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1 // Copyright 2009 The Go Authors. All rights reserved. | 1 // Copyright 2009 The Go Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style | 2 // Use of this source code is governed by a BSD-style |
3 // license that can be found in the LICENSE file. | 3 // license that can be found in the LICENSE file. |
4 | 4 |
5 package tar | 5 package tar |
6 | 6 |
7 // TODO(dsymonds): | 7 // TODO(dsymonds): |
8 // - catch more errors (no first header, etc.) | 8 // - catch more errors (no first header, etc.) |
9 | 9 |
10 import ( | 10 import ( |
11 "bytes" | 11 "bytes" |
12 "errors" | 12 "errors" |
13 "fmt" | 13 "fmt" |
14 "io" | 14 "io" |
15 "os" | 15 "os" |
16 » "path/filepath" | 16 » "path" |
17 "strconv" | 17 "strconv" |
18 "strings" | |
19 "time" | |
18 ) | 20 ) |
19 | 21 |
20 var ( | 22 var ( |
21 ErrWriteTooLong = errors.New("archive/tar: write too long") | 23 ErrWriteTooLong = errors.New("archive/tar: write too long") |
22 ErrFieldTooLong = errors.New("archive/tar: header field too long") | 24 ErrFieldTooLong = errors.New("archive/tar: header field too long") |
23 ErrWriteAfterClose = errors.New("archive/tar: write after close") | 25 ErrWriteAfterClose = errors.New("archive/tar: write after close") |
26 errNameTooLong = errors.New("archive/tar: name too long") | |
24 ) | 27 ) |
25 | 28 |
26 // A Writer provides sequential writing of a tar archive in POSIX.1 format. | 29 // A Writer provides sequential writing of a tar archive in POSIX.1 format. |
27 // A tar archive consists of a sequence of files. | 30 // A tar archive consists of a sequence of files. |
28 // Call WriteHeader to begin a new file, and then call Write to supply that file 's data, | 31 // Call WriteHeader to begin a new file, and then call Write to supply that file 's data, |
29 // writing at most hdr.Size bytes in total. | 32 // writing at most hdr.Size bytes in total. |
30 // | |
31 // Example: | |
32 // tw := tar.NewWriter(w) | |
33 // hdr := new(tar.Header) | |
34 // hdr.Size = length of data in bytes | |
35 // // populate other hdr fields as desired | |
36 // if err := tw.WriteHeader(hdr); err != nil { | |
37 // // handle error | |
38 // } | |
39 // io.Copy(tw, data) | |
40 // tw.Close() | |
41 type Writer struct { | 33 type Writer struct { |
42 w io.Writer | 34 w io.Writer |
43 err error | 35 err error |
44 nb int64 // number of unwritten bytes for current file entry | 36 nb int64 // number of unwritten bytes for current file entry |
45 pad int64 // amount of padding to write after current file entry | 37 pad int64 // amount of padding to write after current file entry |
46 closed bool | 38 closed bool |
47 usedBinary bool // whether the binary numeric field extension was used | 39 usedBinary bool // whether the binary numeric field extension was used |
48 } | 40 } |
49 | 41 |
50 // NewWriter creates a new Writer writing to w. | 42 // NewWriter creates a new Writer writing to w. |
(...skipping 55 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... | |
106 } | 98 } |
107 // Too big: use binary (big-endian). | 99 // Too big: use binary (big-endian). |
108 tw.usedBinary = true | 100 tw.usedBinary = true |
109 for i := len(b) - 1; x > 0 && i >= 0; i-- { | 101 for i := len(b) - 1; x > 0 && i >= 0; i-- { |
110 b[i] = byte(x) | 102 b[i] = byte(x) |
111 x >>= 8 | 103 x >>= 8 |
112 } | 104 } |
113 b[0] |= 0x80 // highest bit indicates binary format | 105 b[0] |= 0x80 // highest bit indicates binary format |
114 } | 106 } |
115 | 107 |
108 var ( | |
109 minTime = time.Unix(0, 0) | |
110 // There is room for 11 octal digits (33 bits) of mtime. | |
111 maxTime = minTime.Add((1<<33 - 1) * time.Second) | |
112 ) | |
113 | |
116 // WriteHeader writes hdr and prepares to accept the file's contents. | 114 // WriteHeader writes hdr and prepares to accept the file's contents. |
117 // WriteHeader calls Flush if it is not the first header. | 115 // WriteHeader calls Flush if it is not the first header. |
118 // Calling after a Close will return ErrWriteAfterClose. | 116 // Calling after a Close will return ErrWriteAfterClose. |
119 func (tw *Writer) WriteHeader(hdr *Header) error { | 117 func (tw *Writer) WriteHeader(hdr *Header) error { |
120 if tw.closed { | 118 if tw.closed { |
121 return ErrWriteAfterClose | 119 return ErrWriteAfterClose |
122 } | 120 } |
123 if tw.err == nil { | 121 if tw.err == nil { |
124 tw.Flush() | 122 tw.Flush() |
125 } | 123 } |
126 if tw.err != nil { | 124 if tw.err != nil { |
127 return tw.err | 125 return tw.err |
128 } | 126 } |
129 // Decide whether or not to use PAX extensions | 127 // Decide whether or not to use PAX extensions |
130 // TODO(shanemhansen): we might want to use PAX headers for | 128 // TODO(shanemhansen): we might want to use PAX headers for |
131 // subsecond time resolution, but for now let's just capture | 129 // subsecond time resolution, but for now let's just capture |
132 // the long name/long symlink use case. | 130 // the long name/long symlink use case. |
133 » if len(hdr.Name) > 100 || len(hdr.Linkname) > 100 { | 131 » suffix := hdr.Name |
134 » » if err := tw.writePAXHeader(hdr); err != nil { | 132 » prefix := "" |
133 » if len(hdr.Name) > fileNameSize || len(hdr.Linkname) > fileNameSize { | |
134 » » var err error | |
135 » » prefix, suffix, err = tw.splitUSTARLongName(hdr.Name) | |
136 » » // Either we were unable to pack the long name into ustar format | |
137 » » // or the link name is too long; use PAX headers. | |
138 » » if err == errNameTooLong || len(hdr.Linkname) > fileNameSize { | |
139 » » » if err := tw.writePAXHeader(hdr); err != nil { | |
140 » » » » return err | |
141 » » » } | |
142 » » } else if err != nil { | |
135 return err | 143 return err |
136 } | 144 } |
137 } | 145 } |
138 tw.nb = int64(hdr.Size) | 146 tw.nb = int64(hdr.Size) |
139 tw.pad = -tw.nb & (blockSize - 1) // blockSize is a power of two | 147 tw.pad = -tw.nb & (blockSize - 1) // blockSize is a power of two |
140 | 148 |
141 header := make([]byte, blockSize) | 149 header := make([]byte, blockSize) |
142 s := slicer(header) | 150 s := slicer(header) |
143 » copy(s.next(100), []byte(hdr.Name)) | 151 » tw.cString(s.next(fileNameSize), suffix) |
144 | 152 |
145 » tw.octal(s.next(8), hdr.Mode) // 100:108 | 153 » // Handle out of range ModTime carefully. |
146 » tw.numeric(s.next(8), int64(hdr.Uid)) // 108:116 | 154 » var modTime int64 |
147 » tw.numeric(s.next(8), int64(hdr.Gid)) // 116:124 | 155 » if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) { |
148 » tw.numeric(s.next(12), hdr.Size) // 124:136 | 156 » » modTime = hdr.ModTime.Unix() |
149 » tw.numeric(s.next(12), hdr.ModTime.Unix()) // 136:148 | 157 » } |
150 » s.next(8) // chksum (148:156) | 158 |
151 » s.next(1)[0] = hdr.Typeflag // 156:157 | 159 » tw.octal(s.next(8), hdr.Mode) // 100:108 |
152 » tw.cString(s.next(100), hdr.Linkname) // linkname (157:257) | 160 » tw.numeric(s.next(8), int64(hdr.Uid)) // 108:116 |
153 » copy(s.next(8), []byte("ustar\x0000")) // 257:265 | 161 » tw.numeric(s.next(8), int64(hdr.Gid)) // 116:124 |
154 » tw.cString(s.next(32), hdr.Uname) // 265:297 | 162 » tw.numeric(s.next(12), hdr.Size) // 124:136 |
155 » tw.cString(s.next(32), hdr.Gname) // 297:329 | 163 » tw.numeric(s.next(12), modTime) // 136:148 |
156 » tw.numeric(s.next(8), hdr.Devmajor) // 329:337 | 164 » s.next(8) // chksum (148:156) |
157 » tw.numeric(s.next(8), hdr.Devminor) // 337:345 | 165 » s.next(1)[0] = hdr.Typeflag // 156:157 |
158 | 166 » tw.cString(s.next(100), hdr.Linkname) // linkname (157:257) |
167 » copy(s.next(8), []byte("ustar\x0000")) // 257:265 | |
168 » tw.cString(s.next(32), hdr.Uname) // 265:297 | |
169 » tw.cString(s.next(32), hdr.Gname) // 297:329 | |
170 » tw.numeric(s.next(8), hdr.Devmajor) // 329:337 | |
171 » tw.numeric(s.next(8), hdr.Devminor) // 337:345 | |
172 » tw.cString(s.next(155), prefix) // 345:500 | |
159 // Use the GNU magic instead of POSIX magic if we used any GNU extension s. | 173 // Use the GNU magic instead of POSIX magic if we used any GNU extension s. |
160 if tw.usedBinary { | 174 if tw.usedBinary { |
161 copy(header[257:265], []byte("ustar \x00")) | 175 copy(header[257:265], []byte("ustar \x00")) |
176 } | |
177 // Use the ustar magic if we used ustar long names. | |
178 if len(prefix) > 0 { | |
179 copy(header[257:265], []byte("ustar\000")) | |
162 } | 180 } |
163 | 181 |
164 // The chksum field is terminated by a NUL and a space. | 182 // The chksum field is terminated by a NUL and a space. |
165 // This is different from the other octal fields. | 183 // This is different from the other octal fields. |
166 chksum, _ := checksum(header) | 184 chksum, _ := checksum(header) |
167 tw.octal(header[148:155], chksum) | 185 tw.octal(header[148:155], chksum) |
168 header[155] = ' ' | 186 header[155] = ' ' |
169 | 187 |
170 if tw.err != nil { | 188 if tw.err != nil { |
171 // problem with header; probably integer too big for a field. | 189 // problem with header; probably integer too big for a field. |
172 return tw.err | 190 return tw.err |
173 } | 191 } |
174 | 192 |
175 _, tw.err = tw.w.Write(header) | 193 _, tw.err = tw.w.Write(header) |
176 | 194 |
177 return tw.err | 195 return tw.err |
178 } | 196 } |
179 | 197 |
198 // writeUSTARLongName splits a USTAR long name hdr.Name. | |
199 // name must be < 256 characters. errNameTooLong is returned | |
200 // if hdr.Name can't be split. The splitting heuristic | |
201 // is compatible with gnu tar. | |
202 func (tw *Writer) splitUSTARLongName(name string) (prefix, suffix string, err er ror) { | |
203 length := len(name) | |
204 if length > fileNamePrefixSize+1 { | |
205 length = fileNamePrefixSize + 1 | |
206 } else if name[length-1] == '/' { | |
207 length-- | |
208 } | |
209 i := strings.LastIndex(name[:length], "/") | |
210 nlen := length - i - 1 | |
211 if i <= 0 || nlen > fileNameSize || nlen == 0 { | |
212 err = errNameTooLong | |
213 return | |
214 } | |
215 prefix, suffix = name[:i], name[i+1:] | |
216 return | |
217 } | |
218 | |
180 // writePaxHeader writes an extended pax header to the | 219 // writePaxHeader writes an extended pax header to the |
181 // archive. | 220 // archive. |
182 func (tw *Writer) writePAXHeader(hdr *Header) error { | 221 func (tw *Writer) writePAXHeader(hdr *Header) error { |
183 // Prepare extended header | 222 // Prepare extended header |
184 » extendedHdr := new(Header) | 223 » ext := new(Header) |
dsymonds
2012/10/31 12:16:25
extendedHdr -> ext
| |
185 » extendedHdr.Typeflag = TypeXHeader | 224 » ext.Typeflag = TypeXHeader |
186 // Setting ModTime is required for reader parsing to | 225 // Setting ModTime is required for reader parsing to |
187 // succeed, and seems harmless enough. | 226 // succeed, and seems harmless enough. |
188 » extendedHdr.ModTime = hdr.ModTime | 227 » ext.ModTime = hdr.ModTime |
189 » // The spec asks that we namespace our psuedo files | 228 » // The spec asks that we namespace our pseudo files |
dsymonds
2012/10/31 12:16:25
"pseudo"
| |
190 // with the current pid. | 229 // with the current pid. |
191 pid := os.Getpid() | 230 pid := os.Getpid() |
192 » dir, file := filepath.Split(hdr.Name) | 231 » dir, file := path.Split(hdr.Name) |
193 » extendedHdr.Name = filepath.Join(dir, | 232 » ext.Name = path.Join(dir, |
194 fmt.Sprintf("PaxHeaders.%d", pid), file)[0:100] | 233 fmt.Sprintf("PaxHeaders.%d", pid), file)[0:100] |
195 // Construct the body | 234 // Construct the body |
196 var buf bytes.Buffer | 235 var buf bytes.Buffer |
197 » if len(hdr.Name) > 100 { | 236 » if len(hdr.Name) > fileNameSize { |
198 » » msg := fmt.Sprintf(" path=%s\n", hdr.Name) | 237 » » fmt.Fprint(&buf, paxHeader("path="+hdr.Name)) |
199 » » size := len(msg) + 1 | 238 » } |
200 » » length := string(size) | 239 » if len(hdr.Linkname) > fileNameSize { |
201 » » size += len(length) | 240 » » fmt.Fprint(&buf, paxHeader("linkpath="+hdr.Linkname)) |
202 » » fmt.Fprintf(&buf, "%d%s", size, msg) | 241 » } |
dsymonds
2012/10/31 12:16:25
I am confused by this construction. Shouldn't it b
shanemhansen
2012/11/01 02:40:57
The pax standard is weird here. It states that the
| |
203 » } | 242 » ext.Size = int64(len(buf.Bytes())) |
204 » if len(hdr.Linkname) > 100 { | 243 » if err := tw.WriteHeader(ext); err != nil { |
205 » » msg := fmt.Sprintf(" linkpath=%s\n", hdr.Name) | |
206 » » size := len(msg) + 1 | |
207 » » length := string(size) | |
208 » » size += len(length) | |
209 » » fmt.Fprintf(&buf, "%d%s", size, msg) | |
210 » } | |
211 » extendedHdr.Size = int64(len(buf.Bytes())) | |
212 » err := tw.WriteHeader(extendedHdr) | |
dsymonds
2012/10/31 12:16:25
snuggle these where possible.
if err := tw.Write
shanemhansen
2012/11/01 02:40:57
Done.
| |
213 » if err != nil { | |
214 return err | 244 return err |
215 } | 245 } |
216 » _, err = tw.Write(buf.Bytes()) | 246 » if _, err := tw.Write(buf.Bytes()); err != nil { |
217 » if err != nil { | |
218 return err | 247 return err |
219 } | 248 } |
220 » err = tw.Flush() | 249 » if err := tw.Flush(); err != nil { |
221 » if err != nil { | |
222 return err | 250 return err |
223 } | 251 } |
224 return nil | 252 return nil |
253 } | |
254 | |
255 // paxHeader formats a single pax record, prefixing it with the appropriate leng th | |
256 func paxHeader(msg string) string { | |
257 const padding = 2 // Extra padding for space and newline | |
258 size := len(msg) + padding | |
259 size += len(strconv.Itoa(size)) | |
260 record := fmt.Sprintf("%d %s\n", size, msg) | |
261 if len(record) != size { | |
262 // Final adjustment if adding size increased | |
263 // the number of digits in size | |
264 size = len(record) | |
265 record = fmt.Sprintf("%d %s\n", size, msg) | |
266 } | |
267 return record | |
225 } | 268 } |
226 | 269 |
227 // Write writes to the current entry in the tar archive. | 270 // Write writes to the current entry in the tar archive. |
228 // Write returns the error ErrWriteTooLong if more than | 271 // Write returns the error ErrWriteTooLong if more than |
229 // hdr.Size bytes are written after WriteHeader. | 272 // hdr.Size bytes are written after WriteHeader. |
230 func (tw *Writer) Write(b []byte) (n int, err error) { | 273 func (tw *Writer) Write(b []byte) (n int, err error) { |
231 if tw.closed { | 274 if tw.closed { |
232 err = ErrWriteTooLong | 275 err = ErrWriteTooLong |
233 return | 276 return |
234 } | 277 } |
(...skipping 26 matching lines...) Expand all Loading... | |
261 | 304 |
262 // trailer: two zero blocks | 305 // trailer: two zero blocks |
263 for i := 0; i < 2; i++ { | 306 for i := 0; i < 2; i++ { |
264 _, tw.err = tw.w.Write(zeroBlock) | 307 _, tw.err = tw.w.Write(zeroBlock) |
265 if tw.err != nil { | 308 if tw.err != nil { |
266 break | 309 break |
267 } | 310 } |
268 } | 311 } |
269 return tw.err | 312 return tw.err |
270 } | 313 } |
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