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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.
// Parsing of Plan 9 a.out executables.
package objfile
import (
"debug/plan9obj"
"fmt"
"os"
"sort"
)
var validSymType = map[rune]bool{
'T': true,
't': true,
'D': true,
'd': true,
'B': true,
'b': true,
}
type plan9File struct {
plan9 *plan9obj.File
}
func openPlan9(r *os.File) (rawFile, error) {
f, err := plan9obj.NewFile(r)
if err != nil {
return nil, err
}
return &plan9File{f}, nil
}
func (f *plan9File) symbols() ([]Sym, error) {
plan9Syms, err := f.plan9.Symbols()
if err != nil {
return nil, err
}
// Build sorted list of addresses of all symbols.
// We infer the size of a symbol by looking at where the next symbol begins.
var addrs []uint64
for _, s := range plan9Syms {
if !validSymType[s.Type] {
continue
}
addrs = append(addrs, s.Value)
}
sort.Sort(uint64s(addrs))
var syms []Sym
for _, s := range plan9Syms {
if !validSymType[s.Type] {
continue
}
sym := Sym{Addr: s.Value, Name: s.Name, Code: rune(s.Type)}
i := sort.Search(len(addrs), func(x int) bool { return addrs[x] > s.Value })
if i < len(addrs) {
sym.Size = int64(addrs[i] - s.Value)
}
syms = append(syms, sym)
}
return syms, nil
}
func (f *plan9File) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
textStart = f.plan9.LoadAddress + f.plan9.HdrSize
if pclntab, err = loadPlan9Table(f.plan9, "runtime.pclntab", "runtime.epclntab"); err != nil {
// We didn't find the symbols, so look for the names used in 1.3 and earlier.
// TODO: Remove code looking for the old symbols when we no longer care about 1.3.
var err2 error
if pclntab, err2 = loadPlan9Table(f.plan9, "pclntab", "epclntab"); err2 != nil {
return 0, nil, nil, err
}
}
if symtab, err = loadPlan9Table(f.plan9, "runtime.symtab", "runtime.esymtab"); err != nil {
// Same as above.
var err2 error
if symtab, err2 = loadPlan9Table(f.plan9, "symtab", "esymtab"); err2 != nil {
return 0, nil, nil, err
}
}
return textStart, symtab, pclntab, nil
}
func findPlan9Symbol(f *plan9obj.File, name string) (*plan9obj.Sym, error) {
syms, err := f.Symbols()
if err != nil {
return nil, err
}
for _, s := range syms {
if s.Name != name {
continue
}
return &s, nil
}
return nil, fmt.Errorf("no %s symbol found", name)
}
func loadPlan9Table(f *plan9obj.File, sname, ename string) ([]byte, error) {
ssym, err := findPlan9Symbol(f, sname)
if err != nil {
return nil, err
}
esym, err := findPlan9Symbol(f, ename)
if err != nil {
return nil, err
}
sect := f.Section("text")
if sect == nil {
return nil, err
}
data, err := sect.Data()
if err != nil {
return nil, err
}
textStart := f.LoadAddress + f.HdrSize
return data[ssym.Value-textStart : esym.Value-textStart], nil
}
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