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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.
// Package objfile implements portable access to OS-specific executable files.
package objfile
import (
"cmd/internal/archive"
"debug/dwarf"
"debug/gosym"
"fmt"
"io"
"os"
"sort"
)
type rawFile interface {
symbols() (syms []Sym, err error)
pcln() (textStart uint64, symtab, pclntab []byte, err error)
text() (textStart uint64, text []byte, err error)
goarch() string
loadAddress() (uint64, error)
dwarf() (*dwarf.Data, error)
}
// A File is an opened executable file.
type File struct {
r *os.File
entries []*Entry
}
type Entry struct {
name string
raw rawFile
}
// A Sym is a symbol defined in an executable file.
type Sym struct {
Name string // symbol name
Addr uint64 // virtual address of symbol
Size int64 // size in bytes
Code rune // nm code (T for text, D for data, and so on)
Type string // XXX?
Relocs []Reloc // in increasing Addr order
}
type Reloc struct {
Addr uint64 // Address of first byte that reloc applies to.
Size uint64 // Number of bytes
Stringer RelocStringer
}
type RelocStringer interface {
// insnOffset is the offset of the instruction containing the relocation
// from the start of the symbol containing the relocation.
String(insnOffset uint64) string
}
var openers = []func(io.ReaderAt) (rawFile, error){
openElf,
openMacho,
openPE,
openPlan9,
openXcoff,
}
// Open opens the named file.
// The caller must call f.Close when the file is no longer needed.
func Open(name string) (*File, error) {
r, err := os.Open(name)
if err != nil {
return nil, err
}
if f, err := openGoFile(r); err == nil {
return f, nil
} else if _, ok := err.(archive.ErrGoObjOtherVersion); ok {
return nil, fmt.Errorf("open %s: %v", name, err)
}
for _, try := range openers {
if raw, err := try(r); err == nil {
return &File{r, []*Entry{{raw: raw}}}, nil
}
}
r.Close()
return nil, fmt.Errorf("open %s: unrecognized object file", name)
}
func (f *File) Close() error {
return f.r.Close()
}
func (f *File) Entries() []*Entry {
return f.entries
}
func (f *File) Symbols() ([]Sym, error) {
return f.entries[0].Symbols()
}
func (f *File) PCLineTable() (Liner, error) {
return f.entries[0].PCLineTable()
}
func (f *File) Text() (uint64, []byte, error) {
return f.entries[0].Text()
}
func (f *File) GOARCH() string {
return f.entries[0].GOARCH()
}
func (f *File) LoadAddress() (uint64, error) {
return f.entries[0].LoadAddress()
}
func (f *File) DWARF() (*dwarf.Data, error) {
return f.entries[0].DWARF()
}
func (f *File) Disasm() (*Disasm, error) {
return f.entries[0].Disasm()
}
func (e *Entry) Name() string {
return e.name
}
func (e *Entry) Symbols() ([]Sym, error) {
syms, err := e.raw.symbols()
if err != nil {
return nil, err
}
sort.Sort(byAddr(syms))
return syms, nil
}
type byAddr []Sym
func (x byAddr) Less(i, j int) bool { return x[i].Addr < x[j].Addr }
func (x byAddr) Len() int { return len(x) }
func (x byAddr) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (e *Entry) PCLineTable() (Liner, error) {
// If the raw file implements Liner directly, use that.
// Currently, only Go intermediate objects and archives (goobj) use this path.
if pcln, ok := e.raw.(Liner); ok {
return pcln, nil
}
// Otherwise, read the pcln tables and build a Liner out of that.
textStart, symtab, pclntab, err := e.raw.pcln()
if err != nil {
return nil, err
}
syms, err := e.raw.symbols()
if err == nil {
for _, s := range syms {
if s.Name == "runtime.text" {
textStart = s.Addr
break
}
}
}
return gosym.NewTable(symtab, gosym.NewLineTable(pclntab, textStart))
}
func (e *Entry) Text() (uint64, []byte, error) {
return e.raw.text()
}
func (e *Entry) GOARCH() string {
return e.raw.goarch()
}
// LoadAddress returns the expected load address of the file.
// This differs from the actual load address for a position-independent
// executable.
func (e *Entry) LoadAddress() (uint64, error) {
return e.raw.loadAddress()
}
// DWARF returns DWARF debug data for the file, if any.
// This is for cmd/pprof to locate cgo functions.
func (e *Entry) DWARF() (*dwarf.Data, error) {
return e.raw.dwarf()
}
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