ustream: add function ustream_read().
[project/libubox.git] / 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         ustream_init_buf(buf, l->buffer_len);
69         ustream_add_buf(l, buf);
70
71         return 0;
72 }
73
74 static void ustream_free_buffers(struct ustream_buf_list *l)
75 {
76         struct ustream_buf *buf = l->head;
77
78         while (buf) {
79                 struct ustream_buf *next = buf->next;
80
81                 free(buf);
82                 buf = next;
83         }
84         l->head = NULL;
85         l->tail = NULL;
86         l->data_tail = NULL;
87 }
88
89 void ustream_free(struct ustream *s)
90 {
91         if (s->free)
92                 s->free(s);
93
94         uloop_timeout_cancel(&s->state_change);
95         ustream_free_buffers(&s->r);
96         ustream_free_buffers(&s->w);
97 }
98
99 static void ustream_state_change_cb(struct uloop_timeout *t)
100 {
101         struct ustream *s = container_of(t, struct ustream, state_change);
102
103         if (s->write_error)
104                 ustream_free_buffers(&s->w);
105         if (s->notify_state)
106                 s->notify_state(s);
107 }
108
109 void ustream_init_defaults(struct ustream *s)
110 {
111 #define DEFAULT_SET(_f, _default)       \
112         do {                            \
113                 if (!_f)                \
114                         _f = _default;  \
115         } while(0)
116
117         DEFAULT_SET(s->r.alloc, ustream_alloc_default);
118         DEFAULT_SET(s->w.alloc, ustream_alloc_default);
119
120         DEFAULT_SET(s->r.min_buffers, 1);
121         DEFAULT_SET(s->r.max_buffers, 1);
122         DEFAULT_SET(s->r.buffer_len, 4096);
123
124         DEFAULT_SET(s->w.min_buffers, 2);
125         DEFAULT_SET(s->w.max_buffers, -1);
126         DEFAULT_SET(s->w.buffer_len, 256);
127
128 #undef DEFAULT_SET
129
130         s->state_change.cb = ustream_state_change_cb;
131         s->write_error = false;
132         s->eof = false;
133         s->eof_write_done = false;
134         s->read_blocked = 0;
135
136         s->r.buffers = 0;
137         s->r.data_bytes = 0;
138
139         s->w.buffers = 0;
140         s->w.data_bytes = 0;
141 }
142
143 static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *buf, int len)
144 {
145         int maxlen;
146         int offset;
147
148         if (buf->data == buf->head)
149                 return false;
150
151         maxlen = buf->end - buf->head;
152         offset = buf->data - buf->head;
153
154         if (offset > maxlen / 2)
155                 return true;
156
157         if (buf->tail - buf->data < 32 && offset > maxlen / 4)
158                 return true;
159
160         if (buf != l->tail || ustream_can_alloc(l))
161                 return false;
162
163         return (buf->end - buf->tail < len);
164 }
165
166 static void ustream_free_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
167 {
168         if (buf == l->head)
169                 l->head = buf->next;
170
171         if (buf == l->data_tail)
172                 l->data_tail = buf->next;
173
174         if (buf == l->tail)
175                 l->tail = NULL;
176
177         if (--l->buffers >= l->min_buffers) {
178                 free(buf);
179                 return;
180         }
181
182         /* recycle */
183         ustream_init_buf(buf, buf->end - buf->head);
184         ustream_add_buf(l, buf);
185 }
186
187 static void __ustream_set_read_blocked(struct ustream *s, unsigned char val)
188 {
189         bool changed = !!s->read_blocked != !!val;
190
191         s->read_blocked = val;
192         if (changed)
193                 s->set_read_blocked(s);
194 }
195
196 void ustream_set_read_blocked(struct ustream *s, bool set)
197 {
198         unsigned char val = s->read_blocked & ~READ_BLOCKED_USER;
199
200         if (set)
201                 val |= READ_BLOCKED_USER;
202
203         __ustream_set_read_blocked(s, val);
204 }
205
206 void ustream_consume(struct ustream *s, int len)
207 {
208         struct ustream_buf *buf = s->r.head;
209
210         if (!len)
211                 return;
212
213         s->r.data_bytes -= len;
214         if (s->r.data_bytes < 0)
215                 abort();
216
217         do {
218                 struct ustream_buf *next = buf->next;
219                 int buf_len = buf->tail - buf->data;
220
221                 if (len < buf_len) {
222                         buf->data += len;
223                         break;
224                 }
225
226                 len -= buf_len;
227                 ustream_free_buf(&s->r, buf);
228                 buf = next;
229         } while(len);
230
231         __ustream_set_read_blocked(s, s->read_blocked & ~READ_BLOCKED_FULL);
232 }
233
234 static void ustream_fixup_string(struct ustream *s, struct ustream_buf *buf)
235 {
236         if (!s->string_data)
237                 return;
238
239         *buf->tail = 0;
240 }
241
242 static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, int len)
243 {
244         struct ustream_buf *buf;
245
246         buf = l->data_tail;
247         if (buf) {
248                 if (ustream_should_move(l, buf, len)) {
249                         int len = buf->tail - buf->data;
250
251                         memmove(buf->head, buf->data, len);
252                         buf->data = buf->head;
253                         buf->tail = buf->data + len;
254
255                         if (l == &s->r)
256                                 ustream_fixup_string(s, buf);
257                 }
258                 if (buf->tail != buf->end)
259                         return true;
260         }
261
262         if (buf && buf->next) {
263                 l->data_tail = buf->next;
264                 return true;
265         }
266
267         if (!ustream_can_alloc(l))
268                 return false;
269
270         if (l->alloc(s, l) < 0)
271                 return false;
272
273         l->data_tail = l->tail;
274         return true;
275 }
276
277 char *ustream_reserve(struct ustream *s, int len, int *maxlen)
278 {
279         struct ustream_buf *buf;
280
281         if (!ustream_prepare_buf(s, &s->r, len)) {
282                 __ustream_set_read_blocked(s, s->read_blocked | READ_BLOCKED_FULL);
283                 *maxlen = 0;
284                 return NULL;
285         }
286
287         buf = s->r.data_tail;
288         *maxlen = buf->end - buf->tail;
289         return buf->tail;
290 }
291
292 void ustream_fill_read(struct ustream *s, int len)
293 {
294         struct ustream_buf *buf = s->r.data_tail;
295         int n = len;
296         int maxlen;
297
298         s->r.data_bytes += len;
299         do {
300                 if (!buf)
301                         abort();
302
303                 maxlen = buf->end - buf->tail;
304                 if (len < maxlen)
305                         maxlen = len;
306
307                 len -= maxlen;
308                 buf->tail += maxlen;
309                 ustream_fixup_string(s, buf);
310
311                 s->r.data_tail = buf;
312                 buf = buf->next;
313         } while (len);
314
315         if (s->notify_read)
316                 s->notify_read(s, n);
317 }
318
319 char *ustream_get_read_buf(struct ustream *s, int *buflen)
320 {
321         char *data = NULL;
322         int len = 0;
323
324         if (s->r.head) {
325                 len = s->r.head->tail - s->r.head->data;
326                 if (len > 0)
327                         data = s->r.head->data;
328         }
329
330         if (buflen)
331                 *buflen = len;
332
333         return data;
334 }
335
336 int ustream_read(struct ustream *s, char *buf, int buflen)
337 {
338         char *chunk;
339         int chunk_len;
340         int len = 0;
341
342         do {
343                 chunk = ustream_get_read_buf(s, &chunk_len);
344                 if (!chunk)
345                         break;
346                 if (chunk_len > buflen - len)
347                         chunk_len = buflen - len;
348                 memcpy(buf + len, chunk, chunk_len);
349                 ustream_consume(s, chunk_len);
350                 len += chunk_len;
351         } while (len < buflen);
352
353         return len;
354 }
355
356 static void ustream_write_error(struct ustream *s)
357 {
358         if (!s->write_error)
359                 ustream_state_change(s);
360         s->write_error = true;
361 }
362
363 bool ustream_write_pending(struct ustream *s)
364 {
365         struct ustream_buf *buf = s->w.head;
366         int wr = 0, len;
367
368         if (s->write_error)
369                 return false;
370
371         while (buf && s->w.data_bytes) {
372                 struct ustream_buf *next = buf->next;
373                 int maxlen = buf->tail - buf->data;
374
375                 len = s->write(s, buf->data, maxlen, !!buf->next);
376                 if (len < 0) {
377                         ustream_write_error(s);
378                         break;
379                 }
380
381                 if (len == 0)
382                         break;
383
384                 wr += len;
385                 s->w.data_bytes -= len;
386                 if (len < maxlen) {
387                         buf->data += len;
388                         break;
389                 }
390
391                 ustream_free_buf(&s->w, buf);
392                 buf = next;
393         }
394
395         if (s->notify_write)
396                 s->notify_write(s, wr);
397
398         if (s->eof && wr && !s->w.data_bytes)
399                 ustream_state_change(s);
400
401         return !s->w.data_bytes;
402 }
403
404 static int ustream_write_buffered(struct ustream *s, const char *data, int len, int wr)
405 {
406         struct ustream_buf_list *l = &s->w;
407         struct ustream_buf *buf;
408         int maxlen;
409
410         while (len) {
411                 if (!ustream_prepare_buf(s, &s->w, len))
412                         break;
413
414                 buf = l->data_tail;
415
416                 maxlen = buf->end - buf->tail;
417                 if (maxlen > len)
418                         maxlen = len;
419
420                 memcpy(buf->tail, data, maxlen);
421                 buf->tail += maxlen;
422                 data += maxlen;
423                 len -= maxlen;
424                 wr += maxlen;
425                 l->data_bytes += maxlen;
426         }
427
428         return wr;
429 }
430
431 int ustream_write(struct ustream *s, const char *data, int len, bool more)
432 {
433         struct ustream_buf_list *l = &s->w;
434         int wr = 0;
435
436         if (s->write_error)
437                 return 0;
438
439         if (!l->data_bytes) {
440                 wr = s->write(s, data, len, more);
441                 if (wr == len)
442                         return wr;
443
444                 if (wr < 0) {
445                         ustream_write_error(s);
446                         return wr;
447                 }
448
449                 data += wr;
450                 len -= wr;
451         }
452
453         return ustream_write_buffered(s, data, len, wr);
454 }
455
456 #define MAX_STACK_BUFLEN        256
457
458 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
459 {
460         struct ustream_buf_list *l = &s->w;
461         char *buf;
462         va_list arg2;
463         int wr, maxlen, buflen;
464
465         if (s->write_error)
466                 return 0;
467
468         if (!l->data_bytes) {
469                 buf = alloca(MAX_STACK_BUFLEN);
470                 va_copy(arg2, arg);
471                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
472                 va_end(arg2);
473                 if (maxlen < MAX_STACK_BUFLEN) {
474                         wr = s->write(s, buf, maxlen, false);
475                         if (wr < 0) {
476                                 ustream_write_error(s);
477                                 return wr;
478                         }
479                         if (wr == maxlen)
480                                 return wr;
481
482                         buf += wr;
483                         maxlen -= wr;
484                         return ustream_write_buffered(s, buf, maxlen, wr);
485                 } else {
486                         buf = malloc(maxlen + 1);
487                         wr = vsnprintf(buf, maxlen + 1, format, arg);
488                         wr = ustream_write(s, buf, wr, false);
489                         free(buf);
490                         return wr;
491                 }
492         }
493
494         if (!ustream_prepare_buf(s, l, 1))
495                 return 0;
496
497         buf = l->data_tail->tail;
498         buflen = l->data_tail->end - buf;
499
500         va_copy(arg2, arg);
501         maxlen = vsnprintf(buf, buflen, format, arg2);
502         va_end(arg2);
503
504         wr = maxlen;
505         if (wr >= buflen)
506                 wr = buflen - 1;
507
508         l->data_tail->tail += wr;
509         l->data_bytes += wr;
510         if (maxlen < buflen)
511                 return wr;
512
513         buf = malloc(maxlen + 1);
514         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
515         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
516         free(buf);
517
518         return wr;
519 }
520
521 int ustream_printf(struct ustream *s, const char *format, ...)
522 {
523         va_list arg;
524         int ret;
525
526         if (s->write_error)
527                 return 0;
528
529         va_start(arg, format);
530         ret = ustream_vprintf(s, format, arg);
531         va_end(arg);
532
533         return ret;
534 }