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Sources/libubox/ustream.c

  1 /*
  2  * ustream - library for stream buffer management
  3  *
  4  * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
  5  *
  6  * Permission to use, copy, modify, and/or distribute this software for any
  7  * purpose with or without fee is hereby granted, provided that the above
  8  * copyright notice and this permission notice appear in all copies.
  9  *
 10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 17  */
 18 
 19 #include <stdlib.h>
 20 #include <string.h>
 21 #include <unistd.h>
 22 #include <stdio.h>
 23 #include <stdarg.h>
 24 
 25 #include "ustream.h"
 26 
 27 static void ustream_init_buf(struct ustream_buf *buf, int len)
 28 {
 29         if (!len)
 30                 abort();
 31 
 32         memset(buf, 0, sizeof(*buf));
 33         buf->data = buf->tail = buf->head;
 34         buf->end = buf->head + len;
 35         *buf->head = 0;
 36 }
 37 
 38 static void ustream_add_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
 39 {
 40         l->buffers++;
 41         if (!l->tail)
 42                 l->head = buf;
 43         else
 44                 l->tail->next = buf;
 45 
 46         buf->next = NULL;
 47         l->tail = buf;
 48         if (!l->data_tail)
 49                 l->data_tail = l->head;
 50 }
 51 
 52 static bool ustream_can_alloc(struct ustream_buf_list *l)
 53 {
 54         if (l->max_buffers <= 0)
 55                 return true;
 56 
 57         return (l->buffers < l->max_buffers);
 58 }
 59 
 60 static int ustream_alloc_default(struct ustream *s, struct ustream_buf_list *l)
 61 {
 62         struct ustream_buf *buf;
 63 
 64         if (!ustream_can_alloc(l))
 65                 return -1;
 66 
 67         buf = malloc(sizeof(*buf) + l->buffer_len + s->string_data);
 68         if (!buf)
 69                 return -1;
 70 
 71         ustream_init_buf(buf, l->buffer_len);
 72         ustream_add_buf(l, buf);
 73 
 74         return 0;
 75 }
 76 
 77 static void ustream_free_buffers(struct ustream_buf_list *l)
 78 {
 79         struct ustream_buf *buf = l->head;
 80 
 81         while (buf) {
 82                 struct ustream_buf *next = buf->next;
 83 
 84                 free(buf);
 85                 buf = next;
 86         }
 87         l->head = NULL;
 88         l->tail = NULL;
 89         l->data_tail = NULL;
 90 }
 91 
 92 void ustream_free(struct ustream *s)
 93 {
 94         if (s->free)
 95                 s->free(s);
 96 
 97         uloop_timeout_cancel(&s->state_change);
 98         ustream_free_buffers(&s->r);
 99         ustream_free_buffers(&s->w);
100 }
101 
102 static void ustream_state_change_cb(struct uloop_timeout *t)
103 {
104         struct ustream *s = container_of(t, struct ustream, state_change);
105 
106         if (s->write_error)
107                 ustream_free_buffers(&s->w);
108         if (s->notify_state)
109                 s->notify_state(s);
110 }
111 
112 void ustream_init_defaults(struct ustream *s)
113 {
114 #define DEFAULT_SET(_f, _default)       \
115         do {                            \
116                 if (!_f)                \
117                         _f = _default;  \
118         } while(0)
119 
120         DEFAULT_SET(s->r.alloc, ustream_alloc_default);
121         DEFAULT_SET(s->w.alloc, ustream_alloc_default);
122 
123         DEFAULT_SET(s->r.min_buffers, 1);
124         DEFAULT_SET(s->r.max_buffers, 1);
125         DEFAULT_SET(s->r.buffer_len, 4096);
126 
127         DEFAULT_SET(s->w.min_buffers, 2);
128         DEFAULT_SET(s->w.max_buffers, -1);
129         DEFAULT_SET(s->w.buffer_len, 256);
130 
131 #undef DEFAULT_SET
132 
133         s->state_change.cb = ustream_state_change_cb;
134         s->write_error = false;
135         s->eof = false;
136         s->eof_write_done = false;
137         s->read_blocked = 0;
138 
139         s->r.buffers = 0;
140         s->r.data_bytes = 0;
141 
142         s->w.buffers = 0;
143         s->w.data_bytes = 0;
144 }
145 
146 static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *buf, int len)
147 {
148         int maxlen;
149         int offset;
150 
151         /* nothing to squeeze */
152         if (buf->data == buf->head)
153                 return false;
154 
155         maxlen = buf->end - buf->head;
156         offset = buf->data - buf->head;
157 
158         /* less than half is available */
159         if (offset > maxlen / 2)
160                 return true;
161 
162         /* less than 32 bytes data but takes more than 1/4 space */
163         if (buf->tail - buf->data < 32 && offset > maxlen / 4)
164                 return true;
165 
166         /* more buf is already in list or can be allocated */
167         if (buf != l->tail || ustream_can_alloc(l))
168                 return false;
169 
170         /* no need to move if len is available at the tail */
171         return (buf->end - buf->tail < len);
172 }
173 
174 static void ustream_free_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
175 {
176         if (buf == l->head)
177                 l->head = buf->next;
178 
179         if (buf == l->data_tail)
180                 l->data_tail = buf->next;
181 
182         if (buf == l->tail)
183                 l->tail = NULL;
184 
185         if (--l->buffers >= l->min_buffers) {
186                 free(buf);
187                 return;
188         }
189 
190         /* recycle */
191         ustream_init_buf(buf, buf->end - buf->head);
192         ustream_add_buf(l, buf);
193 }
194 
195 static void __ustream_set_read_blocked(struct ustream *s, unsigned char val)
196 {
197         bool changed = !!s->read_blocked != !!val;
198 
199         s->read_blocked = val;
200         if (changed)
201                 s->set_read_blocked(s);
202 }
203 
204 void ustream_set_read_blocked(struct ustream *s, bool set)
205 {
206         unsigned char val = s->read_blocked & ~READ_BLOCKED_USER;
207 
208         if (set)
209                 val |= READ_BLOCKED_USER;
210 
211         __ustream_set_read_blocked(s, val);
212 }
213 
214 void ustream_consume(struct ustream *s, int len)
215 {
216         struct ustream_buf *buf = s->r.head;
217 
218         if (!len)
219                 return;
220 
221         s->r.data_bytes -= len;
222         if (s->r.data_bytes < 0)
223                 abort();
224 
225         do {
226                 struct ustream_buf *next = buf->next;
227                 int buf_len = buf->tail - buf->data;
228 
229                 if (len < buf_len) {
230                         buf->data += len;
231                         break;
232                 }
233 
234                 len -= buf_len;
235                 ustream_free_buf(&s->r, buf);
236                 buf = next;
237         } while(len);
238 
239         __ustream_set_read_blocked(s, s->read_blocked & ~READ_BLOCKED_FULL);
240 }
241 
242 static void ustream_fixup_string(struct ustream *s, struct ustream_buf *buf)
243 {
244         if (!s->string_data)
245                 return;
246 
247         *buf->tail = 0;
248 }
249 
250 static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, int len)
251 {
252         struct ustream_buf *buf;
253 
254         buf = l->data_tail;
255         if (buf) {
256                 if (ustream_should_move(l, buf, len)) {
257                         int len = buf->tail - buf->data;
258 
259                         memmove(buf->head, buf->data, len);
260                         buf->data = buf->head;
261                         buf->tail = buf->data + len;
262 
263                         if (l == &s->r)
264                                 ustream_fixup_string(s, buf);
265                 }
266                 /* some chunks available at the tail */
267                 if (buf->tail != buf->end)
268                         return true;
269                 /* next buf available */
270                 if (buf->next) {
271                         l->data_tail = buf->next;
272                         return true;
273                 }
274         }
275 
276         if (!ustream_can_alloc(l))
277                 return false;
278 
279         if (l->alloc(s, l) < 0)
280                 return false;
281 
282         l->data_tail = l->tail;
283         return true;
284 }
285 
286 char *ustream_reserve(struct ustream *s, int len, int *maxlen)
287 {
288         struct ustream_buf *buf;
289 
290         if (!ustream_prepare_buf(s, &s->r, len)) {
291                 __ustream_set_read_blocked(s, s->read_blocked | READ_BLOCKED_FULL);
292                 *maxlen = 0;
293                 return NULL;
294         }
295 
296         buf = s->r.data_tail;
297         *maxlen = buf->end - buf->tail;
298         return buf->tail;
299 }
300 
301 void ustream_fill_read(struct ustream *s, int len)
302 {
303         struct ustream_buf *buf = s->r.data_tail;
304         int n = len;
305         int maxlen;
306 
307         s->r.data_bytes += len;
308         do {
309                 if (!buf)
310                         abort();
311 
312                 maxlen = buf->end - buf->tail;
313                 if (len < maxlen)
314                         maxlen = len;
315 
316                 len -= maxlen;
317                 buf->tail += maxlen;
318                 ustream_fixup_string(s, buf);
319 
320                 s->r.data_tail = buf;
321                 buf = buf->next;
322         } while (len);
323 
324         if (s->notify_read)
325                 s->notify_read(s, n);
326 }
327 
328 char *ustream_get_read_buf(struct ustream *s, int *buflen)
329 {
330         char *data = NULL;
331         int len = 0;
332 
333         if (s->r.head) {
334                 len = s->r.head->tail - s->r.head->data;
335                 if (len > 0)
336                         data = s->r.head->data;
337         }
338 
339         if (buflen)
340                 *buflen = len;
341 
342         return data;
343 }
344 
345 int ustream_read(struct ustream *s, char *buf, int buflen)
346 {
347         char *chunk;
348         int chunk_len;
349         int len = 0;
350 
351         do {
352                 chunk = ustream_get_read_buf(s, &chunk_len);
353                 if (!chunk)
354                         break;
355                 if (chunk_len > buflen - len)
356                         chunk_len = buflen - len;
357                 memcpy(buf + len, chunk, chunk_len);
358                 ustream_consume(s, chunk_len);
359                 len += chunk_len;
360         } while (len < buflen);
361 
362         return len;
363 }
364 
365 static void ustream_write_error(struct ustream *s)
366 {
367         if (!s->write_error)
368                 ustream_state_change(s);
369         s->write_error = true;
370 }
371 
372 bool ustream_write_pending(struct ustream *s)
373 {
374         struct ustream_buf *buf = s->w.head;
375         int wr = 0, len;
376 
377         if (s->write_error)
378                 return false;
379 
380         while (buf && s->w.data_bytes) {
381                 struct ustream_buf *next = buf->next;
382                 int maxlen = buf->tail - buf->data;
383 
384                 len = s->write(s, buf->data, maxlen, !!buf->next);
385                 if (len < 0) {
386                         ustream_write_error(s);
387                         break;
388                 }
389 
390                 if (len == 0)
391                         break;
392 
393                 wr += len;
394                 s->w.data_bytes -= len;
395                 if (len < maxlen) {
396                         buf->data += len;
397                         break;
398                 }
399 
400                 ustream_free_buf(&s->w, buf);
401                 buf = next;
402         }
403 
404         if (s->notify_write)
405                 s->notify_write(s, wr);
406 
407         if (s->eof && wr && !s->w.data_bytes)
408                 ustream_state_change(s);
409 
410         return !s->w.data_bytes;
411 }
412 
413 static int ustream_write_buffered(struct ustream *s, const char *data, int len, int wr)
414 {
415         struct ustream_buf_list *l = &s->w;
416         struct ustream_buf *buf;
417         int maxlen;
418 
419         while (len) {
420                 if (!ustream_prepare_buf(s, &s->w, len))
421                         break;
422 
423                 buf = l->data_tail;
424 
425                 maxlen = buf->end - buf->tail;
426                 if (maxlen > len)
427                         maxlen = len;
428 
429                 memcpy(buf->tail, data, maxlen);
430                 buf->tail += maxlen;
431                 data += maxlen;
432                 len -= maxlen;
433                 wr += maxlen;
434                 l->data_bytes += maxlen;
435         }
436 
437         return wr;
438 }
439 
440 int ustream_write(struct ustream *s, const char *data, int len, bool more)
441 {
442         struct ustream_buf_list *l = &s->w;
443         int wr = 0;
444 
445         if (s->write_error)
446                 return 0;
447 
448         if (!l->data_bytes) {
449                 wr = s->write(s, data, len, more);
450                 if (wr == len)
451                         return wr;
452 
453                 if (wr < 0) {
454                         ustream_write_error(s);
455                         return wr;
456                 }
457 
458                 data += wr;
459                 len -= wr;
460         }
461 
462         return ustream_write_buffered(s, data, len, wr);
463 }
464 
465 #define MAX_STACK_BUFLEN        256
466 
467 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
468 {
469         struct ustream_buf_list *l = &s->w;
470         char *buf;
471         va_list arg2;
472         int wr, maxlen, buflen;
473 
474         if (s->write_error)
475                 return 0;
476 
477         if (!l->data_bytes) {
478                 buf = alloca(MAX_STACK_BUFLEN);
479                 va_copy(arg2, arg);
480                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
481                 va_end(arg2);
482                 if (maxlen < MAX_STACK_BUFLEN) {
483                         wr = s->write(s, buf, maxlen, false);
484                         if (wr < 0) {
485                                 ustream_write_error(s);
486                                 return wr;
487                         }
488                         if (wr == maxlen)
489                                 return wr;
490 
491                         buf += wr;
492                         maxlen -= wr;
493                         return ustream_write_buffered(s, buf, maxlen, wr);
494                 } else {
495                         buf = malloc(maxlen + 1);
496                         if (!buf)
497                                 return 0;
498                         wr = vsnprintf(buf, maxlen + 1, format, arg);
499                         wr = ustream_write(s, buf, wr, false);
500                         free(buf);
501                         return wr;
502                 }
503         }
504 
505         if (!ustream_prepare_buf(s, l, 1))
506                 return 0;
507 
508         buf = l->data_tail->tail;
509         buflen = l->data_tail->end - buf;
510 
511         va_copy(arg2, arg);
512         maxlen = vsnprintf(buf, buflen, format, arg2);
513         va_end(arg2);
514 
515         wr = maxlen;
516         if (wr >= buflen)
517                 wr = buflen - 1;
518 
519         l->data_tail->tail += wr;
520         l->data_bytes += wr;
521         if (maxlen < buflen)
522                 return wr;
523 
524         buf = malloc(maxlen + 1);
525         if (!buf)
526                 return wr;
527         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
528         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
529         free(buf);
530 
531         return wr;
532 }
533 
534 int ustream_printf(struct ustream *s, const char *format, ...)
535 {
536         va_list arg;
537         int ret;
538 
539         if (s->write_error)
540                 return 0;
541 
542         va_start(arg, format);
543         ret = ustream_vprintf(s, format, arg);
544         va_end(arg);
545 
546         return ret;
547 }
548 

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