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matterbridge/vendor/github.com/google/gops/internal/objfile/macho.go

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2017-03-23 22:28:55 +00:00
// Copyright 2013 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 Mach-O executables (OS X).
package objfile
import (
"debug/dwarf"
"debug/macho"
"fmt"
"os"
"sort"
)
const stabTypeMask = 0xe0
type machoFile struct {
macho *macho.File
}
func openMacho(r *os.File) (rawFile, error) {
f, err := macho.NewFile(r)
if err != nil {
return nil, err
}
return &machoFile{f}, nil
}
func (f *machoFile) symbols() ([]Sym, error) {
if f.macho.Symtab == nil {
return nil, fmt.Errorf("missing symbol table")
}
// 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 f.macho.Symtab.Syms {
// Skip stab debug info.
if s.Type&stabTypeMask == 0 {
addrs = append(addrs, s.Value)
}
}
sort.Sort(uint64s(addrs))
var syms []Sym
for _, s := range f.macho.Symtab.Syms {
if s.Type&stabTypeMask != 0 {
// Skip stab debug info.
continue
}
sym := Sym{Name: s.Name, Addr: s.Value, Code: '?'}
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)
}
if s.Sect == 0 {
sym.Code = 'U'
} else if int(s.Sect) <= len(f.macho.Sections) {
sect := f.macho.Sections[s.Sect-1]
switch sect.Seg {
case "__TEXT":
sym.Code = 'R'
case "__DATA":
sym.Code = 'D'
}
switch sect.Seg + " " + sect.Name {
case "__TEXT __text":
sym.Code = 'T'
case "__DATA __bss", "__DATA __noptrbss":
sym.Code = 'B'
}
}
syms = append(syms, sym)
}
return syms, nil
}
func (f *machoFile) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
if sect := f.macho.Section("__text"); sect != nil {
textStart = sect.Addr
}
if sect := f.macho.Section("__gosymtab"); sect != nil {
if symtab, err = sect.Data(); err != nil {
return 0, nil, nil, err
}
}
if sect := f.macho.Section("__gopclntab"); sect != nil {
if pclntab, err = sect.Data(); err != nil {
return 0, nil, nil, err
}
}
return textStart, symtab, pclntab, nil
}
func (f *machoFile) text() (textStart uint64, text []byte, err error) {
sect := f.macho.Section("__text")
if sect == nil {
return 0, nil, fmt.Errorf("text section not found")
}
textStart = sect.Addr
text, err = sect.Data()
return
}
func (f *machoFile) goarch() string {
switch f.macho.Cpu {
case macho.Cpu386:
return "386"
case macho.CpuAmd64:
return "amd64"
case macho.CpuArm:
return "arm"
case macho.CpuPpc64:
return "ppc64"
}
return ""
}
type uint64s []uint64
func (x uint64s) Len() int { return len(x) }
func (x uint64s) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x uint64s) Less(i, j int) bool { return x[i] < x[j] }
func (f *machoFile) loadAddress() (uint64, error) {
return 0, fmt.Errorf("unknown load address")
}
func (f *machoFile) dwarf() (*dwarf.Data, error) {
return f.macho.DWARF()
}