1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
// 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 macho
import (
"encoding/binary"
"fmt"
"io"
"os"
)
// A FatFile is a Mach-O universal binary that contains at least one architecture.
type FatFile struct {
Magic uint32
Arches []FatArch
closer io.Closer
}
// A FatArchHeader represents a fat header for a specific image architecture.
type FatArchHeader struct {
Cpu Cpu
SubCpu uint32
Offset uint32
Size uint32
Align uint32
}
const fatArchHeaderSize = 5 * 4
// A FatArch is a Mach-O File inside a FatFile.
type FatArch struct {
FatArchHeader
*File
}
// ErrNotFat is returned from NewFatFile or OpenFat when the file is not a
// universal binary but may be a thin binary, based on its magic number.
var ErrNotFat = &FormatError{0, "not a fat Mach-O file", nil}
// NewFatFile creates a new FatFile for accessing all the Mach-O images in a
// universal binary. The Mach-O binary is expected to start at position 0 in
// the ReaderAt.
func NewFatFile(r io.ReaderAt) (*FatFile, error) {
var ff FatFile
sr := io.NewSectionReader(r, 0, 1<<63-1)
// Read the fat_header struct, which is always in big endian.
// Start with the magic number.
err := binary.Read(sr, binary.BigEndian, &ff.Magic)
if err != nil {
return nil, &FormatError{0, "error reading magic number", nil}
} else if ff.Magic != MagicFat {
// See if this is a Mach-O file via its magic number. The magic
// must be converted to little endian first though.
var buf [4]byte
binary.BigEndian.PutUint32(buf[:], ff.Magic)
leMagic := binary.LittleEndian.Uint32(buf[:])
if leMagic == Magic32 || leMagic == Magic64 {
return nil, ErrNotFat
} else {
return nil, &FormatError{0, "invalid magic number", nil}
}
}
offset := int64(4)
// Read the number of FatArchHeaders that come after the fat_header.
var narch uint32
err = binary.Read(sr, binary.BigEndian, &narch)
if err != nil {
return nil, &FormatError{offset, "invalid fat_header", nil}
}
offset += 4
if narch < 1 {
return nil, &FormatError{offset, "file contains no images", nil}
}
// Combine the Cpu and SubCpu (both uint32) into a uint64 to make sure
// there are not duplicate architectures.
seenArches := make(map[uint64]bool, narch)
// Make sure that all images are for the same MH_ type.
var machoType Type
// Following the fat_header comes narch fat_arch structs that index
// Mach-O images further in the file.
ff.Arches = make([]FatArch, narch)
for i := uint32(0); i < narch; i++ {
fa := &ff.Arches[i]
err = binary.Read(sr, binary.BigEndian, &fa.FatArchHeader)
if err != nil {
return nil, &FormatError{offset, "invalid fat_arch header", nil}
}
offset += fatArchHeaderSize
fr := io.NewSectionReader(r, int64(fa.Offset), int64(fa.Size))
fa.File, err = NewFile(fr)
if err != nil {
return nil, err
}
// Make sure the architecture for this image is not duplicate.
seenArch := (uint64(fa.Cpu) << 32) | uint64(fa.SubCpu)
if o, k := seenArches[seenArch]; o || k {
return nil, &FormatError{offset, fmt.Sprintf("duplicate architecture cpu=%v, subcpu=%#x", fa.Cpu, fa.SubCpu), nil}
}
seenArches[seenArch] = true
// Make sure the Mach-O type matches that of the first image.
if i == 0 {
machoType = fa.Type
} else {
if fa.Type != machoType {
return nil, &FormatError{offset, fmt.Sprintf("Mach-O type for architecture #%d (type=%#x) does not match first (type=%#x)", i, fa.Type, machoType), nil}
}
}
}
return &ff, nil
}
// OpenFat opens the named file using os.Open and prepares it for use as a Mach-O
// universal binary.
func OpenFat(name string) (ff *FatFile, err error) {
f, err := os.Open(name)
if err != nil {
return nil, err
}
ff, err = NewFatFile(f)
if err != nil {
f.Close()
return nil, err
}
ff.closer = f
return
}
func (ff *FatFile) Close() error {
var err error
if ff.closer != nil {
err = ff.closer.Close()
ff.closer = nil
}
return err
}
|
