Mercurial > hg > ucx / file comparison

comparison: src/ucx/buffer.h

src/ucx/buffer.h

changeset 390
d345541018fa
parent 290
d5d6ab809ad3
equal deleted inserted replaced
389:92e482410453 390:d345541018fa
1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2017 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 */
28
29 /**
30 * @file buffer.h
31 *
32 * Advanced buffer implementation.
33 *
34 * Instances of UcxBuffer can be used to read from or to write to like one
35 * would do with a stream. This allows the use of ucx_stream_copy() to copy
36 * contents from one buffer to another.
37 *
38 * Some features for convenient use of the buffer
39 * can be enabled. See the documentation of the macro constants for more
40 * information.
41 *
42 * @author Mike Becker
43 * @author Olaf Wintermann
44 */
45
46 #ifndef UCX_BUFFER_H
47 #define UCX_BUFFER_H
48
49 #include "ucx.h"
50 #include <sys/types.h>
51 #include <stdio.h>
52
53 #ifdef __cplusplus
54 extern "C" {
55 #endif
56
57 /**
58 * No buffer features enabled (all flags cleared).
59 */
60 #define UCX_BUFFER_DEFAULT 0x00
61
62 /**
63 * If this flag is enabled, the buffer will automatically free its contents.
64 */
65 #define UCX_BUFFER_AUTOFREE 0x01
66
67 /**
68 * If this flag is enabled, the buffer will automatically extends its capacity.
69 */
70 #define UCX_BUFFER_AUTOEXTEND 0x02
71
72 /** UCX Buffer. */
73 typedef struct {
74 /** A pointer to the buffer contents. */
75 char *space;
76 /** Current position of the buffer. */
77 size_t pos;
78 /** Current capacity (i.e. maximum size) of the buffer. */
79 size_t capacity;
80 /** Current size of the buffer content. */
81 size_t size;
82 /**
83 * Flag register for buffer features.
84 * @see #UCX_BUFFER_DEFAULT
85 * @see #UCX_BUFFER_AUTOFREE
86 * @see #UCX_BUFFER_AUTOEXTEND
87 */
88 int flags;
89 } UcxBuffer;
90
91 /**
92 * Creates a new buffer.
93 *
94 * <b>Note:</b> you may provide <code>NULL</code> as argument for
95 * <code>space</code>. Then this function will allocate the space and enforce
96 * the #UCX_BUFFER_AUTOFREE flag.
97 *
98 * @param space pointer to the memory area, or <code>NULL</code> to allocate
99 * new memory
100 * @param capacity the capacity of the buffer
101 * @param flags buffer features (see UcxBuffer.flags)
102 * @return the new buffer
103 */
104 UcxBuffer *ucx_buffer_new(void *space, size_t capacity, int flags);
105
106 /**
107 * Destroys a buffer.
108 *
109 * If the #UCX_BUFFER_AUTOFREE feature is enabled, the contents of the buffer
110 * are also freed.
111 *
112 * @param buffer the buffer to destroy
113 */
114 void ucx_buffer_free(UcxBuffer* buffer);
115
116 /**
117 * Creates a new buffer and fills it with extracted content from another buffer.
118 *
119 * <b>Note:</b> the #UCX_BUFFER_AUTOFREE feature is enforced for the new buffer.
120 *
121 * @param src the source buffer
122 * @param start the start position of extraction
123 * @param length the count of bytes to extract (must not be zero)
124 * @param flags feature mask for the new buffer
125 * @return a new buffer containing the extraction
126 */
127 UcxBuffer* ucx_buffer_extract(UcxBuffer *src,
128 size_t start, size_t length, int flags);
129
130 /**
131 * A shorthand macro for the full extraction of the buffer.
132 *
133 * @param src the source buffer
134 * @param flags feature mask for the new buffer
135 * @return a new buffer with the extracted content
136 */
137 #define ucx_buffer_clone(src,flags) \
138 ucx_buffer_extract(src, 0, (src)->capacity, flags)
139
140
141 /**
142 * Shifts the contents of the buffer by the given offset.
143 *
144 * If the offset is positive, the contents are shifted to the right.
145 * If auto extension is enabled, the buffer grows, if necessary.
146 * In case the auto extension fails, this function returns a non-zero value and
147 * no contents are changed.
148 * If auto extension is disabled, the contents that do not fit into the buffer
149 * are discarded.
150 *
151 * If the offset is negative, the contents are shifted to the left where the
152 * first <code>shift</code> bytes are discarded.
153 * The new size of the buffer is the old size minus
154 * the absolute shift value.
155 * If this value is larger than the buffer size, the buffer is emptied (but
156 * not cleared, see the security note below).
157 *
158 * The buffer position gets shifted alongside with the content but is kept
159 * within the boundaries of the buffer.
160 *
161 * <b>Security note:</b> the shifting operation does <em>not</em> erase the
162 * previously occupied memory cells. You can easily do that manually, e.g. by
163 * calling <code>memset(buffer->space, 0, shift)</code> for a right shift or
164 * <code>memset(buffer->size, 0, buffer->capacity-buffer->size)</code>
165 * for a left shift.
166 *
167 * @param buffer the buffer
168 * @param shift the shift offset (negative means left shift)
169 * @return 0 on success, non-zero if a required auto-extension fails
170 */
171 int ucx_buffer_shift(UcxBuffer* buffer, off_t shift);
172
173 /**
174 * Shifts the buffer to the right.
175 * See ucx_buffer_shift() for details.
176 *
177 * @param buffer the buffer
178 * @param shift the shift offset
179 * @return 0 on success, non-zero if a required auto-extension fails
180 * @see ucx_buffer_shift()
181 */
182 int ucx_buffer_shift_right(UcxBuffer* buffer, size_t shift);
183
184 /**
185 * Shifts the buffer to the left.
186 *
187 * See ucx_buffer_shift() for details. Note, however, that this method expects
188 * a positive shift offset.
189 *
190 * Since a left shift cannot fail due to memory allocation problems, this
191 * function always returns zero.
192 *
193 * @param buffer the buffer
194 * @param shift the shift offset
195 * @return always zero
196 * @see ucx_buffer_shift()
197 */
198 int ucx_buffer_shift_left(UcxBuffer* buffer, size_t shift);
199
200
201 /**
202 * Moves the position of the buffer.
203 *
204 * The new position is relative to the <code>whence</code> argument.
205 *
206 * SEEK_SET marks the start of the buffer.
207 * SEEK_CUR marks the current position.
208 * SEEK_END marks the end of the buffer.
209 *
210 * With an offset of zero, this function sets the buffer position to zero
211 * (SEEK_SET), the buffer size (SEEK_END) or leaves the buffer position
212 * unchanged (SEEK_CUR).
213 *
214 * @param buffer
215 * @param offset position offset relative to <code>whence</code>
216 * @param whence one of SEEK_SET, SEEK_CUR or SEEK_END
217 * @return 0 on success, non-zero if the position is invalid
218 *
219 */
220 int ucx_buffer_seek(UcxBuffer *buffer, off_t offset, int whence);
221
222 /**
223 * Clears the buffer by resetting the position and deleting the data.
224 *
225 * The data is deleted by a zeroing it with call to <code>memset()</code>.
226 *
227 * @param buffer the buffer to be cleared
228 */
229 #define ucx_buffer_clear(buffer) memset((buffer)->space, 0, (buffer)->size); \
230 (buffer)->size = 0; (buffer)->pos = 0;
231
232 /**
233 * Tests, if the buffer position has exceeded the buffer capacity.
234 *
235 * @param buffer the buffer to test
236 * @return non-zero, if the current buffer position has exceeded the last
237 * available byte of the buffer.
238 */
239 int ucx_buffer_eof(UcxBuffer *buffer);
240
241
242 /**
243 * Extends the capacity of the buffer.
244 *
245 * <b>Note:</b> The buffer capacity increased by a power of two. I.e.
246 * the buffer capacity is doubled, as long as it would not hold the current
247 * content plus the additional required bytes.
248 *
249 * <b>Attention:</b> the argument provided is the number of <i>additional</i>
250 * bytes the buffer shall hold. It is <b>NOT</b> the total number of bytes the
251 * buffer shall hold.
252 *
253 * @param buffer the buffer to extend
254 * @param additional_bytes the number of additional bytes the buffer shall
255 * <i>at least</i> hold
256 * @return 0 on success or a non-zero value on failure
257 */
258 int ucx_buffer_extend(UcxBuffer *buffer, size_t additional_bytes);
259
260 /**
261 * Writes data to a UcxBuffer.
262 *
263 * The position of the buffer is increased by the number of bytes written.
264 *
265 * @param ptr a pointer to the memory area containing the bytes to be written
266 * @param size the length of one element
267 * @param nitems the element count
268 * @param buffer the UcxBuffer to write to
269 * @return the total count of bytes written
270 */
271 size_t ucx_buffer_write(const void *ptr, size_t size, size_t nitems,
272 UcxBuffer *buffer);
273
274 /**
275 * Reads data from a UcxBuffer.
276 *
277 * The position of the buffer is increased by the number of bytes read.
278 *
279 * @param ptr a pointer to the memory area where to store the read data
280 * @param size the length of one element
281 * @param nitems the element count
282 * @param buffer the UcxBuffer to read from
283 * @return the total number of elements read
284 */
285 size_t ucx_buffer_read(void *ptr, size_t size, size_t nitems,
286 UcxBuffer *buffer);
287
288 /**
289 * Writes a character to a buffer.
290 *
291 * The least significant byte of the argument is written to the buffer. If the
292 * end of the buffer is reached and #UCX_BUFFER_AUTOEXTEND feature is enabled,
293 * the buffer capacity is extended by ucx_buffer_extend(). If the feature is
294 * disabled or buffer extension fails, <code>EOF</code> is returned.
295 *
296 * On successful write the position of the buffer is increased.
297 *
298 * @param buffer the buffer to write to
299 * @param c the character to write as <code>int</code> value
300 * @return the byte that has bean written as <code>int</code> value or
301 * <code>EOF</code> when the end of the stream is reached and automatic
302 * extension is not enabled or not possible
303 */
304 int ucx_buffer_putc(UcxBuffer *buffer, int c);
305
306 /**
307 * Gets a character from a buffer.
308 *
309 * The current position of the buffer is increased after a successful read.
310 *
311 * @param buffer the buffer to read from
312 * @return the character as <code>int</code> value or <code>EOF</code>, if the
313 * end of the buffer is reached
314 */
315 int ucx_buffer_getc(UcxBuffer *buffer);
316
317 /**
318 * Writes a string to a buffer.
319 *
320 * @param buffer the buffer
321 * @param str the string
322 * @return the number of bytes written
323 */
324 size_t ucx_buffer_puts(UcxBuffer *buffer, const char *str);
325
326 /**
327 * Returns the complete buffer content as sstr_t.
328 * @param buffer the buffer
329 * @return the result of <code>sstrn()</code> with the buffer space and size
330 * as arguments
331 */
332 #define ucx_buffer_to_sstr(buffer) sstrn((buffer)->space, (buffer)->size)
333
334 #ifdef __cplusplus
335 }
336 #endif
337
338 #endif /* UCX_BUFFER_H */
339

Mercurial Repository: ucx

mercurial