aboutsummaryrefslogtreecommitdiff
path: root/common/stream.cpp
blob: 60b40d0df2b2db46181c6ece9c158d7df6b96fd2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include "common/stream.h"
#include "common/memstream.h"
#include "common/substream.h"
#include "common/str.h"

namespace Common {

void WriteStream::writeString(const String &str) {
	write(str.c_str(), str.size());
}

SeekableReadStream *ReadStream::readStream(uint32 dataSize) {
	void *buf = malloc(dataSize);
	dataSize = read(buf, dataSize);
	assert(dataSize > 0);
	return new MemoryReadStream((byte *)buf, dataSize, DisposeAfterUse::YES);
}


uint32 MemoryReadStream::read(void *dataPtr, uint32 dataSize) {
	// Read at most as many bytes as are still available...
	if (dataSize > _size - _pos) {
		dataSize = _size - _pos;
		_eos = true;
	}
	memcpy(dataPtr, _ptr, dataSize);

	_ptr += dataSize;
	_pos += dataSize;

	return dataSize;
}

bool MemoryReadStream::seek(int32 offs, int whence) {
	// Pre-Condition
	assert(_pos <= _size);
	switch (whence) {
	case SEEK_END:
		// SEEK_END works just like SEEK_SET, only 'reversed',
		// i.e. from the end.
		offs = _size + offs;
		// Fall through
	case SEEK_SET:
		_ptr = _ptrOrig + offs;
		_pos = offs;
		break;

	case SEEK_CUR:
		_ptr += offs;
		_pos += offs;
		break;
	}
	// Post-Condition
	assert(_pos <= _size);

	// Reset end-of-stream flag on a successful seek
	_eos = false;
	return true;	// FIXME: STREAM REWRITE
}

bool MemoryWriteStreamDynamic::seek(int32 offs, int whence) {
	// Pre-Condition
	assert(_pos <= _size);
	switch (whence) {
	case SEEK_END:
		// SEEK_END works just like SEEK_SET, only 'reversed',
		// i.e. from the end.
		offs = _size + offs;
		// Fall through
	case SEEK_SET:
		_ptr = _data + offs;
		_pos = offs;
		break;

	case SEEK_CUR:
		_ptr += offs;
		_pos += offs;
		break;
	}
	// Post-Condition
	assert(_pos <= _size);

	return true;	// FIXME: STREAM REWRITE
}

#pragma mark -

enum {
	LF = 0x0A,
	CR = 0x0D
};

char *SeekableReadStream::readLine(char *buf, size_t bufSize) {
	assert(buf != 0 && bufSize > 1);
	char *p = buf;
	size_t len = 0;
	char c = 0;

	// If end-of-file occurs before any characters are read, return NULL
	// and the buffer contents remain unchanged.
	if (eos() || err()) {
		return 0;
	}

	// Loop as long as there is still free space in the buffer,
	// and the line has not ended
	while (len + 1 < bufSize && c != LF) {
		c = readByte();

		if (eos()) {
			// If end-of-file occurs before any characters are read, return
			// NULL and the buffer contents remain unchanged.
			if (len == 0)
				return 0;

			break;
		}

		// If an error occurs, return NULL and the buffer contents
		// are indeterminate.
		if (err())
			return 0;

		// Check for CR or CR/LF
		// * DOS and Windows use CRLF line breaks
		// * Unix and OS X use LF line breaks
		// * Macintosh before OS X used CR line breaks
		if (c == CR) {
			// Look at the next char -- is it LF? If not, seek back
			c = readByte();

			if (err()) {
				return 0; // error: the buffer contents are indeterminate
			}
			if (eos()) {
				// The CR was the last character in the file.
				// Reset the eos() flag since we successfully finished a line
				clearErr();
			} else if (c != LF) {
				seek(-1, SEEK_CUR);
			}

			// Treat CR & CR/LF as plain LF
			c = LF;
		}

		*p++ = c;
		len++;
	}

	// We always terminate the buffer if no error occurred
	*p = 0;
	return buf;
}

String SeekableReadStream::readLine() {
	// Read a line
	String line;
	while (line.lastChar() != '\n') {
		char buf[256];
		if (!readLine(buf, 256))
			break;
		line += buf;
	}

	if (line.lastChar() == '\n')
		line.deleteLastChar();

	return line;
}



uint32 SubReadStream::read(void *dataPtr, uint32 dataSize) {
	if (dataSize > _end - _pos) {
		dataSize = _end - _pos;
		_eos = true;
	}

	dataSize = _parentStream->read(dataPtr, dataSize);
	_pos += dataSize;

	return dataSize;
}

SeekableSubReadStream::SeekableSubReadStream(SeekableReadStream *parentStream, uint32 begin, uint32 end, DisposeAfterUse::Flag disposeParentStream)
	: SubReadStream(parentStream, end, disposeParentStream),
	_parentStream(parentStream),
	_begin(begin) {
	assert(_begin <= _end);
	_pos = _begin;
	_parentStream->seek(_pos);
	_eos = false;
}

bool SeekableSubReadStream::seek(int32 offset, int whence) {
	assert(_pos >= _begin);
	assert(_pos <= _end);

	switch (whence) {
	case SEEK_END:
		offset = size() + offset;
		// fallthrough
	case SEEK_SET:
		_pos = _begin + offset;
		break;
	case SEEK_CUR:
		_pos += offset;
	}

	assert(_pos >= _begin);
	assert(_pos <= _end);

	bool ret = _parentStream->seek(_pos);
	if (ret) _eos = false; // reset eos on successful seek

	return ret;
}

uint32 SafeSubReadStream::read(void *dataPtr, uint32 dataSize) {
	// Make sure the parent stream is at the right position
	seek(0, SEEK_CUR);

	return SeekableSubReadStream::read(dataPtr, dataSize);
}


#pragma mark -

namespace {

/**
 * Wrapper class which adds buffering to any given ReadStream.
 * Users can specify how big the buffer should be, and whether the
 * wrapped stream should be disposed when the wrapper is disposed.
 */
class BufferedReadStream : virtual public ReadStream {
protected:
	ReadStream *_parentStream;
	DisposeAfterUse::Flag _disposeParentStream;
	byte *_buf;
	uint32 _pos;
	bool _eos; // end of stream
	uint32 _bufSize;
	uint32 _realBufSize;

public:
	BufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream);
	virtual ~BufferedReadStream();

	virtual bool eos() const { return _eos; }
	virtual bool err() const { return _parentStream->err(); }
	virtual void clearErr() { _eos = false; _parentStream->clearErr(); }

	virtual uint32 read(void *dataPtr, uint32 dataSize);
};

BufferedReadStream::BufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream)
	: _parentStream(parentStream),
	_disposeParentStream(disposeParentStream),
	_pos(0),
	_eos(false),
	_bufSize(0),
	_realBufSize(bufSize) {

	assert(parentStream);
	_buf = new byte[bufSize];
	assert(_buf);
}

BufferedReadStream::~BufferedReadStream() {
	if (_disposeParentStream)
		delete _parentStream;
	delete[] _buf;
}

uint32 BufferedReadStream::read(void *dataPtr, uint32 dataSize) {
	uint32 alreadyRead = 0;
	const uint32 bufBytesLeft = _bufSize - _pos;

	// Check whether the data left in the buffer suffices....
	if (dataSize > bufBytesLeft) {
		// Nope, we need to read more data

		// First, flush the buffer, if it is non-empty
		if (0 < bufBytesLeft) {
			memcpy(dataPtr, _buf + _pos, bufBytesLeft);
			_pos = _bufSize;
			alreadyRead += bufBytesLeft;
			dataPtr = (byte *)dataPtr + bufBytesLeft;
			dataSize -= bufBytesLeft;
		}

		// At this point the buffer is empty. Now if the read request
		// exceeds the buffer size, just satisfy it directly.
		if (dataSize > _realBufSize) {
			uint32 n = _parentStream->read(dataPtr, dataSize);
			if (_parentStream->eos())
				_eos = true;
			return alreadyRead + n;
		}

		// Refill the buffer.
		// If we didn't read as many bytes as requested, the reason
		// is EOF or an error. In that case we truncate the buffer
		// size, as well as the number of  bytes we are going to
		// return to the caller.
		_bufSize = _parentStream->read(_buf, _realBufSize);
		_pos = 0;
		if (_bufSize < dataSize) {
			// we didn't get enough data from parent
			if (_parentStream->eos())
				_eos = true;
			dataSize = _bufSize;
		}
	}

	if (dataSize) {
		// Satisfy the request from the buffer
		memcpy(dataPtr, _buf + _pos, dataSize);
		_pos += dataSize;
	}
	return alreadyRead + dataSize;
}

}	// End of nameless namespace


ReadStream *wrapBufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream) {
	if (parentStream)
		return new BufferedReadStream(parentStream, bufSize, disposeParentStream);
	return 0;
}

#pragma mark -

namespace {

/**
 * Wrapper class which adds buffering to any given SeekableReadStream.
 * @see BufferedReadStream
 */
class BufferedSeekableReadStream : public BufferedReadStream, public SeekableReadStream {
protected:
	SeekableReadStream *_parentStream;
public:
	BufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream = DisposeAfterUse::NO);

	virtual int32 pos() const { return _parentStream->pos() - (_bufSize - _pos); }
	virtual int32 size() const { return _parentStream->size(); }

	virtual bool seek(int32 offset, int whence = SEEK_SET);
};

BufferedSeekableReadStream::BufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream)
	: BufferedReadStream(parentStream, bufSize, disposeParentStream),
	_parentStream(parentStream) {
}

bool BufferedSeekableReadStream::seek(int32 offset, int whence) {
	// If it is a "local" seek, we may get away with "seeking" around
	// in the buffer only.
	// Note: We could try to handle SEEK_END and SEEK_SET, too, but
	// since they are rarely used, it seems not worth the effort.
	_eos = false;	// seeking always cancels EOS

	if (whence == SEEK_CUR && (int)_pos + offset >= 0 && _pos + offset <= _bufSize) {
		_pos += offset;

		// Note: we do not need to reset parent's eos flag here. It is
		// sufficient that it is reset when actually seeking in the parent.
	} else {
		// Seek was not local enough, so we reset the buffer and
		// just seek normally in the parent stream.
		if (whence == SEEK_CUR)
			offset -= (_bufSize - _pos);
		_pos = _bufSize;
		_parentStream->seek(offset, whence);
	}

	return true;
}

}	// End of nameless namespace

SeekableReadStream *wrapBufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream) {
	if (parentStream)
		return new BufferedSeekableReadStream(parentStream, bufSize, disposeParentStream);
	return 0;
}

#pragma mark -

namespace {

/**
 * Wrapper class which adds buffering to any WriteStream.
 */
class BufferedWriteStream : public WriteStream {
protected:
	WriteStream *_parentStream;
	byte *_buf;
	uint32 _pos;
	const uint32 _bufSize;

	/**
	 * Write out the data in the buffer.
	 *
	 * @note This method is identical to flush() (which actually is
	 * implemented by calling this method), except that it is not
	 * virtual, hence there is less overhead calling it.
	 */
	bool flushBuffer() {
		const uint32 bytesToWrite = _pos;

		if (bytesToWrite) {
			_pos = 0;
			if (_parentStream->write(_buf, bytesToWrite) != bytesToWrite)
				return false;
		}
		return true;
	}

public:
	BufferedWriteStream(WriteStream *parentStream, uint32 bufSize)
		: _parentStream(parentStream),
		_pos(0),
		_bufSize(bufSize) {

		assert(parentStream);
		_buf = new byte[bufSize];
		assert(_buf);
	}

	virtual ~BufferedWriteStream() {
		const bool flushResult = flushBuffer();
		assert(flushResult);

		delete _parentStream;

		delete[] _buf;
	}

	virtual uint32 write(const void *dataPtr, uint32 dataSize) {
		// check if we have enough space for writing to the buffer
		if (_bufSize - _pos >= dataSize) {
			memcpy(_buf + _pos, dataPtr, dataSize);
			_pos += dataSize;
		} else if (_bufSize >= dataSize) {	// check if we can flush the buffer and load the data
			const bool flushResult = flushBuffer();
			assert(flushResult);
			memcpy(_buf, dataPtr, dataSize);
			_pos += dataSize;
		} else	{	// too big for our buffer
			const bool flushResult = flushBuffer();
			assert(flushResult);
			return _parentStream->write(dataPtr, dataSize);
		}
		return dataSize;
	}

	virtual bool flush() { return flushBuffer(); }

};

}	// End of nameless namespace

WriteStream *wrapBufferedWriteStream(WriteStream *parentStream, uint32 bufSize) {
	if (parentStream)
		return new BufferedWriteStream(parentStream, bufSize);
	return 0;
}

}	// End of namespace Common