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         /* nothing to squeeze */
 149         if (buf->data == buf->head)
 150                 return false;
 151
 152         maxlen = buf->end - buf->head;
 153         offset = buf->data - buf->head;
 154
 155         /* less than half is available */
 156         if (offset > maxlen / 2)
 157                 return true;
 158
 159         /* less than 32 bytes data but takes more than 1/4 space */
 160         if (buf->tail - buf->data < 32 && offset > maxlen / 4)
 161                 return true;
 162
 163         /* more buf is already in list or can be allocated */
 164         if (buf != l->tail || ustream_can_alloc(l))
 165                 return false;
 166
 167         /* no need to move if len is available at the tail */
 168         return (buf->end - buf->tail < len);
 169 }
 170
 171 static void ustream_free_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
 172 {
 173         if (buf == l->head)
 174                 l->head = buf->next;
 175
 176         if (buf == l->data_tail)
 177                 l->data_tail = buf->next;
 178
 179         if (buf == l->tail)
 180                 l->tail = NULL;
 181
 182         if (--l->buffers >= l->min_buffers) {
 183                 free(buf);
 184                 return;
 185         }
 186
 187         /* recycle */
 188         ustream_init_buf(buf, buf->end - buf->head);
 189         ustream_add_buf(l, buf);
 190 }
 191
 192 static void __ustream_set_read_blocked(struct ustream *s, unsigned char val)
 193 {
 194         bool changed = !!s->read_blocked != !!val;
 195
 196         s->read_blocked = val;
 197         if (changed)
 198                 s->set_read_blocked(s);
 199 }
 200
 201 void ustream_set_read_blocked(struct ustream *s, bool set)
 202 {
 203         unsigned char val = s->read_blocked & ~READ_BLOCKED_USER;
 204
 205         if (set)
 206                 val |= READ_BLOCKED_USER;
 207
 208         __ustream_set_read_blocked(s, val);
 209 }
 210
 211 void ustream_consume(struct ustream *s, int len)
 212 {
 213         struct ustream_buf *buf = s->r.head;
 214
 215         if (!len)
 216                 return;
 217
 218         s->r.data_bytes -= len;
 219         if (s->r.data_bytes < 0)
 220                 abort();
 221
 222         do {
 223                 struct ustream_buf *next = buf->next;
 224                 int buf_len = buf->tail - buf->data;
 225
 226                 if (len < buf_len) {
 227                         buf->data += len;
 228                         break;
 229                 }
 230
 231                 len -= buf_len;
 232                 ustream_free_buf(&s->r, buf);
 233                 buf = next;
 234         } while(len);
 235
 236         __ustream_set_read_blocked(s, s->read_blocked & ~READ_BLOCKED_FULL);
 237 }
 238
 239 static void ustream_fixup_string(struct ustream *s, struct ustream_buf *buf)
 240 {
 241         if (!s->string_data)
 242                 return;
 243
 244         *buf->tail = 0;
 245 }
 246
 247 static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, int len)
 248 {
 249         struct ustream_buf *buf;
 250
 251         buf = l->data_tail;
 252         if (buf) {
 253                 if (ustream_should_move(l, buf, len)) {
 254                         int len = buf->tail - buf->data;
 255
 256                         memmove(buf->head, buf->data, len);
 257                         buf->data = buf->head;
 258                         buf->tail = buf->data + len;
 259
 260                         if (l == &s->r)
 261                                 ustream_fixup_string(s, buf);
 262                 }
 263                 /* some chunks available at the tail */
 264                 if (buf->tail != buf->end)
 265                         return true;
 266                 /* next buf available */
 267                 if (buf->next) {
 268                         l->data_tail = buf->next;
 269                         return true;
 270                 }
 271         }
 272
 273         if (!ustream_can_alloc(l))
 274                 return false;
 275
 276         if (l->alloc(s, l) < 0)
 277                 return false;
 278
 279         l->data_tail = l->tail;
 280         return true;
 281 }
 282
 283 char *ustream_reserve(struct ustream *s, int len, int *maxlen)
 284 {
 285         struct ustream_buf *buf;
 286
 287         if (!ustream_prepare_buf(s, &s->r, len)) {
 288                 __ustream_set_read_blocked(s, s->read_blocked | READ_BLOCKED_FULL);
 289                 *maxlen = 0;
 290                 return NULL;
 291         }
 292
 293         buf = s->r.data_tail;
 294         *maxlen = buf->end - buf->tail;
 295         return buf->tail;
 296 }
 297
 298 void ustream_fill_read(struct ustream *s, int len)
 299 {
 300         struct ustream_buf *buf = s->r.data_tail;
 301         int n = len;
 302         int maxlen;
 303
 304         s->r.data_bytes += len;
 305         do {
 306                 if (!buf)
 307                         abort();
 308
 309                 maxlen = buf->end - buf->tail;
 310                 if (len < maxlen)
 311                         maxlen = len;
 312
 313                 len -= maxlen;
 314                 buf->tail += maxlen;
 315                 ustream_fixup_string(s, buf);
 316
 317                 s->r.data_tail = buf;
 318                 buf = buf->next;
 319         } while (len);
 320
 321         if (s->notify_read)
 322                 s->notify_read(s, n);
 323 }
 324
 325 char *ustream_get_read_buf(struct ustream *s, int *buflen)
 326 {
 327         char *data = NULL;
 328         int len = 0;
 329
 330         if (s->r.head) {
 331                 len = s->r.head->tail - s->r.head->data;
 332                 if (len > 0)
 333                         data = s->r.head->data;
 334         }
 335
 336         if (buflen)
 337                 *buflen = len;
 338
 339         return data;
 340 }
 341
 342 int ustream_read(struct ustream *s, char *buf, int buflen)
 343 {
 344         char *chunk;
 345         int chunk_len;
 346         int len = 0;
 347
 348         do {
 349                 chunk = ustream_get_read_buf(s, &chunk_len);
 350                 if (!chunk)
 351                         break;
 352                 if (chunk_len > buflen - len)
 353                         chunk_len = buflen - len;
 354                 memcpy(buf + len, chunk, chunk_len);
 355                 ustream_consume(s, chunk_len);
 356                 len += chunk_len;
 357         } while (len < buflen);
 358
 359         return len;
 360 }
 361
 362 static void ustream_write_error(struct ustream *s)
 363 {
 364         if (!s->write_error)
 365                 ustream_state_change(s);
 366         s->write_error = true;
 367 }
 368
 369 bool ustream_write_pending(struct ustream *s)
 370 {
 371         struct ustream_buf *buf = s->w.head;
 372         int wr = 0, len;
 373
 374         if (s->write_error)
 375                 return false;
 376
 377         while (buf && s->w.data_bytes) {
 378                 struct ustream_buf *next = buf->next;
 379                 int maxlen = buf->tail - buf->data;
 380
 381                 len = s->write(s, buf->data, maxlen, !!buf->next);
 382                 if (len < 0) {
 383                         ustream_write_error(s);
 384                         break;
 385                 }
 386
 387                 if (len == 0)
 388                         break;
 389
 390                 wr += len;
 391                 s->w.data_bytes -= len;
 392                 if (len < maxlen) {
 393                         buf->data += len;
 394                         break;
 395                 }
 396
 397                 ustream_free_buf(&s->w, buf);
 398                 buf = next;
 399         }
 400
 401         if (s->notify_write)
 402                 s->notify_write(s, wr);
 403
 404         if (s->eof && wr && !s->w.data_bytes)
 405                 ustream_state_change(s);
 406
 407         return !s->w.data_bytes;
 408 }
 409
 410 static int ustream_write_buffered(struct ustream *s, const char *data, int len, int wr)
 411 {
 412         struct ustream_buf_list *l = &s->w;
 413         struct ustream_buf *buf;
 414         int maxlen;
 415
 416         while (len) {
 417                 if (!ustream_prepare_buf(s, &s->w, len))
 418                         break;
 419
 420                 buf = l->data_tail;
 421
 422                 maxlen = buf->end - buf->tail;
 423                 if (maxlen > len)
 424                         maxlen = len;
 425
 426                 memcpy(buf->tail, data, maxlen);
 427                 buf->tail += maxlen;
 428                 data += maxlen;
 429                 len -= maxlen;
 430                 wr += maxlen;
 431                 l->data_bytes += maxlen;
 432         }
 433
 434         return wr;
 435 }
 436
 437 int ustream_write(struct ustream *s, const char *data, int len, bool more)
 438 {
 439         struct ustream_buf_list *l = &s->w;
 440         int wr = 0;
 441
 442         if (s->write_error)
 443                 return 0;
 444
 445         if (!l->data_bytes) {
 446                 wr = s->write(s, data, len, more);
 447                 if (wr == len)
 448                         return wr;
 449
 450                 if (wr < 0) {
 451                         ustream_write_error(s);
 452                         return wr;
 453                 }
 454
 455                 data += wr;
 456                 len -= wr;
 457         }
 458
 459         return ustream_write_buffered(s, data, len, wr);
 460 }
 461
 462 #define MAX_STACK_BUFLEN        256
 463
 464 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
 465 {
 466         struct ustream_buf_list *l = &s->w;
 467         char *buf;
 468         va_list arg2;
 469         int wr, maxlen, buflen;
 470
 471         if (s->write_error)
 472                 return 0;
 473
 474         if (!l->data_bytes) {
 475                 buf = alloca(MAX_STACK_BUFLEN);
 476                 va_copy(arg2, arg);
 477                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
 478                 va_end(arg2);
 479                 if (maxlen < MAX_STACK_BUFLEN) {
 480                         wr = s->write(s, buf, maxlen, false);
 481                         if (wr < 0) {
 482                                 ustream_write_error(s);
 483                                 return wr;
 484                         }
 485                         if (wr == maxlen)
 486                                 return wr;
 487
 488                         buf += wr;
 489                         maxlen -= wr;
 490                         return ustream_write_buffered(s, buf, maxlen, wr);
 491                 } else {
 492                         buf = malloc(maxlen + 1);
 493                         wr = vsnprintf(buf, maxlen + 1, format, arg);
 494                         wr = ustream_write(s, buf, wr, false);
 495                         free(buf);
 496                         return wr;
 497                 }
 498         }
 499
 500         if (!ustream_prepare_buf(s, l, 1))
 501                 return 0;
 502
 503         buf = l->data_tail->tail;
 504         buflen = l->data_tail->end - buf;
 505
 506         va_copy(arg2, arg);
 507         maxlen = vsnprintf(buf, buflen, format, arg2);
 508         va_end(arg2);
 509
 510         wr = maxlen;
 511         if (wr >= buflen)
 512                 wr = buflen - 1;
 513
 514         l->data_tail->tail += wr;
 515         l->data_bytes += wr;
 516         if (maxlen < buflen)
 517                 return wr;
 518
 519         buf = malloc(maxlen + 1);
 520         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
 521         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
 522         free(buf);
 523
 524         return wr;
 525 }
 526
 527 int ustream_printf(struct ustream *s, const char *format, ...)
 528 {
 529         va_list arg;
 530         int ret;
 531
 532         if (s->write_error)
 533                 return 0;
 534
 535         va_start(arg, format);
 536         ret = ustream_vprintf(s, format, arg);
 537         va_end(arg);
 538
 539         return ret;
 540 }