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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: | |
416 | // Allows insertor to peek at internals | |
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 | ||
455 | // Insertor applies underlying manipulator function to stream | |
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 |