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1 | /* |
2 | * A C++ I/O streams interface to the zlib gz* functions |
3 | * |
4 | * by Ludwig Schwardt <schwardt@sun.ac.za> |
5 | * original version by Kevin Ruland <kevin@rodin.wustl.edu> |
6 | * |
7 | * This version is standard-compliant and compatible with gcc 3.x. |
8 | */ |
9 | |
10 | #ifndef ZFSTREAM_H |
11 | #define ZFSTREAM_H |
12 | |
13 | #include <istream> // not iostream, since we don't need cin/cout |
14 | #include <ostream> |
15 | #include "zlib.h" |
16 | |
17 | /*****************************************************************************/ |
18 | |
19 | /** |
20 | * @brief Gzipped file stream buffer class. |
21 | * |
22 | * This class implements basic_filebuf for gzipped files. It doesn't yet support |
23 | * seeking (allowed by zlib but slow/limited), putback and read/write access |
24 | * (tricky). Otherwise, it attempts to be a drop-in replacement for the standard |
25 | * file streambuf. |
26 | */ |
27 | class gzfilebuf : public std::streambuf |
28 | { |
29 | public: |
30 | // Default constructor. |
31 | gzfilebuf(); |
32 | |
33 | // Destructor. |
34 | virtual |
35 | ~gzfilebuf(); |
36 | |
37 | /** |
38 | * @brief Set compression level and strategy on the fly. |
39 | * @param comp_level Compression level (see zlib.h for allowed values) |
40 | * @param comp_strategy Compression strategy (see zlib.h for allowed values) |
41 | * @return Z_OK on success, Z_STREAM_ERROR otherwise. |
42 | * |
43 | * Unfortunately, these parameters cannot be modified separately, as the |
44 | * previous zfstream version assumed. Since the strategy is seldom changed, |
45 | * it can default and setcompression(level) then becomes like the old |
46 | * setcompressionlevel(level). |
47 | */ |
48 | int |
49 | setcompression(int comp_level, |
50 | int comp_strategy = Z_DEFAULT_STRATEGY); |
51 | |
52 | /** |
53 | * @brief Check if file is open. |
54 | * @return True if file is open. |
55 | */ |
56 | bool |
57 | is_open() const { return (file != NULL); } |
58 | |
59 | /** |
60 | * @brief Open gzipped file. |
61 | * @param name File name. |
62 | * @param mode Open mode flags. |
63 | * @return @c this on success, NULL on failure. |
64 | */ |
65 | gzfilebuf* |
66 | open(const char* name, |
67 | std::ios_base::openmode mode); |
68 | |
69 | /** |
70 | * @brief Attach to already open gzipped file. |
71 | * @param fd File descriptor. |
72 | * @param mode Open mode flags. |
73 | * @return @c this on success, NULL on failure. |
74 | */ |
75 | gzfilebuf* |
76 | attach(int fd, |
77 | std::ios_base::openmode mode); |
78 | |
79 | /** |
80 | * @brief Close gzipped file. |
81 | * @return @c this on success, NULL on failure. |
82 | */ |
83 | gzfilebuf* |
84 | close(); |
85 | |
86 | protected: |
87 | /** |
88 | * @brief Convert ios open mode int to mode string used by zlib. |
89 | * @return True if valid mode flag combination. |
90 | */ |
91 | bool |
92 | open_mode(std::ios_base::openmode mode, |
93 | char* c_mode) const; |
94 | |
95 | /** |
96 | * @brief Number of characters available in stream buffer. |
97 | * @return Number of characters. |
98 | * |
99 | * This indicates number of characters in get area of stream buffer. |
100 | * These characters can be read without accessing the gzipped file. |
101 | */ |
102 | virtual std::streamsize |
103 | showmanyc(); |
104 | |
105 | /** |
106 | * @brief Fill get area from gzipped file. |
107 | * @return First character in get area on success, EOF on error. |
108 | * |
109 | * This actually reads characters from gzipped file to stream |
110 | * buffer. Always buffered. |
111 | */ |
112 | virtual int_type |
113 | underflow(); |
114 | |
115 | /** |
116 | * @brief Write put area to gzipped file. |
117 | * @param c Extra character to add to buffer contents. |
118 | * @return Non-EOF on success, EOF on error. |
119 | * |
120 | * This actually writes characters in stream buffer to |
121 | * gzipped file. With unbuffered output this is done one |
122 | * character at a time. |
123 | */ |
124 | virtual int_type |
125 | overflow(int_type c = traits_type::eof()); |
126 | |
127 | /** |
128 | * @brief Installs external stream buffer. |
129 | * @param p Pointer to char buffer. |
130 | * @param n Size of external buffer. |
131 | * @return @c this on success, NULL on failure. |
132 | * |
133 | * Call setbuf(0,0) to enable unbuffered output. |
134 | */ |
135 | virtual std::streambuf* |
136 | setbuf(char_type* p, |
137 | std::streamsize n); |
138 | |
139 | /** |
140 | * @brief Flush stream buffer to file. |
141 | * @return 0 on success, -1 on error. |
142 | * |
143 | * This calls underflow(EOF) to do the job. |
144 | */ |
145 | virtual int |
146 | sync(); |
147 | |
148 | // |
149 | // Some future enhancements |
150 | // |
151 | // virtual int_type uflow(); |
152 | // virtual int_type pbackfail(int_type c = traits_type::eof()); |
153 | // virtual pos_type |
154 | // seekoff(off_type off, |
155 | // std::ios_base::seekdir way, |
156 | // std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out); |
157 | // virtual pos_type |
158 | // seekpos(pos_type sp, |
159 | // std::ios_base::openmode mode = std::ios_base::in|std::ios_base::out); |
160 | |
161 | private: |
162 | /** |
163 | * @brief Allocate internal buffer. |
164 | * |
165 | * This function is safe to call multiple times. It will ensure |
166 | * that a proper internal buffer exists if it is required. If the |
167 | * buffer already exists or is external, the buffer pointers will be |
168 | * reset to their original state. |
169 | */ |
170 | void |
171 | enable_buffer(); |
172 | |
173 | /** |
174 | * @brief Destroy internal buffer. |
175 | * |
176 | * This function is safe to call multiple times. It will ensure |
177 | * that the internal buffer is deallocated if it exists. In any |
178 | * case, it will also reset the buffer pointers. |
179 | */ |
180 | void |
181 | disable_buffer(); |
182 | |
183 | /** |
184 | * Underlying file pointer. |
185 | */ |
186 | gzFile file; |
187 | |
188 | /** |
189 | * Mode in which file was opened. |
190 | */ |
191 | std::ios_base::openmode io_mode; |
192 | |
193 | /** |
194 | * @brief True if this object owns file descriptor. |
195 | * |
196 | * This makes the class responsible for closing the file |
197 | * upon destruction. |
198 | */ |
199 | bool own_fd; |
200 | |
201 | /** |
202 | * @brief Stream buffer. |
203 | * |
204 | * For simplicity this remains allocated on the free store for the |
205 | * entire life span of the gzfilebuf object, unless replaced by setbuf. |
206 | */ |
207 | char_type* buffer; |
208 | |
209 | /** |
210 | * @brief Stream buffer size. |
211 | * |
212 | * Defaults to system default buffer size (typically 8192 bytes). |
213 | * Modified by setbuf. |
214 | */ |
215 | std::streamsize buffer_size; |
216 | |
217 | /** |
218 | * @brief True if this object owns stream buffer. |
219 | * |
220 | * This makes the class responsible for deleting the buffer |
221 | * upon destruction. |
222 | */ |
223 | bool own_buffer; |
224 | }; |
225 | |
226 | /*****************************************************************************/ |
227 | |
228 | /** |
229 | * @brief Gzipped file input stream class. |
230 | * |
231 | * This class implements ifstream for gzipped files. Seeking and putback |
232 | * is not supported yet. |
233 | */ |
234 | class gzifstream : public std::istream |
235 | { |
236 | public: |
237 | // Default constructor |
238 | gzifstream(); |
239 | |
240 | /** |
241 | * @brief Construct stream on gzipped file to be opened. |
242 | * @param name File name. |
243 | * @param mode Open mode flags (forced to contain ios::in). |
244 | */ |
245 | explicit |
246 | gzifstream(const char* name, |
247 | std::ios_base::openmode mode = std::ios_base::in); |
248 | |
249 | /** |
250 | * @brief Construct stream on already open gzipped file. |
251 | * @param fd File descriptor. |
252 | * @param mode Open mode flags (forced to contain ios::in). |
253 | */ |
254 | explicit |
255 | gzifstream(int fd, |
256 | std::ios_base::openmode mode = std::ios_base::in); |
257 | |
258 | /** |
259 | * Obtain underlying stream buffer. |
260 | */ |
261 | gzfilebuf* |
262 | rdbuf() const |
263 | { return const_cast<gzfilebuf*>(&sb); } |
264 | |
265 | /** |
266 | * @brief Check if file is open. |
267 | * @return True if file is open. |
268 | */ |
269 | bool |
270 | is_open() { return sb.is_open(); } |
271 | |
272 | /** |
273 | * @brief Open gzipped file. |
274 | * @param name File name. |
275 | * @param mode Open mode flags (forced to contain ios::in). |
276 | * |
277 | * Stream will be in state good() if file opens successfully; |
278 | * otherwise in state fail(). This differs from the behavior of |
279 | * ifstream, which never sets the state to good() and therefore |
280 | * won't allow you to reuse the stream for a second file unless |
281 | * you manually clear() the state. The choice is a matter of |
282 | * convenience. |
283 | */ |
284 | void |
285 | open(const char* name, |
286 | std::ios_base::openmode mode = std::ios_base::in); |
287 | |
288 | /** |
289 | * @brief Attach to already open gzipped file. |
290 | * @param fd File descriptor. |
291 | * @param mode Open mode flags (forced to contain ios::in). |
292 | * |
293 | * Stream will be in state good() if attach succeeded; otherwise |
294 | * in state fail(). |
295 | */ |
296 | void |
297 | attach(int fd, |
298 | std::ios_base::openmode mode = std::ios_base::in); |
299 | |
300 | /** |
301 | * @brief Close gzipped file. |
302 | * |
303 | * Stream will be in state fail() if close failed. |
304 | */ |
305 | void |
306 | close(); |
307 | |
308 | private: |
309 | /** |
310 | * Underlying stream buffer. |
311 | */ |
312 | gzfilebuf sb; |
313 | }; |
314 | |
315 | /*****************************************************************************/ |
316 | |
317 | /** |
318 | * @brief Gzipped file output stream class. |
319 | * |
320 | * This class implements ofstream for gzipped files. Seeking and putback |
321 | * is not supported yet. |
322 | */ |
323 | class gzofstream : public std::ostream |
324 | { |
325 | public: |
326 | // Default constructor |
327 | gzofstream(); |
328 | |
329 | /** |
330 | * @brief Construct stream on gzipped file to be opened. |
331 | * @param name File name. |
332 | * @param mode Open mode flags (forced to contain ios::out). |
333 | */ |
334 | explicit |
335 | gzofstream(const char* name, |
336 | std::ios_base::openmode mode = std::ios_base::out); |
337 | |
338 | /** |
339 | * @brief Construct stream on already open gzipped file. |
340 | * @param fd File descriptor. |
341 | * @param mode Open mode flags (forced to contain ios::out). |
342 | */ |
343 | explicit |
344 | gzofstream(int fd, |
345 | std::ios_base::openmode mode = std::ios_base::out); |
346 | |
347 | /** |
348 | * Obtain underlying stream buffer. |
349 | */ |
350 | gzfilebuf* |
351 | rdbuf() const |
352 | { return const_cast<gzfilebuf*>(&sb); } |
353 | |
354 | /** |
355 | * @brief Check if file is open. |
356 | * @return True if file is open. |
357 | */ |
358 | bool |
359 | is_open() { return sb.is_open(); } |
360 | |
361 | /** |
362 | * @brief Open gzipped file. |
363 | * @param name File name. |
364 | * @param mode Open mode flags (forced to contain ios::out). |
365 | * |
366 | * Stream will be in state good() if file opens successfully; |
367 | * otherwise in state fail(). This differs from the behavior of |
368 | * ofstream, which never sets the state to good() and therefore |
369 | * won't allow you to reuse the stream for a second file unless |
370 | * you manually clear() the state. The choice is a matter of |
371 | * convenience. |
372 | */ |
373 | void |
374 | open(const char* name, |
375 | std::ios_base::openmode mode = std::ios_base::out); |
376 | |
377 | /** |
378 | * @brief Attach to already open gzipped file. |
379 | * @param fd File descriptor. |
380 | * @param mode Open mode flags (forced to contain ios::out). |
381 | * |
382 | * Stream will be in state good() if attach succeeded; otherwise |
383 | * in state fail(). |
384 | */ |
385 | void |
386 | attach(int fd, |
387 | std::ios_base::openmode mode = std::ios_base::out); |
388 | |
389 | /** |
390 | * @brief Close gzipped file. |
391 | * |
392 | * Stream will be in state fail() if close failed. |
393 | */ |
394 | void |
395 | close(); |
396 | |
397 | private: |
398 | /** |
399 | * Underlying stream buffer. |
400 | */ |
401 | gzfilebuf sb; |
402 | }; |
403 | |
404 | /*****************************************************************************/ |
405 | |
406 | /** |
407 | * @brief Gzipped file output stream manipulator class. |
408 | * |
409 | * This class defines a two-argument manipulator for gzofstream. It is used |
410 | * as base for the setcompression(int,int) manipulator. |
411 | */ |
412 | template<typename T1, typename T2> |
413 | class gzomanip2 |
414 | { |
415 | public: |
648db22b |
416 | // Allows inserter to peek at internals |
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417 | template <typename Ta, typename Tb> |
418 | friend gzofstream& |
419 | operator<<(gzofstream&, |
420 | const gzomanip2<Ta,Tb>&); |
421 | |
422 | // Constructor |
423 | gzomanip2(gzofstream& (*f)(gzofstream&, T1, T2), |
424 | T1 v1, |
425 | T2 v2); |
426 | private: |
427 | // Underlying manipulator function |
428 | gzofstream& |
429 | (*func)(gzofstream&, T1, T2); |
430 | |
431 | // Arguments for manipulator function |
432 | T1 val1; |
433 | T2 val2; |
434 | }; |
435 | |
436 | /*****************************************************************************/ |
437 | |
438 | // Manipulator function thunks through to stream buffer |
439 | inline gzofstream& |
440 | setcompression(gzofstream &gzs, int l, int s = Z_DEFAULT_STRATEGY) |
441 | { |
442 | (gzs.rdbuf())->setcompression(l, s); |
443 | return gzs; |
444 | } |
445 | |
446 | // Manipulator constructor stores arguments |
447 | template<typename T1, typename T2> |
448 | inline |
449 | gzomanip2<T1,T2>::gzomanip2(gzofstream &(*f)(gzofstream &, T1, T2), |
450 | T1 v1, |
451 | T2 v2) |
452 | : func(f), val1(v1), val2(v2) |
453 | { } |
454 | |
648db22b |
455 | // Inserter applies underlying manipulator function to stream |
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456 | template<typename T1, typename T2> |
457 | inline gzofstream& |
458 | operator<<(gzofstream& s, const gzomanip2<T1,T2>& m) |
459 | { return (*m.func)(s, m.val1, m.val2); } |
460 | |
461 | // Insert this onto stream to simplify setting of compression level |
462 | inline gzomanip2<int,int> |
463 | setcompression(int l, int s = Z_DEFAULT_STRATEGY) |
464 | { return gzomanip2<int,int>(&setcompression, l, s); } |
465 | |
466 | #endif // ZFSTREAM_H |