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
|
package cpio
import (
"io"
"fmt"
)
// A writer enables sequential writing of cpio archives.
// A call to WriteHeader begins a new file. Every call to
// write afterwards appends to that file, writing at most
// hdr.Size bytes in total.
type Writer struct {
w io.Writer
inode int64
length int64
remaining_bytes int
}
func NewWriter(w io.Writer) *Writer {
return &Writer{
w: w,
inode: 721,
}
}
func assemble(mode, typev int64) int64 {
return mode&0xFFF | ((typev & 0xF) << 12)
}
func (w *Writer) WriteHeader(hdr *Header) error {
// Bring last file to the defined length
e := w.zeros(int64(w.remaining_bytes))
if e != nil {
return e
}
e = w.pad(4)
if e != nil {
return e
}
bname := []byte(hdr.Name)
nlinks := 1
if hdr.Type == TYPE_DIR {
nlinks = 2
}
shdr := fmt.Sprintf("%s%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
"070701",
w.inode,
assemble(hdr.Mode, hdr.Type),
hdr.Uid,
hdr.Gid,
nlinks,
hdr.Mtime,
hdr.Size,
3, // major
1, // minor
hdr.Devmajor,
hdr.Devminor,
len(bname)+1, // +1 for terminating zero
0) // check
_, e = w.countedWrite([]byte(shdr))
if e != nil {
return e
}
_, e = w.countedWrite(bname)
if e != nil {
return e
}
_, e = w.countedWrite([]byte{0})
if e != nil {
return e
}
w.inode++
w.remaining_bytes = int(hdr.Size)
return w.pad(4)
}
func (w *Writer) zeros(num int64) error {
for ; num > 0; num-- {
_, e := w.countedWrite([]byte{0})
if e != nil {
return e
}
}
return nil
}
// Brings the length of the file to a multiple of mod
func (w *Writer) pad(mod int64) error {
return w.zeros((mod - (w.length % mod)) % mod)
}
func (w *Writer) Write(b []byte) (n int, e error) {
if len(b) > w.remaining_bytes {
b = b[0:w.remaining_bytes]
}
n, e = w.countedWrite(b)
w.remaining_bytes -= n
return
}
func (w *Writer) countedWrite(b []byte) (n int, e error) {
n, e = w.w.Write(b)
w.length += int64(n)
return n, e
}
// Writes trailer
// Does not close underlying writer
func (w *Writer) Close() error {
e := w.WriteHeader(&trailer)
if e != nil {
return e
}
return w.pad(512)
}
|
