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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Initial scan of packages making up a program.
// TODO(rsc): Rename goobj.SymID.Version to StaticID to avoid confusion with the ELF meaning of version.
// TODO(rsc): Fix file format so that SBSS/SNOPTRBSS with data is listed as SDATA/SNOPTRDATA.
// TODO(rsc): Parallelize scan to overlap file i/o where possible.
package main
import (
"cmd/internal/goobj"
"os"
"sort"
"strings"
)
// scan scans all packages making up the program, starting with package main defined in mainfile.
func (p *Prog) scan(mainfile string) {
p.initScan()
p.scanFile("main", mainfile)
if len(p.Missing) > 0 && !p.omitRuntime {
p.scanImport("runtime")
}
var missing []string
for sym := range p.Missing {
if !p.isAuto(sym) {
missing = append(missing, sym.String())
}
}
if missing != nil {
sort.Strings(missing)
for _, sym := range missing {
p.errorf("undefined: %s", sym)
}
}
// TODO(rsc): Walk import graph to diagnose cycles.
}
// initScan initializes the Prog fields needed by scan.
func (p *Prog) initScan() {
p.Packages = make(map[string]*Package)
p.Syms = make(map[goobj.SymID]*Sym)
p.Missing = make(map[goobj.SymID]bool)
p.Missing[p.startSym] = true
}
// scanFile reads file to learn about the package with the given import path.
func (p *Prog) scanFile(pkgpath string, file string) {
pkg := &Package{
File: file,
}
p.Packages[pkgpath] = pkg
f, err := os.Open(file)
if err != nil {
p.errorf("%v", err)
return
}
gp, err := goobj.Parse(f, pkgpath)
f.Close()
if err != nil {
p.errorf("reading %s: %v", file, err)
return
}
// TODO(rsc): Change cmd/internal/goobj to record package name as gp.Name.
// TODO(rsc): If pkgpath == "main", check that gp.Name == "main".
pkg.Package = gp
for _, gs := range gp.Syms {
// TODO(rsc): Fix file format instead of this workaround.
if gs.Data.Size > 0 {
switch gs.Kind {
case goobj.SBSS:
gs.Kind = goobj.SDATA
case goobj.SNOPTRBSS:
gs.Kind = goobj.SNOPTRDATA
}
}
if gs.Version != 0 {
gs.Version += p.MaxVersion
}
for i := range gs.Reloc {
r := &gs.Reloc[i]
if r.Sym.Version != 0 {
r.Sym.Version += p.MaxVersion
}
if p.Syms[r.Sym] == nil {
p.Missing[r.Sym] = true
}
}
if gs.Func != nil {
for i := range gs.Func.FuncData {
fdata := &gs.Func.FuncData[i]
if fdata.Sym.Name != "" {
if fdata.Sym.Version != 0 {
fdata.Sym.Version += p.MaxVersion
}
if p.Syms[fdata.Sym] == nil {
p.Missing[fdata.Sym] = true
}
}
}
}
if old := p.Syms[gs.SymID]; old != nil {
// Duplicate definition of symbol. Is it okay?
// TODO(rsc): Write test for this code.
switch {
// If both symbols are BSS (no data), take max of sizes
// but otherwise ignore second symbol.
case old.Data.Size == 0 && gs.Data.Size == 0:
if old.Size < gs.Size {
old.Size = gs.Size
}
continue
// If one is in BSS and one is not, use the one that is not.
case old.Data.Size > 0 && gs.Data.Size == 0:
continue
case gs.Data.Size > 0 && old.Data.Size == 0:
break // install gs as new symbol below
// If either is marked as DupOK, we can keep either one.
// Keep the one that we saw first.
case old.DupOK || gs.DupOK:
continue
// Otherwise, there's an actual conflict:
default:
p.errorf("symbol %s defined in both %s and %s %v %v", gs.SymID, old.Package.File, file, old.Data, gs.Data)
continue
}
}
s := &Sym{
Sym: gs,
Package: pkg,
}
p.addSym(s)
delete(p.Missing, gs.SymID)
if s.Data.Size > int64(s.Size) {
p.errorf("%s: initialized data larger than symbol (%d > %d)", s, s.Data.Size, s.Size)
}
}
p.MaxVersion += pkg.MaxVersion
for i, pkgpath := range pkg.Imports {
// TODO(rsc): Fix file format to drop .a from recorded import path.
pkgpath = strings.TrimSuffix(pkgpath, ".a")
pkg.Imports[i] = pkgpath
p.scanImport(pkgpath)
}
}
func (p *Prog) addSym(s *Sym) {
pkg := s.Package
if pkg == nil {
pkg = p.Packages[""]
if pkg == nil {
pkg = &Package{}
p.Packages[""] = pkg
}
s.Package = pkg
}
pkg.Syms = append(pkg.Syms, s)
p.Syms[s.SymID] = s
p.SymOrder = append(p.SymOrder, s)
}
// scanImport finds the object file for the given import path and then scans it.
func (p *Prog) scanImport(pkgpath string) {
if p.Packages[pkgpath] != nil {
return // already loaded
}
// TODO(rsc): Implement correct search to find file.
p.scanFile(pkgpath, p.pkgdir+"/"+pkgpath+".a")
}
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