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1 // Copyright 2016 The LUCI Authors. All rights reserved. | |
2 // Use of this source code is governed under the Apache License, Version 2.0 | |
3 // that can be found in the LICENSE file. | |
4 | |
5 // Write an ar archive file with BSD style filenames. | |
6 | |
7 package ar | |
8 | |
9 import ( | |
10 "fmt" | |
11 "io" | |
12 "log" | |
13 "os" | |
14 ) | |
15 | |
16 // Special UsageError that indicates trying to write after closing. | |
17 var ( | |
M-A Ruel
2016/06/14 14:30:43
since there's only one, do not use ()
I don't thin
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18 ErrWriteAfterClose = UsageError{msg: "write after file closed"} | |
19 ) | |
20 | |
21 // WriteTooLongError indicates trying to write the wrong amount of data into the archive. | |
M-A Ruel
2016/06/14 14:30:43
wrap at 80 cols
mithro
2016/11/06 22:56:53
Done.
| |
22 // WriteTooLongError is never fatal. | |
23 type WriteTooLongError struct { | |
M-A Ruel
2016/06/14 14:30:43
I don't think these error types should be exported
| |
24 needed int64 | |
25 got int64 | |
26 } | |
27 | |
28 func (e *WriteTooLongError) Error() string { | |
29 return fmt.Sprintf("archive/ar: invalid data length (needed %d, got %d)" , e.needed, e.got) | |
30 } | |
31 func (e *WriteTooLongError) Fatal() bool { | |
32 return false | |
33 } | |
34 | |
35 // WriteTooLongFatalError indicates that the wrong amount of data *was* written into the archive. | |
36 // WriteTooLongFatalError is always fatal. | |
37 type WriteTooLongFatalError struct { | |
38 needed int64 | |
39 got int64 | |
40 } | |
41 | |
42 func (e *WriteTooLongFatalError) Error() string { | |
43 return fmt.Sprintf("archive/ar: *archive corrupted* -- invalid data writ ten (needed %d, got %d)", e.needed, e.got) | |
44 } | |
45 func (e *WriteTooLongFatalError) Fatal() bool { | |
46 return true | |
47 } | |
48 | |
49 const DefaultModifyTime = 1447140471 | |
50 const DefaultUser = 1000 | |
51 const DefaultGroup = 1000 | |
52 const DefaultFileMode = 0100640 // 100640 -- Octal | |
53 | |
54 type writerStage uint | |
55 | |
56 const ( | |
57 writeStageHeader writerStage = iota | |
58 writeStageBody | |
59 writeStageClosed | |
60 ) | |
61 | |
62 type Writer struct { | |
63 w io.Writer | |
64 stage writerStage | |
65 | |
66 streamSizeNeeded int64 | |
67 bodyNeedsPadding bool | |
68 } | |
69 | |
70 func NewWriter(w io.Writer) (*Writer, Error) { | |
71 if _, err := io.WriteString(w, "!<arch>\n"); err != nil { | |
72 return nil, &IOError{section: "archive header", err: err} | |
73 } | |
74 return &Writer{w: w, stage: writeStageHeader}, nil | |
75 } | |
76 | |
77 func (aw *Writer) Close() Error { | |
78 switch aw.stage { | |
79 case writeStageHeader: | |
80 // Good | |
81 case writeStageBody: | |
82 return &UsageError{msg: "currently writing a file"} | |
83 case writeStageClosed: | |
84 return &ErrWriteAfterClose | |
85 default: | |
86 log.Fatalf("unknown writer mode: %d", aw.stage) | |
87 } | |
88 aw.stage = writeStageClosed | |
89 aw.w = nil | |
90 return nil | |
91 } | |
92 | |
93 func (aw *Writer) wroteBytes(numbytes int64) Error { | |
94 if numbytes > aw.streamSizeNeeded { | |
95 return &WriteTooLongFatalError{aw.streamSizeNeeded, numbytes} | |
96 } | |
97 | |
98 aw.streamSizeNeeded -= numbytes | |
99 if aw.streamSizeNeeded != 0 { | |
100 return nil | |
101 } | |
102 | |
103 // Padding to 16bit boundary | |
104 if aw.bodyNeedsPadding { | |
105 if _, err := io.WriteString(aw.w, "\n"); err != nil { | |
106 return &IOError{section: "body padding", err: err} | |
107 } | |
108 aw.bodyNeedsPadding = false | |
109 } | |
110 aw.stage = writeStageHeader | |
111 return nil | |
112 } | |
113 | |
114 // checkCanWriteContent returns nil if the stream is in a position to write a | |
115 // stream content. | |
116 func (aw *Writer) checkCanWriteContent() Error { | |
117 switch aw.stage { | |
118 case writeStageHeader: | |
119 return &UsageError{msg: "need to write header first"} | |
120 case writeStageBody: | |
121 // Good | |
122 return nil | |
123 case writeStageClosed: | |
124 return &ErrWriteAfterClose | |
125 default: | |
126 log.Fatalf("unknown writer mode: %d", aw.stage) | |
127 } | |
128 return nil | |
129 } | |
130 | |
131 // Check we have finished writing bytes | |
132 func (aw *Writer) checkFinished() Error { | |
133 if aw.streamSizeNeeded != 0 { | |
134 return &WriteTooLongFatalError{aw.streamSizeNeeded, -1} | |
135 } | |
136 return nil | |
137 } | |
138 | |
139 func (aw *Writer) writePartial(section string, data []byte) Error { | |
140 if err := aw.checkCanWriteContent(); err != nil { | |
141 return err | |
142 } | |
143 | |
144 datalen := int64(len(data)) | |
145 if datalen > aw.streamSizeNeeded { | |
146 return &WriteTooLongError{aw.streamSizeNeeded, datalen} | |
147 } | |
148 | |
149 if _, err := aw.w.Write(data); err != nil { | |
150 return &IOError{section: section, err: err} | |
151 } | |
152 if err := aw.wroteBytes(datalen); err != nil { | |
153 return err | |
154 } | |
155 return nil | |
156 } | |
157 | |
158 // ReaderFrom writes all the data from r (till EOF) into the archive. | |
159 // The size of data should match the value given previously to WriteHeader* | |
160 // functions. | |
161 // ReaderFrom returns the number of bytes written on success. | |
162 // Calling with wrong size data will return ErrFatalWriteToLong, the archive | |
163 // should be considered broken. | |
164 // Calling after Close will return ErrWriteAfterClose | |
165 func (aw *Writer) ReaderFrom(r io.Reader) (int64, Error) { | |
166 if err := aw.checkCanWriteContent(); err != nil { | |
167 return -1, err | |
168 } | |
169 | |
170 count, err := io.Copy(aw.w, r) | |
171 if err != nil { | |
172 return -1, &IOError{section: "body file contents", err: err} | |
173 } | |
174 if err := aw.wroteBytes(count); err != nil { | |
175 return -1, err | |
176 } | |
177 if err := aw.checkFinished(); err != nil { | |
178 return -1, err | |
179 } | |
180 | |
181 return count, nil | |
182 } | |
183 | |
184 // WriteBytes writes the given byte data into the archive. | |
185 // The size of data array should match the value given previously to | |
186 // WriteHeader* functions. | |
187 // WriteBytes returns nil on success. | |
188 // Calling with wrong size data will return WriteTooLongError but the archive wi ll | |
M-A Ruel
2016/06/14 14:30:43
80 cols for comments is helpful
mithro
2016/11/06 22:56:53
Done.
| |
189 // still be valid. | |
190 // Calling after Close will return ErrWriteAfterClose. | |
191 func (aw *Writer) WriteBytes(data []byte) Error { | |
192 if err := aw.checkCanWriteContent(); err != nil { | |
193 return err | |
194 } | |
195 | |
196 if datalen := int64(len(data)); datalen != aw.streamSizeNeeded { | |
197 return &WriteTooLongError{aw.streamSizeNeeded, datalen} | |
198 } | |
199 | |
200 if err := aw.writePartial("body content", data); err != nil { | |
201 return err | |
202 } | |
203 if err := aw.checkFinished(); err != nil { | |
M-A Ruel
2016/06/14 14:30:43
tail call optimisation:
return aw.checkFinished()
mithro
2016/11/06 22:56:53
Done.
| |
204 return err | |
205 } | |
206 return nil | |
207 } | |
208 | |
209 func (aw *Writer) writeHeaderInternal(filepath string, size int64, modtime uint6 4, ownerid uint, groupid uint, filemod uint) Error { | |
210 switch aw.stage { | |
211 case writeStageHeader: | |
212 // Good | |
213 case writeStageBody: | |
214 return &UsageError{msg: "usage error, currently writing a file." } | |
215 case writeStageClosed: | |
216 return &ErrWriteAfterClose | |
217 default: | |
218 log.Fatalf("unknown writer mode: %d", aw.stage) | |
219 } | |
220 | |
221 // File name length prefixed with '#1/' (BSD variant), 16 bytes | |
222 if _, err := fmt.Fprintf(aw.w, "#1/%-13d", len(filepath)); err != nil { | |
223 return &IOError{section: "file header filepath length", err: err } | |
224 } | |
225 | |
226 // Modtime, 12 bytes | |
227 if _, err := fmt.Fprintf(aw.w, "%-12d", modtime); err != nil { | |
228 return &IOError{section: "file header modtime", err: err} | |
229 } | |
230 | |
231 // Owner ID, 6 bytes | |
232 if _, err := fmt.Fprintf(aw.w, "%-6d", ownerid); err != nil { | |
233 return &IOError{section: "file header owner id", err: err} | |
234 } | |
235 | |
236 // Group ID, 6 bytes | |
237 if _, err := fmt.Fprintf(aw.w, "%-6d", groupid); err != nil { | |
238 return &IOError{section: "file header group id", err: err} | |
239 } | |
240 | |
241 // File mode, 8 bytes | |
242 if _, err := fmt.Fprintf(aw.w, "%-8o", filemod); err != nil { | |
243 return &IOError{section: "file header file mode", err: err} | |
244 } | |
245 | |
246 // In BSD variant, file size includes the filepath length | |
247 aw.streamSizeNeeded = int64(len(filepath)) + size | |
248 | |
249 // File size, 10 bytes | |
250 if _, err := fmt.Fprintf(aw.w, "%-10d", aw.streamSizeNeeded); err != nil { | |
251 return &IOError{section: "file header file size", err: err} | |
252 } | |
253 | |
254 // File magic, 2 bytes | |
255 if _, err := io.WriteString(aw.w, "\x60\n"); err != nil { | |
256 return &IOError{section: "file header file magic", err: err} | |
257 } | |
258 | |
259 aw.stage = writeStageBody | |
260 aw.bodyNeedsPadding = (aw.streamSizeNeeded%2 != 0) | |
261 | |
262 // File path - BSD variant | |
263 return aw.writePartial("body filepath", []byte(filepath)) | |
264 } | |
265 | |
266 // WriteHeaderDefault writes header information about a file to the archive | |
267 // using default values for everything apart from name and size. | |
268 // WriteBytes or ReaderFrom should be called after writing the header. | |
269 // Calling at the wrong time will return a UsageError. | |
270 func (aw *Writer) WriteHeaderDefault(filepath string, size int64) Error { | |
271 return aw.writeHeaderInternal(filepath, size, DefaultModifyTime, Default User, DefaultGroup, DefaultFileMode) | |
272 } | |
273 | |
274 // WriteHeader writes header information about a file to the archive using the | |
275 // information from os.Stat. | |
276 // WriteBytes or ReaderFrom should be called after writing the header. | |
277 // Calling at the wrong time will return a UsageError. | |
278 func (aw *Writer) WriteHeader(stat os.FileInfo) Error { | |
279 if stat.IsDir() { | |
280 return &UsageError{msg: "only work with files, not directories"} | |
281 } | |
282 | |
283 mode := stat.Mode() | |
284 if mode&os.ModeSymlink == os.ModeSymlink { | |
285 return &UsageError{msg: "only work with files, not symlinks"} | |
286 } | |
287 | |
288 /* FIXME: Should we also exclude other "special" files? | |
M-A Ruel
2016/06/14 14:30:43
TODO(mithro):
mithro
2016/11/06 22:56:53
Done.
| |
289 if (stat.Mode().ModeType != 0) { | |
290 return &argError{stat, "Only work with plain files."} | |
291 } | |
292 */ | |
293 | |
294 return aw.writeHeaderInternal(stat.Name(), stat.Size(), uint64(stat.ModT ime().Unix()), DefaultUser, DefaultGroup, uint(mode&os.ModePerm)) | |
295 } | |
296 | |
297 // Add a file to the archive. | |
298 // Function is equivalent to calling "WriteHeaderDefault(filepath, len(data); Wr iteBytes(data)". | |
299 func (aw *Writer) Add(filepath string, data []byte) Error { | |
M-A Ruel
2016/06/14 14:30:43
AddRaw(), AddContent() ? I would have liked WriteF
mithro
2016/11/06 22:56:53
Used AddWithContent().
| |
300 if err := aw.WriteHeaderDefault(filepath, int64(len(data))); err != nil { | |
301 return err | |
302 } | |
303 | |
304 return aw.WriteBytes(data) | |
305 } | |
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