ucx/cx/buffer.h

changeset 852
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parent 816
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850:bbe2925eb590 852:83fdf679df99
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE. 26 * POSSIBILITY OF SUCH DAMAGE.
27 */ 27 */
28 28
29 /** 29 /**
30 * \file buffer.h 30 * @file buffer.h
31 * 31 *
32 * \brief Advanced buffer implementation. 32 * @brief Advanced buffer implementation.
33 * 33 *
34 * Instances of CxBuffer can be used to read from or to write to like one 34 * Instances of CxBuffer can be used to read from or to write to like one
35 * would do with a stream. 35 * would do with a stream.
36 * 36 *
37 * Some features for convenient use of the buffer 37 * Some features for convenient use of the buffer
38 * can be enabled. See the documentation of the macro constants for more 38 * can be enabled. See the documentation of the macro constants for more
39 * information. 39 * information.
40 * 40 *
41 * \author Mike Becker 41 * @author Mike Becker
42 * \author Olaf Wintermann 42 * @author Olaf Wintermann
43 * \copyright 2-Clause BSD License 43 * @copyright 2-Clause BSD License
44 */ 44 */
45 45
46 #ifndef UCX_BUFFER_H 46 #ifndef UCX_BUFFER_H
47 #define UCX_BUFFER_H 47 #define UCX_BUFFER_H
48 48
49 #include "common.h" 49 #include "common.h"
50 #include "allocator.h" 50 #include "allocator.h"
51 51
52 #ifdef __cplusplus 52 #ifdef __cplusplus
53 extern "C" { 53 extern "C" {
54 #endif 54 #endif
55 55
56 /** 56 /**
57 * No buffer features enabled (all flags cleared). 57 * No buffer features enabled (all flags cleared).
58 */ 58 */
59 #define CX_BUFFER_DEFAULT 0x00 59 #define CX_BUFFER_DEFAULT 0x00
60 60
61 /** 61 /**
62 * If this flag is enabled, the buffer will automatically free its contents when destroyed. 62 * If this flag is enabled, the buffer will automatically free its contents when destroyed.
63 *
64 * Do NOT set this flag together with #CX_BUFFER_COPY_ON_WRITE. It will be automatically
65 * set when the copy-on-write operations is performed.
63 */ 66 */
64 #define CX_BUFFER_FREE_CONTENTS 0x01 67 #define CX_BUFFER_FREE_CONTENTS 0x01
65 68
66 /** 69 /**
67 * If this flag is enabled, the buffer will automatically extends its capacity. 70 * If this flag is enabled, the buffer will automatically extend its capacity.
68 */ 71 */
69 #define CX_BUFFER_AUTO_EXTEND 0x02 72 #define CX_BUFFER_AUTO_EXTEND 0x02
70 73
74 /**
75 * If this flag is enabled, the buffer will allocate new memory when written to.
76 *
77 * The current contents of the buffer will be copied to the new memory and the flag
78 * will be cleared while the #CX_BUFFER_FREE_CONTENTS flag will be set automatically.
79 */
80 #define CX_BUFFER_COPY_ON_WRITE 0x04
81
82 /**
83 * If this flag is enabled, the buffer will copy its contents to a new memory area on reallocation.
84 *
85 * After performing the copy, the flag is automatically cleared.
86 * This flag has no effect on buffers which do not have #CX_BUFFER_AUTO_EXTEND set, which is why
87 * buffers automatically admit the auto-extend flag when initialized with copy-on-extend enabled.
88 */
89 #define CX_BUFFER_COPY_ON_EXTEND 0x08
90
91 /**
92 * Configuration for automatic flushing.
93 */
94 struct cx_buffer_flush_config_s {
95 /**
96 * The buffer may not extend beyond this threshold before starting to flush.
97 *
98 * Only used when the buffer uses #CX_BUFFER_AUTO_EXTEND.
99 * The threshold will be the maximum capacity the buffer is extended to
100 * before flushing.
101 */
102 size_t threshold;
103 /**
104 * The block size for the elements to flush.
105 */
106 size_t blksize;
107 /**
108 * The maximum number of blocks to flush in one cycle.
109 *
110 * @attention while it is guaranteed that cxBufferFlush() will not flush
111 * more blocks, this is not necessarily the case for cxBufferWrite().
112 * After performing a flush cycle, cxBufferWrite() will retry the write
113 * operation and potentially trigger another flush cycle, until the
114 * flush target accepts no more data.
115 */
116 size_t blkmax;
117
118 /**
119 * The target for write function.
120 */
121 void *target;
122
123 /**
124 * The write-function used for flushing.
125 * If NULL, the flushed content gets discarded.
126 */
127 cx_write_func wfunc;
128 };
129
130 /**
131 * Type alais for the flush configuration struct.
132 *
133 * @code
134 * struct cx_buffer_flush_config_s {
135 * size_t threshold;
136 * size_t blksize;
137 * size_t blkmax;
138 * void *target;
139 * cx_write_func wfunc;
140 * };
141 * @endcode
142 */
143 typedef struct cx_buffer_flush_config_s CxBufferFlushConfig;
144
71 /** Structure for the UCX buffer data. */ 145 /** Structure for the UCX buffer data. */
72 typedef struct { 146 struct cx_buffer_s {
73 /** A pointer to the buffer contents. */ 147 /** A pointer to the buffer contents. */
74 union { 148 union {
75 /** 149 /**
76 * Data is interpreted as text. 150 * Data is interpreted as text.
77 */ 151 */
80 * Data is interpreted as binary. 154 * Data is interpreted as binary.
81 */ 155 */
82 unsigned char *bytes; 156 unsigned char *bytes;
83 }; 157 };
84 /** The allocator to use for automatic memory management. */ 158 /** The allocator to use for automatic memory management. */
85 CxAllocator const *allocator; 159 const CxAllocator *allocator;
160 /**
161 * Optional flush configuration
162 *
163 * @see cxBufferEnableFlushing()
164 */
165 CxBufferFlushConfig* flush;
86 /** Current position of the buffer. */ 166 /** Current position of the buffer. */
87 size_t pos; 167 size_t pos;
88 /** Current capacity (i.e. maximum size) of the buffer. */ 168 /** Current capacity (i.e. maximum size) of the buffer. */
89 size_t capacity; 169 size_t capacity;
90 /** Current size of the buffer content. */ 170 /** Current size of the buffer content. */
91 size_t size; 171 size_t size;
92 /** 172 /**
93 * The buffer may not extend beyond this threshold before starting to flush.
94 * Default is \c SIZE_MAX (flushing disabled when auto extension is enabled).
95 */
96 size_t flush_threshold;
97 /**
98 * The block size for the elements to flush.
99 * Default is 4096 bytes.
100 */
101 size_t flush_blksize;
102 /**
103 * The maximum number of blocks to flush in one cycle.
104 * Zero disables flushing entirely (this is the default).
105 * Set this to \c SIZE_MAX to flush the entire buffer.
106 *
107 * @attention if the maximum number of blocks multiplied with the block size
108 * is smaller than the expected contents written to this buffer within one write
109 * operation, multiple flush cycles are performed after that write.
110 * That means the total number of blocks flushed after one write to this buffer may
111 * be larger than \c flush_blkmax.
112 */
113 size_t flush_blkmax;
114
115 /**
116 * The write function used for flushing.
117 * If NULL, the flushed content gets discarded.
118 */
119 cx_write_func flush_func;
120
121 /**
122 * The target for \c flush_func.
123 */
124 void *flush_target;
125
126 /**
127 * Flag register for buffer features. 173 * Flag register for buffer features.
128 * @see #CX_BUFFER_DEFAULT 174 * @see #CX_BUFFER_DEFAULT
129 * @see #CX_BUFFER_FREE_CONTENTS 175 * @see #CX_BUFFER_FREE_CONTENTS
130 * @see #CX_BUFFER_AUTO_EXTEND 176 * @see #CX_BUFFER_AUTO_EXTEND
177 * @see #CX_BUFFER_COPY_ON_WRITE
131 */ 178 */
132 int flags; 179 int flags;
133 } cx_buffer_s; 180 };
134 181
135 /** 182 /**
136 * UCX buffer. 183 * UCX buffer.
137 */ 184 */
138 typedef cx_buffer_s CxBuffer; 185 typedef struct cx_buffer_s CxBuffer;
139 186
140 /** 187 /**
141 * Initializes a fresh buffer. 188 * Initializes a fresh buffer.
142 * 189 *
143 * \note You may provide \c NULL as argument for \p space. 190 * You may also provide a read-only @p space, in which case
191 * you will need to cast the pointer, and you should set the
192 * #CX_BUFFER_COPY_ON_WRITE flag.
193 *
194 * You need to set the size manually after initialization, if
195 * you provide @p space which already contains data.
196 *
197 * When you specify stack memory as @p space and decide to use
198 * the auto-extension feature, you @em must use the
199 * #CX_BUFFER_COPY_ON_EXTEND flag, instead of the
200 * #CX_BUFFER_AUTO_EXTEND flag.
201 *
202 * @note You may provide @c NULL as argument for @p space.
144 * Then this function will allocate the space and enforce 203 * Then this function will allocate the space and enforce
145 * the #CX_BUFFER_FREE_CONTENTS flag. 204 * the #CX_BUFFER_FREE_CONTENTS flag. In that case, specifying
205 * copy-on-write should be avoided, because the allocated
206 * space will be leaking after the copy-on-write operation.
146 * 207 *
147 * @param buffer the buffer to initialize 208 * @param buffer the buffer to initialize
148 * @param space pointer to the memory area, or \c NULL to allocate 209 * @param space pointer to the memory area, or @c NULL to allocate
149 * new memory 210 * new memory
150 * @param capacity the capacity of the buffer 211 * @param capacity the capacity of the buffer
151 * @param allocator the allocator this buffer shall use for automatic 212 * @param allocator the allocator this buffer shall use for automatic
152 * memory management. If \c NULL, the default heap allocator will be used. 213 * memory management
214 * (if @c NULL, a default stdlib allocator will be used)
153 * @param flags buffer features (see cx_buffer_s.flags) 215 * @param flags buffer features (see cx_buffer_s.flags)
154 * @return zero on success, non-zero if a required allocation failed 216 * @return zero on success, non-zero if a required allocation failed
155 */ 217 */
156 __attribute__((__nonnull__(1))) 218 cx_attr_nonnull_arg(1)
157 int cxBufferInit( 219 int cxBufferInit(
158 CxBuffer *buffer, 220 CxBuffer *buffer,
159 void *space, 221 void *space,
160 size_t capacity, 222 size_t capacity,
161 CxAllocator const *allocator, 223 const CxAllocator *allocator,
162 int flags 224 int flags
163 ); 225 );
164 226
165 /** 227 /**
228 * Configures the buffer for flushing.
229 *
230 * Flushing can happen automatically when data is written
231 * to the buffer (see cxBufferWrite()) or manually when
232 * cxBufferFlush() is called.
233 *
234 * @param buffer the buffer
235 * @param config the flush configuration
236 * @retval zero success
237 * @retval non-zero failure
238 * @see cxBufferFlush()
239 * @see cxBufferWrite()
240 */
241 cx_attr_nonnull
242 int cxBufferEnableFlushing(
243 CxBuffer *buffer,
244 CxBufferFlushConfig config
245 );
246
247 /**
248 * Destroys the buffer contents.
249 *
250 * Has no effect if the #CX_BUFFER_FREE_CONTENTS feature is not enabled.
251 * If you want to free the memory of the entire buffer, use cxBufferFree().
252 *
253 * @param buffer the buffer which contents shall be destroyed
254 * @see cxBufferInit()
255 */
256 cx_attr_nonnull
257 void cxBufferDestroy(CxBuffer *buffer);
258
259 /**
260 * Deallocates the buffer.
261 *
262 * If the #CX_BUFFER_FREE_CONTENTS feature is enabled, this function also destroys
263 * the contents. If you @em only want to destroy the contents, use cxBufferDestroy().
264 *
265 * @remark As with all free() functions, this accepts @c NULL arguments in which
266 * case it does nothing.
267 *
268 * @param buffer the buffer to deallocate
269 * @see cxBufferCreate()
270 */
271 void cxBufferFree(CxBuffer *buffer);
272
273 /**
166 * Allocates and initializes a fresh buffer. 274 * Allocates and initializes a fresh buffer.
167 * 275 *
168 * \note You may provide \c NULL as argument for \p space. 276 * You may also provide a read-only @p space, in which case
277 * you will need to cast the pointer, and you should set the
278 * #CX_BUFFER_COPY_ON_WRITE flag.
279 * When you specify stack memory as @p space and decide to use
280 * the auto-extension feature, you @em must use the
281 * #CX_BUFFER_COPY_ON_EXTEND flag, instead of the
282 * #CX_BUFFER_AUTO_EXTEND flag.
283 *
284 * @note You may provide @c NULL as argument for @p space.
169 * Then this function will allocate the space and enforce 285 * Then this function will allocate the space and enforce
170 * the #CX_BUFFER_FREE_CONTENTS flag. 286 * the #CX_BUFFER_FREE_CONTENTS flag.
171 * 287 *
172 * @param space pointer to the memory area, or \c NULL to allocate 288 * @param space pointer to the memory area, or @c NULL to allocate
173 * new memory 289 * new memory
174 * @param capacity the capacity of the buffer 290 * @param capacity the capacity of the buffer
175 * @param allocator the allocator to use for allocating the structure and the automatic 291 * @param allocator the allocator to use for allocating the structure and the automatic
176 * memory management within the buffer. If \c NULL, the default heap allocator will be used. 292 * memory management within the buffer
293 * (if @c NULL, a default stdlib allocator will be used)
177 * @param flags buffer features (see cx_buffer_s.flags) 294 * @param flags buffer features (see cx_buffer_s.flags)
178 * @return a pointer to the buffer on success, \c NULL if a required allocation failed 295 * @return a pointer to the buffer on success, @c NULL if a required allocation failed
179 */ 296 */
297 cx_attr_malloc
298 cx_attr_dealloc(cxBufferFree, 1)
299 cx_attr_nodiscard
180 CxBuffer *cxBufferCreate( 300 CxBuffer *cxBufferCreate(
181 void *space, 301 void *space,
182 size_t capacity, 302 size_t capacity,
183 CxAllocator const *allocator, 303 const CxAllocator *allocator,
184 int flags 304 int flags
185 ); 305 );
186
187 /**
188 * Destroys the buffer contents.
189 *
190 * Has no effect if the #CX_BUFFER_FREE_CONTENTS feature is not enabled.
191 * If you want to free the memory of the entire buffer, use cxBufferFree().
192 *
193 * @param buffer the buffer which contents shall be destroyed
194 * @see cxBufferInit()
195 */
196 __attribute__((__nonnull__))
197 void cxBufferDestroy(CxBuffer *buffer);
198
199 /**
200 * Deallocates the buffer.
201 *
202 * If the #CX_BUFFER_FREE_CONTENTS feature is enabled, this function also destroys
203 * the contents. If you \em only want to destroy the contents, use cxBufferDestroy().
204 *
205 * @param buffer the buffer to deallocate
206 * @see cxBufferCreate()
207 */
208 __attribute__((__nonnull__))
209 void cxBufferFree(CxBuffer *buffer);
210 306
211 /** 307 /**
212 * Shifts the contents of the buffer by the given offset. 308 * Shifts the contents of the buffer by the given offset.
213 * 309 *
214 * If the offset is positive, the contents are shifted to the right. 310 * If the offset is positive, the contents are shifted to the right.
217 * no contents are changed. 313 * no contents are changed.
218 * If auto extension is disabled, the contents that do not fit into the buffer 314 * If auto extension is disabled, the contents that do not fit into the buffer
219 * are discarded. 315 * are discarded.
220 * 316 *
221 * If the offset is negative, the contents are shifted to the left where the 317 * If the offset is negative, the contents are shifted to the left where the
222 * first \p shift bytes are discarded. 318 * first @p shift bytes are discarded.
223 * The new size of the buffer is the old size minus the absolute shift value. 319 * The new size of the buffer is the old size minus the absolute shift value.
224 * If this value is larger than the buffer size, the buffer is emptied (but 320 * If this value is larger than the buffer size, the buffer is emptied (but
225 * not cleared, see the security note below). 321 * not cleared, see the security note below).
226 * 322 *
227 * The buffer position gets shifted alongside with the content but is kept 323 * The buffer position gets shifted alongside with the content but is kept
228 * within the boundaries of the buffer. 324 * within the boundaries of the buffer.
229 * 325 *
230 * \note For situations where \c off_t is not large enough, there are specialized cxBufferShiftLeft() and 326 * @note For situations where @c off_t is not large enough, there are specialized cxBufferShiftLeft() and
231 * cxBufferShiftRight() functions using a \c size_t as parameter type. 327 * cxBufferShiftRight() functions using a @c size_t as parameter type.
232 * 328 *
233 * \attention 329 * @attention
234 * Security Note: The shifting operation does \em not erase the previously occupied memory cells. 330 * Security Note: The shifting operation does @em not erase the previously occupied memory cells.
235 * But you can easily do that manually, e.g. by calling 331 * But you can easily do that manually, e.g. by calling
236 * <code>memset(buffer->bytes, 0, shift)</code> for a right shift or 332 * <code>memset(buffer->bytes, 0, shift)</code> for a right shift or
237 * <code>memset(buffer->bytes + buffer->size, 0, buffer->capacity - buffer->size)</code> 333 * <code>memset(buffer->bytes + buffer->size, 0, buffer->capacity - buffer->size)</code>
238 * for a left shift. 334 * for a left shift.
239 * 335 *
240 * @param buffer the buffer 336 * @param buffer the buffer
241 * @param shift the shift offset (negative means left shift) 337 * @param shift the shift offset (negative means left shift)
242 * @return 0 on success, non-zero if a required auto-extension fails 338 * @retval zero success
243 */ 339 * @retval non-zero if a required auto-extension or copy-on-write fails
244 __attribute__((__nonnull__)) 340 * @see cxBufferShiftLeft()
341 * @see cxBufferShiftRight()
342 */
343 cx_attr_nonnull
245 int cxBufferShift( 344 int cxBufferShift(
246 CxBuffer *buffer, 345 CxBuffer *buffer,
247 off_t shift 346 off_t shift
248 ); 347 );
249 348
251 * Shifts the buffer to the right. 350 * Shifts the buffer to the right.
252 * See cxBufferShift() for details. 351 * See cxBufferShift() for details.
253 * 352 *
254 * @param buffer the buffer 353 * @param buffer the buffer
255 * @param shift the shift offset 354 * @param shift the shift offset
256 * @return 0 on success, non-zero if a required auto-extension fails 355 * @retval zero success
356 * @retval non-zero if a required auto-extension or copy-on-write fails
257 * @see cxBufferShift() 357 * @see cxBufferShift()
258 */ 358 */
259 __attribute__((__nonnull__)) 359 cx_attr_nonnull
260 int cxBufferShiftRight( 360 int cxBufferShiftRight(
261 CxBuffer *buffer, 361 CxBuffer *buffer,
262 size_t shift 362 size_t shift
263 ); 363 );
264 364
265 /** 365 /**
266 * Shifts the buffer to the left. 366 * Shifts the buffer to the left.
267 * See cxBufferShift() for details. 367 * See cxBufferShift() for details.
268 * 368 *
269 * \note Since a left shift cannot fail due to memory allocation problems, this
270 * function always returns zero.
271 *
272 * @param buffer the buffer 369 * @param buffer the buffer
273 * @param shift the positive shift offset 370 * @param shift the positive shift offset
274 * @return always zero 371 * @retval zero success
372 * @retval non-zero if the buffer uses copy-on-write and the allocation fails
275 * @see cxBufferShift() 373 * @see cxBufferShift()
276 */ 374 */
277 __attribute__((__nonnull__)) 375 cx_attr_nonnull
278 int cxBufferShiftLeft( 376 int cxBufferShiftLeft(
279 CxBuffer *buffer, 377 CxBuffer *buffer,
280 size_t shift 378 size_t shift
281 ); 379 );
282 380
283 381
284 /** 382 /**
285 * Moves the position of the buffer. 383 * Moves the position of the buffer.
286 * 384 *
287 * The new position is relative to the \p whence argument. 385 * The new position is relative to the @p whence argument.
288 * 386 *
289 * \li \c SEEK_SET marks the start of the buffer. 387 * @li @c SEEK_SET marks the start of the buffer.
290 * \li \c SEEK_CUR marks the current position. 388 * @li @c SEEK_CUR marks the current position.
291 * \li \c SEEK_END marks the end of the buffer. 389 * @li @c SEEK_END marks the end of the buffer.
292 * 390 *
293 * With an offset of zero, this function sets the buffer position to zero 391 * With an offset of zero, this function sets the buffer position to zero
294 * (\c SEEK_SET), the buffer size (\c SEEK_END) or leaves the buffer position 392 * (@c SEEK_SET), the buffer size (@c SEEK_END) or leaves the buffer position
295 * unchanged (\c SEEK_CUR). 393 * unchanged (@c SEEK_CUR).
296 * 394 *
297 * @param buffer the buffer 395 * @param buffer the buffer
298 * @param offset position offset relative to \p whence 396 * @param offset position offset relative to @p whence
299 * @param whence one of \c SEEK_SET, \c SEEK_CUR or \c SEEK_END 397 * @param whence one of @c SEEK_SET, @c SEEK_CUR or @c SEEK_END
300 * @return 0 on success, non-zero if the position is invalid 398 * @retval zero success
301 * 399 * @retval non-zero if the position is invalid
302 */ 400 *
303 __attribute__((__nonnull__)) 401 */
402 cx_attr_nonnull
304 int cxBufferSeek( 403 int cxBufferSeek(
305 CxBuffer *buffer, 404 CxBuffer *buffer,
306 off_t offset, 405 off_t offset,
307 int whence 406 int whence
308 ); 407 );
311 * Clears the buffer by resetting the position and deleting the data. 410 * Clears the buffer by resetting the position and deleting the data.
312 * 411 *
313 * The data is deleted by zeroing it with a call to memset(). 412 * The data is deleted by zeroing it with a call to memset().
314 * If you do not need that, you can use the faster cxBufferReset(). 413 * If you do not need that, you can use the faster cxBufferReset().
315 * 414 *
415 * @note If the #CX_BUFFER_COPY_ON_WRITE flag is set, this function
416 * will not erase the data and behave exactly as cxBufferReset().
417 *
316 * @param buffer the buffer to be cleared 418 * @param buffer the buffer to be cleared
317 * @see cxBufferReset() 419 * @see cxBufferReset()
318 */ 420 */
319 __attribute__((__nonnull__)) 421 cx_attr_nonnull
320 void cxBufferClear(CxBuffer *buffer); 422 void cxBufferClear(CxBuffer *buffer);
321 423
322 /** 424 /**
323 * Resets the buffer by resetting the position and size to zero. 425 * Resets the buffer by resetting the position and size to zero.
324 * 426 *
326 * reset of the buffer, use cxBufferClear(). 428 * reset of the buffer, use cxBufferClear().
327 * 429 *
328 * @param buffer the buffer to be cleared 430 * @param buffer the buffer to be cleared
329 * @see cxBufferClear() 431 * @see cxBufferClear()
330 */ 432 */
331 __attribute__((__nonnull__)) 433 cx_attr_nonnull
332 void cxBufferReset(CxBuffer *buffer); 434 void cxBufferReset(CxBuffer *buffer);
333 435
334 /** 436 /**
335 * Tests, if the buffer position has exceeded the buffer size. 437 * Tests, if the buffer position has exceeded the buffer size.
336 * 438 *
337 * @param buffer the buffer to test 439 * @param buffer the buffer to test
338 * @return non-zero, if the current buffer position has exceeded the last 440 * @retval true if the current buffer position has exceeded the last
339 * byte of the buffer's contents. 441 * byte of the buffer's contents
340 */ 442 * @retval false otherwise
341 __attribute__((__nonnull__)) 443 */
342 int cxBufferEof(CxBuffer const *buffer); 444 cx_attr_nonnull
445 cx_attr_nodiscard
446 bool cxBufferEof(const CxBuffer *buffer);
343 447
344 448
345 /** 449 /**
346 * Ensures that the buffer has a minimum capacity. 450 * Ensures that the buffer has a minimum capacity.
347 * 451 *
348 * If the current capacity is not sufficient, the buffer will be extended. 452 * If the current capacity is not sufficient, the buffer will be extended.
349 * 453 *
350 * @param buffer the buffer 454 * @param buffer the buffer
351 * @param capacity the minimum required capacity for this buffer 455 * @param capacity the minimum required capacity for this buffer
352 * @return 0 on success or a non-zero value on failure 456 * @retval zero the capacity was already sufficient or successfully increased
353 */ 457 * @retval non-zero on allocation failure
354 __attribute__((__nonnull__)) 458 */
459 cx_attr_nonnull
355 int cxBufferMinimumCapacity( 460 int cxBufferMinimumCapacity(
356 CxBuffer *buffer, 461 CxBuffer *buffer,
357 size_t capacity 462 size_t capacity
358 ); 463 );
359 464
360 /** 465 /**
361 * Writes data to a CxBuffer. 466 * Writes data to a CxBuffer.
467 *
468 * If automatic flushing is not enabled, the data is simply written into the
469 * buffer at the current position and the position of the buffer is increased
470 * by the number of bytes written.
362 * 471 *
363 * If flushing is enabled and the buffer needs to flush, the data is flushed to 472 * If flushing is enabled and the buffer needs to flush, the data is flushed to
364 * the target until the target signals that it cannot take more data by 473 * the target until the target signals that it cannot take more data by
365 * returning zero via the respective write function. In that case, the remaining 474 * returning zero via the respective write function. In that case, the remaining
366 * data in this buffer is shifted to the beginning of this buffer so that the 475 * data in this buffer is shifted to the beginning of this buffer so that the
367 * newly available space can be used to append as much data as possible. This 476 * newly available space can be used to append as much data as possible. This
368 * function only stops writing more elements, when the flush target and this 477 * function only stops writing more elements, when the flush target and this
369 * buffer are both incapable of taking more data or all data has been written. 478 * buffer are both incapable of taking more data or all data has been written.
370 * The number returned by this function is the total number of elements that 479 * If number of items that shall be written is larger than the buffer can hold,
371 * could be written during the process. It does not necessarily mean that those 480 * the first items from @c ptr are directly relayed to the flush target, if
372 * elements are still in this buffer, because some of them could have also be 481 * possible.
373 * flushed already. 482 * The number returned by this function is only the number of elements from
374 * 483 * @c ptr that could be written to either the flush target or the buffer.
375 * If automatic flushing is not enabled, the position of the buffer is increased 484 *
376 * by the number of bytes written. 485 * @note The signature is compatible with the fwrite() family of functions.
377 *
378 * \note The signature is compatible with the fwrite() family of functions.
379 * 486 *
380 * @param ptr a pointer to the memory area containing the bytes to be written 487 * @param ptr a pointer to the memory area containing the bytes to be written
381 * @param size the length of one element 488 * @param size the length of one element
382 * @param nitems the element count 489 * @param nitems the element count
383 * @param buffer the CxBuffer to write to 490 * @param buffer the CxBuffer to write to
384 * @return the total count of elements written 491 * @return the total count of elements written
385 */ 492 * @see cxBufferAppend()
386 __attribute__((__nonnull__)) 493 * @see cxBufferRead()
494 */
495 cx_attr_nonnull
387 size_t cxBufferWrite( 496 size_t cxBufferWrite(
388 void const *ptr, 497 const void *ptr,
389 size_t size, 498 size_t size,
390 size_t nitems, 499 size_t nitems,
391 CxBuffer *buffer 500 CxBuffer *buffer
392 ); 501 );
393 502
394 /** 503 /**
504 * Appends data to a CxBuffer.
505 *
506 * The data is always appended to current data within the buffer,
507 * regardless of the current position.
508 * This is especially useful when the buffer is primarily meant for reading
509 * while additional data is added to the buffer occasionally.
510 * Consequently, the position of the buffer is unchanged after this operation.
511 *
512 * @note The signature is compatible with the fwrite() family of functions.
513 *
514 * @param ptr a pointer to the memory area containing the bytes to be written
515 * @param size the length of one element
516 * @param nitems the element count
517 * @param buffer the CxBuffer to write to
518 * @return the total count of elements written
519 * @see cxBufferWrite()
520 * @see cxBufferRead()
521 */
522 cx_attr_nonnull
523 size_t cxBufferAppend(
524 const void *ptr,
525 size_t size,
526 size_t nitems,
527 CxBuffer *buffer
528 );
529
530 /**
531 * Performs a single flush-run on the specified buffer.
532 *
533 * Does nothing when the position in the buffer is zero.
534 * Otherwise, the data until the current position minus
535 * one is considered for flushing.
536 * Note carefully that flushing will never exceed the
537 * current @em position, even when the size of the
538 * buffer is larger than the current position.
539 *
540 * One flush run will try to flush @c blkmax many
541 * blocks of size @c blksize until either the @p buffer
542 * has no more data to flush or the write function
543 * used for flushing returns zero.
544 *
545 * The buffer is shifted left for that many bytes
546 * the flush operation has successfully flushed.
547 *
548 * @par Example 1
549 * Assume you have a buffer with size 340 and you are
550 * at position 200. The flush configuration is
551 * @c blkmax=4 and @c blksize=64 .
552 * Assume that the entire flush operation is successful.
553 * All 200 bytes on the left hand-side from the current
554 * position are written.
555 * That means, the size of the buffer is now 140 and the
556 * position is zero.
557 *
558 * @par Example 2
559 * Same as Example 1, but now the @c blkmax is 1.
560 * The size of the buffer is now 276 and the position is 136.
561 *
562 * @par Example 3
563 * Same as Example 1, but now assume the flush target
564 * only accepts 100 bytes before returning zero.
565 * That means, the flush operations manages to flush
566 * one complete block and one partial block, ending
567 * up with a buffer with size 240 and position 100.
568 *
569 * @remark Just returns zero when flushing was not enabled with
570 * cxBufferEnableFlushing().
571 *
572 * @remark When the buffer uses copy-on-write, the memory
573 * is copied first, before attempting any flush.
574 * This is, however, considered an erroneous use of the
575 * buffer, because it does not make much sense to put
576 * readonly data into an UCX buffer for flushing, instead
577 * of writing it directly to the target.
578 *
579 * @param buffer the buffer
580 * @return the number of successfully flushed bytes
581 * @see cxBufferEnableFlushing()
582 */
583 cx_attr_nonnull
584 size_t cxBufferFlush(CxBuffer *buffer);
585
586 /**
395 * Reads data from a CxBuffer. 587 * Reads data from a CxBuffer.
396 * 588 *
397 * The position of the buffer is increased by the number of bytes read. 589 * The position of the buffer is increased by the number of bytes read.
398 * 590 *
399 * \note The signature is compatible with the fread() family of functions. 591 * @note The signature is compatible with the fread() family of functions.
400 * 592 *
401 * @param ptr a pointer to the memory area where to store the read data 593 * @param ptr a pointer to the memory area where to store the read data
402 * @param size the length of one element 594 * @param size the length of one element
403 * @param nitems the element count 595 * @param nitems the element count
404 * @param buffer the CxBuffer to read from 596 * @param buffer the CxBuffer to read from
405 * @return the total number of elements read 597 * @return the total number of elements read
406 */ 598 * @see cxBufferWrite()
407 __attribute__((__nonnull__)) 599 * @see cxBufferAppend()
600 */
601 cx_attr_nonnull
408 size_t cxBufferRead( 602 size_t cxBufferRead(
409 void *ptr, 603 void *ptr,
410 size_t size, 604 size_t size,
411 size_t nitems, 605 size_t nitems,
412 CxBuffer *buffer 606 CxBuffer *buffer
415 /** 609 /**
416 * Writes a character to a buffer. 610 * Writes a character to a buffer.
417 * 611 *
418 * The least significant byte of the argument is written to the buffer. If the 612 * The least significant byte of the argument is written to the buffer. If the
419 * end of the buffer is reached and #CX_BUFFER_AUTO_EXTEND feature is enabled, 613 * end of the buffer is reached and #CX_BUFFER_AUTO_EXTEND feature is enabled,
420 * the buffer capacity is extended by cxBufferMinimumCapacity(). If the feature is 614 * the buffer capacity is extended by cxBufferMinimumCapacity(). If the feature
421 * disabled or buffer extension fails, \c EOF is returned. 615 * is disabled or buffer extension fails, @c EOF is returned.
422 * 616 *
423 * On successful write, the position of the buffer is increased. 617 * On successful write, the position of the buffer is increased.
618 *
619 * If you just want to write a null-terminator at the current position, you
620 * should use cxBufferTerminate() instead.
424 * 621 *
425 * @param buffer the buffer to write to 622 * @param buffer the buffer to write to
426 * @param c the character to write 623 * @param c the character to write
427 * @return the byte that has bean written or \c EOF when the end of the stream is 624 * @return the byte that has been written or @c EOF when the end of the stream is
428 * reached and automatic extension is not enabled or not possible 625 * reached and automatic extension is not enabled or not possible
429 */ 626 * @see cxBufferTerminate()
430 __attribute__((__nonnull__)) 627 */
628 cx_attr_nonnull
431 int cxBufferPut( 629 int cxBufferPut(
432 CxBuffer *buffer, 630 CxBuffer *buffer,
433 int c 631 int c
434 ); 632 );
435 633
436 /** 634 /**
635 * Writes a terminating zero to a buffer at the current position.
636 *
637 * On successful write, @em neither the position @em nor the size of the buffer is
638 * increased.
639 *
640 * The purpose of this function is to have the written data ready to be used as
641 * a C string.
642 *
643 * @param buffer the buffer to write to
644 * @return zero, if the terminator could be written, non-zero otherwise
645 */
646 cx_attr_nonnull
647 int cxBufferTerminate(CxBuffer *buffer);
648
649 /**
437 * Writes a string to a buffer. 650 * Writes a string to a buffer.
651 *
652 * This is a convenience function for <code>cxBufferWrite(str, 1, strlen(str), buffer)</code>.
438 * 653 *
439 * @param buffer the buffer 654 * @param buffer the buffer
440 * @param str the zero-terminated string 655 * @param str the zero-terminated string
441 * @return the number of bytes written 656 * @return the number of bytes written
442 */ 657 */
443 __attribute__((__nonnull__)) 658 cx_attr_nonnull
659 cx_attr_cstr_arg(2)
444 size_t cxBufferPutString( 660 size_t cxBufferPutString(
445 CxBuffer *buffer, 661 CxBuffer *buffer,
446 const char *str 662 const char *str
447 ); 663 );
448 664
450 * Gets a character from a buffer. 666 * Gets a character from a buffer.
451 * 667 *
452 * The current position of the buffer is increased after a successful read. 668 * The current position of the buffer is increased after a successful read.
453 * 669 *
454 * @param buffer the buffer to read from 670 * @param buffer the buffer to read from
455 * @return the character or \c EOF, if the end of the buffer is reached 671 * @return the character or @c EOF, if the end of the buffer is reached
456 */ 672 */
457 __attribute__((__nonnull__)) 673 cx_attr_nonnull
458 int cxBufferGet(CxBuffer *buffer); 674 int cxBufferGet(CxBuffer *buffer);
459 675
460 #ifdef __cplusplus 676 #ifdef __cplusplus
461 } 677 }
462 #endif 678 #endif

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