/
lib.go
2440 lines (2197 loc) · 66.8 KB
/
lib.go
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// 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/loadxcoff"
"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 is an arch-specific hook that assists in
// relocation processing (invoked by 'relocsym'); it handles
// target-specific relocation tasks. Here "rel" is the current
// relocation being examined, "sym" is the symbol containing the
// chunk of data to which the relocation applies, and "off" is the
// contents of the to-be-relocated data item (from sym.P). Return
// value is the appropriately relocated value (to be written back
// to the same spot in sym.P) and a boolean indicating
// success/failure (a failing value indicates a fatal error).
Archreloc func(link *Link, rel *sym.Reloc, sym *sym.Symbol,
offset int64) (relocatedOffset int64, success bool)
// Archrelocvariant is a second arch-specific hook used for
// relocation processing; it handles relocations where r.Type is
// insufficient to describe the relocation (r.Variant !=
// sym.RV_NONE). Here "rel" is the relocation being applied, "sym"
// is the symbol containing the chunk of data to which the
// relocation applies, and "off" is the contents of the
// to-be-relocated data item (from sym.P). Return is an updated
// offset value.
Archrelocvariant func(link *Link, rel *sym.Reloc, sym *sym.Symbol,
offset int64) (relocatedOffset 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)
// optional override for assignAddress
AssignAddress func(ctxt *Link, sect *sym.Section, n int, s *sym.Symbol, va uint64, isTramp bool) (*sym.Section, int, uint64)
}
var (
thearch Arch
Lcsize int32
rpath Rpath
Spsize int32
Symsize int32
)
const (
MINFUNC = 16 // minimum size for a function
)
// DynlinkingGo reports 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 reports whether a plugins can be used
func (ctxt *Link) CanUsePlugins() bool {
return ctxt.Syms.ROLookup("plugin.Open", sym.SymVerABIInternal) != nil
}
// UseRelro reports 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
)
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 _, libdir := range ctxt.Libdir {
if ctxt.linkShared {
shlibname := filepath.Join(libdir, 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(libdir, 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 && !(objabi.GOOS == "darwin" && (ctxt.Arch.Family == sys.AMD64 || ctxt.Arch.Family == sys.I386)) {
// 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.SDATA
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.SDATA
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 := range dynexp {
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 i := range s.R {
r := &s.R[i] // Copying sym.Reloc has measurable impact on performance
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 runtime.GOOS == "openbsd" && *flagLibGCC == "libgcc.a" {
// On OpenBSD `clang --print-libgcc-file-name` returns "libgcc.a".
// In this case we fail to load libgcc.a and can encounter link
// errors - see if we can find libcompiler_rt.a instead.
*flagLibGCC = ctxt.findLibPathCmd("--print-file-name=libcompiler_rt.a", "libcompiler_rt")
}
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 package versioning is required, generate a hash of 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 && ctxt.HeadType != objabi.Hwindows {
if (ctxt.BuildMode == BuildModeCArchive && ctxt.IsELF) || ctxt.BuildMode == BuildModeCShared || 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
}
// Resolve ABI aliases in the list of cgo-exported functions.
// This is necessary because we load the ABI0 symbol for all
// cgo exports.
for i, s := range dynexp {
if s.Type != sym.SABIALIAS {
continue
}
t := resolveABIAlias(s)
t.Attr |= s.Attr
t.SetExtname(s.Extname())
dynexp[i] = t
}
}
// mangleTypeSym shortens the names of symbols that represent Go types
// if they are visible in the symbol table.
//
// 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.
// This also removes characters that upset external linkers.
//
// 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
// those programs loaded dynamically in multiple parts need these
// symbols to have entries in the symbol table.
func (ctxt *Link) mangleTypeSym() {
if ctxt.BuildMode != BuildModeShared && !ctxt.linkShared && ctxt.BuildMode != BuildModePlugin && !ctxt.CanUsePlugins() {
return
}
for _, s := range ctxt.Syms.Allsym {
newName := typeSymbolMangle(s.Name)
if newName != s.Name {
ctxt.Syms.Rename(s.Name, newName, int(s.Version), ctxt.Reachparent)
}
}
}
// typeSymbolMangle mangles the given symbol name into something shorter.
//
// 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.
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
}
if arhdr.name != pkgdef {
Errorf(nil, "%s: missing package data entry", 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)
}
defer f.Close()
defer func() {
if pkg == "main" && !lib.Main {
Exitf("%s: not package main", lib.File)
}
// Ideally, we'd check that *all* object files within
// the archive were marked safe, but here we settle
// for *any*.
//
// Historically, cmd/link only checked the __.PKGDEF
// file, which in turn came from the first object
// file, typically produced by cmd/compile. The
// remaining object files are normally produced by
// cmd/asm, which doesn't support marking files as
// safe anyway. So at least in practice, this matches
// how safe mode has always worked.
if *flagU && !lib.Safe {
Exitf("%s: load of unsafe package %s", lib.File, pkg)
}
}()
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)
return
}
/*
* 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.
*/
var arhdr ArHdr
off := f.Offset()
for {
l := nextar(f, off, &arhdr)
if l == 0 {
break
}
if l < 0 {
Exitf("%s: malformed archive", lib.File)
}
off += l
// __.PKGDEF isn't a real Go object file, and it's
// absent in -linkobj builds anyway. Skipping it
// ensures consistency between -linkobj and normal
// build modes.
if arhdr.name == pkgdef {
continue
}
// Skip other special (non-object-file) sections that
// build tools may have added. Such sections must have
// short names so that the suffix is not truncated.
if len(arhdr.name) < 16 {
if ext := filepath.Ext(arhdr.name); ext != ".o" && ext != ".syso" {
continue
}
}
pname := fmt.Sprintf("%s(%s)", lib.File, arhdr.name)
l = atolwhex(arhdr.size)
ldobj(ctxt, f, lib, l, pname, lib.File)
}
}
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 _, intpkg := range internalpkg {
if pkg == intpkg {
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()
}
}
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(func() {
ctxt.Out.f.Close()
os.RemoveAll(*flagTmpdir)
})
}
// 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)
}