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 #define CB_PENDING_READ (1 << 0)
  28
  29 static void ustream_init_buf(struct ustream_buf *buf, int len)
  30 {
  31         if (!len)
  32                 abort();
  33
  34         memset(buf, 0, sizeof(*buf));
  35         buf->data = buf->tail = buf->head;
  36         buf->end = buf->head + len;
  37         *buf->head = 0;
  38 }
  39
  40 static void ustream_add_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
  41 {
  42         l->buffers++;
  43         if (!l->tail)
  44                 l->head = buf;
  45         else
  46                 l->tail->next = buf;
  47
  48         buf->next = NULL;
  49         l->tail = buf;
  50         if (!l->data_tail)
  51                 l->data_tail = l->head;
  52 }
  53
  54 static bool ustream_can_alloc(struct ustream_buf_list *l)
  55 {
  56         if (l->max_buffers <= 0)
  57                 return true;
  58
  59         return (l->buffers < l->max_buffers);
  60 }
  61
  62 static int ustream_alloc_default(struct ustream *s, struct ustream_buf_list *l)
  63 {
  64         struct ustream_buf *buf;
  65
  66         if (!ustream_can_alloc(l))
  67                 return -1;
  68
  69         buf = malloc(sizeof(*buf) + l->buffer_len + s->string_data);
  70         if (!buf)
  71                 return -1;
  72
  73         ustream_init_buf(buf, l->buffer_len);
  74         ustream_add_buf(l, buf);
  75
  76         return 0;
  77 }
  78
  79 static void ustream_free_buffers(struct ustream_buf_list *l)
  80 {
  81         struct ustream_buf *buf = l->head;
  82
  83         while (buf) {
  84                 struct ustream_buf *next = buf->next;
  85
  86                 free(buf);
  87                 buf = next;
  88         }
  89         l->head = NULL;
  90         l->tail = NULL;
  91         l->data_tail = NULL;
  92 }
  93
  94 void ustream_free(struct ustream *s)
  95 {
  96         if (s->free)
  97                 s->free(s);
  98
  99         uloop_timeout_cancel(&s->state_change);
 100         ustream_free_buffers(&s->r);
 101         ustream_free_buffers(&s->w);
 102 }
 103
 104 static void ustream_state_change_cb(struct uloop_timeout *t)
 105 {
 106         struct ustream *s = container_of(t, struct ustream, state_change);
 107
 108         if (s->write_error)
 109                 ustream_free_buffers(&s->w);
 110         if (s->notify_state)
 111                 s->notify_state(s);
 112 }
 113
 114 void ustream_init_defaults(struct ustream *s)
 115 {
 116 #define DEFAULT_SET(_f, _default)       \
 117         do {                            \
 118                 if (!_f)                \
 119                         _f = _default;  \
 120         } while(0)
 121
 122         DEFAULT_SET(s->r.alloc, ustream_alloc_default);
 123         DEFAULT_SET(s->w.alloc, ustream_alloc_default);
 124
 125         DEFAULT_SET(s->r.min_buffers, 1);
 126         DEFAULT_SET(s->r.max_buffers, 1);
 127         DEFAULT_SET(s->r.buffer_len, 4096);
 128
 129         DEFAULT_SET(s->w.min_buffers, 2);
 130         DEFAULT_SET(s->w.max_buffers, -1);
 131         DEFAULT_SET(s->w.buffer_len, 256);
 132
 133 #undef DEFAULT_SET
 134
 135         s->state_change.cb = ustream_state_change_cb;
 136         s->write_error = false;
 137         s->eof = false;
 138         s->read_blocked = 0;
 139
 140         s->r.buffers = 0;
 141         s->r.data_bytes = 0;
 142
 143         s->w.buffers = 0;
 144         s->w.data_bytes = 0;
 145 }
 146
 147 static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *buf, int len)
 148 {
 149         int maxlen;
 150         int offset;
 151
 152         /* nothing to squeeze */
 153         if (buf->data == buf->head)
 154                 return false;
 155
 156         maxlen = buf->end - buf->head;
 157         offset = buf->data - buf->head;
 158
 159         /* less than half is available */
 160         if (offset > maxlen / 2)
 161                 return true;
 162
 163         /* less than 32 bytes data but takes more than 1/4 space */
 164         if (buf->tail - buf->data < 32 && offset > maxlen / 4)
 165                 return true;
 166
 167         /* more buf is already in list or can be allocated */
 168         if (buf != l->tail || ustream_can_alloc(l))
 169                 return false;
 170
 171         /* no need to move if len is available at the tail */
 172         return (buf->end - buf->tail < len);
 173 }
 174
 175 static void ustream_free_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
 176 {
 177         if (buf == l->head)
 178                 l->head = buf->next;
 179
 180         if (buf == l->data_tail)
 181                 l->data_tail = buf->next;
 182
 183         if (buf == l->tail)
 184                 l->tail = NULL;
 185
 186         if (--l->buffers >= l->min_buffers) {
 187                 free(buf);
 188                 return;
 189         }
 190
 191         /* recycle */
 192         ustream_init_buf(buf, buf->end - buf->head);
 193         ustream_add_buf(l, buf);
 194 }
 195
 196 static void __ustream_set_read_blocked(struct ustream *s, unsigned char val)
 197 {
 198         bool changed = !!s->read_blocked != !!val;
 199
 200         s->read_blocked = val;
 201         if (changed)
 202                 s->set_read_blocked(s);
 203 }
 204
 205 void ustream_set_read_blocked(struct ustream *s, bool set)
 206 {
 207         unsigned char val = s->read_blocked & ~READ_BLOCKED_USER;
 208
 209         if (set)
 210                 val |= READ_BLOCKED_USER;
 211
 212         __ustream_set_read_blocked(s, val);
 213 }
 214
 215 void ustream_consume(struct ustream *s, int len)
 216 {
 217         struct ustream_buf *buf = s->r.head;
 218
 219         if (!len)
 220                 return;
 221
 222         s->r.data_bytes -= len;
 223         if (s->r.data_bytes < 0)
 224                 abort();
 225
 226         do {
 227                 struct ustream_buf *next = buf->next;
 228                 int buf_len = buf->tail - buf->data;
 229
 230                 if (len < buf_len) {
 231                         buf->data += len;
 232                         break;
 233                 }
 234
 235                 len -= buf_len;
 236                 ustream_free_buf(&s->r, buf);
 237                 buf = next;
 238         } while(len);
 239
 240         __ustream_set_read_blocked(s, s->read_blocked & ~READ_BLOCKED_FULL);
 241 }
 242
 243 static void ustream_fixup_string(struct ustream *s, struct ustream_buf *buf)
 244 {
 245         if (!s->string_data)
 246                 return;
 247
 248         *buf->tail = 0;
 249 }
 250
 251 static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, int len)
 252 {
 253         struct ustream_buf *buf;
 254
 255         buf = l->data_tail;
 256         if (buf) {
 257                 if (ustream_should_move(l, buf, len)) {
 258                         int len = buf->tail - buf->data;
 259
 260                         memmove(buf->head, buf->data, len);
 261                         buf->data = buf->head;
 262                         buf->tail = buf->data + len;
 263
 264                         if (l == &s->r)
 265                                 ustream_fixup_string(s, buf);
 266                 }
 267                 /* some chunks available at the tail */
 268                 if (buf->tail != buf->end)
 269                         return true;
 270                 /* next buf available */
 271                 if (buf->next) {
 272                         l->data_tail = buf->next;
 273                         return true;
 274                 }
 275         }
 276
 277         if (!ustream_can_alloc(l))
 278                 return false;
 279
 280         if (l->alloc(s, l) < 0)
 281                 return false;
 282
 283         l->data_tail = l->tail;
 284         return true;
 285 }
 286
 287 char *ustream_reserve(struct ustream *s, int len, int *maxlen)
 288 {
 289         struct ustream_buf *buf;
 290
 291         if (!ustream_prepare_buf(s, &s->r, len)) {
 292                 __ustream_set_read_blocked(s, s->read_blocked | READ_BLOCKED_FULL);
 293                 *maxlen = 0;
 294                 return NULL;
 295         }
 296
 297         buf = s->r.data_tail;
 298         *maxlen = buf->end - buf->tail;
 299         return buf->tail;
 300 }
 301
 302 void ustream_fill_read(struct ustream *s, int len)
 303 {
 304         struct ustream_buf *buf = s->r.data_tail;
 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                 if (s->pending_cb & CB_PENDING_READ)
 326                         return;
 327
 328                 s->pending_cb |= CB_PENDING_READ;
 329                 s->notify_read(s, s->r.data_bytes);
 330                 s->pending_cb &= ~CB_PENDING_READ;
 331         }
 332 }
 333
 334 char *ustream_get_read_buf(struct ustream *s, int *buflen)
 335 {
 336         char *data = NULL;
 337         int len = 0;
 338
 339         if (s->r.head) {
 340                 len = s->r.head->tail - s->r.head->data;
 341                 if (len > 0)
 342                         data = s->r.head->data;
 343         }
 344
 345         if (buflen)
 346                 *buflen = len;
 347
 348         return data;
 349 }
 350
 351 int ustream_read(struct ustream *s, char *buf, int buflen)
 352 {
 353         char *chunk;
 354         int chunk_len;
 355         int len = 0;
 356
 357         do {
 358                 chunk = ustream_get_read_buf(s, &chunk_len);
 359                 if (!chunk)
 360                         break;
 361                 if (chunk_len > buflen - len)
 362                         chunk_len = buflen - len;
 363                 memcpy(buf + len, chunk, chunk_len);
 364                 ustream_consume(s, chunk_len);
 365                 len += chunk_len;
 366         } while (len < buflen);
 367
 368         return len;
 369 }
 370
 371 static void ustream_write_error(struct ustream *s)
 372 {
 373         if (!s->write_error)
 374                 ustream_state_change(s);
 375         s->write_error = true;
 376 }
 377
 378 bool ustream_write_pending(struct ustream *s)
 379 {
 380         struct ustream_buf *buf = s->w.head;
 381         int wr = 0, len;
 382
 383         if (s->write_error)
 384                 return false;
 385
 386         while (buf && s->w.data_bytes) {
 387                 struct ustream_buf *next = buf->next;
 388                 int maxlen = buf->tail - buf->data;
 389
 390                 len = s->write(s, buf->data, maxlen, !!buf->next);
 391                 if (len < 0) {
 392                         ustream_write_error(s);
 393                         break;
 394                 }
 395
 396                 if (len == 0)
 397                         break;
 398
 399                 wr += len;
 400                 s->w.data_bytes -= len;
 401                 if (len < maxlen) {
 402                         buf->data += len;
 403                         break;
 404                 }
 405
 406                 ustream_free_buf(&s->w, buf);
 407                 buf = next;
 408         }
 409
 410         if (s->notify_write)
 411                 s->notify_write(s, wr);
 412
 413         if (s->eof && wr && !s->w.data_bytes)
 414                 ustream_state_change(s);
 415
 416         return !s->w.data_bytes;
 417 }
 418
 419 static int ustream_write_buffered(struct ustream *s, const char *data, int len, int wr)
 420 {
 421         struct ustream_buf_list *l = &s->w;
 422         struct ustream_buf *buf;
 423         int maxlen;
 424
 425         while (len) {
 426                 if (!ustream_prepare_buf(s, &s->w, len))
 427                         break;
 428
 429                 buf = l->data_tail;
 430
 431                 maxlen = buf->end - buf->tail;
 432                 if (maxlen > len)
 433                         maxlen = len;
 434
 435                 memcpy(buf->tail, data, maxlen);
 436                 buf->tail += maxlen;
 437                 data += maxlen;
 438                 len -= maxlen;
 439                 wr += maxlen;
 440                 l->data_bytes += maxlen;
 441         }
 442
 443         return wr;
 444 }
 445
 446 int ustream_write(struct ustream *s, const char *data, int len, bool more)
 447 {
 448         struct ustream_buf_list *l = &s->w;
 449         int wr = 0;
 450
 451         if (s->write_error)
 452                 return 0;
 453
 454         if (!l->data_bytes) {
 455                 wr = s->write(s, data, len, more);
 456                 if (wr == len)
 457                         return wr;
 458
 459                 if (wr < 0) {
 460                         ustream_write_error(s);
 461                         return wr;
 462                 }
 463
 464                 data += wr;
 465                 len -= wr;
 466         }
 467
 468         return ustream_write_buffered(s, data, len, wr);
 469 }
 470
 471 #define MAX_STACK_BUFLEN        256
 472
 473 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
 474 {
 475         struct ustream_buf_list *l = &s->w;
 476         char *buf;
 477         va_list arg2;
 478         int wr, maxlen, buflen;
 479
 480         if (s->write_error)
 481                 return 0;
 482
 483         if (!l->data_bytes) {
 484                 buf = alloca(MAX_STACK_BUFLEN);
 485                 va_copy(arg2, arg);
 486                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
 487                 va_end(arg2);
 488                 if (maxlen < MAX_STACK_BUFLEN) {
 489                         wr = s->write(s, buf, maxlen, false);
 490                         if (wr < 0) {
 491                                 ustream_write_error(s);
 492                                 return wr;
 493                         }
 494                         if (wr == maxlen)
 495                                 return wr;
 496
 497                         buf += wr;
 498                         maxlen -= wr;
 499                         return ustream_write_buffered(s, buf, maxlen, wr);
 500                 } else {
 501                         buf = malloc(maxlen + 1);
 502                         if (!buf)
 503                                 return 0;
 504                         wr = vsnprintf(buf, maxlen + 1, format, arg);
 505                         wr = ustream_write(s, buf, wr, false);
 506                         free(buf);
 507                         return wr;
 508                 }
 509         }
 510
 511         if (!ustream_prepare_buf(s, l, 1))
 512                 return 0;
 513
 514         buf = l->data_tail->tail;
 515         buflen = l->data_tail->end - buf;
 516
 517         va_copy(arg2, arg);
 518         maxlen = vsnprintf(buf, buflen, format, arg2);
 519         va_end(arg2);
 520
 521         wr = maxlen;
 522         if (wr >= buflen)
 523                 wr = buflen - 1;
 524
 525         l->data_tail->tail += wr;
 526         l->data_bytes += wr;
 527         if (maxlen < buflen)
 528                 return wr;
 529
 530         buf = malloc(maxlen + 1);
 531         if (!buf)
 532                 return wr;
 533         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
 534         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
 535         free(buf);
 536
 537         return wr;
 538 }
 539
 540 int ustream_printf(struct ustream *s, const char *format, ...)
 541 {
 542         va_list arg;
 543         int ret;
 544
 545         if (s->write_error)
 546                 return 0;
 547
 548         va_start(arg, format);
 549         ret = ustream_vprintf(s, format, arg);
 550         va_end(arg);
 551
 552         return ret;
 553 }