9e052883 |
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 | #include "zfstream.h" |
11 | #include <cstring> // for strcpy, strcat, strlen (mode strings) |
12 | #include <cstdio> // for BUFSIZ |
13 | |
14 | // Internal buffer sizes (default and "unbuffered" versions) |
15 | #define BIGBUFSIZE BUFSIZ |
16 | #define SMALLBUFSIZE 1 |
17 | |
18 | /*****************************************************************************/ |
19 | |
20 | // Default constructor |
21 | gzfilebuf::gzfilebuf() |
22 | : file(NULL), io_mode(std::ios_base::openmode(0)), own_fd(false), |
23 | buffer(NULL), buffer_size(BIGBUFSIZE), own_buffer(true) |
24 | { |
25 | // No buffers to start with |
26 | this->disable_buffer(); |
27 | } |
28 | |
29 | // Destructor |
30 | gzfilebuf::~gzfilebuf() |
31 | { |
32 | // Sync output buffer and close only if responsible for file |
33 | // (i.e. attached streams should be left open at this stage) |
34 | this->sync(); |
35 | if (own_fd) |
36 | this->close(); |
37 | // Make sure internal buffer is deallocated |
38 | this->disable_buffer(); |
39 | } |
40 | |
41 | // Set compression level and strategy |
42 | int |
43 | gzfilebuf::setcompression(int comp_level, |
44 | int comp_strategy) |
45 | { |
46 | return gzsetparams(file, comp_level, comp_strategy); |
47 | } |
48 | |
49 | // Open gzipped file |
50 | gzfilebuf* |
51 | gzfilebuf::open(const char *name, |
52 | std::ios_base::openmode mode) |
53 | { |
54 | // Fail if file already open |
55 | if (this->is_open()) |
56 | return NULL; |
57 | // Don't support simultaneous read/write access (yet) |
58 | if ((mode & std::ios_base::in) && (mode & std::ios_base::out)) |
59 | return NULL; |
60 | |
61 | // Build mode string for gzopen and check it [27.8.1.3.2] |
62 | char char_mode[6] = "\0\0\0\0\0"; |
63 | if (!this->open_mode(mode, char_mode)) |
64 | return NULL; |
65 | |
66 | // Attempt to open file |
67 | if ((file = gzopen(name, char_mode)) == NULL) |
68 | return NULL; |
69 | |
70 | // On success, allocate internal buffer and set flags |
71 | this->enable_buffer(); |
72 | io_mode = mode; |
73 | own_fd = true; |
74 | return this; |
75 | } |
76 | |
77 | // Attach to gzipped file |
78 | gzfilebuf* |
79 | gzfilebuf::attach(int fd, |
80 | std::ios_base::openmode mode) |
81 | { |
82 | // Fail if file already open |
83 | if (this->is_open()) |
84 | return NULL; |
85 | // Don't support simultaneous read/write access (yet) |
86 | if ((mode & std::ios_base::in) && (mode & std::ios_base::out)) |
87 | return NULL; |
88 | |
89 | // Build mode string for gzdopen and check it [27.8.1.3.2] |
90 | char char_mode[6] = "\0\0\0\0\0"; |
91 | if (!this->open_mode(mode, char_mode)) |
92 | return NULL; |
93 | |
94 | // Attempt to attach to file |
95 | if ((file = gzdopen(fd, char_mode)) == NULL) |
96 | return NULL; |
97 | |
98 | // On success, allocate internal buffer and set flags |
99 | this->enable_buffer(); |
100 | io_mode = mode; |
101 | own_fd = false; |
102 | return this; |
103 | } |
104 | |
105 | // Close gzipped file |
106 | gzfilebuf* |
107 | gzfilebuf::close() |
108 | { |
109 | // Fail immediately if no file is open |
110 | if (!this->is_open()) |
111 | return NULL; |
112 | // Assume success |
113 | gzfilebuf* retval = this; |
114 | // Attempt to sync and close gzipped file |
115 | if (this->sync() == -1) |
116 | retval = NULL; |
117 | if (gzclose(file) < 0) |
118 | retval = NULL; |
119 | // File is now gone anyway (postcondition [27.8.1.3.8]) |
120 | file = NULL; |
121 | own_fd = false; |
122 | // Destroy internal buffer if it exists |
123 | this->disable_buffer(); |
124 | return retval; |
125 | } |
126 | |
127 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
128 | |
129 | // Convert int open mode to mode string |
130 | bool |
131 | gzfilebuf::open_mode(std::ios_base::openmode mode, |
132 | char* c_mode) const |
133 | { |
134 | bool testb = mode & std::ios_base::binary; |
135 | bool testi = mode & std::ios_base::in; |
136 | bool testo = mode & std::ios_base::out; |
137 | bool testt = mode & std::ios_base::trunc; |
138 | bool testa = mode & std::ios_base::app; |
139 | |
140 | // Check for valid flag combinations - see [27.8.1.3.2] (Table 92) |
141 | // Original zfstream hardcoded the compression level to maximum here... |
142 | // Double the time for less than 1% size improvement seems |
143 | // excessive though - keeping it at the default level |
144 | // To change back, just append "9" to the next three mode strings |
145 | if (!testi && testo && !testt && !testa) |
146 | strcpy(c_mode, "w"); |
147 | if (!testi && testo && !testt && testa) |
148 | strcpy(c_mode, "a"); |
149 | if (!testi && testo && testt && !testa) |
150 | strcpy(c_mode, "w"); |
151 | if (testi && !testo && !testt && !testa) |
152 | strcpy(c_mode, "r"); |
153 | // No read/write mode yet |
154 | // if (testi && testo && !testt && !testa) |
155 | // strcpy(c_mode, "r+"); |
156 | // if (testi && testo && testt && !testa) |
157 | // strcpy(c_mode, "w+"); |
158 | |
159 | // Mode string should be empty for invalid combination of flags |
160 | if (strlen(c_mode) == 0) |
161 | return false; |
162 | if (testb) |
163 | strcat(c_mode, "b"); |
164 | return true; |
165 | } |
166 | |
167 | // Determine number of characters in internal get buffer |
168 | std::streamsize |
169 | gzfilebuf::showmanyc() |
170 | { |
171 | // Calls to underflow will fail if file not opened for reading |
172 | if (!this->is_open() || !(io_mode & std::ios_base::in)) |
173 | return -1; |
174 | // Make sure get area is in use |
175 | if (this->gptr() && (this->gptr() < this->egptr())) |
176 | return std::streamsize(this->egptr() - this->gptr()); |
177 | else |
178 | return 0; |
179 | } |
180 | |
181 | // Fill get area from gzipped file |
182 | gzfilebuf::int_type |
183 | gzfilebuf::underflow() |
184 | { |
185 | // If something is left in the get area by chance, return it |
186 | // (this shouldn't normally happen, as underflow is only supposed |
187 | // to be called when gptr >= egptr, but it serves as error check) |
188 | if (this->gptr() && (this->gptr() < this->egptr())) |
189 | return traits_type::to_int_type(*(this->gptr())); |
190 | |
191 | // If the file hasn't been opened for reading, produce error |
192 | if (!this->is_open() || !(io_mode & std::ios_base::in)) |
193 | return traits_type::eof(); |
194 | |
195 | // Attempt to fill internal buffer from gzipped file |
196 | // (buffer must be guaranteed to exist...) |
197 | int bytes_read = gzread(file, buffer, buffer_size); |
198 | // Indicates error or EOF |
199 | if (bytes_read <= 0) |
200 | { |
201 | // Reset get area |
202 | this->setg(buffer, buffer, buffer); |
203 | return traits_type::eof(); |
204 | } |
205 | // Make all bytes read from file available as get area |
206 | this->setg(buffer, buffer, buffer + bytes_read); |
207 | |
208 | // Return next character in get area |
209 | return traits_type::to_int_type(*(this->gptr())); |
210 | } |
211 | |
212 | // Write put area to gzipped file |
213 | gzfilebuf::int_type |
214 | gzfilebuf::overflow(int_type c) |
215 | { |
216 | // Determine whether put area is in use |
217 | if (this->pbase()) |
218 | { |
219 | // Double-check pointer range |
220 | if (this->pptr() > this->epptr() || this->pptr() < this->pbase()) |
221 | return traits_type::eof(); |
222 | // Add extra character to buffer if not EOF |
223 | if (!traits_type::eq_int_type(c, traits_type::eof())) |
224 | { |
225 | *(this->pptr()) = traits_type::to_char_type(c); |
226 | this->pbump(1); |
227 | } |
228 | // Number of characters to write to file |
229 | int bytes_to_write = this->pptr() - this->pbase(); |
230 | // Overflow doesn't fail if nothing is to be written |
231 | if (bytes_to_write > 0) |
232 | { |
233 | // If the file hasn't been opened for writing, produce error |
234 | if (!this->is_open() || !(io_mode & std::ios_base::out)) |
235 | return traits_type::eof(); |
236 | // If gzipped file won't accept all bytes written to it, fail |
237 | if (gzwrite(file, this->pbase(), bytes_to_write) != bytes_to_write) |
238 | return traits_type::eof(); |
239 | // Reset next pointer to point to pbase on success |
240 | this->pbump(-bytes_to_write); |
241 | } |
242 | } |
243 | // Write extra character to file if not EOF |
244 | else if (!traits_type::eq_int_type(c, traits_type::eof())) |
245 | { |
246 | // If the file hasn't been opened for writing, produce error |
247 | if (!this->is_open() || !(io_mode & std::ios_base::out)) |
248 | return traits_type::eof(); |
249 | // Impromptu char buffer (allows "unbuffered" output) |
250 | char_type last_char = traits_type::to_char_type(c); |
251 | // If gzipped file won't accept this character, fail |
252 | if (gzwrite(file, &last_char, 1) != 1) |
253 | return traits_type::eof(); |
254 | } |
255 | |
256 | // If you got here, you have succeeded (even if c was EOF) |
257 | // The return value should therefore be non-EOF |
258 | if (traits_type::eq_int_type(c, traits_type::eof())) |
259 | return traits_type::not_eof(c); |
260 | else |
261 | return c; |
262 | } |
263 | |
264 | // Assign new buffer |
265 | std::streambuf* |
266 | gzfilebuf::setbuf(char_type* p, |
267 | std::streamsize n) |
268 | { |
269 | // First make sure stuff is sync'ed, for safety |
270 | if (this->sync() == -1) |
271 | return NULL; |
272 | // If buffering is turned off on purpose via setbuf(0,0), still allocate one... |
273 | // "Unbuffered" only really refers to put [27.8.1.4.10], while get needs at |
274 | // least a buffer of size 1 (very inefficient though, therefore make it bigger?) |
275 | // This follows from [27.5.2.4.3]/12 (gptr needs to point at something, it seems) |
276 | if (!p || !n) |
277 | { |
278 | // Replace existing buffer (if any) with small internal buffer |
279 | this->disable_buffer(); |
280 | buffer = NULL; |
281 | buffer_size = 0; |
282 | own_buffer = true; |
283 | this->enable_buffer(); |
284 | } |
285 | else |
286 | { |
287 | // Replace existing buffer (if any) with external buffer |
288 | this->disable_buffer(); |
289 | buffer = p; |
290 | buffer_size = n; |
291 | own_buffer = false; |
292 | this->enable_buffer(); |
293 | } |
294 | return this; |
295 | } |
296 | |
297 | // Write put area to gzipped file (i.e. ensures that put area is empty) |
298 | int |
299 | gzfilebuf::sync() |
300 | { |
301 | return traits_type::eq_int_type(this->overflow(), traits_type::eof()) ? -1 : 0; |
302 | } |
303 | |
304 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
305 | |
306 | // Allocate internal buffer |
307 | void |
308 | gzfilebuf::enable_buffer() |
309 | { |
310 | // If internal buffer required, allocate one |
311 | if (own_buffer && !buffer) |
312 | { |
313 | // Check for buffered vs. "unbuffered" |
314 | if (buffer_size > 0) |
315 | { |
316 | // Allocate internal buffer |
317 | buffer = new char_type[buffer_size]; |
318 | // Get area starts empty and will be expanded by underflow as need arises |
319 | this->setg(buffer, buffer, buffer); |
320 | // Setup entire internal buffer as put area. |
321 | // The one-past-end pointer actually points to the last element of the buffer, |
322 | // so that overflow(c) can safely add the extra character c to the sequence. |
323 | // These pointers remain in place for the duration of the buffer |
324 | this->setp(buffer, buffer + buffer_size - 1); |
325 | } |
326 | else |
327 | { |
328 | // Even in "unbuffered" case, (small?) get buffer is still required |
329 | buffer_size = SMALLBUFSIZE; |
330 | buffer = new char_type[buffer_size]; |
331 | this->setg(buffer, buffer, buffer); |
332 | // "Unbuffered" means no put buffer |
333 | this->setp(0, 0); |
334 | } |
335 | } |
336 | else |
337 | { |
338 | // If buffer already allocated, reset buffer pointers just to make sure no |
339 | // stale chars are lying around |
340 | this->setg(buffer, buffer, buffer); |
341 | this->setp(buffer, buffer + buffer_size - 1); |
342 | } |
343 | } |
344 | |
345 | // Destroy internal buffer |
346 | void |
347 | gzfilebuf::disable_buffer() |
348 | { |
349 | // If internal buffer exists, deallocate it |
350 | if (own_buffer && buffer) |
351 | { |
352 | // Preserve unbuffered status by zeroing size |
353 | if (!this->pbase()) |
354 | buffer_size = 0; |
355 | delete[] buffer; |
356 | buffer = NULL; |
357 | this->setg(0, 0, 0); |
358 | this->setp(0, 0); |
359 | } |
360 | else |
361 | { |
362 | // Reset buffer pointers to initial state if external buffer exists |
363 | this->setg(buffer, buffer, buffer); |
364 | if (buffer) |
365 | this->setp(buffer, buffer + buffer_size - 1); |
366 | else |
367 | this->setp(0, 0); |
368 | } |
369 | } |
370 | |
371 | /*****************************************************************************/ |
372 | |
373 | // Default constructor initializes stream buffer |
374 | gzifstream::gzifstream() |
375 | : std::istream(NULL), sb() |
376 | { this->init(&sb); } |
377 | |
378 | // Initialize stream buffer and open file |
379 | gzifstream::gzifstream(const char* name, |
380 | std::ios_base::openmode mode) |
381 | : std::istream(NULL), sb() |
382 | { |
383 | this->init(&sb); |
384 | this->open(name, mode); |
385 | } |
386 | |
387 | // Initialize stream buffer and attach to file |
388 | gzifstream::gzifstream(int fd, |
389 | std::ios_base::openmode mode) |
390 | : std::istream(NULL), sb() |
391 | { |
392 | this->init(&sb); |
393 | this->attach(fd, mode); |
394 | } |
395 | |
396 | // Open file and go into fail() state if unsuccessful |
397 | void |
398 | gzifstream::open(const char* name, |
399 | std::ios_base::openmode mode) |
400 | { |
401 | if (!sb.open(name, mode | std::ios_base::in)) |
402 | this->setstate(std::ios_base::failbit); |
403 | else |
404 | this->clear(); |
405 | } |
406 | |
407 | // Attach to file and go into fail() state if unsuccessful |
408 | void |
409 | gzifstream::attach(int fd, |
410 | std::ios_base::openmode mode) |
411 | { |
412 | if (!sb.attach(fd, mode | std::ios_base::in)) |
413 | this->setstate(std::ios_base::failbit); |
414 | else |
415 | this->clear(); |
416 | } |
417 | |
418 | // Close file |
419 | void |
420 | gzifstream::close() |
421 | { |
422 | if (!sb.close()) |
423 | this->setstate(std::ios_base::failbit); |
424 | } |
425 | |
426 | /*****************************************************************************/ |
427 | |
428 | // Default constructor initializes stream buffer |
429 | gzofstream::gzofstream() |
430 | : std::ostream(NULL), sb() |
431 | { this->init(&sb); } |
432 | |
433 | // Initialize stream buffer and open file |
434 | gzofstream::gzofstream(const char* name, |
435 | std::ios_base::openmode mode) |
436 | : std::ostream(NULL), sb() |
437 | { |
438 | this->init(&sb); |
439 | this->open(name, mode); |
440 | } |
441 | |
442 | // Initialize stream buffer and attach to file |
443 | gzofstream::gzofstream(int fd, |
444 | std::ios_base::openmode mode) |
445 | : std::ostream(NULL), sb() |
446 | { |
447 | this->init(&sb); |
448 | this->attach(fd, mode); |
449 | } |
450 | |
451 | // Open file and go into fail() state if unsuccessful |
452 | void |
453 | gzofstream::open(const char* name, |
454 | std::ios_base::openmode mode) |
455 | { |
456 | if (!sb.open(name, mode | std::ios_base::out)) |
457 | this->setstate(std::ios_base::failbit); |
458 | else |
459 | this->clear(); |
460 | } |
461 | |
462 | // Attach to file and go into fail() state if unsuccessful |
463 | void |
464 | gzofstream::attach(int fd, |
465 | std::ios_base::openmode mode) |
466 | { |
467 | if (!sb.attach(fd, mode | std::ios_base::out)) |
468 | this->setstate(std::ios_base::failbit); |
469 | else |
470 | this->clear(); |
471 | } |
472 | |
473 | // Close file |
474 | void |
475 | gzofstream::close() |
476 | { |
477 | if (!sb.close()) |
478 | this->setstate(std::ios_base::failbit); |
479 | } |