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 static void ustream_write_error(struct ustream *s)
 337 {
 338         if (!s->write_error)
 339                 ustream_state_change(s);
 340         s->write_error = true;
 341 }
 342
 343 bool ustream_write_pending(struct ustream *s)
 344 {
 345         struct ustream_buf *buf = s->w.head;
 346         int wr = 0, len;
 347
 348         if (s->write_error)
 349                 return false;
 350
 351         while (buf && s->w.data_bytes) {
 352                 struct ustream_buf *next = buf->next;
 353                 int maxlen = buf->tail - buf->data;
 354
 355                 len = s->write(s, buf->data, maxlen, !!buf->next);
 356                 if (len < 0) {
 357                         ustream_write_error(s);
 358                         break;
 359                 }
 360
 361                 if (len == 0)
 362                         break;
 363
 364                 wr += len;
 365                 s->w.data_bytes -= len;
 366                 if (len < maxlen) {
 367                         buf->data += len;
 368                         break;
 369                 }
 370
 371                 ustream_free_buf(&s->w, buf);
 372                 buf = next;
 373         }
 374
 375         if (s->notify_write)
 376                 s->notify_write(s, wr);
 377
 378         if (s->eof && wr && !s->w.data_bytes)
 379                 ustream_state_change(s);
 380
 381         return !s->w.data_bytes;
 382 }
 383
 384 static int ustream_write_buffered(struct ustream *s, const char *data, int len, int wr)
 385 {
 386         struct ustream_buf_list *l = &s->w;
 387         struct ustream_buf *buf;
 388         int maxlen;
 389
 390         while (len) {
 391                 if (!ustream_prepare_buf(s, &s->w, len))
 392                         break;
 393
 394                 buf = l->data_tail;
 395
 396                 maxlen = buf->end - buf->tail;
 397                 if (maxlen > len)
 398                         maxlen = len;
 399
 400                 memcpy(buf->tail, data, maxlen);
 401                 buf->tail += maxlen;
 402                 data += maxlen;
 403                 len -= maxlen;
 404                 wr += maxlen;
 405                 l->data_bytes += maxlen;
 406         }
 407
 408         return wr;
 409 }
 410
 411 int ustream_write(struct ustream *s, const char *data, int len, bool more)
 412 {
 413         struct ustream_buf_list *l = &s->w;
 414         int wr = 0;
 415
 416         if (s->write_error)
 417                 return 0;
 418
 419         if (!l->data_bytes) {
 420                 wr = s->write(s, data, len, more);
 421                 if (wr == len)
 422                         return wr;
 423
 424                 if (wr < 0) {
 425                         ustream_write_error(s);
 426                         return wr;
 427                 }
 428
 429                 data += wr;
 430                 len -= wr;
 431         }
 432
 433         return ustream_write_buffered(s, data, len, wr);
 434 }
 435
 436 #define MAX_STACK_BUFLEN        256
 437
 438 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
 439 {
 440         struct ustream_buf_list *l = &s->w;
 441         char *buf;
 442         va_list arg2;
 443         int wr, maxlen, buflen;
 444
 445         if (s->write_error)
 446                 return 0;
 447
 448         if (!l->data_bytes) {
 449                 buf = alloca(MAX_STACK_BUFLEN);
 450                 va_copy(arg2, arg);
 451                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
 452                 va_end(arg2);
 453                 if (maxlen < MAX_STACK_BUFLEN) {
 454                         wr = s->write(s, buf, maxlen, false);
 455                         if (wr < 0) {
 456                                 ustream_write_error(s);
 457                                 return wr;
 458                         }
 459                         if (wr == maxlen)
 460                                 return wr;
 461
 462                         buf += wr;
 463                         maxlen -= wr;
 464                         return ustream_write_buffered(s, buf, maxlen, wr);
 465                 } else {
 466                         buf = malloc(maxlen + 1);
 467                         wr = vsnprintf(buf, maxlen + 1, format, arg);
 468                         wr = ustream_write(s, buf, wr, false);
 469                         free(buf);
 470                         return wr;
 471                 }
 472         }
 473
 474         if (!ustream_prepare_buf(s, l, 1))
 475                 return 0;
 476
 477         buf = l->data_tail->tail;
 478         buflen = l->data_tail->end - buf;
 479
 480         va_copy(arg2, arg);
 481         maxlen = vsnprintf(buf, buflen, format, arg2);
 482         va_end(arg2);
 483
 484         wr = maxlen;
 485         if (wr >= buflen)
 486                 wr = buflen - 1;
 487
 488         l->data_tail->tail += wr;
 489         l->data_bytes += wr;
 490         if (maxlen < buflen)
 491                 return wr;
 492
 493         buf = malloc(maxlen + 1);
 494         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
 495         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
 496         free(buf);
 497
 498         return wr;
 499 }
 500
 501 int ustream_printf(struct ustream *s, const char *format, ...)
 502 {
 503         va_list arg;
 504         int ret;
 505
 506         if (s->write_error)
 507                 return 0;
 508
 509         va_start(arg, format);
 510         ret = ustream_vprintf(s, format, arg);
 511         va_end(arg);
 512
 513         return ret;
 514 }