1 // Copyright 2012 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // Plan 9 directory marshalling. See intro(5).
12 ErrShortStat = errors.New("stat buffer too short")
13 ErrBadStat = errors.New("malformed stat buffer")
14 ErrBadName = errors.New("bad character in file name")
17 // A Qid represents a 9P server's unique identification for a file.
19 Path uint64 // the file server's unique identification for the file
20 Vers uint32 // version number for given Path
21 Type uint8 // the type of the file (plan9.QTDIR for example)
24 // A Dir contains the metadata for a file.
26 // system-modified data
27 Type uint16 // server type
28 Dev uint32 // server subtype
31 Qid Qid // unique id from server
32 Mode uint32 // permissions
33 Atime uint32 // last read time
34 Mtime uint32 // last write time
35 Length int64 // file length
36 Name string // last element of path
37 Uid string // owner name
38 Gid string // group name
39 Muid string // last modifier name
56 // Null assigns special "don't touch" values to members of d to
57 // avoid modifying them during plan9.Wstat.
58 func (d *Dir) Null() { *d = nullDir }
60 // Marshal encodes a 9P stat message corresponding to d into b
62 // If there isn't enough space in b for a stat message, ErrShortStat is returned.
63 func (d *Dir) Marshal(b []byte) (n int, err error) {
64 n = STATFIXLEN + len(d.Name) + len(d.Uid) + len(d.Gid) + len(d.Muid)
66 return n, ErrShortStat
69 for _, c := range d.Name {
75 b = pbit16(b, uint16(n)-2)
78 b = pbit8(b, d.Qid.Type)
79 b = pbit32(b, d.Qid.Vers)
80 b = pbit64(b, d.Qid.Path)
82 b = pbit32(b, d.Atime)
83 b = pbit32(b, d.Mtime)
84 b = pbit64(b, uint64(d.Length))
85 b = pstring(b, d.Name)
88 b = pstring(b, d.Muid)
93 // UnmarshalDir decodes a single 9P stat message from b and returns the resulting Dir.
95 // If b is too small to hold a valid stat message, ErrShortStat is returned.
97 // If the stat message itself is invalid, ErrBadStat is returned.
98 func UnmarshalDir(b []byte) (*Dir, error) {
99 if len(b) < STATFIXLEN {
100 return nil, ErrShortStat
102 size, buf := gbit16(b)
103 if len(b) != int(size)+2 {
104 return nil, ErrBadStat
109 d.Type, b = gbit16(b)
111 d.Qid.Type, b = gbit8(b)
112 d.Qid.Vers, b = gbit32(b)
113 d.Qid.Path, b = gbit64(b)
114 d.Mode, b = gbit32(b)
115 d.Atime, b = gbit32(b)
116 d.Mtime, b = gbit32(b)
122 if d.Name, b, ok = gstring(b); !ok {
123 return nil, ErrBadStat
125 if d.Uid, b, ok = gstring(b); !ok {
126 return nil, ErrBadStat
128 if d.Gid, b, ok = gstring(b); !ok {
129 return nil, ErrBadStat
131 if d.Muid, b, ok = gstring(b); !ok {
132 return nil, ErrBadStat
138 // pbit8 copies the 8-bit number v to b and returns the remaining slice of b.
139 func pbit8(b []byte, v uint8) []byte {
144 // pbit16 copies the 16-bit number v to b in little-endian order and returns the remaining slice of b.
145 func pbit16(b []byte, v uint16) []byte {
151 // pbit32 copies the 32-bit number v to b in little-endian order and returns the remaining slice of b.
152 func pbit32(b []byte, v uint32) []byte {
160 // pbit64 copies the 64-bit number v to b in little-endian order and returns the remaining slice of b.
161 func pbit64(b []byte, v uint64) []byte {
173 // pstring copies the string s to b, prepending it with a 16-bit length in little-endian order, and
174 // returning the remaining slice of b..
175 func pstring(b []byte, s string) []byte {
176 b = pbit16(b, uint16(len(s)))
181 // gbit8 reads an 8-bit number from b and returns it with the remaining slice of b.
182 func gbit8(b []byte) (uint8, []byte) {
183 return uint8(b[0]), b[1:]
186 // gbit16 reads a 16-bit number in little-endian order from b and returns it with the remaining slice of b.
187 func gbit16(b []byte) (uint16, []byte) {
188 return uint16(b[0]) | uint16(b[1])<<8, b[2:]
191 // gbit32 reads a 32-bit number in little-endian order from b and returns it with the remaining slice of b.
192 func gbit32(b []byte) (uint32, []byte) {
193 return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24, b[4:]
196 // gbit64 reads a 64-bit number in little-endian order from b and returns it with the remaining slice of b.
197 func gbit64(b []byte) (uint64, []byte) {
198 lo := uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
199 hi := uint32(b[4]) | uint32(b[5])<<8 | uint32(b[6])<<16 | uint32(b[7])<<24
200 return uint64(lo) | uint64(hi)<<32, b[8:]
203 // gstring reads a string from b, prefixed with a 16-bit length in little-endian order.
204 // It returns the string with the remaining slice of b and a boolean. If the length is
205 // greater than the number of bytes in b, the boolean will be false.
206 func gstring(b []byte) (string, []byte, bool) {
211 return string(b[:n]), b[n:], true