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comparison: src/ucx/buffer.h

src/ucx/buffer.h

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1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2016 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 * Moves the position of the buffer.
142 *
143 * The new position is relative to the <code>whence</code> argument.
144 *
145 * SEEK_SET marks the start of the buffer.
146 * SEEK_CUR marks the current position.
147 * SEEK_END marks the end of the buffer.
148 *
149 * With an offset of zero, this function sets the buffer position to zero
150 * (SEEK_SET), the buffer size (SEEK_END) or leaves the buffer position
151 * unchanged (SEEK_CUR).
152 *
153 * @param buffer
154 * @param offset position offset relative to <code>whence</code>
155 * @param whence one of SEEK_SET, SEEK_CUR or SEEK_END
156 * @return 0 on success, non-zero if the position is invalid
157 *
158 */
159 int ucx_buffer_seek(UcxBuffer *buffer, off_t offset, int whence);
160
161 /**
162 * Clears the buffer by resetting the position and deleting the data.
163 *
164 * The data is deleted by a zeroing it with call to <code>memset()</code>.
165 *
166 * @param buffer the buffer to be cleared
167 */
168 #define ucx_buffer_clear(buffer) memset(buffer->space, 0, buffer->size); \
169 buffer->size = 0; buffer->pos = 0;
170
171 /**
172 * Tests, if the buffer position has exceeded the buffer capacity.
173 *
174 * @param buffer the buffer to test
175 * @return non-zero, if the current buffer position has exceeded the last
176 * available byte of the buffer.
177 */
178 int ucx_buffer_eof(UcxBuffer *buffer);
179
180
181 /**
182 * Extends the capacity of the buffer.
183 *
184 * <b>Note:</b> The buffer capacity increased by a power of two. I.e.
185 * the buffer capacity is doubled, as long as it would not hold the current
186 * content plus the additional required bytes.
187 *
188 * <b>Attention:</b> the argument provided is the number of <i>additional</i>
189 * bytes the buffer shall hold. It is <b>NOT</b> the total number of bytes the
190 * buffer shall hold.
191 *
192 * @param buffer the buffer to extend
193 * @param additional_bytes the number of additional bytes the buffer shall
194 * <i>at least</i> hold
195 * @return 0 on success or a non-zero value on failure
196 */
197 int ucx_buffer_extend(UcxBuffer *buffer, size_t additional_bytes);
198
199 /**
200 * Writes data to a UcxBuffer.
201 *
202 * The position of the buffer is increased by the number of bytes written.
203 *
204 * @param ptr a pointer to the memory area containing the bytes to be written
205 * @param size the length of one element
206 * @param nitems the element count
207 * @param buffer the UcxBuffer to write to
208 * @return the total count of bytes written
209 */
210 size_t ucx_buffer_write(const void *ptr, size_t size, size_t nitems,
211 UcxBuffer *buffer);
212
213 /**
214 * Reads data from a UcxBuffer.
215 *
216 * The position of the buffer is increased by the number of bytes read.
217 *
218 * @param ptr a pointer to the memory area where to store the read data
219 * @param size the length of one element
220 * @param nitems the element count
221 * @param buffer the UcxBuffer to read from
222 * @return the total number of elements read
223 */
224 size_t ucx_buffer_read(void *ptr, size_t size, size_t nitems,
225 UcxBuffer *buffer);
226
227 /**
228 * Writes a character to a buffer.
229 *
230 * The least significant byte of the argument is written to the buffer. If the
231 * end of the buffer is reached and #UCX_BUFFER_AUTOEXTEND feature is enabled,
232 * the buffer capacity is extended by ucx_buffer_extend(). If the feature is
233 * disabled or buffer extension fails, <code>EOF</code> is returned.
234 *
235 * On successful write the position of the buffer is increased.
236 *
237 * @param buffer the buffer to write to
238 * @param c the character to write as <code>int</code> value
239 * @return the byte that has bean written as <code>int</code> value or
240 * <code>EOF</code> when the end of the stream is reached and automatic
241 * extension is not enabled or not possible
242 */
243 int ucx_buffer_putc(UcxBuffer *buffer, int c);
244
245 /**
246 * Gets a character from a buffer.
247 *
248 * The current position of the buffer is increased after a successful read.
249 *
250 * @param buffer the buffer to read from
251 * @return the character as <code>int</code> value or <code>EOF</code>, if the
252 * end of the buffer is reached
253 */
254 int ucx_buffer_getc(UcxBuffer *buffer);
255
256 /**
257 * Writes a string to a buffer.
258 *
259 * @param buffer the buffer
260 * @param str the string
261 * @return the number of bytes written
262 */
263 size_t ucx_buffer_puts(UcxBuffer *buffer, char *str);
264
265 #ifdef __cplusplus
266 }
267 #endif
268
269 #endif /* UCX_BUFFER_H */
270

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