go/src/cmd/link/internal/ld/ld.go

// Derived from Inferno utils/6l/obj.c and utils/6l/span.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/span.c
//
//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
//	Portions Copyright © 1997-1999 Vita Nuova Limited
//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
//	Portions Copyright © 2004,2006 Bruce Ellis
//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
//	Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package ld

import (
	"log"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"

	"cmd/internal/goobj"
	"cmd/link/internal/loader"
	"cmd/link/internal/sym"
)

func (ctxt *Link) readImportCfg(file string) {
	ctxt.PackageFile = make(map[string]string)
	ctxt.PackageShlib = make(map[string]string)
	data, err := os.ReadFile(file)
	if err != nil {
		log.Fatalf("-importcfg: %v", err)
	}

	for lineNum, line := range strings.Split(string(data), "\n") {
		lineNum++ // 1-based
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		verb, args, found := strings.Cut(line, " ")
		if found {
			args = strings.TrimSpace(args)
		}
		before, after, exist := strings.Cut(args, "=")
		if !exist {
			before = ""
		}
		switch verb {
		default:
			log.Fatalf("%s:%d: unknown directive %q", file, lineNum, verb)
		case "packagefile":
			if before == "" || after == "" {
				log.Fatalf(`%s:%d: invalid packagefile: syntax is "packagefile path=filename"`, file, lineNum)
			}
			ctxt.PackageFile[before] = after
		case "packageshlib":
			if before == "" || after == "" {
				log.Fatalf(`%s:%d: invalid packageshlib: syntax is "packageshlib path=filename"`, file, lineNum)
			}
			ctxt.PackageShlib[before] = after
		case "modinfo":
			s, err := strconv.Unquote(args)
			if err != nil {
				log.Fatalf("%s:%d: invalid modinfo: %v", file, lineNum, err)
			}
			addstrdata1(ctxt, "runtime.modinfo="+s)
		}
	}
}

func pkgname(ctxt *Link, lib string) string {
	return path.Clean(lib)
}

func findlib(ctxt *Link, lib string) (string, bool) {
	name := path.Clean(lib)

	var pname string
	isshlib := false

	if ctxt.linkShared && ctxt.PackageShlib[name] != "" {
		pname = ctxt.PackageShlib[name]
		isshlib = true
	} else if ctxt.PackageFile != nil {
		pname = ctxt.PackageFile[name]
		if pname == "" {
			ctxt.Logf("cannot find package %s (using -importcfg)\n", name)
			return "", false
		}
	} else {
		pkg := pkgname(ctxt, lib)

		// search -L "libdir" directories
		for _, dir := range ctxt.Libdir {
			if ctxt.linkShared {
				pname = filepath.Join(dir, pkg+".shlibname")
				if _, err := os.Stat(pname); err == nil {
					isshlib = true
					break
				}
			}
			pname = filepath.Join(dir, name+".a")
			if _, err := os.Stat(pname); err == nil {
				break
			}
			pname = filepath.Join(dir, name+".o")
			if _, err := os.Stat(pname); err == nil {
				break
			}
		}
		pname = filepath.Clean(pname)
	}

	return pname, isshlib
}

func addlib(ctxt *Link, src, obj, lib string, fingerprint goobj.FingerprintType) *sym.Library {
	pkg := pkgname(ctxt, lib)

	// already loaded?
	if l := ctxt.LibraryByPkg[pkg]; l != nil && !l.Fingerprint.IsZero() {
		// Normally, packages are loaded in dependency order, and if l != nil
		// l is already loaded with the actual fingerprint. In shared build mode,
		// however, packages may be added not in dependency order, and it is
		// possible that l's fingerprint is not yet loaded -- exclude it in
		// checking.
		checkFingerprint(l, l.Fingerprint, src, fingerprint)
		return l
	}

	pname, isshlib := findlib(ctxt, lib)

	if ctxt.Debugvlog > 1 {
		ctxt.Logf("addlib: %s %s pulls in %s isshlib %v\n", obj, src, pname, isshlib)
	}

	if isshlib {
		return addlibpath(ctxt, src, obj, "", pkg, pname, fingerprint)
	}
	return addlibpath(ctxt, src, obj, pname, pkg, "", fingerprint)
}

/*
 * add library to library list, return added library.
 *	srcref: src file referring to package
 *	objref: object file referring to package
 *	file: object file, e.g., /home/rsc/go/pkg/container/vector.a
 *	pkg: package import path, e.g. container/vector
 *	shlib: path to shared library, or .shlibname file holding path
 *	fingerprint: if not 0, expected fingerprint for import from srcref
 *	             fingerprint is 0 if the library is not imported (e.g. main)
 */
func addlibpath(ctxt *Link, srcref, objref, file, pkg, shlib string, fingerprint goobj.FingerprintType) *sym.Library {
	if l := ctxt.LibraryByPkg[pkg]; l != nil {
		return l
	}

	if ctxt.Debugvlog > 1 {
		ctxt.Logf("addlibpath: srcref: %s objref: %s file: %s pkg: %s shlib: %s fingerprint: %x\n", srcref, objref, file, pkg, shlib, fingerprint)
	}

	l := &sym.Library{}
	ctxt.LibraryByPkg[pkg] = l
	ctxt.Library = append(ctxt.Library, l)
	l.Objref = objref
	l.Srcref = srcref
	l.File = file
	l.Pkg = pkg
	l.Fingerprint = fingerprint
	if shlib != "" {
		if strings.HasSuffix(shlib, ".shlibname") {
			data, err := os.ReadFile(shlib)
			if err != nil {
				Errorf("cannot read %s: %v", shlib, err)
			}
			shlib = strings.TrimSpace(string(data))
		}
		l.Shlib = shlib
	}
	return l
}

func atolwhex(s string) int64 {
	n, _ := strconv.ParseInt(s, 0, 64)
	return n
}

// PrepareAddmoduledata returns a symbol builder that target-specific
// code can use to build up the linker-generated go.link.addmoduledata
// function, along with the sym for runtime.addmoduledata itself. If
// this function is not needed (for example in cases where we're
// linking a module that contains the runtime) the returned builder
// will be nil.
func PrepareAddmoduledata(ctxt *Link) (*loader.SymbolBuilder, loader.Sym) {
	if !ctxt.DynlinkingGo() {
		return nil, 0
	}
	amd := ctxt.loader.LookupOrCreateSym("runtime.addmoduledata", 0)
	if ctxt.loader.SymType(amd).IsText() && ctxt.BuildMode != BuildModePlugin {
		// we're linking a module containing the runtime -> no need for
		// an init function
		return nil, 0
	}
	ctxt.loader.SetAttrReachable(amd, true)

	// Create a new init func text symbol. Caller will populate this
	// sym with arch-specific content.
	ifs := ctxt.loader.LookupOrCreateSym("go:link.addmoduledata", 0)
	initfunc := ctxt.loader.MakeSymbolUpdater(ifs)
	ctxt.loader.SetAttrReachable(ifs, true)
	ctxt.loader.SetAttrLocal(ifs, true)
	initfunc.SetType(sym.STEXT)

	// Add the init func and/or addmoduledata to Textp.
	if ctxt.BuildMode == BuildModePlugin {
		ctxt.Textp = append(ctxt.Textp, amd)
	}
	ctxt.Textp = append(ctxt.Textp, initfunc.Sym())

	// Create an init array entry
	amdi := ctxt.loader.LookupOrCreateSym("go:link.addmoduledatainit", 0)
	initarray_entry := ctxt.loader.MakeSymbolUpdater(amdi)
	ctxt.loader.SetAttrReachable(amdi, true)
	ctxt.loader.SetAttrLocal(amdi, true)
	initarray_entry.SetType(sym.SINITARR)
	initarray_entry.AddAddr(ctxt.Arch, ifs)

	return initfunc, amd
}