(ctxt, f, pkg, import1-import0-2, pn, whence) // -2 for !\n
f.Seek(import1, 0)
objfile.Load(ctxt.Arch, ctxt.Syms, f, lib, eof-f.Offset(), pn)
addImports(ctxt, lib, pn)
return nil
}
func readelfsymboldata(ctxt *Link, f *elf.File, sym *elf.Symbol) []byte {
data := make([]byte, sym.Size)
sect := f.Sections[sym.Section]
if sect.Type != elf.SHT_PROGBITS && sect.Type != elf.SHT_NOTE {
Errorf(nil, "reading %s from non-data section", sym.Name)
}
n, err := sect.ReadAt(data, int64(sym.Value-sect.Addr))
if uint64(n) != sym.Size {
Errorf(nil, "reading contents of %s: %v", sym.Name, err)
}
return data
}
func readwithpad(r io.Reader, sz int32) ([]byte, error) {
data := make([]byte, Rnd(int64(sz), 4))
_, err := io.ReadFull(r, data)
if err != nil {
return nil, err
}
data = data[:sz]
return data, nil
}
func readnote(f *elf.File, name []byte, typ int32) ([]byte, error) {
for _, sect := range f.Sections {
if sect.Type != elf.SHT_NOTE {
continue
}
r := sect.Open()
for {
var namesize, descsize, noteType int32
err := binary.Read(r, f.ByteOrder, &namesize)
if err != nil {
if err == io.EOF {
break
}
return nil, fmt.Errorf("read namesize failed: %v", err)
}
err = binary.Read(r, f.ByteOrder, &descsize)
if err != nil {
return nil, fmt.Errorf("read descsize failed: %v", err)
}
err = binary.Read(r, f.ByteOrder, ¬eType)
if err != nil {
return nil, fmt.Errorf("read type failed: %v", err)
}
noteName, err := readwithpad(r, namesize)
if err != nil {
return nil, fmt.Errorf("read name failed: %v", err)
}
desc, err := readwithpad(r, descsize)
if err != nil {
return nil, fmt.Errorf("read desc failed: %v", err)
}
if string(name) == string(noteName) && typ == noteType {
return desc, nil
}
}
}
return nil, nil
}
func findshlib(ctxt *Link, shlib string) string {
if filepath.IsAbs(shlib) {
return shlib
}
for _, libdir := range ctxt.Libdir {
libpath := filepath.Join(libdir, shlib)
if _, err := os.Stat(libpath); err == nil {
return libpath
}
}
Errorf(nil, "cannot find shared library: %s", shlib)
return ""
}
func ldshlibsyms(ctxt *Link, shlib string) {
var libpath string
if filepath.IsAbs(shlib) {
libpath = shlib
shlib = filepath.Base(shlib)
} else {
libpath = findshlib(ctxt, shlib)
if libpath == "" {
return
}
}
for _, processedlib := range ctxt.Shlibs {
if processedlib.Path == libpath {
return
}
}
if ctxt.Debugvlog > 1 {
ctxt.Logf("%5.2f ldshlibsyms: found library with name %s at %s\n", Cputime(), shlib, libpath)
}
f, err := elf.Open(libpath)
if err != nil {
Errorf(nil, "cannot open shared library: %s", libpath)
return
}
defer f.Close()
hash, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GOABIHASH_TAG)
if err != nil {
Errorf(nil, "cannot read ABI hash from shared library %s: %v", libpath, err)
return
}
depsbytes, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GODEPS_TAG)
if err != nil {
Errorf(nil, "cannot read dep list from shared library %s: %v", libpath, err)
return
}
var deps []string
for _, dep := range strings.Split(string(depsbytes), "\n") {
if dep == "" {
continue
}
if !filepath.IsAbs(dep) {
// If the dep can be interpreted as a path relative to the shlib
// in which it was found, do that. Otherwise, we will leave it
// to be resolved by libdir lookup.
abs := filepath.Join(filepath.Dir(libpath), dep)
if _, err := os.Stat(abs); err == nil {
dep = abs
}
}
deps = append(deps, dep)
}
syms, err := f.DynamicSymbols()
if err != nil {
Errorf(nil, "cannot read symbols from shared library: %s", libpath)
return
}
gcdataLocations := make(map[uint64]*sym.Symbol)
for _, elfsym := range syms {
if elf.ST_TYPE(elfsym.Info) == elf.STT_NOTYPE || elf.ST_TYPE(elfsym.Info) == elf.STT_SECTION {
continue
}
lsym := ctxt.Syms.Lookup(elfsym.Name, 0)
// Because loadlib above loads all .a files before loading any shared
// libraries, any non-dynimport symbols we find that duplicate symbols
// already loaded should be ignored (the symbols from the .a files
// "win").
if lsym.Type != 0 && lsym.Type != sym.SDYNIMPORT {
continue
}
lsym.Type = sym.SDYNIMPORT
lsym.ElfType = elf.ST_TYPE(elfsym.Info)
lsym.Size = int64(elfsym.Size)
if elfsym.Section != elf.SHN_UNDEF {
// Set .File for the library that actually defines the symbol.
lsym.File = libpath
// The decodetype_* functions in decodetype.go need access to
// the type data.
if strings.HasPrefix(lsym.Name, "type.") && !strings.HasPrefix(lsym.Name, "type..") {
lsym.P = readelfsymboldata(ctxt, f, &elfsym)
gcdataLocations[elfsym.Value+2*uint64(ctxt.Arch.PtrSize)+8+1*uint64(ctxt.Arch.PtrSize)] = lsym
}
}
}
gcdataAddresses := make(map[*sym.Symbol]uint64)
if ctxt.Arch.Family == sys.ARM64 {
for _, sect := range f.Sections {
if sect.Type == elf.SHT_RELA {
var rela elf.Rela64
rdr := sect.Open()
for {
err := binary.Read(rdr, f.ByteOrder, &rela)
if err == io.EOF {
break
} else if err != nil {
Errorf(nil, "reading relocation failed %v", err)
return
}
t := elf.R_AARCH64(rela.Info & 0xffff)
if t != elf.R_AARCH64_RELATIVE {
continue
}
if lsym, ok := gcdataLocations[rela.Off]; ok {
gcdataAddresses[lsym] = uint64(rela.Addend)
}
}
}
}
}
ctxt.Shlibs = append(ctxt.Shlibs, Shlib{Path: libpath, Hash: hash, Deps: deps, File: f, gcdataAddresses: gcdataAddresses})
}
func addsection(arch *sys.Arch, seg *sym.Segment, name string, rwx int) *sym.Section {
sect := new(sym.Section)
sect.Rwx = uint8(rwx)
sect.Name = name
sect.Seg = seg
sect.Align = int32(arch.PtrSize) // everything is at least pointer-aligned
seg.Sections = append(seg.Sections, sect)
return sect
}
func Le16(b []byte) uint16 {
return uint16(b[0]) | uint16(b[1])<<8
}
func Le32(b []byte) uint32 {
return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
}
func Le64(b []byte) uint64 {
return uint64(Le32(b)) | uint64(Le32(b[4:]))<<32
}
func Be16(b []byte) uint16 {
return uint16(b[0])<<8 | uint16(b[1])
}
func Be32(b []byte) uint32 {
return uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3])
}
type chain struct {
sym *sym.Symbol
up *chain
limit int // limit on entry to sym
}
var morestack *sym.Symbol
// TODO: Record enough information in new object files to
// allow stack checks here.
func haslinkregister(ctxt *Link) bool {
return ctxt.FixedFrameSize() != 0
}
func callsize(ctxt *Link) int {
if haslinkregister(ctxt) {
return 0
}
return ctxt.Arch.RegSize
}
func (ctxt *Link) dostkcheck() {
var ch chain
morestack = ctxt.Syms.Lookup("runtime.morestack", 0)
// Every splitting function ensures that there are at least StackLimit
// bytes available below SP when the splitting prologue finishes.
// If the splitting function calls F, then F begins execution with
// at least StackLimit - callsize() bytes available.
// Check that every function behaves correctly with this amount
// of stack, following direct calls in order to piece together chains
// of non-splitting functions.
ch.up = nil
ch.limit = objabi.StackLimit - callsize(ctxt)
// Check every function, but do the nosplit functions in a first pass,
// to make the printed failure chains as short as possible.
for _, s := range ctxt.Textp {
// runtime.racesymbolizethunk is called from gcc-compiled C
// code running on the operating system thread stack.
// It uses more than the usual amount of stack but that's okay.
if s.Name == "runtime.racesymbolizethunk" {
continue
}
if s.Attr.NoSplit() {
ch.sym = s
stkcheck(ctxt, &ch, 0)
}
}
for _, s := range ctxt.Textp {
if !s.Attr.NoSplit() {
ch.sym = s
stkcheck(ctxt, &ch, 0)
}
}
}
func stkcheck(ctxt *Link, up *chain, depth int) int {
limit := up.limit
s := up.sym
// Don't duplicate work: only need to consider each
// function at top of safe zone once.
top := limit == objabi.StackLimit-callsize(ctxt)
if top {
if s.Attr.StackCheck() {
return 0
}
s.Attr |= sym.AttrStackCheck
}
if depth > 100 {
Errorf(s, "nosplit stack check too deep")
stkbroke(ctxt, up, 0)
return -1
}
if s.Attr.External() || s.FuncInfo == nil {
// external function.
// should never be called directly.
// onlyctxt.Diagnose the direct caller.
// TODO(mwhudson): actually think about this.
if depth == 1 && s.Type != sym.SXREF && !ctxt.DynlinkingGo() &&
ctxt.BuildMode != BuildModeCArchive && ctxt.BuildMode != BuildModePIE && ctxt.BuildMode != BuildModeCShared && ctxt.BuildMode != BuildModePlugin {
Errorf(s, "call to external function")
}
return -1
}
if limit < 0 {
stkbroke(ctxt, up, limit)
return -1
}
// morestack looks like it calls functions,
// but it switches the stack pointer first.
if s == morestack {
return 0
}
var ch chain
ch.up = up
if !s.Attr.NoSplit() {
// Ensure we have enough stack to call morestack.
ch.limit = limit - callsize(ctxt)
ch.sym = morestack
if stkcheck(ctxt, &ch, depth+1) < 0 {
return -1
}
if !top {
return 0
}
// Raise limit to allow frame.
locals := int32(0)
if s.FuncInfo != nil {
locals = s.FuncInfo.Locals
}
limit = int(objabi.StackLimit+locals) + int(ctxt.FixedFrameSize())
}
// Walk through sp adjustments in function, consuming relocs.
ri := 0
endr := len(s.R)
var ch1 chain
var pcsp Pciter
var r *sym.Reloc
for pciterinit(ctxt, &pcsp, &s.FuncInfo.Pcsp); pcsp.done == 0; pciternext(&pcsp) {
// pcsp.value is in effect for [pcsp.pc, pcsp.nextpc).
// Check stack size in effect for this span.
if int32(limit)-pcsp.value < 0 {
stkbroke(ctxt, up, int(int32(limit)-pcsp.value))
return -1
}
// Process calls in this span.
for ; ri < endr && uint32(s.R[ri].Off) < pcsp.nextpc; ri++ {
r = &s.R[ri]
switch r.Type {
// Direct call.
case objabi.R_CALL, objabi.R_CALLARM, objabi.R_CALLARM64, objabi.R_CALLPOWER, objabi.R_CALLMIPS:
ch.limit = int(int32(limit) - pcsp.value - int32(callsize(ctxt)))
ch.sym = r.Sym
if stkcheck(ctxt, &ch, depth+1) < 0 {
return -1
}
// Indirect call. Assume it is a call to a splitting function,
// so we have to make sure it can call morestack.
// Arrange the data structures to report both calls, so that
// if there is an error, stkprint shows all the steps involved.
case objabi.R_CALLIND:
ch.limit = int(int32(limit) - pcsp.value - int32(callsize(ctxt)))
ch.sym = nil
ch1.limit = ch.limit - callsize(ctxt) // for morestack in called prologue
ch1.up = &ch
ch1.sym = morestack
if stkcheck(ctxt, &ch1, depth+2) < 0 {
return -1
}
}
}
}
return 0
}
func stkbroke(ctxt *Link, ch *chain, limit int) {
Errorf(ch.sym, "nosplit stack overflow")
stkprint(ctxt, ch, limit)
}
func stkprint(ctxt *Link, ch *chain, limit int) {
var name string
if ch.sym != nil {
name = ch.sym.Name
if ch.sym.Attr.NoSplit() {
name += " (nosplit)"
}
} else {
name = "function pointer"
}
if ch.up == nil {
// top of chain. ch->sym != nil.
if ch.sym.Attr.NoSplit() {
fmt.Printf("\t%d\tassumed on entry to %s\n", ch.limit, name)
} else {
fmt.Printf("\t%d\tguaranteed after split check in %s\n", ch.limit, name)
}
} else {
stkprint(ctxt, ch.up, ch.limit+callsize(ctxt))
if !haslinkregister(ctxt) {
fmt.Printf("\t%d\ton entry to %s\n", ch.limit, name)
}
}
if ch.limit != limit {
fmt.Printf("\t%d\tafter %s uses %d\n", limit, name, ch.limit-limit)
}
}
func usage() {
fmt.Fprintf(os.Stderr, "usage: link [options] main.o\n")
objabi.Flagprint(2)
Exit(2)
}
func doversion() {
Exitf("version %s", objabi.Version)
}
type SymbolType int8
const (
// see also http://9p.io/magic/man2html/1/nm
TextSym SymbolType = 'T'
DataSym = 'D'
BSSSym = 'B'
UndefinedSym = 'U'
TLSSym = 't'
FrameSym = 'm'
ParamSym = 'p'
AutoSym = 'a'
// Deleted auto (not a real sym, just placeholder for type)
DeletedAutoSym = 'x'
)
func genasmsym(ctxt *Link, put func(*Link, *sym.Symbol, string, SymbolType, int64, *sym.Symbol)) {
// These symbols won't show up in the first loop below because we
// skip sym.STEXT symbols. Normal sym.STEXT symbols are emitted by walking textp.
s := ctxt.Syms.Lookup("runtime.text", 0)
if s.Type == sym.STEXT {
// We've already included this symbol in ctxt.Textp
// if ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin.
// See data.go:/textaddress
if !(ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin) {
put(ctxt, s, s.Name, TextSym, s.Value, nil)
}
}
n := 0
// Generate base addresses for all text sections if there are multiple
for _, sect := range Segtext.Sections {
if n == 0 {
n++
continue
}
if sect.Name != ".text" {
break
}
s = ctxt.Syms.ROLookup(fmt.Sprintf("runtime.text.%d", n), 0)
if s == nil {
break
}
if s.Type == sym.STEXT {
put(ctxt, s, s.Name, TextSym, s.Value, nil)
}
n++
}
s = ctxt.Syms.Lookup("runtime.etext", 0)
if s.Type == sym.STEXT {
// We've already included this symbol in ctxt.Textp
// if ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin.
// See data.go:/textaddress
if !(ctxt.DynlinkingGo() && ctxt.HeadType == objabi.Hdarwin) {
put(ctxt, s, s.Name, TextSym, s.Value, nil)
}
}
for _, s := range ctxt.Syms.Allsym {
if s.Attr.NotInSymbolTable() {
continue
}
if (s.Name == "" || s.Name[0] == '.') && s.Version == 0 && s.Name != ".rathole" && s.Name != ".TOC." {
continue
}
switch s.Type {
case sym.SCONST,
sym.SRODATA,
sym.SSYMTAB,
sym.SPCLNTAB,
sym.SINITARR,
sym.SDATA,
sym.SNOPTRDATA,
sym.SELFROSECT,
sym.SMACHOGOT,
sym.STYPE,
sym.SSTRING,
sym.SGOSTRING,
sym.SGOFUNC,
sym.SGCBITS,
sym.STYPERELRO,
sym.SSTRINGRELRO,
sym.SGOSTRINGRELRO,
sym.SGOFUNCRELRO,
sym.SGCBITSRELRO,
sym.SRODATARELRO,
sym.STYPELINK,
sym.SITABLINK,
sym.SWINDOWS:
if !s.Attr.Reachable() {
continue
}
put(ctxt, s, s.Name, DataSym, Symaddr(s), s.Gotype)
case sym.SBSS, sym.SNOPTRBSS:
if !s.Attr.Reachable() {
continue
}
if len(s.P) > 0 {
Errorf(s, "should not be bss (size=%d type=%v special=%v)", len(s.P), s.Type, s.Attr.Special())
}
put(ctxt, s, s.Name, BSSSym, Symaddr(s), s.Gotype)
case sym.SHOSTOBJ:
if ctxt.HeadType == objabi.Hwindows || ctxt.IsELF {
put(ctxt, s, s.Name, UndefinedSym, s.Value, nil)
}
case sym.SDYNIMPORT:
if !s.Attr.Reachable() {
continue
}
put(ctxt, s, s.Extname, UndefinedSym, 0, nil)
case sym.STLSBSS:
if ctxt.LinkMode == LinkExternal {
put(ctxt, s, s.Name, TLSSym, Symaddr(s), s.Gotype)
}
}
}
var off int32
for _, s := range ctxt.Textp {
put(ctxt, s, s.Name, TextSym, s.Value, s.Gotype)
locals := int32(0)
if s.FuncInfo != nil {
locals = s.FuncInfo.Locals
}
// NOTE(ality): acid can't produce a stack trace without .frame symbols
put(ctxt, nil, ".frame", FrameSym, int64(locals)+int64(ctxt.Arch.PtrSize), nil)
if s.FuncInfo == nil {
continue
}
for _, a := range s.FuncInfo.Autom {
if a.Name == objabi.A_DELETED_AUTO {
put(ctxt, nil, "", DeletedAutoSym, 0, a.Gotype)
continue
}
// Emit a or p according to actual offset, even if label is wrong.
// This avoids negative offsets, which cannot be encoded.
if a.Name != objabi.A_AUTO && a.Name != objabi.A_PARAM {
continue
}
// compute offset relative to FP
if a.Name == objabi.A_PARAM {
off = a.Aoffset
} else {
off = a.Aoffset - int32(ctxt.Arch.PtrSize)
}
// FP
if off >= 0 {
put(ctxt, nil, a.Asym.Name, ParamSym, int64(off), a.Gotype)
continue
}
// SP
if off <= int32(-ctxt.Arch.PtrSize) {
put(ctxt, nil, a.Asym.Name, AutoSym, -(int64(off) + int64(ctxt.Arch.PtrSize)), a.Gotype)
continue
}
// Otherwise, off is addressing the saved program counter.
// Something underhanded is going on. Say nothing.
}
}
if ctxt.Debugvlog != 0 || *flagN {
ctxt.Logf("%5.2f symsize = %d\n", Cputime(), uint32(Symsize))
}
}
func Symaddr(s *sym.Symbol) int64 {
if !s.Attr.Reachable() {
Errorf(s, "unreachable symbol in symaddr")
}
return s.Value
}
func (ctxt *Link) xdefine(p string, t sym.SymKind, v int64) {
s := ctxt.Syms.Lookup(p, 0)
s.Type = t
s.Value = v
s.Attr |= sym.AttrReachable
s.Attr |= sym.AttrSpecial
s.Attr |= sym.AttrLocal
}
func datoff(s *sym.Symbol, addr int64) int64 {
if uint64(addr) >= Segdata.Vaddr {
return int64(uint64(addr) - Segdata.Vaddr + Segdata.Fileoff)
}
if uint64(addr) >= Segtext.Vaddr {
return int64(uint64(addr) - Segtext.Vaddr + Segtext.Fileoff)
}
Errorf(s, "invalid datoff %#x", addr)
return 0
}
func Entryvalue(ctxt *Link) int64 {
a := *flagEntrySymbol
if a[0] >= '0' && a[0] <= '9' {
return atolwhex(a)
}
s := ctxt.Syms.Lookup(a, 0)
if s.Type == 0 {
return *FlagTextAddr
}
if s.Type != sym.STEXT {
Errorf(s, "entry not text")
}
return s.Value
}
func undefsym(ctxt *Link, s *sym.Symbol) {
var r *sym.Reloc
for i := 0; i < len(s.R); i++ {
r = &s.R[i]
if r.Sym == nil { // happens for some external ARM relocs
continue
}
// TODO(mwhudson): the test of VisibilityHidden here probably doesn't make
// sense and should be removed when someone has thought about it properly.
if (r.Sym.Type == sym.Sxxx || r.Sym.Type == sym.SXREF) && !r.Sym.Attr.VisibilityHidden() {
Errorf(s, "undefined: %q", r.Sym.Name)
}
if !r.Sym.Attr.Reachable() && r.Type != objabi.R_WEAKADDROFF {
Errorf(s, "relocation target %q", r.Sym.Name)
}
}
}
func (ctxt *Link) undef() {
for _, s := range ctxt.Textp {
undefsym(ctxt, s)
}
for _, s := range datap {
undefsym(ctxt, s)
}
if nerrors > 0 {
errorexit()
}
}
func (ctxt *Link) callgraph() {
if !*FlagC {
return
}
var i int
var r *sym.Reloc
for _, s := range ctxt.Textp {
for i = 0; i < len(s.R); i++ {
r = &s.R[i]
if r.Sym == nil {
continue
}
if (r.Type == objabi.R_CALL || r.Type == objabi.R_CALLARM || r.Type == objabi.R_CALLPOWER || r.Type == objabi.R_CALLMIPS) && r.Sym.Type == sym.STEXT {
ctxt.Logf("%s calls %s\n", s.Name, r.Sym.Name)
}
}
}
}
func Rnd(v int64, r int64) int64 {
if r <= 0 {
return v
}
v += r - 1
c := v % r
if c < 0 {
c += r
}
v -= c
return v
}
func bgetc(r *bio.Reader) int {
c, err := r.ReadByte()
if err != nil {
if err != io.EOF {
log.Fatalf("reading input: %v", err)
}
return -1
}
return int(c)
}
type markKind uint8 // for postorder traversal
const (
unvisited markKind = iota
visiting
visited
)
func postorder(libs []*sym.Library) []*sym.Library {
order := make([]*sym.Library, 0, len(libs)) // hold the result
mark := make(map[*sym.Library]markKind, len(libs))
for _, lib := range libs {
dfs(lib, mark, &order)
}
return order
}
func dfs(lib *sym.Library, mark map[*sym.Library]markKind, order *[]*sym.Library) {
if mark[lib] == visited {
return
}
if mark[lib] == visiting {
panic("found import cycle while visiting " + lib.Pkg)
}
mark[lib] = visiting
for _, i := range lib.Imports {
dfs(i, mark, order)
}
mark[lib] = visited
*order = append(*order, lib)
}