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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 /** | |
6 * Write an ar archive file. | |
M-A Ruel
2016/06/06 23:01:05
If you want to have a comment for the file, use th
mithro
2016/06/07 12:28:52
Done.
| |
7 */ | |
8 package ar | |
9 | |
10 import ( | |
11 "errors" | |
12 "fmt" | |
13 "io" | |
14 "os" | |
15 ) | |
16 | |
17 const DEFAULT_MODTIME = 1447140471 | |
18 const DEFAULT_USER = 1000 | |
19 const DEFAULT_GROUP = 1000 | |
20 const DEFAULT_MODE = 0100640 // 100640 -- Octal | |
21 | |
22 type WriterStage uint | |
23 | |
24 const ( | |
25 WRITE_HEADER WriterStage = iota | |
26 WRITE_BODY = iota | |
27 WRITE_CLOSED = iota | |
28 ) | |
29 | |
30 type Writer struct { | |
31 w io.Writer | |
32 stage WriterStage | |
33 | |
34 bytesrequired int64 | |
35 needspadding bool | |
36 } | |
37 | |
38 func NewWriter(w io.Writer) *Writer { | |
39 io.WriteString(w, "!<arch>\n") | |
40 return &Writer{w: w, stage: WRITE_HEADER, bytesrequired: 0, needspadding : false} | |
41 } | |
42 | |
43 func (aw *Writer) Close() error { | |
44 switch aw.stage { | |
45 case WRITE_HEADER: | |
46 // Good | |
47 case WRITE_BODY: | |
48 return errors.New("Usage error, writing a file.") | |
49 case WRITE_CLOSED: | |
50 return errors.New("Usage error, archive already closed.") | |
51 default: | |
52 panic(fmt.Sprintf("Unknown writer mode: %d", aw.stage)) | |
53 } | |
54 //aw.w.Close() | |
55 aw.stage = WRITE_CLOSED | |
56 return nil | |
57 } | |
58 | |
59 func (aw *Writer) wroteBytes(numbytes int64) error { | |
60 if numbytes > aw.bytesrequired { | |
61 panic(fmt.Sprintf("To much data written! Needed %d, got %d", aw. bytesrequired, numbytes)) | |
62 } | |
63 | |
64 aw.bytesrequired -= numbytes | |
65 if aw.bytesrequired != 0 { | |
66 return nil | |
67 } | |
68 | |
69 // Padding to 16bit boundary | |
70 if aw.needspadding { | |
71 io.WriteString(aw.w, "\n") | |
72 aw.needspadding = false | |
73 } | |
74 aw.stage = WRITE_HEADER | |
75 return nil | |
76 } | |
77 | |
78 // Check you can write bytes to the ar at this moment. | |
79 func (aw *Writer) checkWrite() error { | |
80 switch aw.stage { | |
81 case WRITE_HEADER: | |
82 return errors.New("Usage error, need to write header first.") | |
83 // Good | |
84 case WRITE_BODY: | |
85 return nil | |
86 case WRITE_CLOSED: | |
87 return errors.New("Usage error, archive closed.") | |
88 default: | |
89 panic(fmt.Sprintf("Unknown writer mode: %d", aw.stage)) | |
90 } | |
91 } | |
92 | |
93 // Check we have finished writing bytes | |
94 func (aw *Writer) checkFinished() { | |
95 if aw.bytesrequired != 0 { | |
96 panic(fmt.Sprintf("Didn't write enough bytes %d still needed, ar chive corrupted!", aw.bytesrequired)) | |
97 } | |
98 } | |
99 | |
100 func (aw *Writer) writePartial(data []byte) error { | |
101 err := aw.checkWrite() | |
102 if err != nil { | |
103 return err | |
104 } | |
105 | |
106 datalen := int64(len(data)) | |
107 if datalen > aw.bytesrequired { | |
108 return errors.New(fmt.Sprintf("To much data! Needed %d, got %d", aw.bytesrequired, datalen)) | |
109 } | |
110 | |
111 aw.w.Write(data) | |
112 aw.wroteBytes(datalen) | |
113 return nil | |
114 } | |
115 | |
116 func (aw *Writer) WriteReader(data io.Reader) error { | |
117 err := aw.checkWrite() | |
118 if err != nil { | |
119 return err | |
120 } | |
121 | |
122 count, err := io.Copy(aw.w, data) | |
123 if err != nil { | |
124 panic(fmt.Sprintf("err while copying (%s), archive is probably c orrupted!", err)) | |
125 } | |
126 aw.wroteBytes(count) | |
127 aw.checkFinished() | |
128 | |
129 return nil | |
130 } | |
131 | |
132 func (aw *Writer) WriteBytes(data []byte) error { | |
133 err := aw.checkWrite() | |
134 if err != nil { | |
135 return err | |
136 } | |
137 | |
138 datalen := int64(len(data)) | |
139 if datalen != aw.bytesrequired { | |
140 return errors.New(fmt.Sprintf("Wrong amount of data! Needed %d, got %d", aw.bytesrequired, datalen)) | |
141 } | |
142 | |
143 aw.writePartial(data) | |
144 aw.checkFinished() | |
145 return nil | |
146 } | |
147 | |
148 func (aw *Writer) writeHeaderBytes(name string, size int64, modtime uint64, owne rid uint, groupid uint, filemod uint) error { | |
149 switch aw.stage { | |
150 case WRITE_HEADER: | |
151 // Good | |
152 case WRITE_BODY: | |
153 return errors.New("Usage error, already writing a file.") | |
154 case WRITE_CLOSED: | |
155 return errors.New("Usage error, archive closed.") | |
156 default: | |
157 panic(fmt.Sprintf("Unknown writer mode: %d", aw.stage)) | |
158 } | |
159 | |
160 // File name length prefixed with '#1/' (BSD variant), 16 bytes | |
161 fmt.Fprintf(aw.w, "#1/%-13d", len(name)) | |
162 | |
163 // Modtime, 12 bytes | |
164 fmt.Fprintf(aw.w, "%-12d", modtime) | |
165 | |
166 // Owner ID, 6 bytes | |
167 fmt.Fprintf(aw.w, "%-6d", ownerid) | |
168 | |
169 // Group ID, 6 bytes | |
170 fmt.Fprintf(aw.w, "%-6d", groupid) | |
171 | |
172 // File mode, 8 bytes | |
173 fmt.Fprintf(aw.w, "%-8o", filemod) | |
174 | |
175 // In BSD variant, file size includes the filename length | |
176 aw.bytesrequired = int64(len(name)) + size | |
177 | |
178 // File size, 10 bytes | |
179 fmt.Fprintf(aw.w, "%-10d", aw.bytesrequired) | |
180 | |
181 // File magic, 2 bytes | |
182 io.WriteString(aw.w, "\x60\n") | |
183 | |
184 aw.stage = WRITE_BODY | |
185 aw.needspadding = (aw.bytesrequired%2 != 0) | |
186 | |
187 // Filename - BSD variant | |
188 return aw.writePartial([]byte(name)) | |
189 } | |
190 | |
191 func (aw *Writer) WriteHeaderDefault(name string, size int64) error { | |
192 return aw.writeHeaderBytes(name, size, 1447140471, DEFAULT_USER, DEFAULT _GROUP, DEFAULT_MODE) | |
193 } | |
194 | |
195 func (aw *Writer) WriteHeader(stat os.FileInfo) error { | |
196 if stat.IsDir() { | |
197 return errors.New("Only work with files, not directories.") | |
198 } | |
199 | |
200 mode := stat.Mode() | |
201 if mode&os.ModeSymlink == os.ModeSymlink { | |
202 return errors.New("Only work with files, not symlinks.") | |
203 } | |
204 | |
205 /* FIXME: Should we also exclude other "special" files? | |
206 if (stat.Mode().ModeType != 0) { | |
207 return &argError{stat, "Only work with plain files."} | |
208 } | |
209 */ | |
210 | |
211 // FIXME: Where do we get user/group from - they don't appear to be in G o's Mode() object? | |
212 return aw.writeHeaderBytes(stat.Name(), stat.Size(), uint64(stat.ModTime ().Unix()), DEFAULT_USER, DEFAULT_GROUP, uint(mode&os.ModePerm)) | |
213 } | |
214 | |
215 func (aw *Writer) Add(name string, data []byte) error { | |
216 err := aw.WriteHeaderDefault(name, int64(len(data))) | |
217 if err != nil { | |
218 return err | |
219 } | |
220 | |
221 return aw.WriteBytes(data) | |
222 } | |
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