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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
// Copyright 2017 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package fs
// This is based on the readdir implementation from Go 1.9:
// Copyright 2009 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.
import (
"os"
"syscall"
"unsafe"
)
const (
blockSize = 4096
)
func readdir(path string) ([]DirEntryInfo, error) {
f, err := os.Open(path)
defer f.Close()
if err != nil {
return nil, err
}
// This implicitly switches the fd to non-blocking mode, which is less efficient than what
// file.ReadDir does since it will keep a thread blocked and not just a goroutine.
fd := int(f.Fd())
buf := make([]byte, blockSize)
entries := make([]*dirEntryInfo, 0, 100)
for {
n, errno := syscall.ReadDirent(fd, buf)
if errno != nil {
err = os.NewSyscallError("readdirent", errno)
break
}
if n <= 0 {
break // EOF
}
entries = parseDirent(buf[:n], entries)
}
ret := make([]DirEntryInfo, 0, len(entries))
for _, entry := range entries {
if !entry.modeExists {
mode, lerr := lstatFileMode(path + "/" + entry.name)
if os.IsNotExist(lerr) {
// File disappeared between readdir + stat.
// Just treat it as if it didn't exist.
continue
}
if lerr != nil {
return ret, lerr
}
entry.mode = mode
entry.modeExists = true
}
ret = append(ret, entry)
}
return ret, err
}
func parseDirent(buf []byte, entries []*dirEntryInfo) []*dirEntryInfo {
for len(buf) > 0 {
reclen, ok := direntReclen(buf)
if !ok || reclen > uint64(len(buf)) {
return entries
}
rec := buf[:reclen]
buf = buf[reclen:]
ino, ok := direntIno(rec)
if !ok {
break
}
if ino == 0 { // File absent in directory.
continue
}
typ, ok := direntType(rec)
if !ok {
break
}
const namoff = uint64(unsafe.Offsetof(syscall.Dirent{}.Name))
namlen, ok := direntNamlen(rec)
if !ok || namoff+namlen > uint64(len(rec)) {
break
}
name := rec[namoff : namoff+namlen]
for i, c := range name {
if c == 0 {
name = name[:i]
break
}
}
// Check for useless names before allocating a string.
if string(name) == "." || string(name) == ".." {
continue
}
mode, modeExists := direntTypeToFileMode(typ)
entries = append(entries, &dirEntryInfo{string(name), mode, modeExists})
}
return entries
}
func direntIno(buf []byte) (uint64, bool) {
return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Ino), unsafe.Sizeof(syscall.Dirent{}.Ino))
}
func direntType(buf []byte) (uint64, bool) {
return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Type), unsafe.Sizeof(syscall.Dirent{}.Type))
}
func direntReclen(buf []byte) (uint64, bool) {
return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Reclen), unsafe.Sizeof(syscall.Dirent{}.Reclen))
}
func direntNamlen(buf []byte) (uint64, bool) {
reclen, ok := direntReclen(buf)
if !ok {
return 0, false
}
return reclen - uint64(unsafe.Offsetof(syscall.Dirent{}.Name)), true
}
// readInt returns the size-bytes unsigned integer in native byte order at offset off.
func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
if len(b) < int(off+size) {
return 0, false
}
return readIntLE(b[off:], size), true
}
func readIntLE(b []byte, size uintptr) uint64 {
switch size {
case 1:
return uint64(b[0])
case 2:
_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
return uint64(b[0]) | uint64(b[1])<<8
case 4:
_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24
case 8:
_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
default:
panic("syscall: readInt with unsupported size")
}
}
// If the directory entry doesn't specify the type, fall back to using lstat to get the type.
func lstatFileMode(name string) (os.FileMode, error) {
stat, err := os.Lstat(name)
if err != nil {
return 0, err
}
return stat.Mode() & (os.ModeType | os.ModeCharDevice), nil
}
// from Linux and Darwin dirent.h
const (
DT_UNKNOWN = 0
DT_FIFO = 1
DT_CHR = 2
DT_DIR = 4
DT_BLK = 6
DT_REG = 8
DT_LNK = 10
DT_SOCK = 12
)
func direntTypeToFileMode(typ uint64) (os.FileMode, bool) {
exists := true
var mode os.FileMode
switch typ {
case DT_UNKNOWN:
exists = false
case DT_FIFO:
mode = os.ModeNamedPipe
case DT_CHR:
mode = os.ModeDevice | os.ModeCharDevice
case DT_DIR:
mode = os.ModeDir
case DT_BLK:
mode = os.ModeDevice
case DT_REG:
mode = 0
case DT_LNK:
mode = os.ModeSymlink
case DT_SOCK:
mode = os.ModeSocket
default:
exists = false
}
return mode, exists
}
|
