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macho.go
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macho.go
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// This file is part of GoRE.
//
// Copyright (C) 2019-2024 GoRE Authors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package gore
import (
"bytes"
"cmp"
"compress/zlib"
"debug/dwarf"
"encoding/binary"
"fmt"
"io"
"slices"
"strings"
"sync"
"github.com/blacktop/go-macho"
"github.com/blacktop/go-macho/types"
)
func openMachO(r io.ReaderAt) (*machoFile, error) {
f, err := macho.NewFile(r)
if err != nil {
return nil, fmt.Errorf("error when parsing the Mach-O file: %w", err)
}
ret := &machoFile{file: f, reader: r}
ret.getsymtab = sync.OnceValue(ret.initSymtab)
return ret, nil
}
var _ fileHandler = (*machoFile)(nil)
type machoFile struct {
file *macho.File
reader io.ReaderAt
getsymtab func() map[string]Symbol
}
func (m *machoFile) initSymtab() map[string]Symbol {
if m.file.Symtab == nil {
// just do nothing, keep err nil and table empty
return nil
}
const stabTypeMask = 0xe0
// Build a sorted list of all symbols.
// We infer the size of a symbol by looking at where the next symbol begins.
syms := make([]Symbol, 0)
for _, s := range m.file.Symtab.Syms {
if s.Type&stabTypeMask != 0 {
// Skip stab debug info.
continue
}
syms = append(syms, Symbol{Name: s.Name, Value: s.Value})
}
slices.SortStableFunc(syms, func(a, b Symbol) int {
return cmp.Compare(a.Value, b.Value)
})
for i := 0; i < len(syms)-1; i++ {
syms[i].Size = syms[i+1].Value - syms[i].Value
}
symm := make(map[string]Symbol)
for _, sym := range syms {
symm[sym.Name] = sym
}
return symm
}
func (m *machoFile) getSymbol(name string) (Symbol, error) {
sym, ok := m.getsymtab()[name]
if !ok {
return Symbol{}, ErrSymbolNotFound
}
return sym, nil
}
func (m *machoFile) getParsedFile() any {
return m.file
}
func (m *machoFile) getReader() io.ReaderAt {
return m.reader
}
func (m *machoFile) Close() error {
err := m.file.Close()
if err != nil {
return err
}
return tryClose(m.reader)
}
func (m *machoFile) getRData() ([]byte, error) {
_, data, err := m.getSectionData("__rodata")
return data, err
}
func (m *machoFile) getCodeSection() (uint64, []byte, error) {
return m.getSectionData("__text")
}
func (m *machoFile) getSectionDataFromAddress(address uint64) (uint64, []byte, error) {
for _, section := range m.file.Sections {
if section.Offset == 0 {
// Only exist in memory
continue
}
if section.Addr <= address && address < (section.Addr+section.Size) {
data, err := section.Data()
return section.Addr, data, err
}
}
return 0, nil, ErrSectionDoesNotExist
}
func (m *machoFile) getSectionData(s string) (uint64, []byte, error) {
var section *types.Section
for _, sect := range m.file.Sections {
if sect.Name == s {
section = sect
break
}
}
if section == nil {
return 0, nil, ErrSectionDoesNotExist
}
data, err := section.Data()
return section.Addr, data, err
}
func (m *machoFile) getFileInfo() *FileInfo {
fi := &FileInfo{
ByteOrder: m.file.ByteOrder,
OS: "macOS",
}
switch m.file.CPU {
case types.CPUI386:
fi.WordSize = intSize32
fi.Arch = Arch386
case types.CPUAmd64:
fi.WordSize = intSize64
fi.Arch = ArchAMD64
case types.CPUArm64:
fi.WordSize = intSize64
fi.Arch = ArchARM64
default:
panic("Unsupported architecture")
}
return fi
}
func (m *machoFile) getPCLNTABData() (uint64, []byte, error) {
return m.getSectionData("__gopclntab")
}
func (m *machoFile) moduledataSection() string {
return "__noptrdata"
}
func (m *machoFile) getBuildID() (string, error) {
_, data, err := m.getCodeSection()
if err != nil {
return "", fmt.Errorf("failed to get code section: %w", err)
}
return parseBuildIDFromRaw(data)
}
// getDwarf mostly a copy of github.com/blacktop/go-macho.File.DWARF() function
// removes dependency on github.com/blacktop/go-dwarf package
func (m *machoFile) getDwarf() (*dwarf.Data, error) {
dwarfSuffix := func(s *types.Section) string {
switch {
case strings.HasPrefix(s.Name, "__debug_"):
return s.Name[8:]
case strings.HasPrefix(s.Name, "__zdebug_"):
return s.Name[9:]
default:
return ""
}
}
sectionData := func(s *types.Section) ([]byte, error) {
b, err := s.Data()
if err != nil && uint64(len(b)) < s.Size {
return nil, err
}
if len(b) >= 12 && string(b[:4]) == "ZLIB" {
dlen := binary.BigEndian.Uint64(b[4:12])
dbuf := make([]byte, dlen)
r, err := zlib.NewReader(bytes.NewBuffer(b[12:]))
if err != nil {
return nil, err
}
if _, err := io.ReadFull(r, dbuf); err != nil {
return nil, err
}
if err := r.Close(); err != nil {
return nil, err
}
b = dbuf
}
return b, nil
}
// There are many other DWARF sections, but these
// are the ones the debug/dwarf package uses.
// Don't bother loading others.
var dat = map[string][]byte{"abbrev": nil, "info": nil, "str": nil, "line": nil, "ranges": nil}
for _, s := range m.file.Sections {
suffix := dwarfSuffix(s)
if suffix == "" {
continue
}
if _, ok := dat[suffix]; !ok {
continue
}
b, err := sectionData(s)
if err != nil {
return nil, err
}
dat[suffix] = b
}
d, err := dwarf.New(dat["abbrev"], nil, nil, dat["info"], dat["line"], nil, dat["ranges"], dat["str"])
if err != nil {
return nil, err
}
// Look for DWARF4 .debug_types sections and DWARF5 sections.
for i, s := range m.file.Sections {
suffix := dwarfSuffix(s)
if suffix == "" {
continue
}
if _, ok := dat[suffix]; ok {
// Already handled.
continue
}
b, err := sectionData(s)
if err != nil {
return nil, err
}
if suffix == "types" {
err = d.AddTypes(fmt.Sprintf("types-%d", i), b)
} else {
err = d.AddSection(".debug_"+suffix, b)
}
if err != nil {
return nil, err
}
}
return d, nil
}