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 */
28
29 #include "cx/buffer.h"
30 #include "cx/utils.h"
31
32 #include <stdio.h>
33 #include <string.h>
34
35 int cxBufferInit(
36 CxBuffer *buffer,
37 void *space,
38 size_t capacity,
39 CxAllocator const *allocator,
40 int flags
41 ) {
42 if (allocator == NULL) allocator = cxDefaultAllocator;
43 buffer->allocator = allocator;
44 buffer->flags = flags;
45 if (!space) {
46 buffer->bytes = cxMalloc(allocator, capacity);
47 if (buffer->bytes == NULL) {
48 return 1;
49 }
50 buffer->flags |= CX_BUFFER_FREE_CONTENTS;
51 } else {
52 buffer->bytes = space;
53 }
54 buffer->capacity = capacity;
55 buffer->size = 0;
56 buffer->pos = 0;
57
58 buffer->flush_func = NULL;
59 buffer->flush_target = NULL;
60 buffer->flush_blkmax = 0;
61 buffer->flush_blksize = 4096;
62 buffer->flush_threshold = SIZE_MAX;
63
64 return 0;
65 }
66
67 void cxBufferDestroy(CxBuffer *buffer) {
68 if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {
69 cxFree(buffer->allocator, buffer->bytes);
70 }
71 }
72
73 CxBuffer *cxBufferCreate(
74 void *space,
75 size_t capacity,
76 CxAllocator const *allocator,
77 int flags
78 ) {
79 CxBuffer *buf = cxMalloc(allocator, sizeof(CxBuffer));
80 if (buf == NULL) return NULL;
81 if (0 == cxBufferInit(buf, space, capacity, allocator, flags)) {
82 return buf;
83 } else {
84 cxFree(allocator, buf);
85 return NULL;
86 }
87 }
88
89 void cxBufferFree(CxBuffer *buffer) {
90 if ((buffer->flags & CX_BUFFER_FREE_CONTENTS) == CX_BUFFER_FREE_CONTENTS) {
91 cxFree(buffer->allocator, buffer->bytes);
92 }
93 cxFree(buffer->allocator, buffer);
94 }
95
96 int cxBufferSeek(
97 CxBuffer *buffer,
98 off_t offset,
99 int whence
100 ) {
101 size_t npos;
102 switch (whence) {
103 case SEEK_CUR:
104 npos = buffer->pos;
105 break;
106 case SEEK_END:
107 npos = buffer->size;
108 break;
109 case SEEK_SET:
110 npos = 0;
111 break;
112 default:
113 return -1;
114 }
115
116 size_t opos = npos;
117 npos += offset;
118
119 if ((offset > 0 && npos < opos) || (offset < 0 && npos > opos)) {
120 return -1;
121 }
122
123 if (npos >= buffer->size) {
124 return -1;
125 } else {
126 buffer->pos = npos;
127 return 0;
128 }
129
130 }
131
132 void cxBufferClear(CxBuffer *buffer) {
133 memset(buffer->bytes, 0, buffer->size);
134 buffer->size = 0;
135 buffer->pos = 0;
136 }
137
138 int cxBufferEof(CxBuffer const *buffer) {
139 return buffer->pos >= buffer->size;
140 }
141
142 int cxBufferMinimumCapacity(
143 CxBuffer *buffer,
144 size_t newcap
145 ) {
146 if (newcap <= buffer->capacity) {
147 return 0;
148 }
149
150 if (cxReallocate(buffer->allocator,
151 (void **) &buffer->bytes, newcap) == 0) {
152 buffer->capacity = newcap;
153 return 0;
154 } else {
155 return -1;
156 }
157 }
158
159 /**
160 * Helps flushing data to the flush target of a buffer.
161 *
162 * @param buffer the buffer containing the config
163 * @param space the data to flush
164 * @param size the element size
165 * @param nitems the number of items
166 * @return the number of items flushed
167 */
168 static size_t cx_buffer_write_flush_helper(
169 CxBuffer *buffer,
170 unsigned char const *space,
171 size_t size,
172 size_t nitems
173 ) {
174 size_t pos = 0;
175 size_t remaining = nitems;
176 size_t max_items = buffer->flush_blksize / size;
177 while (remaining > 0) {
178 size_t items = remaining > max_items ? max_items : remaining;
179 size_t flushed = buffer->flush_func(
180 space + pos,
181 size, items,
182 buffer->flush_target);
183 if (flushed > 0) {
184 pos += (flushed * size);
185 remaining -= flushed;
186 } else {
187 // if no bytes can be flushed out anymore, we give up
188 break;
189 }
190 }
191 return nitems - remaining;
192 }
193
194 size_t cxBufferWrite(
195 void const *ptr,
196 size_t size,
197 size_t nitems,
198 CxBuffer *buffer
199 ) {
200 // optimize for easy case
201 if (size == 1 && (buffer->capacity - buffer->pos) >= nitems) {
202 memcpy(buffer->bytes + buffer->pos, ptr, nitems);
203 buffer->pos += nitems;
204 if (buffer->pos > buffer->size) {
205 buffer->size = buffer->pos;
206 }
207 return nitems;
208 }
209
210 size_t len;
211 size_t nitems_out = nitems;
212 if (cx_szmul(size, nitems, &len)) {
213 return 0;
214 }
215 size_t required = buffer->pos + len;
216 if (buffer->pos > required) {
217 return 0;
218 }
219
220 bool perform_flush = false;
221 if (required > buffer->capacity) {
222 if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND && required) {
223 if (buffer->flush_blkmax > 0 && required > buffer->flush_threshold) {
224 perform_flush = true;
225 } else {
226 if (cxBufferMinimumCapacity(buffer, required)) {
227 return 0;
228 }
229 }
230 } else {
231 if (buffer->flush_blkmax > 0) {
232 perform_flush = true;
233 } else {
234 // truncate data to be written, if we can neither extend nor flush
235 len = buffer->capacity - buffer->pos;
236 if (size > 1) {
237 len -= len % size;
238 }
239 nitems_out = len / size;
240 }
241 }
242 }
243
244 if (len == 0) {
245 return len;
246 }
247
248 if (perform_flush) {
249 size_t flush_max;
250 if (cx_szmul(buffer->flush_blkmax, buffer->flush_blksize, &flush_max)) {
251 return 0;
252 }
253 size_t flush_pos = buffer->flush_func == NULL || buffer->flush_target == NULL
254 ? buffer->pos
255 : cx_buffer_write_flush_helper(buffer, buffer->bytes, 1, buffer->pos);
256 if (flush_pos == buffer->pos) {
257 // entire buffer has been flushed, we can reset
258 buffer->size = buffer->pos = 0;
259
260 size_t items_flush; // how many items can also be directly flushed
261 size_t items_keep; // how many items have to be written to the buffer
262
263 items_flush = flush_max >= required ? nitems : (flush_max - flush_pos) / size;
264 if (items_flush > 0) {
265 items_flush = cx_buffer_write_flush_helper(buffer, ptr, size, items_flush / size);
266 // in case we could not flush everything, keep the rest
267 }
268 items_keep = nitems - items_flush;
269 if (items_keep > 0) {
270 // try again with the remaining stuff
271 unsigned char const *new_ptr = ptr;
272 new_ptr += items_flush * size;
273 // report the directly flushed items as written plus the remaining stuff
274 return items_flush + cxBufferWrite(new_ptr, size, items_keep, buffer);
275 } else {
276 // all items have been flushed - report them as written
277 return nitems;
278 }
279 } else if (flush_pos == 0) {
280 // nothing could be flushed at all, we immediately give up without writing any data
281 return 0;
282 } else {
283 // we were partially successful, we shift left and try again
284 cxBufferShiftLeft(buffer, flush_pos);
285 return cxBufferWrite(ptr, size, nitems, buffer);
286 }
287 } else {
288 memcpy(buffer->bytes + buffer->pos, ptr, len);
289 buffer->pos += len;
290 if (buffer->pos > buffer->size) {
291 buffer->size = buffer->pos;
292 }
293 return nitems_out;
294 }
295
296 }
297
298 int cxBufferPut(
299 CxBuffer *buffer,
300 int c
301 ) {
302 c &= 0xFF;
303 unsigned char const ch = c;
304 if (cxBufferWrite(&ch, 1, 1, buffer) == 1) {
305 return c;
306 } else {
307 return EOF;
308 }
309 }
310
311 size_t cxBufferPutString(
312 CxBuffer *buffer,
313 const char *str
314 ) {
315 return cxBufferWrite(str, 1, strlen(str), buffer);
316 }
317
318 size_t cxBufferRead(
319 void *ptr,
320 size_t size,
321 size_t nitems,
322 CxBuffer *buffer
323 ) {
324 size_t len;
325 if (cx_szmul(size, nitems, &len)) {
326 return 0;
327 }
328 if (buffer->pos + len > buffer->size) {
329 len = buffer->size - buffer->pos;
330 if (size > 1) len -= len % size;
331 }
332
333 if (len <= 0) {
334 return len;
335 }
336
337 memcpy(ptr, buffer->bytes + buffer->pos, len);
338 buffer->pos += len;
339
340 return len / size;
341 }
342
343 int cxBufferGet(CxBuffer *buffer) {
344 if (cxBufferEof(buffer)) {
345 return EOF;
346 } else {
347 int c = buffer->bytes[buffer->pos];
348 buffer->pos++;
349 return c;
350 }
351 }
352
353 int cxBufferShiftLeft(
354 CxBuffer *buffer,
355 size_t shift
356 ) {
357 if (shift >= buffer->size) {
358 buffer->pos = buffer->size = 0;
359 } else {
360 memmove(buffer->bytes, buffer->bytes + shift, buffer->size - shift);
361 buffer->size -= shift;
362
363 if (buffer->pos >= shift) {
364 buffer->pos -= shift;
365 } else {
366 buffer->pos = 0;
367 }
368 }
369 return 0;
370 }
371
372 int cxBufferShiftRight(
373 CxBuffer *buffer,
374 size_t shift
375 ) {
376 size_t req_capacity = buffer->size + shift;
377 size_t movebytes;
378
379 // auto extend buffer, if required and enabled
380 if (buffer->capacity < req_capacity) {
381 if ((buffer->flags & CX_BUFFER_AUTO_EXTEND) == CX_BUFFER_AUTO_EXTEND) {
382 if (cxBufferMinimumCapacity(buffer, req_capacity)) {
383 return 1;
384 }
385 movebytes = buffer->size;
386 } else {
387 movebytes = buffer->capacity - shift;
388 }
389 } else {
390 movebytes = buffer->size;
391 }
392
393 memmove(buffer->bytes + shift, buffer->bytes, movebytes);
394 buffer->size = shift + movebytes;
395
396 buffer->pos += shift;
397 if (buffer->pos > buffer->size) {
398 buffer->pos = buffer->size;
399 }
400
401 return 0;
402 }
403
404 int cxBufferShift(
405 CxBuffer *buffer,
406 off_t shift
407 ) {
408 if (shift < 0) {
409 return cxBufferShiftLeft(buffer, (size_t) (-shift));
410 } else if (shift > 0) {
411 return cxBufferShiftRight(buffer, (size_t) shift);
412 } else {
413 return 0;
414 }
415 }
416