Mon, 31 Jan 2022 17:15:59 +0100
add allocator support to CxBuffer
Also change how the buffer itself is allocated and destroyed.
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
29 /**
30 * \file buffer.h
31 *
32 * \brief Advanced buffer implementation.
33 *
34 * Instances of CxBuffer can be used to read from or to write to like one
35 * would do with a stream.
36 *
37 * Some features for convenient use of the buffer
38 * can be enabled. See the documentation of the macro constants for more
39 * information.
40 *
41 * \author Mike Becker
42 * \author Olaf Wintermann
43 * \version 3.0
44 * \copyright 2-Clause BSD License
45 */
47 #ifndef UCX_BUFFER_H
48 #define UCX_BUFFER_H
50 #include "common.h"
51 #include "allocator.h"
52 #include <stdio.h>
54 #ifdef __cplusplus
55 extern "C" {
56 #endif
58 /**
59 * No buffer features enabled (all flags cleared).
60 */
61 #define CX_BUFFER_DEFAULT 0x00
63 /**
64 * If this flag is enabled, the buffer will automatically free its contents when destroyed.
65 */
66 #define CX_BUFFER_FREE_CONTENTS 0x01
68 /**
69 * If this flag is enabled, the buffer will automatically extends its capacity.
70 */
71 #define CX_BUFFER_AUTO_EXTEND 0x02
73 /** Structure for the UCX buffer data. */
74 typedef struct {
75 /** A pointer to the buffer contents. */
76 union {
77 /**
78 * Data is interpreted as text.
79 */
80 char *space;
81 /**
82 * Data is interpreted as binary.
83 */
84 unsigned char *bytes;
85 };
86 /** The allocator to use for automatic memory management. */
87 CxAllocator *allocator;
88 /** Current position of the buffer. */
89 size_t pos;
90 /** Current capacity (i.e. maximum size) of the buffer. */
91 size_t capacity;
92 /** Current size of the buffer content. */
93 size_t size;
94 /**
95 * Flag register for buffer features.
96 * @see #CX_BUFFER_DEFAULT
97 * @see #CX_BUFFER_FREE_CONTENTS
98 * @see #CX_BUFFER_AUTO_EXTEND
99 */
100 int flags;
101 } cx_buffer_s;
103 /**
104 * UCX buffer.
105 */
106 typedef cx_buffer_s CxBuffer;
108 /**
109 * Initializes a fresh buffer.
110 *
111 * \note You may provide \c NULL as argument for \p space.
112 * Then this function will allocate the space and enforce
113 * the #CX_BUFFER_FREE_CONTENTS flag.
114 *
115 * @param buffer the buffer to initialize
116 * @param space pointer to the memory area, or \c NULL to allocate
117 * new memory
118 * @param capacity the capacity of the buffer
119 * @param allocator the allocator this buffer shall use for automatic memory management
120 * @param flags buffer features (see cx_buffer_s.flags)
121 * @return zero on success, non-zero if a required allocation failed
122 */
123 int cxBufferInit(
124 CxBuffer *buffer,
125 void *space,
126 size_t capacity,
127 CxAllocator *allocator,
128 int flags
129 );
131 /**
132 * Destroys the buffer contents.
133 *
134 * Has no effect if the #CX_BUFFER_FREE_CONTENTS feature is not enabled.
135 *
136 * @param buffer the buffer which contents shall be destroyed
137 */
138 void cxBufferDestroy(CxBuffer *buffer);
140 /**
141 * Creates a new buffer and fills it with content copied from another buffer.
142 *
143 * \note The #CX_BUFFER_FREE_CONTENTS feature is enforced for the new buffer.
144 *
145 * @param src the source buffer
146 * @param start the start position of extraction
147 * @param length the count of bytes to extract (must not be zero)
148 * @param flags features for the new buffer (#CX_BUFFER_FREE_CONTENTS will always be enabled)
149 * @return a new buffer containing the extraction
150 */
151 CxBuffer *cxBufferExtract(
152 CxBuffer *src,
153 size_t start,
154 size_t length,
155 int flags
156 );
158 /**
159 * A shorthand macro for copying an entire buffer.
160 *
161 * @param src the source buffer
162 * @param flags features for the new buffer (#CX_BUFFER_FREE_CONTENTS will always be enabled)
163 * @return a new buffer with the copied content
164 */
165 #define cxBufferClone(src, flags) cxBufferExtract(src, 0, (src)->capacity, flags)
168 /**
169 * Shifts the contents of the buffer by the given offset.
170 *
171 * If the offset is positive, the contents are shifted to the right.
172 * If auto extension is enabled, the buffer grows, if necessary.
173 * In case the auto extension fails, this function returns a non-zero value and
174 * no contents are changed.
175 * If auto extension is disabled, the contents that do not fit into the buffer
176 * are discarded.
177 *
178 * If the offset is negative, the contents are shifted to the left where the
179 * first \p shift bytes are discarded.
180 * The new size of the buffer is the old size minus the absolute shift value.
181 * If this value is larger than the buffer size, the buffer is emptied (but
182 * not cleared, see the security note below).
183 *
184 * The buffer position gets shifted alongside with the content but is kept
185 * within the boundaries of the buffer.
186 *
187 * \note For situations where \c off_t is not large enough, there are specialized cxBufferShiftLeft() and
188 * cxBufferShiftRight() functions using a \c size_t as parameter type.
189 *
190 * \attention
191 * Security Note: The shifting operation does \em not erase the previously occupied memory cells.
192 * But you can easily do that manually, e.g. by calling
193 * <code>memset(buffer->bytes, 0, shift)</code> for a right shift or
194 * <code>memset(buffer->size, 0, buffer->capacity - buffer->size)</code>
195 * for a left shift.
196 *
197 * @param buffer the buffer
198 * @param shift the shift offset (negative means left shift)
199 * @return 0 on success, non-zero if a required auto-extension fails
200 */
201 int cxBufferShift(
202 CxBuffer *buffer,
203 off_t shift
204 );
206 /**
207 * Shifts the buffer to the right.
208 * See cxBufferShift() for details.
209 *
210 * @param buffer the buffer
211 * @param shift the shift offset
212 * @return 0 on success, non-zero if a required auto-extension fails
213 * @see cxBufferShift()
214 */
215 int cxBufferShiftRight(
216 CxBuffer *buffer,
217 size_t shift
218 );
220 /**
221 * Shifts the buffer to the left.
222 * See cxBufferShift() for details.
223 *
224 * \note Since a left shift cannot fail due to memory allocation problems, this
225 * function always returns zero.
226 *
227 * @param buffer the buffer
228 * @param shift the positive shift offset
229 * @return always zero
230 * @see cxBufferShift()
231 */
232 int cxBufferShiftLeft(
233 CxBuffer *buffer,
234 size_t shift
235 );
238 /**
239 * Moves the position of the buffer.
240 *
241 * The new position is relative to the \p whence argument.
242 *
243 * \li \c SEEK_SET marks the start of the buffer.
244 * \li \c SEEK_CUR marks the current position.
245 * \li \c SEEK_END marks the end of the buffer.
246 *
247 * With an offset of zero, this function sets the buffer position to zero
248 * (\c SEEK_SET), the buffer size (\c SEEK_END) or leaves the buffer position
249 * unchanged (\c SEEK_CUR).
250 *
251 * @param buffer the buffer
252 * @param offset position offset relative to \p whence
253 * @param whence one of \c SEEK_SET, \c SEEK_CUR or \c SEEK_END
254 * @return 0 on success, non-zero if the position is invalid
255 *
256 */
257 int cxBufferSeek(
258 CxBuffer *buffer,
259 off_t offset,
260 int whence
261 );
263 /**
264 * Clears the buffer by resetting the position and deleting the data.
265 *
266 * The data is deleted by zeroing it with a call to memset().
267 *
268 * @param buffer the buffer to be cleared
269 */
270 #define cxBufferClear(buffer) memset((buffer)->bytes, 0, (buffer)->size); \
271 (buffer)->size = 0; (buffer)->pos = 0;
273 /**
274 * Tests, if the buffer position has exceeded the buffer capacity.
275 *
276 * @param buffer the buffer to test
277 * @return non-zero, if the current buffer position has exceeded the last
278 * available byte of the buffer.
279 */
280 int cxBufferEof(CxBuffer *buffer);
283 /**
284 * Ensures that the buffer has a minimum capacity.
285 *
286 * If the current capacity is not sufficient, the buffer will be extended.
287 *
288 * @param buffer the buffer
289 * @param capacity the minimum required capacity for this buffer
290 * @return 0 on success or a non-zero value on failure
291 */
292 int cxBufferMinimumCapacity(
293 CxBuffer *buffer,
294 size_t capacity
295 );
297 /**
298 * Writes data to a CxBuffer.
299 *
300 * The position of the buffer is increased by the number of bytes written.
301 *
302 * \note The signature is compatible with the fwrite() family of functions.
303 *
304 * @param ptr a pointer to the memory area containing the bytes to be written
305 * @param size the length of one element
306 * @param nitems the element count
307 * @param buffer the CxBuffer to write to
308 * @return the total count of bytes written
309 */
310 size_t cxBufferWrite(
311 void const *ptr,
312 size_t size,
313 size_t nitems,
314 CxBuffer *buffer
315 );
317 /**
318 * Reads data from a CxBuffer.
319 *
320 * The position of the buffer is increased by the number of bytes read.
321 *
322 * \note The signature is compatible with the fread() family of functions.
323 *
324 * @param ptr a pointer to the memory area where to store the read data
325 * @param size the length of one element
326 * @param nitems the element count
327 * @param buffer the CxBuffer to read from
328 * @return the total number of elements read
329 */
330 size_t cxBufferRead(
331 void *ptr,
332 size_t size,
333 size_t nitems,
334 CxBuffer *buffer
335 );
337 /**
338 * Writes a character to a buffer.
339 *
340 * The least significant byte of the argument is written to the buffer. If the
341 * end of the buffer is reached and #CX_BUFFER_AUTO_EXTEND feature is enabled,
342 * the buffer capacity is extended by cxBufferMinimumCapacity(). If the feature is
343 * disabled or buffer extension fails, \c EOF is returned.
344 *
345 * On successful write, the position of the buffer is increased.
346 *
347 * @param buffer the buffer to write to
348 * @param c the character to write
349 * @return the byte that has bean written or \c EOF when the end of the stream is
350 * reached and automatic extension is not enabled or not possible
351 */
352 int cxBufferPut(
353 CxBuffer *buffer,
354 int c
355 );
357 /**
358 * Gets a character from a buffer.
359 *
360 * The current position of the buffer is increased after a successful read.
361 *
362 * @param buffer the buffer to read from
363 * @return the character or \c EOF, if the end of the buffer is reached
364 */
365 int cxBufferGet(CxBuffer *buffer);
367 /**
368 * Writes a string to a buffer.
369 *
370 * @param buffer the buffer
371 * @param str the zero-terminated string
372 * @return the number of bytes written
373 */
374 size_t cxBufferPutString(
375 CxBuffer *buffer,
376 const char *str
377 );
379 #ifdef __cplusplus
380 }
381 #endif
383 #endif /* UCX_BUFFER_H */