Source file src/cmd/link/internal/ld/lib.go

     1  // Inferno utils/8l/asm.c
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/8l/asm.c
     3  //
     4  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     5  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     6  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     7  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     8  //	Portions Copyright © 2004,2006 Bruce Ellis
     9  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    10  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    11  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    12  //
    13  // Permission is hereby granted, free of charge, to any person obtaining a copy
    14  // of this software and associated documentation files (the "Software"), to deal
    15  // in the Software without restriction, including without limitation the rights
    16  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    17  // copies of the Software, and to permit persons to whom the Software is
    18  // furnished to do so, subject to the following conditions:
    19  //
    20  // The above copyright notice and this permission notice shall be included in
    21  // all copies or substantial portions of the Software.
    22  //
    23  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    24  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    25  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    26  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    27  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    28  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    29  // THE SOFTWARE.
    30  
    31  package ld
    32  
    33  import (
    34  	"bytes"
    35  	"debug/elf"
    36  	"debug/macho"
    37  	"encoding/base64"
    38  	"encoding/binary"
    39  	"fmt"
    40  	"internal/buildcfg"
    41  	"internal/platform"
    42  	"io"
    43  	"log"
    44  	"os"
    45  	"os/exec"
    46  	"path/filepath"
    47  	"runtime"
    48  	"slices"
    49  	"sort"
    50  	"strings"
    51  	"sync"
    52  	"time"
    53  
    54  	"cmd/internal/bio"
    55  	"cmd/internal/goobj"
    56  	"cmd/internal/hash"
    57  	"cmd/internal/objabi"
    58  	"cmd/internal/sys"
    59  	"cmd/link/internal/loadelf"
    60  	"cmd/link/internal/loader"
    61  	"cmd/link/internal/loadmacho"
    62  	"cmd/link/internal/loadpe"
    63  	"cmd/link/internal/loadxcoff"
    64  	"cmd/link/internal/sym"
    65  )
    66  
    67  // Data layout and relocation.
    68  
    69  // Derived from Inferno utils/6l/l.h
    70  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/l.h
    71  //
    72  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
    73  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
    74  //	Portions Copyright © 1997-1999 Vita Nuova Limited
    75  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
    76  //	Portions Copyright © 2004,2006 Bruce Ellis
    77  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    78  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    79  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    80  //
    81  // Permission is hereby granted, free of charge, to any person obtaining a copy
    82  // of this software and associated documentation files (the "Software"), to deal
    83  // in the Software without restriction, including without limitation the rights
    84  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    85  // copies of the Software, and to permit persons to whom the Software is
    86  // furnished to do so, subject to the following conditions:
    87  //
    88  // The above copyright notice and this permission notice shall be included in
    89  // all copies or substantial portions of the Software.
    90  //
    91  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    92  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    93  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    94  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    95  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    96  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    97  // THE SOFTWARE.
    98  
    99  // ArchSyms holds a number of architecture specific symbols used during
   100  // relocation.  Rather than allowing them universal access to all symbols,
   101  // we keep a subset for relocation application.
   102  type ArchSyms struct {
   103  	Rel     loader.Sym
   104  	Rela    loader.Sym
   105  	RelPLT  loader.Sym
   106  	RelaPLT loader.Sym
   107  
   108  	LinkEditGOT loader.Sym
   109  	LinkEditPLT loader.Sym
   110  
   111  	TOC    loader.Sym
   112  	DotTOC []loader.Sym // for each version
   113  
   114  	GOT    loader.Sym
   115  	PLT    loader.Sym
   116  	GOTPLT loader.Sym
   117  
   118  	Tlsg      loader.Sym
   119  	Tlsoffset int
   120  
   121  	Dynamic loader.Sym
   122  	DynSym  loader.Sym
   123  	DynStr  loader.Sym
   124  
   125  	unreachableMethod loader.Sym
   126  
   127  	// Symbol containing a list of all the inittasks that need
   128  	// to be run at startup.
   129  	mainInittasks loader.Sym
   130  }
   131  
   132  // mkArchSym is a helper for setArchSyms, to set up a special symbol.
   133  func (ctxt *Link) mkArchSym(name string, ver int, ls *loader.Sym) {
   134  	*ls = ctxt.loader.LookupOrCreateSym(name, ver)
   135  	ctxt.loader.SetAttrReachable(*ls, true)
   136  }
   137  
   138  // mkArchSymVec is similar to  setArchSyms, but operates on elements within
   139  // a slice, where each element corresponds to some symbol version.
   140  func (ctxt *Link) mkArchSymVec(name string, ver int, ls []loader.Sym) {
   141  	ls[ver] = ctxt.loader.LookupOrCreateSym(name, ver)
   142  	ctxt.loader.SetAttrReachable(ls[ver], true)
   143  }
   144  
   145  // setArchSyms sets up the ArchSyms structure, and must be called before
   146  // relocations are applied.
   147  func (ctxt *Link) setArchSyms() {
   148  	ctxt.mkArchSym(".got", 0, &ctxt.GOT)
   149  	ctxt.mkArchSym(".plt", 0, &ctxt.PLT)
   150  	ctxt.mkArchSym(".got.plt", 0, &ctxt.GOTPLT)
   151  	ctxt.mkArchSym(".dynamic", 0, &ctxt.Dynamic)
   152  	ctxt.mkArchSym(".dynsym", 0, &ctxt.DynSym)
   153  	ctxt.mkArchSym(".dynstr", 0, &ctxt.DynStr)
   154  	ctxt.mkArchSym("runtime.unreachableMethod", abiInternalVer, &ctxt.unreachableMethod)
   155  
   156  	if ctxt.IsPPC64() {
   157  		ctxt.mkArchSym("TOC", 0, &ctxt.TOC)
   158  
   159  		ctxt.DotTOC = make([]loader.Sym, ctxt.MaxVersion()+1)
   160  		for i := 0; i <= ctxt.MaxVersion(); i++ {
   161  			if i >= sym.SymVerABICount && i < sym.SymVerStatic { // these versions are not used currently
   162  				continue
   163  			}
   164  			ctxt.mkArchSymVec(".TOC.", i, ctxt.DotTOC)
   165  		}
   166  	}
   167  	if ctxt.IsElf() {
   168  		ctxt.mkArchSym(".rel", 0, &ctxt.Rel)
   169  		ctxt.mkArchSym(".rela", 0, &ctxt.Rela)
   170  		ctxt.mkArchSym(".rel.plt", 0, &ctxt.RelPLT)
   171  		ctxt.mkArchSym(".rela.plt", 0, &ctxt.RelaPLT)
   172  	}
   173  	if ctxt.IsDarwin() {
   174  		ctxt.mkArchSym(".linkedit.got", 0, &ctxt.LinkEditGOT)
   175  		ctxt.mkArchSym(".linkedit.plt", 0, &ctxt.LinkEditPLT)
   176  	}
   177  }
   178  
   179  type Arch struct {
   180  	Funcalign  int
   181  	Maxalign   int
   182  	Minalign   int
   183  	Dwarfregsp int
   184  	Dwarfreglr int
   185  
   186  	// Threshold of total text size, used for trampoline insertion. If the total
   187  	// text size is smaller than TrampLimit, we won't need to insert trampolines.
   188  	// It is pretty close to the offset range of a direct CALL machine instruction.
   189  	// We leave some room for extra stuff like PLT stubs.
   190  	TrampLimit uint64
   191  
   192  	// Empty spaces between codeblocks will be padded with this value.
   193  	// For example an architecture might want to pad with a trap instruction to
   194  	// catch wayward programs. Architectures that do not define a padding value
   195  	// are padded with zeros.
   196  	CodePad []byte
   197  
   198  	// Plan 9 variables.
   199  	Plan9Magic  uint32
   200  	Plan9_64Bit bool
   201  
   202  	Adddynrel func(*Target, *loader.Loader, *ArchSyms, loader.Sym, loader.Reloc, int) bool
   203  	Archinit  func(*Link)
   204  	// Archreloc is an arch-specific hook that assists in relocation processing
   205  	// (invoked by 'relocsym'); it handles target-specific relocation tasks.
   206  	// Here "rel" is the current relocation being examined, "sym" is the symbol
   207  	// containing the chunk of data to which the relocation applies, and "off"
   208  	// is the contents of the to-be-relocated data item (from sym.P). Return
   209  	// value is the appropriately relocated value (to be written back to the
   210  	// same spot in sym.P), number of external _host_ relocations needed (i.e.
   211  	// ELF/Mach-O/etc. relocations, not Go relocations, this must match ELF.Reloc1,
   212  	// etc.), and a boolean indicating success/failure (a failing value indicates
   213  	// a fatal error).
   214  	Archreloc func(*Target, *loader.Loader, *ArchSyms, loader.Reloc, loader.Sym,
   215  		int64) (relocatedOffset int64, nExtReloc int, ok bool)
   216  	// Archrelocvariant is a second arch-specific hook used for
   217  	// relocation processing; it handles relocations where r.Type is
   218  	// insufficient to describe the relocation (r.Variant !=
   219  	// sym.RV_NONE). Here "rel" is the relocation being applied, "sym"
   220  	// is the symbol containing the chunk of data to which the
   221  	// relocation applies, and "off" is the contents of the
   222  	// to-be-relocated data item (from sym.P). Return is an updated
   223  	// offset value.
   224  	Archrelocvariant func(target *Target, ldr *loader.Loader, rel loader.Reloc,
   225  		rv sym.RelocVariant, sym loader.Sym, offset int64, data []byte) (relocatedOffset int64)
   226  
   227  	// Generate a trampoline for a call from s to rs if necessary. ri is
   228  	// index of the relocation.
   229  	Trampoline func(ctxt *Link, ldr *loader.Loader, ri int, rs, s loader.Sym)
   230  
   231  	// Assembling the binary breaks into two phases, writing the code/data/
   232  	// dwarf information (which is rather generic), and some more architecture
   233  	// specific work like setting up the elf headers/dynamic relocations, etc.
   234  	// The phases are called "Asmb" and "Asmb2". Asmb2 needs to be defined for
   235  	// every architecture, but only if architecture has an Asmb function will
   236  	// it be used for assembly.  Otherwise a generic assembly Asmb function is
   237  	// used.
   238  	Asmb  func(*Link, *loader.Loader)
   239  	Asmb2 func(*Link, *loader.Loader)
   240  
   241  	// Extreloc is an arch-specific hook that converts a Go relocation to an
   242  	// external relocation. Return the external relocation and whether it is
   243  	// needed.
   244  	Extreloc func(*Target, *loader.Loader, loader.Reloc, loader.Sym) (loader.ExtReloc, bool)
   245  
   246  	Gentext        func(*Link, *loader.Loader) // Generate text before addressing has been performed.
   247  	Machoreloc1    func(*sys.Arch, *OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int64) bool
   248  	MachorelocSize uint32 // size of an Mach-O relocation record, must match Machoreloc1.
   249  	PEreloc1       func(*sys.Arch, *OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int64) bool
   250  	Xcoffreloc1    func(*sys.Arch, *OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int64) bool
   251  
   252  	// Generate additional symbols for the native symbol table just prior to
   253  	// code generation.
   254  	GenSymsLate func(*Link, *loader.Loader)
   255  
   256  	// TLSIEtoLE converts a TLS Initial Executable relocation to
   257  	// a TLS Local Executable relocation.
   258  	//
   259  	// This is possible when a TLS IE relocation refers to a local
   260  	// symbol in an executable, which is typical when internally
   261  	// linking PIE binaries.
   262  	TLSIEtoLE func(P []byte, off, size int)
   263  
   264  	// optional override for assignAddress
   265  	AssignAddress func(ldr *loader.Loader, sect *sym.Section, n int, s loader.Sym, va uint64, isTramp bool) (*sym.Section, int, uint64)
   266  
   267  	// ELF specific information.
   268  	ELF ELFArch
   269  }
   270  
   271  var (
   272  	thearch Arch
   273  	lcSize  int32
   274  	rpath   Rpath
   275  	spSize  int32
   276  	symSize int32
   277  )
   278  
   279  // Symbol version of ABIInternal symbols. It is sym.SymVerABIInternal if ABI wrappers
   280  // are used, 0 otherwise.
   281  var abiInternalVer = sym.SymVerABIInternal
   282  
   283  // DynlinkingGo reports whether we are producing Go code that can live
   284  // in separate shared libraries linked together at runtime.
   285  func (ctxt *Link) DynlinkingGo() bool {
   286  	if !ctxt.Loaded {
   287  		panic("DynlinkingGo called before all symbols loaded")
   288  	}
   289  	return ctxt.BuildMode == BuildModeShared || ctxt.linkShared || ctxt.BuildMode == BuildModePlugin || ctxt.canUsePlugins
   290  }
   291  
   292  // CanUsePlugins reports whether a plugins can be used
   293  func (ctxt *Link) CanUsePlugins() bool {
   294  	if !ctxt.Loaded {
   295  		panic("CanUsePlugins called before all symbols loaded")
   296  	}
   297  	return ctxt.canUsePlugins
   298  }
   299  
   300  // NeedCodeSign reports whether we need to code-sign the output binary.
   301  func (ctxt *Link) NeedCodeSign() bool {
   302  	return ctxt.IsDarwin() && ctxt.IsARM64()
   303  }
   304  
   305  var (
   306  	dynlib          []string
   307  	ldflag          []string
   308  	havedynamic     int
   309  	Funcalign       int
   310  	iscgo           bool
   311  	elfglobalsymndx int
   312  	interpreter     string
   313  
   314  	debug_s bool // backup old value of debug['s']
   315  	HEADR   int32
   316  
   317  	nerrors  int
   318  	liveness int64 // size of liveness data (funcdata), printed if -v
   319  
   320  	// See -strictdups command line flag.
   321  	checkStrictDups   int // 0=off 1=warning 2=error
   322  	strictDupMsgCount int
   323  )
   324  
   325  var (
   326  	Segtext      sym.Segment
   327  	Segrodata    sym.Segment
   328  	Segrelrodata sym.Segment
   329  	Segdata      sym.Segment
   330  	Segdwarf     sym.Segment
   331  	Segpdata     sym.Segment // windows-only
   332  	Segxdata     sym.Segment // windows-only
   333  
   334  	Segments = []*sym.Segment{&Segtext, &Segrodata, &Segrelrodata, &Segdata, &Segdwarf, &Segpdata, &Segxdata}
   335  )
   336  
   337  const pkgdef = "__.PKGDEF"
   338  
   339  var (
   340  	// externalobj is set to true if we see an object compiled by
   341  	// the host compiler that is not from a package that is known
   342  	// to support internal linking mode.
   343  	externalobj = false
   344  
   345  	// dynimportfail is a list of packages for which generating
   346  	// the dynimport file, _cgo_import.go, failed. If there are
   347  	// any of these objects, we must link externally. Issue 52863.
   348  	dynimportfail []string
   349  
   350  	// preferlinkext is a list of packages for which the Go command
   351  	// noticed use of peculiar C flags. If we see any of these,
   352  	// default to linking externally unless overridden by the
   353  	// user. See issues #58619, #58620, and #58848.
   354  	preferlinkext []string
   355  
   356  	// unknownObjFormat is set to true if we see an object whose
   357  	// format we don't recognize.
   358  	unknownObjFormat = false
   359  
   360  	theline string
   361  )
   362  
   363  func Lflag(ctxt *Link, arg string) {
   364  	ctxt.Libdir = append(ctxt.Libdir, arg)
   365  }
   366  
   367  /*
   368   * Unix doesn't like it when we write to a running (or, sometimes,
   369   * recently run) binary, so remove the output file before writing it.
   370   * On Windows 7, remove() can force a subsequent create() to fail.
   371   * S_ISREG() does not exist on Plan 9.
   372   */
   373  func mayberemoveoutfile() {
   374  	if fi, err := os.Lstat(*flagOutfile); err == nil && !fi.Mode().IsRegular() {
   375  		return
   376  	}
   377  	os.Remove(*flagOutfile)
   378  }
   379  
   380  func libinit(ctxt *Link) {
   381  	if *FlagFuncAlign != 0 {
   382  		Funcalign = *FlagFuncAlign
   383  	} else {
   384  		Funcalign = thearch.Funcalign
   385  	}
   386  
   387  	// add goroot to the end of the libdir list.
   388  	suffix := ""
   389  
   390  	suffixsep := ""
   391  	if *flagInstallSuffix != "" {
   392  		suffixsep = "_"
   393  		suffix = *flagInstallSuffix
   394  	} else if *flagRace {
   395  		suffixsep = "_"
   396  		suffix = "race"
   397  	} else if *flagMsan {
   398  		suffixsep = "_"
   399  		suffix = "msan"
   400  	} else if *flagAsan {
   401  		suffixsep = "_"
   402  		suffix = "asan"
   403  	}
   404  
   405  	if buildcfg.GOROOT != "" {
   406  		Lflag(ctxt, filepath.Join(buildcfg.GOROOT, "pkg", fmt.Sprintf("%s_%s%s%s", buildcfg.GOOS, buildcfg.GOARCH, suffixsep, suffix)))
   407  	}
   408  
   409  	mayberemoveoutfile()
   410  
   411  	if err := ctxt.Out.Open(*flagOutfile); err != nil {
   412  		Exitf("cannot create %s: %v", *flagOutfile, err)
   413  	}
   414  
   415  	if *flagEntrySymbol == "" {
   416  		switch ctxt.BuildMode {
   417  		case BuildModeCShared, BuildModeCArchive:
   418  			*flagEntrySymbol = fmt.Sprintf("_rt0_%s_%s_lib", buildcfg.GOARCH, buildcfg.GOOS)
   419  		case BuildModeExe, BuildModePIE:
   420  			*flagEntrySymbol = fmt.Sprintf("_rt0_%s_%s", buildcfg.GOARCH, buildcfg.GOOS)
   421  		case BuildModeShared, BuildModePlugin:
   422  			// No *flagEntrySymbol for -buildmode=shared and plugin
   423  		default:
   424  			Errorf("unknown *flagEntrySymbol for buildmode %v", ctxt.BuildMode)
   425  		}
   426  	}
   427  }
   428  
   429  func exitIfErrors() {
   430  	if nerrors != 0 || checkStrictDups > 1 && strictDupMsgCount > 0 {
   431  		mayberemoveoutfile()
   432  		Exit(2)
   433  	}
   434  
   435  }
   436  
   437  func errorexit() {
   438  	exitIfErrors()
   439  	Exit(0)
   440  }
   441  
   442  func loadinternal(ctxt *Link, name string) *sym.Library {
   443  	zerofp := goobj.FingerprintType{}
   444  	if ctxt.linkShared && ctxt.PackageShlib != nil {
   445  		if shlib := ctxt.PackageShlib[name]; shlib != "" {
   446  			return addlibpath(ctxt, "internal", "internal", "", name, shlib, zerofp)
   447  		}
   448  	}
   449  	if ctxt.PackageFile != nil {
   450  		if pname := ctxt.PackageFile[name]; pname != "" {
   451  			return addlibpath(ctxt, "internal", "internal", pname, name, "", zerofp)
   452  		}
   453  		ctxt.Logf("loadinternal: cannot find %s\n", name)
   454  		return nil
   455  	}
   456  
   457  	for _, libdir := range ctxt.Libdir {
   458  		if ctxt.linkShared {
   459  			shlibname := filepath.Join(libdir, name+".shlibname")
   460  			if ctxt.Debugvlog != 0 {
   461  				ctxt.Logf("searching for %s.a in %s\n", name, shlibname)
   462  			}
   463  			if _, err := os.Stat(shlibname); err == nil {
   464  				return addlibpath(ctxt, "internal", "internal", "", name, shlibname, zerofp)
   465  			}
   466  		}
   467  		pname := filepath.Join(libdir, name+".a")
   468  		if ctxt.Debugvlog != 0 {
   469  			ctxt.Logf("searching for %s.a in %s\n", name, pname)
   470  		}
   471  		if _, err := os.Stat(pname); err == nil {
   472  			return addlibpath(ctxt, "internal", "internal", pname, name, "", zerofp)
   473  		}
   474  	}
   475  
   476  	if name == "runtime" {
   477  		Exitf("error: unable to find runtime.a")
   478  	}
   479  	ctxt.Logf("warning: unable to find %s.a\n", name)
   480  	return nil
   481  }
   482  
   483  // extld returns the current external linker.
   484  func (ctxt *Link) extld() []string {
   485  	if len(flagExtld) == 0 {
   486  		// Return the default external linker for the platform.
   487  		// This only matters when link tool is called directly without explicit -extld,
   488  		// go tool already passes the correct linker in other cases.
   489  		switch buildcfg.GOOS {
   490  		case "darwin", "freebsd", "openbsd":
   491  			flagExtld = []string{"clang"}
   492  		default:
   493  			flagExtld = []string{"gcc"}
   494  		}
   495  	}
   496  	return flagExtld
   497  }
   498  
   499  // findLibPathCmd uses cmd command to find gcc library libname.
   500  // It returns library full path if found, or "none" if not found.
   501  func (ctxt *Link) findLibPathCmd(cmd, libname string) string {
   502  	extld := ctxt.extld()
   503  	name, args := extld[0], extld[1:]
   504  	args = append(args, hostlinkArchArgs(ctxt.Arch)...)
   505  	args = append(args, cmd)
   506  	if ctxt.Debugvlog != 0 {
   507  		ctxt.Logf("%s %v\n", extld, args)
   508  	}
   509  	out, err := exec.Command(name, args...).Output()
   510  	if err != nil {
   511  		if ctxt.Debugvlog != 0 {
   512  			ctxt.Logf("not using a %s file because compiler failed\n%v\n%s\n", libname, err, out)
   513  		}
   514  		return "none"
   515  	}
   516  	return strings.TrimSpace(string(out))
   517  }
   518  
   519  // findLibPath searches for library libname.
   520  // It returns library full path if found, or "none" if not found.
   521  func (ctxt *Link) findLibPath(libname string) string {
   522  	return ctxt.findLibPathCmd("--print-file-name="+libname, libname)
   523  }
   524  
   525  func (ctxt *Link) loadlib() {
   526  	var flags uint32
   527  	if *flagCheckLinkname {
   528  		flags |= loader.FlagCheckLinkname
   529  	}
   530  	switch *FlagStrictDups {
   531  	case 0:
   532  		// nothing to do
   533  	case 1, 2:
   534  		flags |= loader.FlagStrictDups
   535  	default:
   536  		log.Fatalf("invalid -strictdups flag value %d", *FlagStrictDups)
   537  	}
   538  	ctxt.loader = loader.NewLoader(flags, &ctxt.ErrorReporter.ErrorReporter)
   539  	ctxt.ErrorReporter.SymName = func(s loader.Sym) string {
   540  		return ctxt.loader.SymName(s)
   541  	}
   542  
   543  	// ctxt.Library grows during the loop, so not a range loop.
   544  	i := 0
   545  	for ; i < len(ctxt.Library); i++ {
   546  		lib := ctxt.Library[i]
   547  		if lib.Shlib == "" {
   548  			if ctxt.Debugvlog > 1 {
   549  				ctxt.Logf("autolib: %s (from %s)\n", lib.File, lib.Objref)
   550  			}
   551  			loadobjfile(ctxt, lib)
   552  		}
   553  	}
   554  
   555  	// load internal packages, if not already
   556  	if *flagRace {
   557  		loadinternal(ctxt, "runtime/race")
   558  	}
   559  	if *flagMsan {
   560  		loadinternal(ctxt, "runtime/msan")
   561  	}
   562  	if *flagAsan {
   563  		loadinternal(ctxt, "runtime/asan")
   564  	}
   565  	loadinternal(ctxt, "runtime")
   566  	for ; i < len(ctxt.Library); i++ {
   567  		lib := ctxt.Library[i]
   568  		if lib.Shlib == "" {
   569  			loadobjfile(ctxt, lib)
   570  		}
   571  	}
   572  	// At this point, the Go objects are "preloaded". Not all the symbols are
   573  	// added to the symbol table (only defined package symbols are). Looking
   574  	// up symbol by name may not get expected result.
   575  
   576  	iscgo = ctxt.LibraryByPkg["runtime/cgo"] != nil
   577  
   578  	// Plugins a require cgo support to function. Similarly, plugins may require additional
   579  	// internal linker support on some platforms which may not be implemented.
   580  	ctxt.canUsePlugins = ctxt.LibraryByPkg["plugin"] != nil && iscgo &&
   581  		platform.BuildModeSupported("gc", "plugin", buildcfg.GOOS, buildcfg.GOARCH)
   582  
   583  	// We now have enough information to determine the link mode.
   584  	determineLinkMode(ctxt)
   585  
   586  	if ctxt.LinkMode == LinkExternal && !iscgo && !(buildcfg.GOOS == "darwin" && ctxt.BuildMode != BuildModePlugin && ctxt.Arch.Family == sys.AMD64) {
   587  		// This indicates a user requested -linkmode=external.
   588  		// The startup code uses an import of runtime/cgo to decide
   589  		// whether to initialize the TLS.  So give it one. This could
   590  		// be handled differently but it's an unusual case.
   591  		if lib := loadinternal(ctxt, "runtime/cgo"); lib != nil && lib.Shlib == "" {
   592  			if ctxt.BuildMode == BuildModeShared || ctxt.linkShared {
   593  				Exitf("cannot implicitly include runtime/cgo in a shared library")
   594  			}
   595  			for ; i < len(ctxt.Library); i++ {
   596  				lib := ctxt.Library[i]
   597  				if lib.Shlib == "" {
   598  					loadobjfile(ctxt, lib)
   599  				}
   600  			}
   601  		}
   602  	}
   603  
   604  	// Add non-package symbols and references of externally defined symbols.
   605  	ctxt.loader.LoadSyms(ctxt.Arch)
   606  
   607  	// Load symbols from shared libraries, after all Go object symbols are loaded.
   608  	for _, lib := range ctxt.Library {
   609  		if lib.Shlib != "" {
   610  			if ctxt.Debugvlog > 1 {
   611  				ctxt.Logf("autolib: %s (from %s)\n", lib.Shlib, lib.Objref)
   612  			}
   613  			ldshlibsyms(ctxt, lib.Shlib)
   614  		}
   615  	}
   616  
   617  	// Process cgo directives (has to be done before host object loading).
   618  	ctxt.loadcgodirectives()
   619  
   620  	// Conditionally load host objects, or setup for external linking.
   621  	hostobjs(ctxt)
   622  	hostlinksetup(ctxt)
   623  
   624  	if ctxt.LinkMode == LinkInternal && len(hostobj) != 0 {
   625  		// If we have any undefined symbols in external
   626  		// objects, try to read them from the libgcc file.
   627  		any := false
   628  		undefs, froms := ctxt.loader.UndefinedRelocTargets(1)
   629  		if len(undefs) > 0 {
   630  			any = true
   631  			if ctxt.Debugvlog > 1 {
   632  				ctxt.Logf("loadlib: first unresolved is %s [%d] from %s [%d]\n",
   633  					ctxt.loader.SymName(undefs[0]), undefs[0],
   634  					ctxt.loader.SymName(froms[0]), froms[0])
   635  			}
   636  		}
   637  		if any {
   638  			if *flagLibGCC == "" {
   639  				*flagLibGCC = ctxt.findLibPathCmd("--print-libgcc-file-name", "libgcc")
   640  			}
   641  			if runtime.GOOS == "freebsd" && strings.HasPrefix(filepath.Base(*flagLibGCC), "libclang_rt.builtins") {
   642  				// On newer versions of FreeBSD, libgcc is returned as something like
   643  				// /usr/lib/clang/18/lib/freebsd/libclang_rt.builtins-x86_64.a.
   644  				// Unfortunately this ends up missing a bunch of symbols we need from
   645  				// libcompiler_rt.
   646  				*flagLibGCC = ctxt.findLibPathCmd("--print-file-name=libcompiler_rt.a", "libcompiler_rt")
   647  			}
   648  			if runtime.GOOS == "openbsd" && *flagLibGCC == "libgcc.a" {
   649  				// On OpenBSD `clang --print-libgcc-file-name` returns "libgcc.a".
   650  				// In this case we fail to load libgcc.a and can encounter link
   651  				// errors - see if we can find libcompiler_rt.a instead.
   652  				*flagLibGCC = ctxt.findLibPathCmd("--print-file-name=libcompiler_rt.a", "libcompiler_rt")
   653  			}
   654  			if ctxt.HeadType == objabi.Hwindows {
   655  				loadWindowsHostArchives(ctxt)
   656  			}
   657  			if *flagLibGCC != "none" {
   658  				hostArchive(ctxt, *flagLibGCC)
   659  			}
   660  			// For glibc systems, the linker setup used by GCC
   661  			// looks like
   662  			//
   663  			//  GROUP ( /lib/x86_64-linux-gnu/libc.so.6
   664  			//      /usr/lib/x86_64-linux-gnu/libc_nonshared.a
   665  			//      AS_NEEDED ( /lib64/ld-linux-x86-64.so.2 ) )
   666  			//
   667  			// where libc_nonshared.a contains a small set of
   668  			// symbols including "__stack_chk_fail_local" and a
   669  			// few others. Thus if we are doing internal linking
   670  			// and "__stack_chk_fail_local" is unresolved (most
   671  			// likely due to the use of -fstack-protector), try
   672  			// loading libc_nonshared.a to resolve it.
   673  			//
   674  			// On Alpine Linux (musl-based), the library providing
   675  			// this symbol is called libssp_nonshared.a.
   676  			isunresolved := symbolsAreUnresolved(ctxt, []string{"__stack_chk_fail_local"})
   677  			if isunresolved[0] {
   678  				if p := ctxt.findLibPath("libc_nonshared.a"); p != "none" {
   679  					hostArchive(ctxt, p)
   680  				}
   681  				if p := ctxt.findLibPath("libssp_nonshared.a"); p != "none" {
   682  					hostArchive(ctxt, p)
   683  				}
   684  			}
   685  		}
   686  	}
   687  
   688  	loadfips(ctxt)
   689  
   690  	// We've loaded all the code now.
   691  	ctxt.Loaded = true
   692  
   693  	strictDupMsgCount = ctxt.loader.NStrictDupMsgs()
   694  }
   695  
   696  // loadWindowsHostArchives loads in host archives and objects when
   697  // doing internal linking on windows. Older toolchains seem to require
   698  // just a single pass through the various archives, but some modern
   699  // toolchains when linking a C program with mingw pass library paths
   700  // multiple times to the linker, e.g. "... -lmingwex -lmingw32 ...
   701  // -lmingwex -lmingw32 ...". To accommodate this behavior, we make two
   702  // passes over the host archives below.
   703  func loadWindowsHostArchives(ctxt *Link) {
   704  	any := true
   705  	for i := 0; any && i < 2; i++ {
   706  		// Link crt2.o (if present) to resolve "atexit" when
   707  		// using LLVM-based compilers.
   708  		isunresolved := symbolsAreUnresolved(ctxt, []string{"atexit"})
   709  		if isunresolved[0] {
   710  			if p := ctxt.findLibPath("crt2.o"); p != "none" {
   711  				hostObject(ctxt, "crt2", p)
   712  			}
   713  		}
   714  		if *flagRace {
   715  			if p := ctxt.findLibPath("libsynchronization.a"); p != "none" {
   716  				hostArchive(ctxt, p)
   717  			}
   718  		}
   719  		if p := ctxt.findLibPath("libmingwex.a"); p != "none" {
   720  			hostArchive(ctxt, p)
   721  		}
   722  		if p := ctxt.findLibPath("libmingw32.a"); p != "none" {
   723  			hostArchive(ctxt, p)
   724  		}
   725  		// Link libmsvcrt.a to resolve '__acrt_iob_func' symbol
   726  		// (see https://golang.org/issue/23649 for details).
   727  		if p := ctxt.findLibPath("libmsvcrt.a"); p != "none" {
   728  			hostArchive(ctxt, p)
   729  		}
   730  		any = false
   731  		undefs, froms := ctxt.loader.UndefinedRelocTargets(1)
   732  		if len(undefs) > 0 {
   733  			any = true
   734  			if ctxt.Debugvlog > 1 {
   735  				ctxt.Logf("loadWindowsHostArchives: remaining unresolved is %s [%d] from %s [%d]\n",
   736  					ctxt.loader.SymName(undefs[0]), undefs[0],
   737  					ctxt.loader.SymName(froms[0]), froms[0])
   738  			}
   739  		}
   740  	}
   741  	// If needed, create the __CTOR_LIST__ and __DTOR_LIST__
   742  	// symbols (referenced by some of the mingw support library
   743  	// routines). Creation of these symbols is normally done by the
   744  	// linker if not already present.
   745  	want := []string{"__CTOR_LIST__", "__DTOR_LIST__"}
   746  	isunresolved := symbolsAreUnresolved(ctxt, want)
   747  	for k, w := range want {
   748  		if isunresolved[k] {
   749  			sb := ctxt.loader.CreateSymForUpdate(w, 0)
   750  			sb.SetType(sym.SDATA)
   751  			sb.AddUint64(ctxt.Arch, 0)
   752  			sb.SetReachable(true)
   753  			ctxt.loader.SetAttrSpecial(sb.Sym(), true)
   754  		}
   755  	}
   756  
   757  	// Fix up references to DLL import symbols now that we're done
   758  	// pulling in new objects.
   759  	if err := loadpe.PostProcessImports(); err != nil {
   760  		Errorf("%v", err)
   761  	}
   762  
   763  	// TODO: maybe do something similar to peimporteddlls to collect
   764  	// all lib names and try link them all to final exe just like
   765  	// libmingwex.a and libmingw32.a:
   766  	/*
   767  		for:
   768  		#cgo windows LDFLAGS: -lmsvcrt -lm
   769  		import:
   770  		libmsvcrt.a libm.a
   771  	*/
   772  }
   773  
   774  // loadcgodirectives reads the previously discovered cgo directives, creating
   775  // symbols in preparation for host object loading or use later in the link.
   776  func (ctxt *Link) loadcgodirectives() {
   777  	l := ctxt.loader
   778  	hostObjSyms := make(map[loader.Sym]struct{})
   779  	for _, d := range ctxt.cgodata {
   780  		setCgoAttr(ctxt, d.file, d.pkg, d.directives, hostObjSyms)
   781  	}
   782  	ctxt.cgodata = nil
   783  
   784  	if ctxt.LinkMode == LinkInternal {
   785  		// Drop all the cgo_import_static declarations.
   786  		// Turns out we won't be needing them.
   787  		for symIdx := range hostObjSyms {
   788  			if l.SymType(symIdx) == sym.SHOSTOBJ {
   789  				// If a symbol was marked both
   790  				// cgo_import_static and cgo_import_dynamic,
   791  				// then we want to make it cgo_import_dynamic
   792  				// now.
   793  				su := l.MakeSymbolUpdater(symIdx)
   794  				if l.SymExtname(symIdx) != "" && l.SymDynimplib(symIdx) != "" && !(l.AttrCgoExportStatic(symIdx) || l.AttrCgoExportDynamic(symIdx)) {
   795  					su.SetType(sym.SDYNIMPORT)
   796  				} else {
   797  					su.SetType(0)
   798  				}
   799  			}
   800  		}
   801  	}
   802  }
   803  
   804  // Set up flags and special symbols depending on the platform build mode.
   805  // This version works with loader.Loader.
   806  func (ctxt *Link) linksetup() {
   807  	switch ctxt.BuildMode {
   808  	case BuildModeCShared, BuildModePlugin:
   809  		symIdx := ctxt.loader.LookupOrCreateSym("runtime.islibrary", 0)
   810  		sb := ctxt.loader.MakeSymbolUpdater(symIdx)
   811  		sb.SetType(sym.SNOPTRDATA)
   812  		sb.AddUint8(1)
   813  	case BuildModeCArchive:
   814  		symIdx := ctxt.loader.LookupOrCreateSym("runtime.isarchive", 0)
   815  		sb := ctxt.loader.MakeSymbolUpdater(symIdx)
   816  		sb.SetType(sym.SNOPTRDATA)
   817  		sb.AddUint8(1)
   818  	}
   819  
   820  	// Recalculate pe parameters now that we have ctxt.LinkMode set.
   821  	if ctxt.HeadType == objabi.Hwindows {
   822  		Peinit(ctxt)
   823  	}
   824  
   825  	if ctxt.LinkMode == LinkExternal {
   826  		// When external linking, we are creating an object file. The
   827  		// absolute address is irrelevant.
   828  		*FlagTextAddr = 0
   829  	}
   830  
   831  	// If there are no dynamic libraries needed, gcc disables dynamic linking.
   832  	// Because of this, glibc's dynamic ELF loader occasionally (like in version 2.13)
   833  	// assumes that a dynamic binary always refers to at least one dynamic library.
   834  	// Rather than be a source of test cases for glibc, disable dynamic linking
   835  	// the same way that gcc would.
   836  	//
   837  	// Exception: on OS X, programs such as Shark only work with dynamic
   838  	// binaries, so leave it enabled on OS X (Mach-O) binaries.
   839  	// Also leave it enabled on Solaris which doesn't support
   840  	// statically linked binaries.
   841  	if ctxt.BuildMode == BuildModeExe {
   842  		if havedynamic == 0 && ctxt.HeadType != objabi.Hdarwin && ctxt.HeadType != objabi.Hsolaris {
   843  			*FlagD = true
   844  		}
   845  	}
   846  
   847  	if ctxt.LinkMode == LinkExternal && ctxt.Arch.Family == sys.PPC64 && buildcfg.GOOS != "aix" {
   848  		toc := ctxt.loader.LookupOrCreateSym(".TOC.", 0)
   849  		sb := ctxt.loader.MakeSymbolUpdater(toc)
   850  		sb.SetType(sym.SDYNIMPORT)
   851  	}
   852  
   853  	// The Android Q linker started to complain about underalignment of the our TLS
   854  	// section. We don't actually use the section on android, so don't
   855  	// generate it.
   856  	if buildcfg.GOOS != "android" {
   857  		tlsg := ctxt.loader.LookupOrCreateSym("runtime.tlsg", 0)
   858  		sb := ctxt.loader.MakeSymbolUpdater(tlsg)
   859  
   860  		// runtime.tlsg is used for external linking on platforms that do not define
   861  		// a variable to hold g in assembly (currently only intel).
   862  		if sb.Type() == 0 {
   863  			sb.SetType(sym.STLSBSS)
   864  			sb.SetSize(int64(ctxt.Arch.PtrSize))
   865  		} else if sb.Type() != sym.SDYNIMPORT {
   866  			Errorf("runtime declared tlsg variable %v", sb.Type())
   867  		}
   868  		ctxt.loader.SetAttrReachable(tlsg, true)
   869  		ctxt.Tlsg = tlsg
   870  	}
   871  
   872  	var moduledata loader.Sym
   873  	var mdsb *loader.SymbolBuilder
   874  	if ctxt.BuildMode == BuildModePlugin {
   875  		moduledata = ctxt.loader.LookupOrCreateSym("local.pluginmoduledata", 0)
   876  		mdsb = ctxt.loader.MakeSymbolUpdater(moduledata)
   877  		ctxt.loader.SetAttrLocal(moduledata, true)
   878  	} else {
   879  		moduledata = ctxt.loader.LookupOrCreateSym("runtime.firstmoduledata", 0)
   880  		mdsb = ctxt.loader.MakeSymbolUpdater(moduledata)
   881  	}
   882  	if mdsb.Type() != 0 && mdsb.Type() != sym.SDYNIMPORT {
   883  		// If the module (toolchain-speak for "executable or shared
   884  		// library") we are linking contains the runtime package, it
   885  		// will define the runtime.firstmoduledata symbol and we
   886  		// truncate it back to 0 bytes so we can define its entire
   887  		// contents in symtab.go:symtab().
   888  		mdsb.SetSize(0)
   889  
   890  		// In addition, on ARM, the runtime depends on the linker
   891  		// recording the value of GOARM.
   892  		if ctxt.Arch.Family == sys.ARM {
   893  			goarm := ctxt.loader.LookupOrCreateSym("runtime.goarm", 0)
   894  			sb := ctxt.loader.MakeSymbolUpdater(goarm)
   895  			sb.SetType(sym.SNOPTRDATA)
   896  			sb.SetSize(0)
   897  			sb.AddUint8(uint8(buildcfg.GOARM.Version))
   898  
   899  			goarmsoftfp := ctxt.loader.LookupOrCreateSym("runtime.goarmsoftfp", 0)
   900  			sb2 := ctxt.loader.MakeSymbolUpdater(goarmsoftfp)
   901  			sb2.SetType(sym.SNOPTRDATA)
   902  			sb2.SetSize(0)
   903  			if buildcfg.GOARM.SoftFloat {
   904  				sb2.AddUint8(1)
   905  			} else {
   906  				sb2.AddUint8(0)
   907  			}
   908  		}
   909  
   910  		// Set runtime.disableMemoryProfiling bool if
   911  		// runtime.memProfileInternal is not retained in the binary after
   912  		// deadcode (and we're not dynamically linking).
   913  		memProfile := ctxt.loader.Lookup("runtime.memProfileInternal", abiInternalVer)
   914  		if memProfile != 0 && !ctxt.loader.AttrReachable(memProfile) && !ctxt.DynlinkingGo() {
   915  			memProfSym := ctxt.loader.LookupOrCreateSym("runtime.disableMemoryProfiling", 0)
   916  			sb := ctxt.loader.MakeSymbolUpdater(memProfSym)
   917  			sb.SetType(sym.SNOPTRDATA)
   918  			sb.SetSize(0)
   919  			sb.AddUint8(1) // true bool
   920  		}
   921  	} else {
   922  		// If OTOH the module does not contain the runtime package,
   923  		// create a local symbol for the moduledata.
   924  		moduledata = ctxt.loader.LookupOrCreateSym("local.moduledata", 0)
   925  		mdsb = ctxt.loader.MakeSymbolUpdater(moduledata)
   926  		ctxt.loader.SetAttrLocal(moduledata, true)
   927  	}
   928  	mdsb.SetType(sym.SMODULEDATA)
   929  	ctxt.loader.SetAttrReachable(moduledata, true)
   930  	ctxt.Moduledata = moduledata
   931  
   932  	if ctxt.Arch == sys.Arch386 && ctxt.HeadType != objabi.Hwindows {
   933  		if (ctxt.BuildMode == BuildModeCArchive && ctxt.IsELF) || ctxt.BuildMode == BuildModeCShared || ctxt.BuildMode == BuildModePIE || ctxt.DynlinkingGo() {
   934  			got := ctxt.loader.LookupOrCreateSym("_GLOBAL_OFFSET_TABLE_", 0)
   935  			sb := ctxt.loader.MakeSymbolUpdater(got)
   936  			sb.SetType(sym.SDYNIMPORT)
   937  			ctxt.loader.SetAttrReachable(got, true)
   938  		}
   939  	}
   940  
   941  	// DWARF-gen and other phases require that the unit Textp slices
   942  	// be populated, so that it can walk the functions in each unit.
   943  	// Call into the loader to do this (requires that we collect the
   944  	// set of internal libraries first). NB: might be simpler if we
   945  	// moved isRuntimeDepPkg to cmd/internal and then did the test in
   946  	// loader.AssignTextSymbolOrder.
   947  	ctxt.Library = postorder(ctxt.Library)
   948  	intlibs := []bool{}
   949  	for _, lib := range ctxt.Library {
   950  		intlibs = append(intlibs, isRuntimeDepPkg(lib.Pkg))
   951  	}
   952  	ctxt.Textp = ctxt.loader.AssignTextSymbolOrder(ctxt.Library, intlibs, ctxt.Textp)
   953  }
   954  
   955  // mangleTypeSym shortens the names of symbols that represent Go types
   956  // if they are visible in the symbol table.
   957  //
   958  // As the names of these symbols are derived from the string of
   959  // the type, they can run to many kilobytes long. So we shorten
   960  // them using a SHA-1 when the name appears in the final binary.
   961  // This also removes characters that upset external linkers.
   962  //
   963  // These are the symbols that begin with the prefix 'type.' and
   964  // contain run-time type information used by the runtime and reflect
   965  // packages. All Go binaries contain these symbols, but only
   966  // those programs loaded dynamically in multiple parts need these
   967  // symbols to have entries in the symbol table.
   968  func (ctxt *Link) mangleTypeSym() {
   969  	if ctxt.BuildMode != BuildModeShared && !ctxt.linkShared && ctxt.BuildMode != BuildModePlugin && !ctxt.CanUsePlugins() {
   970  		return
   971  	}
   972  
   973  	ldr := ctxt.loader
   974  	for s := loader.Sym(1); s < loader.Sym(ldr.NSym()); s++ {
   975  		if !ldr.AttrReachable(s) && !ctxt.linkShared {
   976  			// If -linkshared, the gc mask generation code may need to reach
   977  			// out to the shared library for the type descriptor's data, even
   978  			// the type descriptor itself is not actually needed at run time
   979  			// (therefore not reachable). We still need to mangle its name,
   980  			// so it is consistent with the one stored in the shared library.
   981  			continue
   982  		}
   983  		name := ldr.SymName(s)
   984  		newName := typeSymbolMangle(name)
   985  		if newName != name {
   986  			ldr.SetSymExtname(s, newName)
   987  
   988  			// When linking against a shared library, the Go object file may
   989  			// have reference to the original symbol name whereas the shared
   990  			// library provides a symbol with the mangled name. We need to
   991  			// copy the payload of mangled to original.
   992  			// XXX maybe there is a better way to do this.
   993  			dup := ldr.Lookup(newName, ldr.SymVersion(s))
   994  			if dup != 0 {
   995  				st := ldr.SymType(s)
   996  				dt := ldr.SymType(dup)
   997  				if st == sym.Sxxx && dt != sym.Sxxx {
   998  					ldr.CopySym(dup, s)
   999  				}
  1000  			}
  1001  		}
  1002  	}
  1003  }
  1004  
  1005  // typeSymbolMangle mangles the given symbol name into something shorter.
  1006  //
  1007  // Keep the type:. prefix, which parts of the linker (like the
  1008  // DWARF generator) know means the symbol is not decodable.
  1009  // Leave type:runtime. symbols alone, because other parts of
  1010  // the linker manipulates them.
  1011  func typeSymbolMangle(name string) string {
  1012  	isType := strings.HasPrefix(name, "type:")
  1013  	if !isType && !strings.Contains(name, "@") {
  1014  		// Issue 58800: instantiated symbols may include a type name, which may contain "@"
  1015  		return name
  1016  	}
  1017  	if strings.HasPrefix(name, "type:runtime.") {
  1018  		return name
  1019  	}
  1020  	if strings.HasPrefix(name, "go:string.") {
  1021  		// String symbols will be grouped to a single go:string.* symbol.
  1022  		// No need to mangle individual symbol names.
  1023  		return name
  1024  	}
  1025  	if len(name) <= 14 && !strings.Contains(name, "@") { // Issue 19529
  1026  		return name
  1027  	}
  1028  	if isType {
  1029  		hb := hash.Sum32([]byte(name[5:]))
  1030  		prefix := "type:"
  1031  		if name[5] == '.' {
  1032  			prefix = "type:."
  1033  		}
  1034  		return prefix + base64.StdEncoding.EncodeToString(hb[:6])
  1035  	}
  1036  	// instantiated symbol, replace type name in []
  1037  	i := strings.IndexByte(name, '[')
  1038  	j := strings.LastIndexByte(name, ']')
  1039  	if j == -1 || j <= i {
  1040  		j = len(name)
  1041  	}
  1042  	hb := hash.Sum32([]byte(name[i+1 : j]))
  1043  	return name[:i+1] + base64.StdEncoding.EncodeToString(hb[:6]) + name[j:]
  1044  }
  1045  
  1046  /*
  1047   * look for the next file in an archive.
  1048   * adapted from libmach.
  1049   */
  1050  func nextar(bp *bio.Reader, off int64, a *ArHdr) int64 {
  1051  	if off&1 != 0 {
  1052  		off++
  1053  	}
  1054  	bp.MustSeek(off, 0)
  1055  	var buf [SAR_HDR]byte
  1056  	if n, err := io.ReadFull(bp, buf[:]); err != nil {
  1057  		if n == 0 && err != io.EOF {
  1058  			return -1
  1059  		}
  1060  		return 0
  1061  	}
  1062  
  1063  	a.name = artrim(buf[0:16])
  1064  	a.date = artrim(buf[16:28])
  1065  	a.uid = artrim(buf[28:34])
  1066  	a.gid = artrim(buf[34:40])
  1067  	a.mode = artrim(buf[40:48])
  1068  	a.size = artrim(buf[48:58])
  1069  	a.fmag = artrim(buf[58:60])
  1070  
  1071  	arsize := atolwhex(a.size)
  1072  	if arsize&1 != 0 {
  1073  		arsize++
  1074  	}
  1075  	return arsize + SAR_HDR
  1076  }
  1077  
  1078  func loadobjfile(ctxt *Link, lib *sym.Library) {
  1079  	pkg := objabi.PathToPrefix(lib.Pkg)
  1080  
  1081  	if ctxt.Debugvlog > 1 {
  1082  		ctxt.Logf("ldobj: %s (%s)\n", lib.File, pkg)
  1083  	}
  1084  	f, err := bio.Open(lib.File)
  1085  	if err != nil {
  1086  		Exitf("cannot open file %s: %v", lib.File, err)
  1087  	}
  1088  	defer f.Close()
  1089  	defer func() {
  1090  		if pkg == "main" && !lib.Main {
  1091  			Exitf("%s: not package main", lib.File)
  1092  		}
  1093  	}()
  1094  
  1095  	for i := 0; i < len(ARMAG); i++ {
  1096  		if c, err := f.ReadByte(); err == nil && c == ARMAG[i] {
  1097  			continue
  1098  		}
  1099  
  1100  		/* load it as a regular file */
  1101  		l := f.MustSeek(0, 2)
  1102  		f.MustSeek(0, 0)
  1103  		ldobj(ctxt, f, lib, l, lib.File, lib.File)
  1104  		return
  1105  	}
  1106  
  1107  	/*
  1108  	 * load all the object files from the archive now.
  1109  	 * this gives us sequential file access and keeps us
  1110  	 * from needing to come back later to pick up more
  1111  	 * objects.  it breaks the usual C archive model, but
  1112  	 * this is Go, not C.  the common case in Go is that
  1113  	 * we need to load all the objects, and then we throw away
  1114  	 * the individual symbols that are unused.
  1115  	 *
  1116  	 * loading every object will also make it possible to
  1117  	 * load foreign objects not referenced by __.PKGDEF.
  1118  	 */
  1119  	var arhdr ArHdr
  1120  	off := f.Offset()
  1121  	for {
  1122  		l := nextar(f, off, &arhdr)
  1123  		if l == 0 {
  1124  			break
  1125  		}
  1126  		if l < 0 {
  1127  			Exitf("%s: malformed archive", lib.File)
  1128  		}
  1129  		off += l
  1130  
  1131  		// __.PKGDEF isn't a real Go object file, and it's
  1132  		// absent in -linkobj builds anyway. Skipping it
  1133  		// ensures consistency between -linkobj and normal
  1134  		// build modes.
  1135  		if arhdr.name == pkgdef {
  1136  			continue
  1137  		}
  1138  
  1139  		if arhdr.name == "dynimportfail" {
  1140  			dynimportfail = append(dynimportfail, lib.Pkg)
  1141  		}
  1142  		if arhdr.name == "preferlinkext" {
  1143  			// Ignore this directive if -linkmode has been
  1144  			// set explicitly.
  1145  			if ctxt.LinkMode == LinkAuto {
  1146  				preferlinkext = append(preferlinkext, lib.Pkg)
  1147  			}
  1148  		}
  1149  
  1150  		// Skip other special (non-object-file) sections that
  1151  		// build tools may have added. Such sections must have
  1152  		// short names so that the suffix is not truncated.
  1153  		if len(arhdr.name) < 16 {
  1154  			if ext := filepath.Ext(arhdr.name); ext != ".o" && ext != ".syso" {
  1155  				continue
  1156  			}
  1157  		}
  1158  
  1159  		pname := fmt.Sprintf("%s(%s)", lib.File, arhdr.name)
  1160  		l = atolwhex(arhdr.size)
  1161  		ldobj(ctxt, f, lib, l, pname, lib.File)
  1162  	}
  1163  }
  1164  
  1165  type Hostobj struct {
  1166  	ld     func(*Link, *bio.Reader, string, int64, string)
  1167  	pkg    string
  1168  	pn     string
  1169  	file   string
  1170  	off    int64
  1171  	length int64
  1172  }
  1173  
  1174  var hostobj []Hostobj
  1175  
  1176  // These packages can use internal linking mode.
  1177  // Others trigger external mode.
  1178  var internalpkg = []string{
  1179  	"crypto/internal/boring",
  1180  	"crypto/internal/boring/syso",
  1181  	"crypto/x509",
  1182  	"net",
  1183  	"os/user",
  1184  	"runtime/cgo",
  1185  	"runtime/race",
  1186  	"runtime/race/internal/amd64v1",
  1187  	"runtime/race/internal/amd64v3",
  1188  	"runtime/msan",
  1189  	"runtime/asan",
  1190  }
  1191  
  1192  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 {
  1193  	isinternal := false
  1194  	for _, intpkg := range internalpkg {
  1195  		if pkg == intpkg {
  1196  			isinternal = true
  1197  			break
  1198  		}
  1199  	}
  1200  
  1201  	// DragonFly declares errno with __thread, which results in a symbol
  1202  	// type of R_386_TLS_GD or R_X86_64_TLSGD. The Go linker does not
  1203  	// currently know how to handle TLS relocations, hence we have to
  1204  	// force external linking for any libraries that link in code that
  1205  	// uses errno. This can be removed if the Go linker ever supports
  1206  	// these relocation types.
  1207  	if headType == objabi.Hdragonfly {
  1208  		if pkg == "net" || pkg == "os/user" {
  1209  			isinternal = false
  1210  		}
  1211  	}
  1212  
  1213  	if !isinternal {
  1214  		externalobj = true
  1215  	}
  1216  
  1217  	hostobj = append(hostobj, Hostobj{})
  1218  	h := &hostobj[len(hostobj)-1]
  1219  	h.ld = ld
  1220  	h.pkg = pkg
  1221  	h.pn = pn
  1222  	h.file = file
  1223  	h.off = f.Offset()
  1224  	h.length = length
  1225  	return h
  1226  }
  1227  
  1228  func hostobjs(ctxt *Link) {
  1229  	if ctxt.LinkMode != LinkInternal {
  1230  		return
  1231  	}
  1232  	var h *Hostobj
  1233  
  1234  	for i := 0; i < len(hostobj); i++ {
  1235  		h = &hostobj[i]
  1236  		f, err := bio.Open(h.file)
  1237  		if err != nil {
  1238  			Exitf("cannot reopen %s: %v", h.pn, err)
  1239  		}
  1240  		f.MustSeek(h.off, 0)
  1241  		if h.ld == nil {
  1242  			Errorf("%s: unrecognized object file format", h.pn)
  1243  			continue
  1244  		}
  1245  		h.ld(ctxt, f, h.pkg, h.length, h.pn)
  1246  		if *flagCaptureHostObjs != "" {
  1247  			captureHostObj(h)
  1248  		}
  1249  		f.Close()
  1250  	}
  1251  }
  1252  
  1253  func hostlinksetup(ctxt *Link) {
  1254  	if ctxt.LinkMode != LinkExternal {
  1255  		return
  1256  	}
  1257  
  1258  	// For external link, record that we need to tell the external linker -s,
  1259  	// and turn off -s internally: the external linker needs the symbol
  1260  	// information for its final link.
  1261  	debug_s = *FlagS
  1262  	*FlagS = false
  1263  
  1264  	// create temporary directory and arrange cleanup
  1265  	if *flagTmpdir == "" {
  1266  		dir, err := os.MkdirTemp("", "go-link-")
  1267  		if err != nil {
  1268  			log.Fatal(err)
  1269  		}
  1270  		*flagTmpdir = dir
  1271  		ownTmpDir = true
  1272  		AtExit(func() {
  1273  			os.RemoveAll(*flagTmpdir)
  1274  		})
  1275  	}
  1276  
  1277  	// change our output to temporary object file
  1278  	if err := ctxt.Out.Close(); err != nil {
  1279  		Exitf("error closing output file")
  1280  	}
  1281  	mayberemoveoutfile()
  1282  
  1283  	p := filepath.Join(*flagTmpdir, "go.o")
  1284  	if err := ctxt.Out.Open(p); err != nil {
  1285  		Exitf("cannot create %s: %v", p, err)
  1286  	}
  1287  }
  1288  
  1289  // cleanTimeStamps resets the timestamps for the specified list of
  1290  // existing files to the Unix epoch (1970-01-01 00:00:00 +0000 UTC).
  1291  // We take this step in order to help preserve reproducible builds;
  1292  // this seems to be primarily needed for external linking on Darwin
  1293  // with later versions of xcode, which (unfortunately) seem to want to
  1294  // incorporate object file times into the final output file's build
  1295  // ID. See issue 64947 for the unpleasant details.
  1296  func cleanTimeStamps(files []string) {
  1297  	epocht := time.Unix(0, 0)
  1298  	for _, f := range files {
  1299  		if err := os.Chtimes(f, epocht, epocht); err != nil {
  1300  			Exitf("cannot chtimes %s: %v", f, err)
  1301  		}
  1302  	}
  1303  }
  1304  
  1305  // hostobjCopy creates a copy of the object files in hostobj in a
  1306  // temporary directory.
  1307  func (ctxt *Link) hostobjCopy() (paths []string) {
  1308  	var wg sync.WaitGroup
  1309  	sema := make(chan struct{}, runtime.NumCPU()) // limit open file descriptors
  1310  	for i, h := range hostobj {
  1311  		h := h
  1312  		dst := filepath.Join(*flagTmpdir, fmt.Sprintf("%06d.o", i))
  1313  		paths = append(paths, dst)
  1314  		if ctxt.Debugvlog != 0 {
  1315  			ctxt.Logf("host obj copy: %s from pkg %s -> %s\n", h.pn, h.pkg, dst)
  1316  		}
  1317  
  1318  		wg.Add(1)
  1319  		go func() {
  1320  			sema <- struct{}{}
  1321  			defer func() {
  1322  				<-sema
  1323  				wg.Done()
  1324  			}()
  1325  			f, err := os.Open(h.file)
  1326  			if err != nil {
  1327  				Exitf("cannot reopen %s: %v", h.pn, err)
  1328  			}
  1329  			defer f.Close()
  1330  			if _, err := f.Seek(h.off, 0); err != nil {
  1331  				Exitf("cannot seek %s: %v", h.pn, err)
  1332  			}
  1333  
  1334  			w, err := os.Create(dst)
  1335  			if err != nil {
  1336  				Exitf("cannot create %s: %v", dst, err)
  1337  			}
  1338  			if _, err := io.CopyN(w, f, h.length); err != nil {
  1339  				Exitf("cannot write %s: %v", dst, err)
  1340  			}
  1341  			if err := w.Close(); err != nil {
  1342  				Exitf("cannot close %s: %v", dst, err)
  1343  			}
  1344  		}()
  1345  	}
  1346  	wg.Wait()
  1347  	return paths
  1348  }
  1349  
  1350  // writeGDBLinkerScript creates gcc linker script file in temp
  1351  // directory. writeGDBLinkerScript returns created file path.
  1352  // The script is used to work around gcc bug
  1353  // (see https://golang.org/issue/20183 for details).
  1354  func writeGDBLinkerScript() string {
  1355  	name := "fix_debug_gdb_scripts.ld"
  1356  	path := filepath.Join(*flagTmpdir, name)
  1357  	src := `SECTIONS
  1358  {
  1359    .debug_gdb_scripts BLOCK(__section_alignment__) (NOLOAD) :
  1360    {
  1361      *(.debug_gdb_scripts)
  1362    }
  1363  }
  1364  INSERT AFTER .debug_types;
  1365  `
  1366  	err := os.WriteFile(path, []byte(src), 0666)
  1367  	if err != nil {
  1368  		Errorf("WriteFile %s failed: %v", name, err)
  1369  	}
  1370  	return path
  1371  }
  1372  
  1373  type machoUpdateFunc func(ctxt *Link, exef *os.File, exem *macho.File, outexe string) error
  1374  
  1375  // archive builds a .a archive from the hostobj object files.
  1376  func (ctxt *Link) archive() {
  1377  	if ctxt.BuildMode != BuildModeCArchive {
  1378  		return
  1379  	}
  1380  
  1381  	exitIfErrors()
  1382  
  1383  	if *flagExtar == "" {
  1384  		const printProgName = "--print-prog-name=ar"
  1385  		cc := ctxt.extld()
  1386  		*flagExtar = "ar"
  1387  		if linkerFlagSupported(ctxt.Arch, cc[0], "", printProgName) {
  1388  			*flagExtar = ctxt.findExtLinkTool("ar")
  1389  		}
  1390  	}
  1391  
  1392  	mayberemoveoutfile()
  1393  
  1394  	// Force the buffer to flush here so that external
  1395  	// tools will see a complete file.
  1396  	if err := ctxt.Out.Close(); err != nil {
  1397  		Exitf("error closing %v", *flagOutfile)
  1398  	}
  1399  
  1400  	argv := []string{*flagExtar, "-q", "-c", "-s"}
  1401  	if ctxt.HeadType == objabi.Haix {
  1402  		argv = append(argv, "-X64")
  1403  	}
  1404  	godotopath := filepath.Join(*flagTmpdir, "go.o")
  1405  	cleanTimeStamps([]string{godotopath})
  1406  	hostObjCopyPaths := ctxt.hostobjCopy()
  1407  	cleanTimeStamps(hostObjCopyPaths)
  1408  
  1409  	argv = append(argv, *flagOutfile)
  1410  	argv = append(argv, godotopath)
  1411  	argv = append(argv, hostObjCopyPaths...)
  1412  
  1413  	if ctxt.Debugvlog != 0 {
  1414  		ctxt.Logf("archive: %s\n", strings.Join(argv, " "))
  1415  	}
  1416  
  1417  	// If supported, use syscall.Exec() to invoke the archive command,
  1418  	// which should be the final remaining step needed for the link.
  1419  	// This will reduce peak RSS for the link (and speed up linking of
  1420  	// large applications), since when the archive command runs we
  1421  	// won't be holding onto all of the linker's live memory.
  1422  	if syscallExecSupported && !ownTmpDir {
  1423  		runAtExitFuncs()
  1424  		ctxt.execArchive(argv)
  1425  		panic("should not get here")
  1426  	}
  1427  
  1428  	// Otherwise invoke 'ar' in the usual way (fork + exec).
  1429  	if out, err := exec.Command(argv[0], argv[1:]...).CombinedOutput(); err != nil {
  1430  		Exitf("running %s failed: %v\n%s", argv[0], err, out)
  1431  	}
  1432  }
  1433  
  1434  func (ctxt *Link) hostlink() {
  1435  	if ctxt.LinkMode != LinkExternal || nerrors > 0 {
  1436  		return
  1437  	}
  1438  	if ctxt.BuildMode == BuildModeCArchive {
  1439  		return
  1440  	}
  1441  
  1442  	var argv []string
  1443  	argv = append(argv, ctxt.extld()...)
  1444  	argv = append(argv, hostlinkArchArgs(ctxt.Arch)...)
  1445  
  1446  	if *FlagS || debug_s {
  1447  		if ctxt.HeadType == objabi.Hdarwin {
  1448  			// Recent versions of macOS print
  1449  			//	ld: warning: option -s is obsolete and being ignored
  1450  			// so do not pass any arguments (but we strip symbols below).
  1451  		} else {
  1452  			argv = append(argv, "-s")
  1453  		}
  1454  	} else if *FlagW {
  1455  		if !ctxt.IsAIX() && !ctxt.IsSolaris() { // The AIX and Solaris linkers' -S has different meaning
  1456  			argv = append(argv, "-Wl,-S") // suppress debugging symbols
  1457  		}
  1458  	}
  1459  
  1460  	// On darwin, whether to combine DWARF into executable.
  1461  	// Only macOS supports unmapped segments such as our __DWARF segment.
  1462  	combineDwarf := ctxt.IsDarwin() && !*FlagW && machoPlatform == PLATFORM_MACOS
  1463  
  1464  	var isMSVC bool // used on Windows
  1465  	wlPrefix := "-Wl,--"
  1466  
  1467  	switch ctxt.HeadType {
  1468  	case objabi.Hdarwin:
  1469  		if combineDwarf {
  1470  			// Leave room for DWARF combining.
  1471  			// -headerpad is incompatible with -fembed-bitcode.
  1472  			argv = append(argv, "-Wl,-headerpad,1144")
  1473  		}
  1474  		if ctxt.DynlinkingGo() && buildcfg.GOOS != "ios" {
  1475  			// -flat_namespace is deprecated on iOS.
  1476  			// It is useful for supporting plugins. We don't support plugins on iOS.
  1477  			// -flat_namespace may cause the dynamic linker to hang at forkExec when
  1478  			// resolving a lazy binding. See issue 38824.
  1479  			// Force eager resolution to work around.
  1480  			argv = append(argv, "-Wl,-flat_namespace", "-Wl,-bind_at_load")
  1481  		}
  1482  		if !combineDwarf {
  1483  			argv = append(argv, "-Wl,-S") // suppress STAB (symbolic debugging) symbols
  1484  			if debug_s {
  1485  				// We are generating a binary with symbol table suppressed.
  1486  				// Suppress local symbols. We need to keep dynamically exported
  1487  				// and referenced symbols so the dynamic linker can resolve them.
  1488  				argv = append(argv, "-Wl,-x")
  1489  			}
  1490  		}
  1491  		if *flagHostBuildid == "none" {
  1492  			argv = append(argv, "-Wl,-no_uuid")
  1493  		}
  1494  	case objabi.Hopenbsd:
  1495  		argv = append(argv, "-pthread")
  1496  		if ctxt.BuildMode != BuildModePIE {
  1497  			argv = append(argv, "-Wl,-nopie")
  1498  		}
  1499  		if linkerFlagSupported(ctxt.Arch, argv[0], "", "-Wl,-z,nobtcfi") {
  1500  			// -Wl,-z,nobtcfi is only supported on OpenBSD 7.4+, remove guard
  1501  			// when OpenBSD 7.5 is released and 7.3 is no longer supported.
  1502  			argv = append(argv, "-Wl,-z,nobtcfi")
  1503  		}
  1504  		if ctxt.Arch.InFamily(sys.ARM64) {
  1505  			// Disable execute-only on openbsd/arm64 - the Go arm64 assembler
  1506  			// currently stores constants in the text section rather than in rodata.
  1507  			// See issue #59615.
  1508  			argv = append(argv, "-Wl,--no-execute-only")
  1509  		}
  1510  	case objabi.Hwindows:
  1511  		isMSVC = ctxt.isMSVC()
  1512  		if isMSVC {
  1513  			// For various options, MSVC lld-link only accepts one dash.
  1514  			// TODO: It seems mingw clang supports one or two dashes,
  1515  			// maybe we can always use one dash,  but I'm not sure about
  1516  			// legacy compilers that currently work.
  1517  			wlPrefix = "-Wl,-"
  1518  		}
  1519  
  1520  		if windowsgui {
  1521  			argv = append(argv, "-mwindows")
  1522  		} else {
  1523  			argv = append(argv, "-mconsole")
  1524  		}
  1525  		// Mark as having awareness of terminal services, to avoid
  1526  		// ancient compatibility hacks.
  1527  
  1528  		argv = append(argv, wlPrefix+"tsaware")
  1529  
  1530  		// Enable DEP
  1531  		argv = append(argv, wlPrefix+"nxcompat")
  1532  
  1533  		if !isMSVC {
  1534  			argv = append(argv, fmt.Sprintf("-Wl,--major-os-version=%d", PeMinimumTargetMajorVersion))
  1535  			argv = append(argv, fmt.Sprintf("-Wl,--minor-os-version=%d", PeMinimumTargetMinorVersion))
  1536  			argv = append(argv, fmt.Sprintf("-Wl,--major-subsystem-version=%d", PeMinimumTargetMajorVersion))
  1537  			argv = append(argv, fmt.Sprintf("-Wl,--minor-subsystem-version=%d", PeMinimumTargetMinorVersion))
  1538  		}
  1539  	case objabi.Haix:
  1540  		argv = append(argv, "-pthread")
  1541  		// prevent ld to reorder .text functions to keep the same
  1542  		// first/last functions for moduledata.
  1543  		argv = append(argv, "-Wl,-bnoobjreorder")
  1544  		// mcmodel=large is needed for every gcc generated files, but
  1545  		// ld still need -bbigtoc in order to allow larger TOC.
  1546  		argv = append(argv, "-mcmodel=large")
  1547  		argv = append(argv, "-Wl,-bbigtoc")
  1548  	}
  1549  
  1550  	// On PPC64, verify the external toolchain supports Power10. This is needed when
  1551  	// PC relative relocations might be generated by Go. Only targets compiling ELF
  1552  	// binaries might generate these relocations.
  1553  	if ctxt.IsPPC64() && ctxt.IsElf() && buildcfg.GOPPC64 >= 10 {
  1554  		if !linkerFlagSupported(ctxt.Arch, argv[0], "", "-mcpu=power10") {
  1555  			Exitf("The external toolchain does not support -mcpu=power10. " +
  1556  				" This is required to externally link GOPPC64 >= power10")
  1557  		}
  1558  	}
  1559  
  1560  	// Enable/disable ASLR on Windows.
  1561  	addASLRargs := func(argv []string, val bool) []string {
  1562  		// Old/ancient versions of GCC support "--dynamicbase" and
  1563  		// "--high-entropy-va" but don't enable it by default. In
  1564  		// addition, they don't accept "--disable-dynamicbase" or
  1565  		// "--no-dynamicbase", so the only way to disable ASLR is to
  1566  		// not pass any flags at all.
  1567  		//
  1568  		// More modern versions of GCC (and also clang) enable ASLR
  1569  		// by default. With these compilers, however you can turn it
  1570  		// off if you want using "--disable-dynamicbase" or
  1571  		// "--no-dynamicbase".
  1572  		//
  1573  		// The strategy below is to try using "--disable-dynamicbase";
  1574  		// if this succeeds, then assume we're working with more
  1575  		// modern compilers and act accordingly. If it fails, assume
  1576  		// an ancient compiler with ancient defaults.
  1577  		var dbopt string
  1578  		var heopt string
  1579  		dbon := wlPrefix + "dynamicbase"
  1580  		heon := wlPrefix + "high-entropy-va"
  1581  		dboff := wlPrefix + "disable-dynamicbase"
  1582  		heoff := wlPrefix + "disable-high-entropy-va"
  1583  		if isMSVC {
  1584  			heon = wlPrefix + "highentropyva"
  1585  			heoff = wlPrefix + "highentropyva:no"
  1586  			dboff = wlPrefix + "dynamicbase:no"
  1587  		}
  1588  		if val {
  1589  			dbopt = dbon
  1590  			heopt = heon
  1591  		} else {
  1592  			// Test to see whether "--disable-dynamicbase" works.
  1593  			newer := linkerFlagSupported(ctxt.Arch, argv[0], "", dboff)
  1594  			if newer {
  1595  				// Newer compiler, which supports both on/off options.
  1596  				dbopt = dboff
  1597  				heopt = heoff
  1598  			} else {
  1599  				// older toolchain: we have to say nothing in order to
  1600  				// get a no-ASLR binary.
  1601  				dbopt = ""
  1602  				heopt = ""
  1603  			}
  1604  		}
  1605  		if dbopt != "" {
  1606  			argv = append(argv, dbopt)
  1607  		}
  1608  		// enable high-entropy ASLR on 64-bit.
  1609  		if ctxt.Arch.PtrSize >= 8 && heopt != "" {
  1610  			argv = append(argv, heopt)
  1611  		}
  1612  		return argv
  1613  	}
  1614  
  1615  	switch ctxt.BuildMode {
  1616  	case BuildModeExe:
  1617  		if ctxt.HeadType == objabi.Hdarwin {
  1618  			if machoPlatform == PLATFORM_MACOS && ctxt.IsAMD64() {
  1619  				argv = append(argv, "-Wl,-no_pie")
  1620  			}
  1621  		}
  1622  		if *flagRace && ctxt.HeadType == objabi.Hwindows {
  1623  			// Current windows/amd64 race detector tsan support
  1624  			// library can't handle PIE mode (see #53539 for more details).
  1625  			// For now, explicitly disable PIE (since some compilers
  1626  			// default to it) if -race is in effect.
  1627  			argv = addASLRargs(argv, false)
  1628  		}
  1629  	case BuildModePIE:
  1630  		switch ctxt.HeadType {
  1631  		case objabi.Hdarwin, objabi.Haix:
  1632  		case objabi.Hwindows:
  1633  			if *flagAslr && *flagRace {
  1634  				// Current windows/amd64 race detector tsan support
  1635  				// library can't handle PIE mode (see #53539 for more details).
  1636  				// Disable alsr if -race in effect.
  1637  				*flagAslr = false
  1638  			}
  1639  			argv = addASLRargs(argv, *flagAslr)
  1640  		default:
  1641  			// ELF.
  1642  			if ctxt.UseRelro() {
  1643  				argv = append(argv, "-Wl,-z,relro")
  1644  			}
  1645  			argv = append(argv, "-pie")
  1646  		}
  1647  	case BuildModeCShared:
  1648  		if ctxt.HeadType == objabi.Hdarwin {
  1649  			argv = append(argv, "-dynamiclib")
  1650  		} else {
  1651  			if ctxt.UseRelro() {
  1652  				argv = append(argv, "-Wl,-z,relro")
  1653  			}
  1654  			argv = append(argv, "-shared")
  1655  			if ctxt.HeadType == objabi.Hwindows {
  1656  				argv = addASLRargs(argv, *flagAslr)
  1657  			} else {
  1658  				// Pass -z nodelete to mark the shared library as
  1659  				// non-closeable: a dlclose will do nothing.
  1660  				argv = append(argv, "-Wl,-z,nodelete")
  1661  				// Only pass Bsymbolic on non-Windows.
  1662  				argv = append(argv, "-Wl,-Bsymbolic")
  1663  			}
  1664  		}
  1665  	case BuildModeShared:
  1666  		if ctxt.UseRelro() {
  1667  			argv = append(argv, "-Wl,-z,relro")
  1668  		}
  1669  		argv = append(argv, "-shared")
  1670  	case BuildModePlugin:
  1671  		if ctxt.HeadType == objabi.Hdarwin {
  1672  			argv = append(argv, "-dynamiclib")
  1673  		} else {
  1674  			if ctxt.UseRelro() {
  1675  				argv = append(argv, "-Wl,-z,relro")
  1676  			}
  1677  			argv = append(argv, "-shared")
  1678  		}
  1679  	}
  1680  
  1681  	var altLinker string
  1682  	if ctxt.IsELF && (ctxt.DynlinkingGo() || *flagBindNow) {
  1683  		// For ELF targets, when producing dynamically linked Go code
  1684  		// or when immediate binding is explicitly requested,
  1685  		// we force all symbol resolution to be done at program startup
  1686  		// because lazy PLT resolution can use large amounts of stack at
  1687  		// times we cannot allow it to do so.
  1688  		argv = append(argv, "-Wl,-z,now")
  1689  	}
  1690  
  1691  	if ctxt.IsELF && ctxt.DynlinkingGo() {
  1692  		// Do not let the host linker generate COPY relocations. These
  1693  		// can move symbols out of sections that rely on stable offsets
  1694  		// from the beginning of the section (like sym.STYPE).
  1695  		argv = append(argv, "-Wl,-z,nocopyreloc")
  1696  
  1697  		if buildcfg.GOOS == "android" {
  1698  			// Use lld to avoid errors from default linker (issue #38838)
  1699  			altLinker = "lld"
  1700  		}
  1701  
  1702  		if ctxt.Arch.InFamily(sys.ARM64) && buildcfg.GOOS == "linux" {
  1703  			// On ARM64, the GNU linker will fail with
  1704  			// -znocopyreloc if it thinks a COPY relocation is
  1705  			// required. Switch to gold.
  1706  			// https://sourceware.org/bugzilla/show_bug.cgi?id=19962
  1707  			// https://go.dev/issue/22040
  1708  			altLinker = "gold"
  1709  
  1710  			// If gold is not installed, gcc will silently switch
  1711  			// back to ld.bfd. So we parse the version information
  1712  			// and provide a useful error if gold is missing.
  1713  			name, args := flagExtld[0], flagExtld[1:]
  1714  			args = append(args, "-fuse-ld=gold", "-Wl,--version")
  1715  			cmd := exec.Command(name, args...)
  1716  			if out, err := cmd.CombinedOutput(); err == nil {
  1717  				if !bytes.Contains(out, []byte("GNU gold")) {
  1718  					log.Fatalf("ARM64 external linker must be gold (issue #15696, 22040), but is not: %s", out)
  1719  				}
  1720  			}
  1721  		}
  1722  	}
  1723  	if ctxt.Arch.Family == sys.ARM64 && buildcfg.GOOS == "freebsd" {
  1724  		// Switch to ld.bfd on freebsd/arm64.
  1725  		altLinker = "bfd"
  1726  
  1727  		// Provide a useful error if ld.bfd is missing.
  1728  		name, args := flagExtld[0], flagExtld[1:]
  1729  		args = append(args, "-fuse-ld=bfd", "-Wl,--version")
  1730  		cmd := exec.Command(name, args...)
  1731  		if out, err := cmd.CombinedOutput(); err == nil {
  1732  			if !bytes.Contains(out, []byte("GNU ld")) {
  1733  				log.Fatalf("ARM64 external linker must be ld.bfd (issue #35197), please install devel/binutils")
  1734  			}
  1735  		}
  1736  	}
  1737  	if altLinker != "" {
  1738  		argv = append(argv, "-fuse-ld="+altLinker)
  1739  	}
  1740  
  1741  	if ctxt.IsELF && linkerFlagSupported(ctxt.Arch, argv[0], "", "-Wl,--build-id=0x1234567890abcdef") { // Solaris ld doesn't support --build-id.
  1742  		if len(buildinfo) > 0 {
  1743  			argv = append(argv, fmt.Sprintf("-Wl,--build-id=0x%x", buildinfo))
  1744  		} else if *flagHostBuildid == "none" {
  1745  			argv = append(argv, "-Wl,--build-id=none")
  1746  		}
  1747  	}
  1748  
  1749  	// On Windows, given -o foo, GCC will append ".exe" to produce
  1750  	// "foo.exe".  We have decided that we want to honor the -o
  1751  	// option. To make this work, we append a '.' so that GCC
  1752  	// will decide that the file already has an extension. We
  1753  	// only want to do this when producing a Windows output file
  1754  	// on a Windows host.
  1755  	outopt := *flagOutfile
  1756  	if buildcfg.GOOS == "windows" && runtime.GOOS == "windows" && filepath.Ext(outopt) == "" {
  1757  		outopt += "."
  1758  	}
  1759  	argv = append(argv, "-o")
  1760  	argv = append(argv, outopt)
  1761  
  1762  	if rpath.val != "" {
  1763  		argv = append(argv, fmt.Sprintf("-Wl,-rpath,%s", rpath.val))
  1764  	}
  1765  
  1766  	if *flagInterpreter != "" {
  1767  		// Many linkers support both -I and the --dynamic-linker flags
  1768  		// to set the ELF interpreter, but lld only supports
  1769  		// --dynamic-linker so prefer that (ld on very old Solaris only
  1770  		// supports -I but that seems less important).
  1771  		argv = append(argv, fmt.Sprintf("-Wl,--dynamic-linker,%s", *flagInterpreter))
  1772  	}
  1773  
  1774  	// Force global symbols to be exported for dlopen, etc.
  1775  	switch {
  1776  	case ctxt.IsELF:
  1777  		if ctxt.DynlinkingGo() || ctxt.BuildMode == BuildModeCShared || !linkerFlagSupported(ctxt.Arch, argv[0], altLinker, "-Wl,--export-dynamic-symbol=main") {
  1778  			argv = append(argv, "-rdynamic")
  1779  		} else {
  1780  			var exports []string
  1781  			ctxt.loader.ForAllCgoExportDynamic(func(s loader.Sym) {
  1782  				exports = append(exports, "-Wl,--export-dynamic-symbol="+ctxt.loader.SymExtname(s))
  1783  			})
  1784  			sort.Strings(exports)
  1785  			argv = append(argv, exports...)
  1786  		}
  1787  	case ctxt.IsAIX():
  1788  		fileName := xcoffCreateExportFile(ctxt)
  1789  		argv = append(argv, "-Wl,-bE:"+fileName)
  1790  	case ctxt.IsWindows() && !slices.Contains(flagExtldflags, wlPrefix+"export-all-symbols"):
  1791  		fileName := peCreateExportFile(ctxt, filepath.Base(outopt))
  1792  		prefix := ""
  1793  		if isMSVC {
  1794  			prefix = "-Wl,-def:"
  1795  		}
  1796  		argv = append(argv, prefix+fileName)
  1797  	}
  1798  
  1799  	const unusedArguments = "-Qunused-arguments"
  1800  	if linkerFlagSupported(ctxt.Arch, argv[0], altLinker, unusedArguments) {
  1801  		argv = append(argv, unusedArguments)
  1802  	}
  1803  
  1804  	if ctxt.IsWindows() {
  1805  		// Suppress generation of the PE file header timestamp,
  1806  		// so as to avoid spurious build ID differences between
  1807  		// linked binaries that are otherwise identical other than
  1808  		// the date/time they were linked.
  1809  		const noTimeStamp = "-Wl,--no-insert-timestamp"
  1810  		if linkerFlagSupported(ctxt.Arch, argv[0], altLinker, noTimeStamp) {
  1811  			argv = append(argv, noTimeStamp)
  1812  		}
  1813  	}
  1814  
  1815  	const compressDWARF = "-Wl,--compress-debug-sections=zlib"
  1816  	if ctxt.compressDWARF && linkerFlagSupported(ctxt.Arch, argv[0], altLinker, compressDWARF) {
  1817  		argv = append(argv, compressDWARF)
  1818  	}
  1819  
  1820  	hostObjCopyPaths := ctxt.hostobjCopy()
  1821  	cleanTimeStamps(hostObjCopyPaths)
  1822  	godotopath := filepath.Join(*flagTmpdir, "go.o")
  1823  	cleanTimeStamps([]string{godotopath})
  1824  
  1825  	argv = append(argv, godotopath)
  1826  	argv = append(argv, hostObjCopyPaths...)
  1827  	if ctxt.HeadType == objabi.Haix {
  1828  		// We want to have C files after Go files to remove
  1829  		// trampolines csects made by ld.
  1830  		argv = append(argv, "-nostartfiles")
  1831  		argv = append(argv, "/lib/crt0_64.o")
  1832  
  1833  		extld := ctxt.extld()
  1834  		name, args := extld[0], extld[1:]
  1835  		// Get starting files.
  1836  		getPathFile := func(file string) string {
  1837  			args := append(args, "-maix64", "--print-file-name="+file)
  1838  			out, err := exec.Command(name, args...).CombinedOutput()
  1839  			if err != nil {
  1840  				log.Fatalf("running %s failed: %v\n%s", extld, err, out)
  1841  			}
  1842  			return strings.Trim(string(out), "\n")
  1843  		}
  1844  		// Since GCC version 11, the 64-bit version of GCC starting files
  1845  		// are now suffixed by "_64". Even under "-maix64" multilib directory
  1846  		// "crtcxa.o" is 32-bit.
  1847  		crtcxa := getPathFile("crtcxa_64.o")
  1848  		if !filepath.IsAbs(crtcxa) {
  1849  			crtcxa = getPathFile("crtcxa.o")
  1850  		}
  1851  		crtdbase := getPathFile("crtdbase_64.o")
  1852  		if !filepath.IsAbs(crtdbase) {
  1853  			crtdbase = getPathFile("crtdbase.o")
  1854  		}
  1855  		argv = append(argv, crtcxa)
  1856  		argv = append(argv, crtdbase)
  1857  	}
  1858  
  1859  	if ctxt.linkShared {
  1860  		seenDirs := make(map[string]bool)
  1861  		seenLibs := make(map[string]bool)
  1862  		addshlib := func(path string) {
  1863  			dir, base := filepath.Split(path)
  1864  			if !seenDirs[dir] {
  1865  				argv = append(argv, "-L"+dir)
  1866  				if !rpath.set {
  1867  					argv = append(argv, "-Wl,-rpath="+dir)
  1868  				}
  1869  				seenDirs[dir] = true
  1870  			}
  1871  			base = strings.TrimSuffix(base, ".so")
  1872  			base = strings.TrimPrefix(base, "lib")
  1873  			if !seenLibs[base] {
  1874  				argv = append(argv, "-l"+base)
  1875  				seenLibs[base] = true
  1876  			}
  1877  		}
  1878  		for _, shlib := range ctxt.Shlibs {
  1879  			addshlib(shlib.Path)
  1880  			for _, dep := range shlib.Deps {
  1881  				if dep == "" {
  1882  					continue
  1883  				}
  1884  				libpath := findshlib(ctxt, dep)
  1885  				if libpath != "" {
  1886  					addshlib(libpath)
  1887  				}
  1888  			}
  1889  		}
  1890  	}
  1891  
  1892  	// clang, unlike GCC, passes -rdynamic to the linker
  1893  	// even when linking with -static, causing a linker
  1894  	// error when using GNU ld. So take out -rdynamic if
  1895  	// we added it. We do it in this order, rather than
  1896  	// only adding -rdynamic later, so that -extldflags
  1897  	// can override -rdynamic without using -static.
  1898  	// Similarly for -Wl,--dynamic-linker.
  1899  	checkStatic := func(arg string) {
  1900  		if ctxt.IsELF && arg == "-static" {
  1901  			for i := range argv {
  1902  				if argv[i] == "-rdynamic" || strings.HasPrefix(argv[i], "-Wl,--dynamic-linker,") {
  1903  					argv[i] = "-static"
  1904  				}
  1905  			}
  1906  		}
  1907  	}
  1908  
  1909  	for _, p := range ldflag {
  1910  		argv = append(argv, p)
  1911  		checkStatic(p)
  1912  	}
  1913  
  1914  	// When building a program with the default -buildmode=exe the
  1915  	// gc compiler generates code requires DT_TEXTREL in a
  1916  	// position independent executable (PIE). On systems where the
  1917  	// toolchain creates PIEs by default, and where DT_TEXTREL
  1918  	// does not work, the resulting programs will not run. See
  1919  	// issue #17847. To avoid this problem pass -no-pie to the
  1920  	// toolchain if it is supported.
  1921  	if ctxt.BuildMode == BuildModeExe && !ctxt.linkShared && !(ctxt.IsDarwin() && ctxt.IsARM64()) {
  1922  		// GCC uses -no-pie, clang uses -nopie.
  1923  		for _, nopie := range []string{"-no-pie", "-nopie"} {
  1924  			if linkerFlagSupported(ctxt.Arch, argv[0], altLinker, nopie) {
  1925  				argv = append(argv, nopie)
  1926  				break
  1927  			}
  1928  		}
  1929  	}
  1930  
  1931  	for _, p := range flagExtldflags {
  1932  		argv = append(argv, p)
  1933  		checkStatic(p)
  1934  	}
  1935  	if ctxt.HeadType == objabi.Hwindows {
  1936  		// Determine which linker we're using. Add in the extldflags in
  1937  		// case used has specified "-fuse-ld=...".
  1938  		extld := ctxt.extld()
  1939  		name, args := extld[0], extld[1:]
  1940  		args = append(args, trimLinkerArgv(flagExtldflags)...)
  1941  		args = append(args, "-Wl,--version")
  1942  		cmd := exec.Command(name, args...)
  1943  		usingLLD := false
  1944  		if out, err := cmd.CombinedOutput(); err == nil {
  1945  			if bytes.Contains(out, []byte("LLD ")) {
  1946  				usingLLD = true
  1947  			}
  1948  		}
  1949  
  1950  		// use gcc linker script to work around gcc bug
  1951  		// (see https://golang.org/issue/20183 for details).
  1952  		if !usingLLD {
  1953  			p := writeGDBLinkerScript()
  1954  			argv = append(argv, "-Wl,-T,"+p)
  1955  		}
  1956  		if *flagRace {
  1957  			// Apparently --print-file-name doesn't work with -msvc clang.
  1958  			// (The library name is synchronization.lib, but even with that
  1959  			// name it still doesn't print the full path.) Assume it always
  1960  			// it.
  1961  			if isMSVC || ctxt.findLibPath("libsynchronization.a") != "libsynchronization.a" {
  1962  				argv = append(argv, "-lsynchronization")
  1963  			}
  1964  		}
  1965  		if !isMSVC {
  1966  			// libmingw32 and libmingwex have some inter-dependencies,
  1967  			// so must use linker groups.
  1968  			argv = append(argv, "-Wl,--start-group", "-lmingwex", "-lmingw32", "-Wl,--end-group")
  1969  		}
  1970  		argv = append(argv, peimporteddlls()...)
  1971  	}
  1972  
  1973  	argv = ctxt.passLongArgsInResponseFile(argv, altLinker)
  1974  
  1975  	if ctxt.Debugvlog != 0 {
  1976  		ctxt.Logf("host link:")
  1977  		for _, v := range argv {
  1978  			ctxt.Logf(" %q", v)
  1979  		}
  1980  		ctxt.Logf("\n")
  1981  	}
  1982  
  1983  	cmd := exec.Command(argv[0], argv[1:]...)
  1984  	out, err := cmd.CombinedOutput()
  1985  	if err != nil {
  1986  		Exitf("running %s failed: %v\n%s\n%s", argv[0], err, cmd, out)
  1987  	}
  1988  
  1989  	// Filter out useless linker warnings caused by bugs outside Go.
  1990  	// See also cmd/go/internal/work/exec.go's gccld method.
  1991  	var save [][]byte
  1992  	var skipLines int
  1993  	for _, line := range bytes.SplitAfter(out, []byte("\n")) {
  1994  		// golang.org/issue/26073 - Apple Xcode bug
  1995  		if bytes.Contains(line, []byte("ld: warning: text-based stub file")) {
  1996  			continue
  1997  		}
  1998  
  1999  		if skipLines > 0 {
  2000  			skipLines--
  2001  			continue
  2002  		}
  2003  
  2004  		// Remove TOC overflow warning on AIX.
  2005  		if bytes.Contains(line, []byte("ld: 0711-783")) {
  2006  			skipLines = 2
  2007  			continue
  2008  		}
  2009  
  2010  		save = append(save, line)
  2011  	}
  2012  	out = bytes.Join(save, nil)
  2013  
  2014  	if len(out) > 0 {
  2015  		// always print external output even if the command is successful, so that we don't
  2016  		// swallow linker warnings (see https://golang.org/issue/17935).
  2017  		if ctxt.IsDarwin() && ctxt.IsAMD64() {
  2018  			const noPieWarning = "ld: warning: -no_pie is deprecated when targeting new OS versions\n"
  2019  			if i := bytes.Index(out, []byte(noPieWarning)); i >= 0 {
  2020  				// swallow -no_pie deprecation warning, issue 54482
  2021  				out = append(out[:i], out[i+len(noPieWarning):]...)
  2022  			}
  2023  		}
  2024  		if ctxt.IsDarwin() {
  2025  			const bindAtLoadWarning = "ld: warning: -bind_at_load is deprecated on macOS\n"
  2026  			if i := bytes.Index(out, []byte(bindAtLoadWarning)); i >= 0 {
  2027  				// -bind_at_load is deprecated with ld-prime, but needed for
  2028  				// correctness with older versions of ld64. Swallow the warning.
  2029  				// TODO: maybe pass -bind_at_load conditionally based on C
  2030  				// linker version.
  2031  				out = append(out[:i], out[i+len(bindAtLoadWarning):]...)
  2032  			}
  2033  		}
  2034  		ctxt.Logf("%s", out)
  2035  	}
  2036  
  2037  	// Helper for updating a Macho binary in some way (shared between
  2038  	// dwarf combining and UUID update).
  2039  	updateMachoOutFile := func(op string, updateFunc machoUpdateFunc) {
  2040  		// For os.Rename to work reliably, must be in same directory as outfile.
  2041  		rewrittenOutput := *flagOutfile + "~"
  2042  		exef, err := os.Open(*flagOutfile)
  2043  		if err != nil {
  2044  			Exitf("%s: %s failed: %v", os.Args[0], op, err)
  2045  		}
  2046  		defer exef.Close()
  2047  		exem, err := macho.NewFile(exef)
  2048  		if err != nil {
  2049  			Exitf("%s: parsing Mach-O header failed: %v", os.Args[0], err)
  2050  		}
  2051  		if err := updateFunc(ctxt, exef, exem, rewrittenOutput); err != nil {
  2052  			Exitf("%s: %s failed: %v", os.Args[0], op, err)
  2053  		}
  2054  		os.Remove(*flagOutfile)
  2055  		if err := os.Rename(rewrittenOutput, *flagOutfile); err != nil {
  2056  			Exitf("%s: %v", os.Args[0], err)
  2057  		}
  2058  	}
  2059  
  2060  	uuidUpdated := false
  2061  	if combineDwarf {
  2062  		// Find "dsymutils" and "strip" tools using CC --print-prog-name.
  2063  		dsymutilCmd := ctxt.findExtLinkTool("dsymutil")
  2064  		stripCmd := ctxt.findExtLinkTool("strip")
  2065  
  2066  		dsym := filepath.Join(*flagTmpdir, "go.dwarf")
  2067  		cmd := exec.Command(dsymutilCmd, "-f", *flagOutfile, "-o", dsym)
  2068  		// dsymutil may not clean up its temp directory at exit.
  2069  		// Set DSYMUTIL_REPRODUCER_PATH to work around. see issue 59026.
  2070  		// dsymutil (Apple LLVM version 16.0.0) deletes the directory
  2071  		// even if it is not empty. We still need our tmpdir, so give a
  2072  		// subdirectory to dsymutil.
  2073  		dsymDir := filepath.Join(*flagTmpdir, "dsymutil")
  2074  		err := os.MkdirAll(dsymDir, 0777)
  2075  		if err != nil {
  2076  			Exitf("fail to create temp dir: %v", err)
  2077  		}
  2078  		cmd.Env = append(os.Environ(), "DSYMUTIL_REPRODUCER_PATH="+dsymDir)
  2079  		if ctxt.Debugvlog != 0 {
  2080  			ctxt.Logf("host link dsymutil:")
  2081  			for _, v := range cmd.Args {
  2082  				ctxt.Logf(" %q", v)
  2083  			}
  2084  			ctxt.Logf("\n")
  2085  		}
  2086  		if out, err := cmd.CombinedOutput(); err != nil {
  2087  			Exitf("%s: running dsymutil failed: %v\n%s\n%s", os.Args[0], err, cmd, out)
  2088  		}
  2089  		// Remove STAB (symbolic debugging) symbols after we are done with them (by dsymutil).
  2090  		// They contain temporary file paths and make the build not reproducible.
  2091  		var stripArgs = []string{"-S"}
  2092  		if debug_s {
  2093  			// We are generating a binary with symbol table suppressed.
  2094  			// Suppress local symbols. We need to keep dynamically exported
  2095  			// and referenced symbols so the dynamic linker can resolve them.
  2096  			stripArgs = append(stripArgs, "-x")
  2097  		}
  2098  		stripArgs = append(stripArgs, *flagOutfile)
  2099  		if ctxt.Debugvlog != 0 {
  2100  			ctxt.Logf("host link strip: %q", stripCmd)
  2101  			for _, v := range stripArgs {
  2102  				ctxt.Logf(" %q", v)
  2103  			}
  2104  			ctxt.Logf("\n")
  2105  		}
  2106  		cmd = exec.Command(stripCmd, stripArgs...)
  2107  		if out, err := cmd.CombinedOutput(); err != nil {
  2108  			Exitf("%s: running strip failed: %v\n%s\n%s", os.Args[0], err, cmd, out)
  2109  		}
  2110  		// Skip combining if `dsymutil` didn't generate a file. See #11994.
  2111  		if _, err := os.Stat(dsym); err == nil {
  2112  			updateMachoOutFile("combining dwarf",
  2113  				func(ctxt *Link, exef *os.File, exem *macho.File, outexe string) error {
  2114  					return machoCombineDwarf(ctxt, exef, exem, dsym, outexe)
  2115  				})
  2116  			uuidUpdated = true
  2117  		}
  2118  	}
  2119  	if ctxt.IsDarwin() && !uuidUpdated && len(buildinfo) > 0 {
  2120  		updateMachoOutFile("rewriting uuid",
  2121  			func(ctxt *Link, exef *os.File, exem *macho.File, outexe string) error {
  2122  				return machoRewriteUuid(ctxt, exef, exem, outexe)
  2123  			})
  2124  	}
  2125  	hostlinkfips(ctxt, *flagOutfile, *flagFipso)
  2126  	if ctxt.NeedCodeSign() {
  2127  		err := machoCodeSign(ctxt, *flagOutfile)
  2128  		if err != nil {
  2129  			Exitf("%s: code signing failed: %v", os.Args[0], err)
  2130  		}
  2131  	}
  2132  }
  2133  
  2134  // passLongArgsInResponseFile writes the arguments into a file if they
  2135  // are very long.
  2136  func (ctxt *Link) passLongArgsInResponseFile(argv []string, altLinker string) []string {
  2137  	c := 0
  2138  	for _, arg := range argv {
  2139  		c += len(arg)
  2140  	}
  2141  
  2142  	if c < sys.ExecArgLengthLimit {
  2143  		return argv
  2144  	}
  2145  
  2146  	// Only use response files if they are supported.
  2147  	response := filepath.Join(*flagTmpdir, "response")
  2148  	if err := os.WriteFile(response, nil, 0644); err != nil {
  2149  		log.Fatalf("failed while testing response file: %v", err)
  2150  	}
  2151  	if !linkerFlagSupported(ctxt.Arch, argv[0], altLinker, "@"+response) {
  2152  		if ctxt.Debugvlog != 0 {
  2153  			ctxt.Logf("not using response file because linker does not support one")
  2154  		}
  2155  		return argv
  2156  	}
  2157  
  2158  	var buf bytes.Buffer
  2159  	for _, arg := range argv[1:] {
  2160  		// The external linker response file supports quoted strings.
  2161  		fmt.Fprintf(&buf, "%q\n", arg)
  2162  	}
  2163  	if err := os.WriteFile(response, buf.Bytes(), 0644); err != nil {
  2164  		log.Fatalf("failed while writing response file: %v", err)
  2165  	}
  2166  	if ctxt.Debugvlog != 0 {
  2167  		ctxt.Logf("response file %s contents:\n%s", response, buf.Bytes())
  2168  	}
  2169  	return []string{
  2170  		argv[0],
  2171  		"@" + response,
  2172  	}
  2173  }
  2174  
  2175  var createTrivialCOnce sync.Once
  2176  
  2177  func linkerFlagSupported(arch *sys.Arch, linker, altLinker, flag string) bool {
  2178  	createTrivialCOnce.Do(func() {
  2179  		src := filepath.Join(*flagTmpdir, "trivial.c")
  2180  		if err := os.WriteFile(src, []byte("int main() { return 0; }"), 0666); err != nil {
  2181  			Errorf("WriteFile trivial.c failed: %v", err)
  2182  		}
  2183  	})
  2184  
  2185  	flags := hostlinkArchArgs(arch)
  2186  
  2187  	moreFlags := trimLinkerArgv(append(ldflag, flagExtldflags...))
  2188  	flags = append(flags, moreFlags...)
  2189  
  2190  	if altLinker != "" {
  2191  		flags = append(flags, "-fuse-ld="+altLinker)
  2192  	}
  2193  	trivialPath := filepath.Join(*flagTmpdir, "trivial.c")
  2194  	outPath := filepath.Join(*flagTmpdir, "a.out")
  2195  	flags = append(flags, "-o", outPath, flag, trivialPath)
  2196  
  2197  	cmd := exec.Command(linker, flags...)
  2198  	cmd.Env = append([]string{"LC_ALL=C"}, os.Environ()...)
  2199  	out, err := cmd.CombinedOutput()
  2200  	// GCC says "unrecognized command line option ‘-no-pie’"
  2201  	// clang says "unknown argument: '-no-pie'"
  2202  	return err == nil && !bytes.Contains(out, []byte("unrecognized")) && !bytes.Contains(out, []byte("unknown"))
  2203  }
  2204  
  2205  // trimLinkerArgv returns a new copy of argv that does not include flags
  2206  // that are not relevant for testing whether some linker option works.
  2207  func trimLinkerArgv(argv []string) []string {
  2208  	flagsWithNextArgSkip := []string{
  2209  		"-F",
  2210  		"-l",
  2211  		"-L",
  2212  		"-framework",
  2213  		"-Wl,-framework",
  2214  		"-Wl,-rpath",
  2215  		"-Wl,-undefined",
  2216  	}
  2217  	flagsWithNextArgKeep := []string{
  2218  		"-arch",
  2219  		"-isysroot",
  2220  		"--sysroot",
  2221  		"-target",
  2222  		"--target",
  2223  	}
  2224  	prefixesToKeep := []string{
  2225  		"-f",
  2226  		"-m",
  2227  		"-p",
  2228  		"-Wl,",
  2229  		"-arch",
  2230  		"-isysroot",
  2231  		"--sysroot",
  2232  		"-target",
  2233  		"--target",
  2234  	}
  2235  
  2236  	var flags []string
  2237  	keep := false
  2238  	skip := false
  2239  	for _, f := range argv {
  2240  		if keep {
  2241  			flags = append(flags, f)
  2242  			keep = false
  2243  		} else if skip {
  2244  			skip = false
  2245  		} else if f == "" || f[0] != '-' {
  2246  		} else if slices.Contains(flagsWithNextArgSkip, f) {
  2247  			skip = true
  2248  		} else if slices.Contains(flagsWithNextArgKeep, f) {
  2249  			flags = append(flags, f)
  2250  			keep = true
  2251  		} else {
  2252  			for _, p := range prefixesToKeep {
  2253  				if strings.HasPrefix(f, p) {
  2254  					flags = append(flags, f)
  2255  					break
  2256  				}
  2257  			}
  2258  		}
  2259  	}
  2260  	return flags
  2261  }
  2262  
  2263  // hostlinkArchArgs returns arguments to pass to the external linker
  2264  // based on the architecture.
  2265  func hostlinkArchArgs(arch *sys.Arch) []string {
  2266  	switch arch.Family {
  2267  	case sys.I386:
  2268  		return []string{"-m32"}
  2269  	case sys.AMD64:
  2270  		if buildcfg.GOOS == "darwin" {
  2271  			return []string{"-arch", "x86_64", "-m64"}
  2272  		}
  2273  		return []string{"-m64"}
  2274  	case sys.S390X:
  2275  		return []string{"-m64"}
  2276  	case sys.ARM:
  2277  		return []string{"-marm"}
  2278  	case sys.ARM64:
  2279  		if buildcfg.GOOS == "darwin" {
  2280  			return []string{"-arch", "arm64"}
  2281  		}
  2282  	case sys.Loong64:
  2283  		return []string{"-mabi=lp64d"}
  2284  	case sys.MIPS64:
  2285  		return []string{"-mabi=64"}
  2286  	case sys.MIPS:
  2287  		return []string{"-mabi=32"}
  2288  	case sys.PPC64:
  2289  		if buildcfg.GOOS == "aix" {
  2290  			return []string{"-maix64"}
  2291  		} else {
  2292  			return []string{"-m64"}
  2293  		}
  2294  
  2295  	}
  2296  	return nil
  2297  }
  2298  
  2299  var wantHdr = objabi.HeaderString()
  2300  
  2301  // ldobj loads an input object. If it is a host object (an object
  2302  // compiled by a non-Go compiler) it returns the Hostobj pointer. If
  2303  // it is a Go object, it returns nil.
  2304  func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string, file string) *Hostobj {
  2305  	pkg := objabi.PathToPrefix(lib.Pkg)
  2306  
  2307  	eof := f.Offset() + length
  2308  	start := f.Offset()
  2309  	c1 := bgetc(f)
  2310  	c2 := bgetc(f)
  2311  	c3 := bgetc(f)
  2312  	c4 := bgetc(f)
  2313  	f.MustSeek(start, 0)
  2314  
  2315  	unit := &sym.CompilationUnit{Lib: lib}
  2316  	lib.Units = append(lib.Units, unit)
  2317  
  2318  	magic := uint32(c1)<<24 | uint32(c2)<<16 | uint32(c3)<<8 | uint32(c4)
  2319  	if magic == 0x7f454c46 { // \x7F E L F
  2320  		ldelf := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
  2321  			textp, flags, err := loadelf.Load(ctxt.loader, ctxt.Arch, ctxt.IncVersion(), f, pkg, length, pn, ehdr.Flags)
  2322  			if err != nil {
  2323  				Errorf("%v", err)
  2324  				return
  2325  			}
  2326  			ehdr.Flags = flags
  2327  			ctxt.Textp = append(ctxt.Textp, textp...)
  2328  		}
  2329  		return ldhostobj(ldelf, ctxt.HeadType, f, pkg, length, pn, file)
  2330  	}
  2331  
  2332  	if magic&^1 == 0xfeedface || magic&^0x01000000 == 0xcefaedfe {
  2333  		ldmacho := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
  2334  			textp, err := loadmacho.Load(ctxt.loader, ctxt.Arch, ctxt.IncVersion(), f, pkg, length, pn)
  2335  			if err != nil {
  2336  				Errorf("%v", err)
  2337  				return
  2338  			}
  2339  			ctxt.Textp = append(ctxt.Textp, textp...)
  2340  		}
  2341  		return ldhostobj(ldmacho, ctxt.HeadType, f, pkg, length, pn, file)
  2342  	}
  2343  
  2344  	switch c1<<8 | c2 {
  2345  	case 0x4c01, // 386
  2346  		0x6486, // amd64
  2347  		0xc401, // arm
  2348  		0x64aa: // arm64
  2349  		ldpe := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
  2350  			ls, err := loadpe.Load(ctxt.loader, ctxt.Arch, ctxt.IncVersion(), f, pkg, length, pn)
  2351  			if err != nil {
  2352  				Errorf("%v", err)
  2353  				return
  2354  			}
  2355  			if len(ls.Resources) != 0 {
  2356  				setpersrc(ctxt, ls.Resources)
  2357  			}
  2358  			if ls.PData != 0 {
  2359  				sehp.pdata = append(sehp.pdata, ls.PData)
  2360  			}
  2361  			if ls.XData != 0 {
  2362  				sehp.xdata = append(sehp.xdata, ls.XData)
  2363  			}
  2364  			ctxt.Textp = append(ctxt.Textp, ls.Textp...)
  2365  		}
  2366  		return ldhostobj(ldpe, ctxt.HeadType, f, pkg, length, pn, file)
  2367  	}
  2368  
  2369  	if c1 == 0x01 && (c2 == 0xD7 || c2 == 0xF7) {
  2370  		ldxcoff := func(ctxt *Link, f *bio.Reader, pkg string, length int64, pn string) {
  2371  			textp, err := loadxcoff.Load(ctxt.loader, ctxt.Arch, ctxt.IncVersion(), f, pkg, length, pn)
  2372  			if err != nil {
  2373  				Errorf("%v", err)
  2374  				return
  2375  			}
  2376  			ctxt.Textp = append(ctxt.Textp, textp...)
  2377  		}
  2378  		return ldhostobj(ldxcoff, ctxt.HeadType, f, pkg, length, pn, file)
  2379  	}
  2380  
  2381  	if c1 != 'g' || c2 != 'o' || c3 != ' ' || c4 != 'o' {
  2382  		// An unrecognized object is just passed to the external linker.
  2383  		// If we try to read symbols from this object, we will
  2384  		// report an error at that time.
  2385  		unknownObjFormat = true
  2386  		return ldhostobj(nil, ctxt.HeadType, f, pkg, length, pn, file)
  2387  	}
  2388  
  2389  	/* check the header */
  2390  	line, err := f.ReadString('\n')
  2391  	if err != nil {
  2392  		Errorf("truncated object file: %s: %v", pn, err)
  2393  		return nil
  2394  	}
  2395  
  2396  	if !strings.HasPrefix(line, "go object ") {
  2397  		if strings.HasSuffix(pn, ".go") {
  2398  			Exitf("%s: uncompiled .go source file", pn)
  2399  			return nil
  2400  		}
  2401  
  2402  		if line == ctxt.Arch.Name {
  2403  			// old header format: just $GOOS
  2404  			Errorf("%s: stale object file", pn)
  2405  			return nil
  2406  		}
  2407  
  2408  		Errorf("%s: not an object file: @%d %q", pn, start, line)
  2409  		return nil
  2410  	}
  2411  
  2412  	// First, check that the basic GOOS, GOARCH, and Version match.
  2413  	if line != wantHdr {
  2414  		Errorf("%s: linked object header mismatch:\nhave %q\nwant %q\n", pn, line, wantHdr)
  2415  	}
  2416  
  2417  	// Skip over exports and other info -- ends with \n!\n.
  2418  	//
  2419  	// Note: It's possible for "\n!\n" to appear within the binary
  2420  	// package export data format. To avoid truncating the package
  2421  	// definition prematurely (issue 21703), we keep track of
  2422  	// how many "$$" delimiters we've seen.
  2423  
  2424  	import0 := f.Offset()
  2425  
  2426  	c1 = '\n' // the last line ended in \n
  2427  	c2 = bgetc(f)
  2428  	c3 = bgetc(f)
  2429  	markers := 0
  2430  	for {
  2431  		if c1 == '\n' {
  2432  			if markers%2 == 0 && c2 == '!' && c3 == '\n' {
  2433  				break
  2434  			}
  2435  			if c2 == '$' && c3 == '$' {
  2436  				markers++
  2437  			}
  2438  		}
  2439  
  2440  		c1 = c2
  2441  		c2 = c3
  2442  		c3 = bgetc(f)
  2443  		if c3 == -1 {
  2444  			Errorf("truncated object file: %s", pn)
  2445  			return nil
  2446  		}
  2447  	}
  2448  
  2449  	import1 := f.Offset()
  2450  
  2451  	f.MustSeek(import0, 0)
  2452  	ldpkg(ctxt, f, lib, import1-import0-2, pn) // -2 for !\n
  2453  	f.MustSeek(import1, 0)
  2454  
  2455  	fingerprint := ctxt.loader.Preload(ctxt.IncVersion(), f, lib, unit, eof-f.Offset())
  2456  	if !fingerprint.IsZero() { // Assembly objects don't have fingerprints. Ignore them.
  2457  		// Check fingerprint, to ensure the importing and imported packages
  2458  		// have consistent view of symbol indices.
  2459  		// Normally the go command should ensure this. But in case something
  2460  		// goes wrong, it could lead to obscure bugs like run-time crash.
  2461  		// Check it here to be sure.
  2462  		if lib.Fingerprint.IsZero() { // Not yet imported. Update its fingerprint.
  2463  			lib.Fingerprint = fingerprint
  2464  		}
  2465  		checkFingerprint(lib, fingerprint, lib.Srcref, lib.Fingerprint)
  2466  	}
  2467  
  2468  	addImports(ctxt, lib, pn)
  2469  	return nil
  2470  }
  2471  
  2472  // symbolsAreUnresolved scans through the loader's list of unresolved
  2473  // symbols and checks to see whether any of them match the names of the
  2474  // symbols in 'want'. Return value is a list of bools, with list[K] set
  2475  // to true if there is an unresolved reference to the symbol in want[K].
  2476  func symbolsAreUnresolved(ctxt *Link, want []string) []bool {
  2477  	returnAllUndefs := -1
  2478  	undefs, _ := ctxt.loader.UndefinedRelocTargets(returnAllUndefs)
  2479  	seen := make(map[loader.Sym]struct{})
  2480  	rval := make([]bool, len(want))
  2481  	wantm := make(map[string]int)
  2482  	for k, w := range want {
  2483  		wantm[w] = k
  2484  	}
  2485  	count := 0
  2486  	for _, s := range undefs {
  2487  		if _, ok := seen[s]; ok {
  2488  			continue
  2489  		}
  2490  		seen[s] = struct{}{}
  2491  		if k, ok := wantm[ctxt.loader.SymName(s)]; ok {
  2492  			rval[k] = true
  2493  			count++
  2494  			if count == len(want) {
  2495  				return rval
  2496  			}
  2497  		}
  2498  	}
  2499  	return rval
  2500  }
  2501  
  2502  // hostObject reads a single host object file (compare to "hostArchive").
  2503  // This is used as part of internal linking when we need to pull in
  2504  // files such as "crt?.o".
  2505  func hostObject(ctxt *Link, objname string, path string) {
  2506  	if ctxt.Debugvlog > 1 {
  2507  		ctxt.Logf("hostObject(%s)\n", path)
  2508  	}
  2509  	objlib := sym.Library{
  2510  		Pkg: objname,
  2511  	}
  2512  	f, err := bio.Open(path)
  2513  	if err != nil {
  2514  		Exitf("cannot open host object %q file %s: %v", objname, path, err)
  2515  	}
  2516  	defer f.Close()
  2517  	h := ldobj(ctxt, f, &objlib, 0, path, path)
  2518  	if h.ld == nil {
  2519  		Exitf("unrecognized object file format in %s", path)
  2520  	}
  2521  	h.file = path
  2522  	h.length = f.MustSeek(0, 2)
  2523  	f.MustSeek(h.off, 0)
  2524  	h.ld(ctxt, f, h.pkg, h.length, h.pn)
  2525  	if *flagCaptureHostObjs != "" {
  2526  		captureHostObj(h)
  2527  	}
  2528  }
  2529  
  2530  func checkFingerprint(lib *sym.Library, libfp goobj.FingerprintType, src string, srcfp goobj.FingerprintType) {
  2531  	if libfp != srcfp {
  2532  		Exitf("fingerprint mismatch: %s has %x, import from %s expecting %x", lib, libfp, src, srcfp)
  2533  	}
  2534  }
  2535  
  2536  func readelfsymboldata(ctxt *Link, f *elf.File, sym *elf.Symbol) []byte {
  2537  	data := make([]byte, sym.Size)
  2538  	sect := f.Sections[sym.Section]
  2539  	if sect.Type != elf.SHT_PROGBITS && sect.Type != elf.SHT_NOTE {
  2540  		Errorf("reading %s from non-data section", sym.Name)
  2541  	}
  2542  	n, err := sect.ReadAt(data, int64(sym.Value-sect.Addr))
  2543  	if uint64(n) != sym.Size {
  2544  		Errorf("reading contents of %s: %v", sym.Name, err)
  2545  	}
  2546  	return data
  2547  }
  2548  
  2549  func readwithpad(r io.Reader, sz int32) ([]byte, error) {
  2550  	data := make([]byte, Rnd(int64(sz), 4))
  2551  	_, err := io.ReadFull(r, data)
  2552  	if err != nil {
  2553  		return nil, err
  2554  	}
  2555  	data = data[:sz]
  2556  	return data, nil
  2557  }
  2558  
  2559  func readnote(f *elf.File, name []byte, typ int32) ([]byte, error) {
  2560  	for _, sect := range f.Sections {
  2561  		if sect.Type != elf.SHT_NOTE {
  2562  			continue
  2563  		}
  2564  		r := sect.Open()
  2565  		for {
  2566  			var namesize, descsize, noteType int32
  2567  			err := binary.Read(r, f.ByteOrder, &namesize)
  2568  			if err != nil {
  2569  				if err == io.EOF {
  2570  					break
  2571  				}
  2572  				return nil, fmt.Errorf("read namesize failed: %v", err)
  2573  			}
  2574  			err = binary.Read(r, f.ByteOrder, &descsize)
  2575  			if err != nil {
  2576  				return nil, fmt.Errorf("read descsize failed: %v", err)
  2577  			}
  2578  			err = binary.Read(r, f.ByteOrder, &noteType)
  2579  			if err != nil {
  2580  				return nil, fmt.Errorf("read type failed: %v", err)
  2581  			}
  2582  			noteName, err := readwithpad(r, namesize)
  2583  			if err != nil {
  2584  				return nil, fmt.Errorf("read name failed: %v", err)
  2585  			}
  2586  			desc, err := readwithpad(r, descsize)
  2587  			if err != nil {
  2588  				return nil, fmt.Errorf("read desc failed: %v", err)
  2589  			}
  2590  			if string(name) == string(noteName) && typ == noteType {
  2591  				return desc, nil
  2592  			}
  2593  		}
  2594  	}
  2595  	return nil, nil
  2596  }
  2597  
  2598  func findshlib(ctxt *Link, shlib string) string {
  2599  	if filepath.IsAbs(shlib) {
  2600  		return shlib
  2601  	}
  2602  	for _, libdir := range ctxt.Libdir {
  2603  		libpath := filepath.Join(libdir, shlib)
  2604  		if _, err := os.Stat(libpath); err == nil {
  2605  			return libpath
  2606  		}
  2607  	}
  2608  	Errorf("cannot find shared library: %s", shlib)
  2609  	return ""
  2610  }
  2611  
  2612  func ldshlibsyms(ctxt *Link, shlib string) {
  2613  	var libpath string
  2614  	if filepath.IsAbs(shlib) {
  2615  		libpath = shlib
  2616  		shlib = filepath.Base(shlib)
  2617  	} else {
  2618  		libpath = findshlib(ctxt, shlib)
  2619  		if libpath == "" {
  2620  			return
  2621  		}
  2622  	}
  2623  	for _, processedlib := range ctxt.Shlibs {
  2624  		if processedlib.Path == libpath {
  2625  			return
  2626  		}
  2627  	}
  2628  	if ctxt.Debugvlog > 1 {
  2629  		ctxt.Logf("ldshlibsyms: found library with name %s at %s\n", shlib, libpath)
  2630  	}
  2631  
  2632  	f, err := elf.Open(libpath)
  2633  	if err != nil {
  2634  		Errorf("cannot open shared library: %s", libpath)
  2635  		return
  2636  	}
  2637  	// Keep the file open as decodetypeGcprog needs to read from it.
  2638  	// TODO: fix. Maybe mmap the file.
  2639  	//defer f.Close()
  2640  
  2641  	hash, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GOABIHASH_TAG)
  2642  	if err != nil {
  2643  		Errorf("cannot read ABI hash from shared library %s: %v", libpath, err)
  2644  		return
  2645  	}
  2646  
  2647  	depsbytes, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GODEPS_TAG)
  2648  	if err != nil {
  2649  		Errorf("cannot read dep list from shared library %s: %v", libpath, err)
  2650  		return
  2651  	}
  2652  	var deps []string
  2653  	for _, dep := range strings.Split(string(depsbytes), "\n") {
  2654  		if dep == "" {
  2655  			continue
  2656  		}
  2657  		if !filepath.IsAbs(dep) {
  2658  			// If the dep can be interpreted as a path relative to the shlib
  2659  			// in which it was found, do that. Otherwise, we will leave it
  2660  			// to be resolved by libdir lookup.
  2661  			abs := filepath.Join(filepath.Dir(libpath), dep)
  2662  			if _, err := os.Stat(abs); err == nil {
  2663  				dep = abs
  2664  			}
  2665  		}
  2666  		deps = append(deps, dep)
  2667  	}
  2668  
  2669  	syms, err := f.DynamicSymbols()
  2670  	if err != nil {
  2671  		Errorf("cannot read symbols from shared library: %s", libpath)
  2672  		return
  2673  	}
  2674  
  2675  	symAddr := map[string]uint64{}
  2676  	for _, elfsym := range syms {
  2677  		if elf.ST_TYPE(elfsym.Info) == elf.STT_NOTYPE || elf.ST_TYPE(elfsym.Info) == elf.STT_SECTION {
  2678  			continue
  2679  		}
  2680  
  2681  		// Symbols whose names start with "type:" are compiler generated,
  2682  		// so make functions with that prefix internal.
  2683  		ver := 0
  2684  		symname := elfsym.Name // (unmangled) symbol name
  2685  		if elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC && strings.HasPrefix(elfsym.Name, "type:") {
  2686  			ver = abiInternalVer
  2687  		} else if buildcfg.Experiment.RegabiWrappers && elf.ST_TYPE(elfsym.Info) == elf.STT_FUNC {
  2688  			// Demangle the ABI name. Keep in sync with symtab.go:mangleABIName.
  2689  			if strings.HasSuffix(elfsym.Name, ".abiinternal") {
  2690  				ver = sym.SymVerABIInternal
  2691  				symname = strings.TrimSuffix(elfsym.Name, ".abiinternal")
  2692  			} else if strings.HasSuffix(elfsym.Name, ".abi0") {
  2693  				ver = 0
  2694  				symname = strings.TrimSuffix(elfsym.Name, ".abi0")
  2695  			}
  2696  		}
  2697  
  2698  		l := ctxt.loader
  2699  		s := l.LookupOrCreateSym(symname, ver)
  2700  
  2701  		// Because loadlib above loads all .a files before loading
  2702  		// any shared libraries, any non-dynimport symbols we find
  2703  		// that duplicate symbols already loaded should be ignored
  2704  		// (the symbols from the .a files "win").
  2705  		if l.SymType(s) != 0 && l.SymType(s) != sym.SDYNIMPORT {
  2706  			continue
  2707  		}
  2708  		su := l.MakeSymbolUpdater(s)
  2709  		su.SetType(sym.SDYNIMPORT)
  2710  		l.SetSymElfType(s, elf.ST_TYPE(elfsym.Info))
  2711  		su.SetSize(int64(elfsym.Size))
  2712  		if elfsym.Section != elf.SHN_UNDEF {
  2713  			// Set .File for the library that actually defines the symbol.
  2714  			l.SetSymPkg(s, libpath)
  2715  
  2716  			// The decodetype_* functions in decodetype.go need access to
  2717  			// the type data.
  2718  			sname := l.SymName(s)
  2719  			if strings.HasPrefix(sname, "type:") && !strings.HasPrefix(sname, "type:.") {
  2720  				su.SetData(readelfsymboldata(ctxt, f, &elfsym))
  2721  			}
  2722  		}
  2723  
  2724  		if symname != elfsym.Name {
  2725  			l.SetSymExtname(s, elfsym.Name)
  2726  		}
  2727  		symAddr[elfsym.Name] = elfsym.Value
  2728  	}
  2729  
  2730  	// Load relocations.
  2731  	// We only really need these for grokking the links between type descriptors
  2732  	// when dynamic linking.
  2733  	relocTarget := map[uint64]string{}
  2734  	addends := false
  2735  	sect := f.SectionByType(elf.SHT_REL)
  2736  	if sect == nil {
  2737  		sect = f.SectionByType(elf.SHT_RELA)
  2738  		if sect == nil {
  2739  			log.Fatalf("can't find SHT_REL or SHT_RELA section of %s", shlib)
  2740  		}
  2741  		addends = true
  2742  	}
  2743  	// TODO: Multiple SHT_RELA/SHT_REL sections?
  2744  	data, err := sect.Data()
  2745  	if err != nil {
  2746  		log.Fatalf("can't read relocation section of %s: %v", shlib, err)
  2747  	}
  2748  	bo := f.ByteOrder
  2749  	for len(data) > 0 {
  2750  		var off, idx uint64
  2751  		var addend int64
  2752  		switch f.Class {
  2753  		case elf.ELFCLASS64:
  2754  			off = bo.Uint64(data)
  2755  			info := bo.Uint64(data[8:])
  2756  			data = data[16:]
  2757  			if addends {
  2758  				addend = int64(bo.Uint64(data))
  2759  				data = data[8:]
  2760  			}
  2761  
  2762  			idx = info >> 32
  2763  			typ := info & 0xffff
  2764  			// buildmode=shared is only supported for amd64,arm64,loong64,s390x,ppc64le.
  2765  			// (List found by looking at the translation of R_ADDR by ../$ARCH/asm.go:elfreloc1)
  2766  			switch typ {
  2767  			case uint64(elf.R_X86_64_64):
  2768  			case uint64(elf.R_AARCH64_ABS64):
  2769  			case uint64(elf.R_LARCH_64):
  2770  			case uint64(elf.R_390_64):
  2771  			case uint64(elf.R_PPC64_ADDR64):
  2772  			default:
  2773  				continue
  2774  			}
  2775  		case elf.ELFCLASS32:
  2776  			off = uint64(bo.Uint32(data))
  2777  			info := bo.Uint32(data[4:])
  2778  			data = data[8:]
  2779  			if addends {
  2780  				addend = int64(int32(bo.Uint32(data)))
  2781  				data = data[4:]
  2782  			}
  2783  
  2784  			idx = uint64(info >> 8)
  2785  			typ := info & 0xff
  2786  			// buildmode=shared is only supported for 386,arm.
  2787  			switch typ {
  2788  			case uint32(elf.R_386_32):
  2789  			case uint32(elf.R_ARM_ABS32):
  2790  			default:
  2791  				continue
  2792  			}
  2793  		default:
  2794  			log.Fatalf("unknown bit size %s", f.Class)
  2795  		}
  2796  		if addend != 0 {
  2797  			continue
  2798  		}
  2799  		relocTarget[off] = syms[idx-1].Name
  2800  	}
  2801  
  2802  	ctxt.Shlibs = append(ctxt.Shlibs, Shlib{Path: libpath, Hash: hash, Deps: deps, File: f, symAddr: symAddr, relocTarget: relocTarget})
  2803  }
  2804  
  2805  func addsection(ldr *loader.Loader, arch *sys.Arch, seg *sym.Segment, name string, rwx int) *sym.Section {
  2806  	sect := ldr.NewSection()
  2807  	sect.Rwx = uint8(rwx)
  2808  	sect.Name = name
  2809  	sect.Seg = seg
  2810  	sect.Align = int32(arch.PtrSize) // everything is at least pointer-aligned
  2811  	seg.Sections = append(seg.Sections, sect)
  2812  	return sect
  2813  }
  2814  
  2815  func usage() {
  2816  	fmt.Fprintf(os.Stderr, "usage: link [options] main.o\n")
  2817  	objabi.Flagprint(os.Stderr)
  2818  	Exit(2)
  2819  }
  2820  
  2821  type SymbolType int8 // TODO: after genasmsym is gone, maybe rename to plan9typeChar or something
  2822  
  2823  const (
  2824  	// see also https://9p.io/magic/man2html/1/nm
  2825  	TextSym      SymbolType = 'T'
  2826  	DataSym      SymbolType = 'D'
  2827  	BSSSym       SymbolType = 'B'
  2828  	UndefinedSym SymbolType = 'U'
  2829  	TLSSym       SymbolType = 't'
  2830  	FrameSym     SymbolType = 'm'
  2831  	ParamSym     SymbolType = 'p'
  2832  	AutoSym      SymbolType = 'a'
  2833  
  2834  	// Deleted auto (not a real sym, just placeholder for type)
  2835  	DeletedAutoSym = 'x'
  2836  )
  2837  
  2838  // defineInternal defines a symbol used internally by the go runtime.
  2839  func (ctxt *Link) defineInternal(p string, t sym.SymKind) loader.Sym {
  2840  	s := ctxt.loader.CreateSymForUpdate(p, 0)
  2841  	s.SetType(t)
  2842  	s.SetSpecial(true)
  2843  	s.SetLocal(true)
  2844  	return s.Sym()
  2845  }
  2846  
  2847  func (ctxt *Link) xdefine(p string, t sym.SymKind, v int64) loader.Sym {
  2848  	s := ctxt.defineInternal(p, t)
  2849  	ctxt.loader.SetSymValue(s, v)
  2850  	return s
  2851  }
  2852  
  2853  func datoff(ldr *loader.Loader, s loader.Sym, addr int64) int64 {
  2854  	if uint64(addr) >= Segdata.Vaddr {
  2855  		return int64(uint64(addr) - Segdata.Vaddr + Segdata.Fileoff)
  2856  	}
  2857  	if uint64(addr) >= Segtext.Vaddr {
  2858  		return int64(uint64(addr) - Segtext.Vaddr + Segtext.Fileoff)
  2859  	}
  2860  	ldr.Errorf(s, "invalid datoff %#x", addr)
  2861  	return 0
  2862  }
  2863  
  2864  func Entryvalue(ctxt *Link) int64 {
  2865  	a := *flagEntrySymbol
  2866  	if a[0] >= '0' && a[0] <= '9' {
  2867  		return atolwhex(a)
  2868  	}
  2869  	ldr := ctxt.loader
  2870  	s := ldr.Lookup(a, 0)
  2871  	if s == 0 {
  2872  		Errorf("missing entry symbol %q", a)
  2873  		return 0
  2874  	}
  2875  	st := ldr.SymType(s)
  2876  	if st == 0 {
  2877  		return *FlagTextAddr
  2878  	}
  2879  	if !ctxt.IsAIX() && !st.IsText() {
  2880  		ldr.Errorf(s, "entry not text")
  2881  	}
  2882  	return ldr.SymValue(s)
  2883  }
  2884  
  2885  func (ctxt *Link) callgraph() {
  2886  	if !*FlagC {
  2887  		return
  2888  	}
  2889  
  2890  	ldr := ctxt.loader
  2891  	for _, s := range ctxt.Textp {
  2892  		relocs := ldr.Relocs(s)
  2893  		for i := 0; i < relocs.Count(); i++ {
  2894  			r := relocs.At(i)
  2895  			rs := r.Sym()
  2896  			if rs == 0 {
  2897  				continue
  2898  			}
  2899  			if r.Type().IsDirectCall() && ldr.SymType(rs).IsText() {
  2900  				ctxt.Logf("%s calls %s\n", ldr.SymName(s), ldr.SymName(rs))
  2901  			}
  2902  		}
  2903  	}
  2904  }
  2905  
  2906  func Rnd(v int64, r int64) int64 {
  2907  	if r <= 0 {
  2908  		return v
  2909  	}
  2910  	v += r - 1
  2911  	c := v % r
  2912  	if c < 0 {
  2913  		c += r
  2914  	}
  2915  	v -= c
  2916  	return v
  2917  }
  2918  
  2919  func bgetc(r *bio.Reader) int {
  2920  	c, err := r.ReadByte()
  2921  	if err != nil {
  2922  		if err != io.EOF {
  2923  			log.Fatalf("reading input: %v", err)
  2924  		}
  2925  		return -1
  2926  	}
  2927  	return int(c)
  2928  }
  2929  
  2930  type markKind uint8 // for postorder traversal
  2931  const (
  2932  	_ markKind = iota
  2933  	visiting
  2934  	visited
  2935  )
  2936  
  2937  func postorder(libs []*sym.Library) []*sym.Library {
  2938  	order := make([]*sym.Library, 0, len(libs)) // hold the result
  2939  	mark := make(map[*sym.Library]markKind, len(libs))
  2940  	for _, lib := range libs {
  2941  		dfs(lib, mark, &order)
  2942  	}
  2943  	return order
  2944  }
  2945  
  2946  func dfs(lib *sym.Library, mark map[*sym.Library]markKind, order *[]*sym.Library) {
  2947  	if mark[lib] == visited {
  2948  		return
  2949  	}
  2950  	if mark[lib] == visiting {
  2951  		panic("found import cycle while visiting " + lib.Pkg)
  2952  	}
  2953  	mark[lib] = visiting
  2954  	for _, i := range lib.Imports {
  2955  		dfs(i, mark, order)
  2956  	}
  2957  	mark[lib] = visited
  2958  	*order = append(*order, lib)
  2959  }
  2960  
  2961  func ElfSymForReloc(ctxt *Link, s loader.Sym) int32 {
  2962  	// If putelfsym created a local version of this symbol, use that in all
  2963  	// relocations.
  2964  	les := ctxt.loader.SymLocalElfSym(s)
  2965  	if les != 0 {
  2966  		return les
  2967  	} else {
  2968  		return ctxt.loader.SymElfSym(s)
  2969  	}
  2970  }
  2971  
  2972  func AddGotSym(target *Target, ldr *loader.Loader, syms *ArchSyms, s loader.Sym, elfRelocTyp uint32) {
  2973  	if ldr.SymGot(s) >= 0 {
  2974  		return
  2975  	}
  2976  
  2977  	Adddynsym(ldr, target, syms, s)
  2978  	got := ldr.MakeSymbolUpdater(syms.GOT)
  2979  	ldr.SetGot(s, int32(got.Size()))
  2980  	got.AddUint(target.Arch, 0)
  2981  
  2982  	if target.IsElf() {
  2983  		if target.Arch.PtrSize == 8 {
  2984  			rela := ldr.MakeSymbolUpdater(syms.Rela)
  2985  			rela.AddAddrPlus(target.Arch, got.Sym(), int64(ldr.SymGot(s)))
  2986  			rela.AddUint64(target.Arch, elf.R_INFO(uint32(ldr.SymDynid(s)), elfRelocTyp))
  2987  			rela.AddUint64(target.Arch, 0)
  2988  		} else {
  2989  			rel := ldr.MakeSymbolUpdater(syms.Rel)
  2990  			rel.AddAddrPlus(target.Arch, got.Sym(), int64(ldr.SymGot(s)))
  2991  			rel.AddUint32(target.Arch, elf.R_INFO32(uint32(ldr.SymDynid(s)), elfRelocTyp))
  2992  		}
  2993  	} else if target.IsDarwin() {
  2994  		leg := ldr.MakeSymbolUpdater(syms.LinkEditGOT)
  2995  		leg.AddUint32(target.Arch, uint32(ldr.SymDynid(s)))
  2996  		if target.IsPIE() && target.IsInternal() {
  2997  			// Mach-O relocations are a royal pain to lay out.
  2998  			// They use a compact stateful bytecode representation.
  2999  			// Here we record what are needed and encode them later.
  3000  			MachoAddBind(int64(ldr.SymGot(s)), s)
  3001  		}
  3002  	} else {
  3003  		ldr.Errorf(s, "addgotsym: unsupported binary format")
  3004  	}
  3005  }
  3006  
  3007  var hostobjcounter int
  3008  
  3009  // captureHostObj writes out the content of a host object (pulled from
  3010  // an archive or loaded from a *.o file directly) to a directory
  3011  // specified via the linker's "-capturehostobjs" debugging flag. This
  3012  // is intended to make it easier for a developer to inspect the actual
  3013  // object feeding into "CGO internal" link step.
  3014  func captureHostObj(h *Hostobj) {
  3015  	// Form paths for info file and obj file.
  3016  	ofile := fmt.Sprintf("captured-obj-%d.o", hostobjcounter)
  3017  	ifile := fmt.Sprintf("captured-obj-%d.txt", hostobjcounter)
  3018  	hostobjcounter++
  3019  	opath := filepath.Join(*flagCaptureHostObjs, ofile)
  3020  	ipath := filepath.Join(*flagCaptureHostObjs, ifile)
  3021  
  3022  	// Write the info file.
  3023  	info := fmt.Sprintf("pkg: %s\npn: %s\nfile: %s\noff: %d\nlen: %d\n",
  3024  		h.pkg, h.pn, h.file, h.off, h.length)
  3025  	if err := os.WriteFile(ipath, []byte(info), 0666); err != nil {
  3026  		log.Fatalf("error writing captured host obj info %s: %v", ipath, err)
  3027  	}
  3028  
  3029  	readObjData := func() []byte {
  3030  		inf, err := os.Open(h.file)
  3031  		if err != nil {
  3032  			log.Fatalf("capturing host obj: open failed on %s: %v", h.pn, err)
  3033  		}
  3034  		defer inf.Close()
  3035  		res := make([]byte, h.length)
  3036  		if n, err := inf.ReadAt(res, h.off); err != nil || n != int(h.length) {
  3037  			log.Fatalf("capturing host obj: readat failed on %s: %v", h.pn, err)
  3038  		}
  3039  		return res
  3040  	}
  3041  
  3042  	// Write the object file.
  3043  	if err := os.WriteFile(opath, readObjData(), 0666); err != nil {
  3044  		log.Fatalf("error writing captured host object %s: %v", opath, err)
  3045  	}
  3046  
  3047  	fmt.Fprintf(os.Stderr, "link: info: captured host object %s to %s\n",
  3048  		h.file, opath)
  3049  }
  3050  
  3051  // findExtLinkTool invokes the external linker CC with --print-prog-name
  3052  // passing the name of the tool we're interested in, such as "strip",
  3053  // "ar", or "dsymutil", and returns the path passed back from the command.
  3054  func (ctxt *Link) findExtLinkTool(toolname string) string {
  3055  	var cc []string
  3056  	cc = append(cc, ctxt.extld()...)
  3057  	cc = append(cc, hostlinkArchArgs(ctxt.Arch)...)
  3058  	cc = append(cc, "--print-prog-name", toolname)
  3059  	out, err := exec.Command(cc[0], cc[1:]...).CombinedOutput()
  3060  	if err != nil {
  3061  		Exitf("%s: finding %s failed: %v\n%s", os.Args[0], toolname, err, out)
  3062  	}
  3063  	cmdpath := strings.TrimRight(string(out), "\r\n")
  3064  	return cmdpath
  3065  }
  3066  
  3067  // isMSVC reports whether the C toolchain is clang with a -msvc target,
  3068  // e.g. the clang bundled in MSVC.
  3069  func (ctxt *Link) isMSVC() bool {
  3070  	extld := ctxt.extld()
  3071  	name, args := extld[0], extld[1:]
  3072  	args = append(args, trimLinkerArgv(flagExtldflags)...)
  3073  	args = append(args, "--version")
  3074  	cmd := exec.Command(name, args...)
  3075  	if out, err := cmd.CombinedOutput(); err == nil {
  3076  		if bytes.Contains(out, []byte("-msvc\n")) || bytes.Contains(out, []byte("-msvc\r")) {
  3077  			return true
  3078  		}
  3079  	}
  3080  	return false
  3081  }
  3082  

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