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
|
package main
import (
"encoding/binary"
"os"
)
type PathPair struct {
input string
output string
}
var byteOrder binary.ByteOrder = binary.NativeEndian
func main() {
var inputFiles []PathPair
for i, arg := range os.Args[1:] {
switch arg {
case "-b":
byteOrder = binary.BigEndian
case "-l":
byteOrder = binary.LittleEndian
case "-o":
inputFiles = append(inputFiles, PathPair{os.Args[i+3], os.Args[i+2]})
}
}
for _, p := range inputFiles {
AssembleFile(p)
}
}
func AssembleFile(path PathPair) {
tempData, err := os.CreateTemp("", "data*")
Check(err)
dName := tempData.Name()
defer os.Remove(dName)
tempRoData, err := os.CreateTemp("", "rodata*")
Check(err)
rName := tempRoData.Name()
defer os.Remove(rName)
tempText, err := os.CreateTemp("", "text*")
Check(err)
tName := tempText.Name()
defer os.Remove(tName)
// First pass to find the address of all labels and encode the data
LabelFind(path.input, tempData, tempRoData)
var names [3]string
var PHeaders [4]ProgramHeader
i := 0
n := 0
if SectionPos[TEXT] > 0 {
PHeaders[i] = ProgramHeader{PT_LOAD, 0, 0, 0,
uint32(SectionPos[TEXT]), uint32(SectionPos[TEXT]), PF_READ +
PF_EXEC, 0}
names[i] = tName
i++
n++
// Second pass to assemble the instructions.
Assemble(path.input, tempText)
}
if SectionPos[DATA] > 0 {
PHeaders[i] = ProgramHeader{PT_LOAD, 0, 0, 0,
uint32(SectionPos[DATA]), uint32(SectionPos[DATA]), PF_READ +
PF_WRITE, 0}
names[i] = dName
i++
n++
}
if SectionPos[RODATA] > 0 {
PHeaders[i] = ProgramHeader{PT_LOAD, 0, 0, 0,
uint32(SectionPos[RODATA]), uint32(SectionPos[RODATA]), PF_READ, 0}
names[i] = rName
i++
n++
}
if SectionPos[BSS] > 0 {
PHeaders[i] = ProgramHeader{PT_LOAD, 0, 0, 0, 0,
uint32(SectionPos[BSS]), PF_READ + PF_WRITE, 0}
i++
}
var fOffset, mOffset uint32 = 0, 0
for j, p := range PHeaders[:i] {
PHeaders[j].offset = uint32(i*PHENSIZE) + fOffset + EHSIZE
fOffset += p.filesz
PHeaders[j].vaddr = mOffset
mOffset += p.memsz
}
EHeader := EHInit(0, uint16(i))
WriteBinary(path, EHeader, PHeaders[:i], names[:n])
}
func WriteBinary(path PathPair, e ElfHeader, ps []ProgramHeader, ns []string) {
out, err := os.Create(path.output)
Check(err)
defer out.Close()
_, err = out.Write(e.ToBytes())
Check(err)
for _, p := range ps {
_, err = out.Write(p.ToBytes())
Check(err)
}
for _, name := range ns {
b, err := os.ReadFile(name)
Check(err)
_, err = out.Write(b)
Check(err)
}
}
func Check(err error) {
if err != nil {
panic(err)
}
}
|
