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 }