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