ld.go

Documentation: cmd/link/internal/ld

     1  // Derived from Inferno utils/6l/obj.c and utils/6l/span.c
     2  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c
     3  // https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/span.c
     4  //
     5  //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     6  //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
     7  //	Portions Copyright © 1997-1999 Vita Nuova Limited
     8  //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
     9  //	Portions Copyright © 2004,2006 Bruce Ellis
    10  //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
    11  //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
    12  //	Portions Copyright © 2009 The Go Authors. All rights reserved.
    13  //
    14  // Permission is hereby granted, free of charge, to any person obtaining a copy
    15  // of this software and associated documentation files (the "Software"), to deal
    16  // in the Software without restriction, including without limitation the rights
    17  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    18  // copies of the Software, and to permit persons to whom the Software is
    19  // furnished to do so, subject to the following conditions:
    20  //
    21  // The above copyright notice and this permission notice shall be included in
    22  // all copies or substantial portions of the Software.
    23  //
    24  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    25  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    26  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    27  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    28  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    29  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    30  // THE SOFTWARE.
    31  
    32  package ld
    33  
    34  import (
    35  	"log"
    36  	"os"
    37  	"path"
    38  	"path/filepath"
    39  	"strconv"
    40  	"strings"
    41  
    42  	"cmd/internal/goobj"
    43  	"cmd/link/internal/loader"
    44  	"cmd/link/internal/sym"
    45  )
    46  
    47  func (ctxt *Link) readImportCfg(file string) {
    48  	ctxt.PackageFile = make(map[string]string)
    49  	ctxt.PackageShlib = make(map[string]string)
    50  	data, err := os.ReadFile(file)
    51  	if err != nil {
    52  		log.Fatalf("-importcfg: %v", err)
    53  	}
    54  
    55  	for lineNum, line := range strings.Split(string(data), "\n") {
    56  		lineNum++ // 1-based
    57  		line = strings.TrimSpace(line)
    58  		if line == "" {
    59  			continue
    60  		}
    61  		if line == "" || strings.HasPrefix(line, "#") {
    62  			continue
    63  		}
    64  
    65  		verb, args, found := strings.Cut(line, " ")
    66  		if found {
    67  			args = strings.TrimSpace(args)
    68  		}
    69  		before, after, exist := strings.Cut(args, "=")
    70  		if !exist {
    71  			before = ""
    72  		}
    73  		switch verb {
    74  		default:
    75  			log.Fatalf("%s:%d: unknown directive %q", file, lineNum, verb)
    76  		case "packagefile":
    77  			if before == "" || after == "" {
    78  				log.Fatalf(`%s:%d: invalid packagefile: syntax is "packagefile path=filename"`, file, lineNum)
    79  			}
    80  			ctxt.PackageFile[before] = after
    81  		case "packageshlib":
    82  			if before == "" || after == "" {
    83  				log.Fatalf(`%s:%d: invalid packageshlib: syntax is "packageshlib path=filename"`, file, lineNum)
    84  			}
    85  			ctxt.PackageShlib[before] = after
    86  		case "modinfo":
    87  			s, err := strconv.Unquote(args)
    88  			if err != nil {
    89  				log.Fatalf("%s:%d: invalid modinfo: %v", file, lineNum, err)
    90  			}
    91  			addstrdata1(ctxt, "runtime.modinfo="+s)
    92  		}
    93  	}
    94  }
    95  
    96  func pkgname(ctxt *Link, lib string) string {
    97  	return path.Clean(lib)
    98  }
    99  
   100  func findlib(ctxt *Link, lib string) (string, bool) {
   101  	name := path.Clean(lib)
   102  
   103  	var pname string
   104  	isshlib := false
   105  
   106  	if ctxt.linkShared && ctxt.PackageShlib[name] != "" {
   107  		pname = ctxt.PackageShlib[name]
   108  		isshlib = true
   109  	} else if ctxt.PackageFile != nil {
   110  		pname = ctxt.PackageFile[name]
   111  		if pname == "" {
   112  			ctxt.Logf("cannot find package %s (using -importcfg)\n", name)
   113  			return "", false
   114  		}
   115  	} else {
   116  		pkg := pkgname(ctxt, lib)
   117  
   118  		// search -L "libdir" directories
   119  		for _, dir := range ctxt.Libdir {
   120  			if ctxt.linkShared {
   121  				pname = filepath.Join(dir, pkg+".shlibname")
   122  				if _, err := os.Stat(pname); err == nil {
   123  					isshlib = true
   124  					break
   125  				}
   126  			}
   127  			pname = filepath.Join(dir, name+".a")
   128  			if _, err := os.Stat(pname); err == nil {
   129  				break
   130  			}
   131  			pname = filepath.Join(dir, name+".o")
   132  			if _, err := os.Stat(pname); err == nil {
   133  				break
   134  			}
   135  		}
   136  		pname = filepath.Clean(pname)
   137  	}
   138  
   139  	return pname, isshlib
   140  }
   141  
   142  func addlib(ctxt *Link, src, obj, lib string, fingerprint goobj.FingerprintType) *sym.Library {
   143  	pkg := pkgname(ctxt, lib)
   144  
   145  	// already loaded?
   146  	if l := ctxt.LibraryByPkg[pkg]; l != nil && !l.Fingerprint.IsZero() {
   147  		// Normally, packages are loaded in dependency order, and if l != nil
   148  		// l is already loaded with the actual fingerprint. In shared build mode,
   149  		// however, packages may be added not in dependency order, and it is
   150  		// possible that l's fingerprint is not yet loaded -- exclude it in
   151  		// checking.
   152  		checkFingerprint(l, l.Fingerprint, src, fingerprint)
   153  		return l
   154  	}
   155  
   156  	pname, isshlib := findlib(ctxt, lib)
   157  
   158  	if ctxt.Debugvlog > 1 {
   159  		ctxt.Logf("addlib: %s %s pulls in %s isshlib %v\n", obj, src, pname, isshlib)
   160  	}
   161  
   162  	if isshlib {
   163  		return addlibpath(ctxt, src, obj, "", pkg, pname, fingerprint)
   164  	}
   165  	return addlibpath(ctxt, src, obj, pname, pkg, "", fingerprint)
   166  }
   167  
   168  /*
   169   * add library to library list, return added library.
   170   *	srcref: src file referring to package
   171   *	objref: object file referring to package
   172   *	file: object file, e.g., /home/rsc/go/pkg/container/vector.a
   173   *	pkg: package import path, e.g. container/vector
   174   *	shlib: path to shared library, or .shlibname file holding path
   175   *	fingerprint: if not 0, expected fingerprint for import from srcref
   176   *	             fingerprint is 0 if the library is not imported (e.g. main)
   177   */
   178  func addlibpath(ctxt *Link, srcref, objref, file, pkg, shlib string, fingerprint goobj.FingerprintType) *sym.Library {
   179  	if l := ctxt.LibraryByPkg[pkg]; l != nil {
   180  		return l
   181  	}
   182  
   183  	if ctxt.Debugvlog > 1 {
   184  		ctxt.Logf("addlibpath: srcref: %s objref: %s file: %s pkg: %s shlib: %s fingerprint: %x\n", srcref, objref, file, pkg, shlib, fingerprint)
   185  	}
   186  
   187  	l := &sym.Library{}
   188  	ctxt.LibraryByPkg[pkg] = l
   189  	ctxt.Library = append(ctxt.Library, l)
   190  	l.Objref = objref
   191  	l.Srcref = srcref
   192  	l.File = file
   193  	l.Pkg = pkg
   194  	l.Fingerprint = fingerprint
   195  	if shlib != "" {
   196  		if strings.HasSuffix(shlib, ".shlibname") {
   197  			data, err := os.ReadFile(shlib)
   198  			if err != nil {
   199  				Errorf(nil, "cannot read %s: %v", shlib, err)
   200  			}
   201  			shlib = strings.TrimSpace(string(data))
   202  		}
   203  		l.Shlib = shlib
   204  	}
   205  	return l
   206  }
   207  
   208  func atolwhex(s string) int64 {
   209  	n, _ := strconv.ParseInt(s, 0, 64)
   210  	return n
   211  }
   212  
   213  // PrepareAddmoduledata returns a symbol builder that target-specific
   214  // code can use to build up the linker-generated go.link.addmoduledata
   215  // function, along with the sym for runtime.addmoduledata itself. If
   216  // this function is not needed (for example in cases where we're
   217  // linking a module that contains the runtime) the returned builder
   218  // will be nil.
   219  func PrepareAddmoduledata(ctxt *Link) (*loader.SymbolBuilder, loader.Sym) {
   220  	if !ctxt.DynlinkingGo() {
   221  		return nil, 0
   222  	}
   223  	amd := ctxt.loader.LookupOrCreateSym("runtime.addmoduledata", 0)
   224  	if ctxt.loader.SymType(amd) == sym.STEXT && ctxt.BuildMode != BuildModePlugin {
   225  		// we're linking a module containing the runtime -> no need for
   226  		// an init function
   227  		return nil, 0
   228  	}
   229  	ctxt.loader.SetAttrReachable(amd, true)
   230  
   231  	// Create a new init func text symbol. Caller will populate this
   232  	// sym with arch-specific content.
   233  	ifs := ctxt.loader.LookupOrCreateSym("go:link.addmoduledata", 0)
   234  	initfunc := ctxt.loader.MakeSymbolUpdater(ifs)
   235  	ctxt.loader.SetAttrReachable(ifs, true)
   236  	ctxt.loader.SetAttrLocal(ifs, true)
   237  	initfunc.SetType(sym.STEXT)
   238  
   239  	// Add the init func and/or addmoduledata to Textp.
   240  	if ctxt.BuildMode == BuildModePlugin {
   241  		ctxt.Textp = append(ctxt.Textp, amd)
   242  	}
   243  	ctxt.Textp = append(ctxt.Textp, initfunc.Sym())
   244  
   245  	// Create an init array entry
   246  	amdi := ctxt.loader.LookupOrCreateSym("go:link.addmoduledatainit", 0)
   247  	initarray_entry := ctxt.loader.MakeSymbolUpdater(amdi)
   248  	ctxt.loader.SetAttrReachable(amdi, true)
   249  	ctxt.loader.SetAttrLocal(amdi, true)
   250  	initarray_entry.SetType(sym.SINITARR)
   251  	initarray_entry.AddAddr(ctxt.Arch, ifs)
   252  
   253  	return initfunc, amd
   254  }
   255
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