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         if (!l->tail)
  41                 l->head = buf;
  42         else
  43                 l->tail->next = buf;
  44
  45         buf->next = NULL;
  46         l->tail = buf;
  47         if (!l->data_tail)
  48                 l->data_tail = l->head;
  49 }
  50
  51 static bool ustream_can_alloc(struct ustream_buf_list *l)
  52 {
  53         if (l->max_buffers <= 0)
  54                 return true;
  55
  56         return (l->buffers < l->max_buffers);
  57 }
  58
  59 static int ustream_alloc_default(struct ustream *s, struct ustream_buf_list *l)
  60 {
  61         struct ustream_buf *buf;
  62
  63         if (!ustream_can_alloc(l))
  64                 return -1;
  65
  66         buf = malloc(sizeof(*buf) + l->buffer_len + s->string_data);
  67         ustream_init_buf(buf, l->buffer_len);
  68         ustream_add_buf(l, buf);
  69
  70         return 0;
  71 }
  72
  73 static void ustream_free_buffers(struct ustream_buf_list *l)
  74 {
  75         struct ustream_buf *buf = l->head;
  76
  77         while (buf) {
  78                 struct ustream_buf *next = buf->next;
  79
  80                 free(buf);
  81                 buf = next;
  82         }
  83         l->head = NULL;
  84         l->tail = NULL;
  85         l->data_tail = NULL;
  86 }
  87
  88 void ustream_free(struct ustream *s)
  89 {
  90         if (s->free)
  91                 s->free(s);
  92
  93         uloop_timeout_cancel(&s->state_change);
  94         ustream_free_buffers(&s->r);
  95         ustream_free_buffers(&s->w);
  96         s->write_error = false;
  97         s->eof = false;
  98         s->read_blocked = 0;
  99 }
 100
 101 static void ustream_state_change_cb(struct uloop_timeout *t)
 102 {
 103         struct ustream *s = container_of(t, struct ustream, state_change);
 104
 105         if (s->write_error)
 106                 ustream_free_buffers(&s->w);
 107         s->notify_state(s);
 108 }
 109
 110 void ustream_init_defaults(struct ustream *s)
 111 {
 112 #define DEFAULT_SET(_f, _default)       \
 113         do {                            \
 114                 if (!_f)                \
 115                         _f = _default;  \
 116         } while(0)
 117
 118         DEFAULT_SET(s->r.alloc, ustream_alloc_default);
 119         DEFAULT_SET(s->w.alloc, ustream_alloc_default);
 120
 121         DEFAULT_SET(s->r.min_buffers, 1);
 122         DEFAULT_SET(s->r.max_buffers, 1);
 123         DEFAULT_SET(s->r.buffer_len, 4096);
 124
 125         DEFAULT_SET(s->w.min_buffers, 2);
 126         DEFAULT_SET(s->w.max_buffers, -1);
 127         DEFAULT_SET(s->w.buffer_len, 256);
 128
 129 #undef DEFAULT_SET
 130
 131         s->state_change.cb = ustream_state_change_cb;
 132 }
 133
 134 static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *buf, int len)
 135 {
 136         int maxlen;
 137         int offset;
 138
 139         if (buf->data == buf->head)
 140                 return false;
 141
 142         maxlen = buf->end - buf->head;
 143         offset = buf->data - buf->head;
 144
 145         if (offset > maxlen / 2)
 146                 return true;
 147
 148         if (buf->tail - buf->data < 32 && offset > maxlen / 4)
 149                 return true;
 150
 151         if (buf != l->tail || ustream_can_alloc(l))
 152                 return false;
 153
 154         return (buf->end - buf->tail < len);
 155 }
 156
 157 static void ustream_free_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
 158 {
 159         if (buf == l->head)
 160                 l->head = buf->next;
 161
 162         if (buf == l->data_tail)
 163                 l->data_tail = buf->next;
 164
 165         if (buf == l->tail)
 166                 l->tail = NULL;
 167
 168         if (--l->buffers >= l->min_buffers) {
 169                 free(buf);
 170                 return;
 171         }
 172
 173         /* recycle */
 174         ustream_init_buf(buf, buf->end - buf->head);
 175         ustream_add_buf(l, buf);
 176 }
 177
 178 static void __ustream_set_read_blocked(struct ustream *s, unsigned char val)
 179 {
 180         bool changed = !!s->read_blocked != !!val;
 181
 182         s->read_blocked = val;
 183         if (changed)
 184                 s->set_read_blocked(s);
 185 }
 186
 187 void ustream_set_read_blocked(struct ustream *s, bool set)
 188 {
 189         unsigned char val = s->read_blocked & ~READ_BLOCKED_USER;
 190
 191         if (set)
 192                 val |= READ_BLOCKED_USER;
 193
 194         __ustream_set_read_blocked(s, val);
 195 }
 196
 197 void ustream_consume(struct ustream *s, int len)
 198 {
 199         struct ustream_buf *buf = s->r.head;
 200
 201         if (!len)
 202                 return;
 203
 204         s->r.data_bytes -= len;
 205         if (s->r.data_bytes < 0)
 206                 abort();
 207
 208         do {
 209                 struct ustream_buf *next = buf->next;
 210                 int buf_len = buf->tail - buf->data;
 211
 212                 if (len < buf_len) {
 213                         buf->data += len;
 214                         break;
 215                 }
 216
 217                 len -= buf_len;
 218                 ustream_free_buf(&s->r, buf);
 219                 buf = next;
 220         } while(len);
 221
 222         __ustream_set_read_blocked(s, s->read_blocked & ~READ_BLOCKED_FULL);
 223 }
 224
 225 static void ustream_fixup_string(struct ustream *s, struct ustream_buf *buf)
 226 {
 227         if (!s->string_data)
 228                 return;
 229
 230         *buf->tail = 0;
 231 }
 232
 233 static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, int len)
 234 {
 235         struct ustream_buf *buf;
 236
 237         buf = l->data_tail;
 238         if (buf) {
 239                 if (ustream_should_move(l, buf, len)) {
 240                         int len = buf->tail - buf->data;
 241
 242                         memmove(buf->head, buf->data, len);
 243                         buf->data = buf->head;
 244                         buf->tail = buf->data + len;
 245
 246                         if (l == &s->r)
 247                                 ustream_fixup_string(s, buf);
 248                 }
 249                 if (buf->tail != buf->end)
 250                         return true;
 251         }
 252
 253         if (buf && buf->next) {
 254                 l->data_tail = buf->next;
 255                 return true;
 256         }
 257
 258         if (!ustream_can_alloc(l))
 259                 return false;
 260
 261         if (l->alloc(s, l) < 0)
 262                 return false;
 263
 264         l->data_tail = l->tail;
 265         return true;
 266 }
 267
 268 char *ustream_reserve(struct ustream *s, int len, int *maxlen)
 269 {
 270         struct ustream_buf *buf = s->r.head;
 271
 272         if (!ustream_prepare_buf(s, &s->r, len)) {
 273                 __ustream_set_read_blocked(s, s->read_blocked | READ_BLOCKED_FULL);
 274                 *maxlen = 0;
 275                 return NULL;
 276         }
 277
 278         buf = s->r.data_tail;
 279         *maxlen = buf->end - buf->tail;
 280         return buf->tail;
 281 }
 282
 283 void ustream_fill_read(struct ustream *s, int len)
 284 {
 285         struct ustream_buf *buf = s->r.data_tail;
 286         int n = len;
 287         int maxlen;
 288
 289         s->r.data_bytes += len;
 290         do {
 291                 if (!buf)
 292                         abort();
 293
 294                 maxlen = buf->end - buf->tail;
 295                 if (len < maxlen)
 296                         maxlen = len;
 297
 298                 len -= maxlen;
 299                 buf->tail += maxlen;
 300                 ustream_fixup_string(s, buf);
 301
 302                 s->r.data_tail = buf;
 303                 buf = buf->next;
 304         } while (len);
 305
 306         if (s->notify_read)
 307                 s->notify_read(s, n);
 308 }
 309
 310 char *ustream_get_read_buf(struct ustream *s, int *buflen)
 311 {
 312         char *data;
 313         int len;
 314
 315         if (s->r.head) {
 316                 len = s->r.head->tail - s->r.head->data;
 317                 data = s->r.head->data;
 318         } else {
 319                 len = 0;
 320                 data = NULL;
 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         s->write_error = true;
 332         ustream_state_change(s);
 333 }
 334
 335 bool ustream_write_pending(struct ustream *s)
 336 {
 337         struct ustream_buf *buf = s->w.head;
 338         int wr = 0, len;
 339
 340         if (s->write_error)
 341                 return false;
 342
 343         while (buf) {
 344                 struct ustream_buf *next = buf->next;
 345                 int maxlen = buf->tail - buf->data;
 346
 347                 len = s->write(s, buf->data, maxlen, !!buf->next);
 348                 if (len < 0) {
 349                         ustream_write_error(s);
 350                         break;
 351                 }
 352
 353                 if (len == 0)
 354                         break;
 355
 356                 wr += len;
 357                 s->w.data_bytes -= len;
 358                 if (len < maxlen) {
 359                         buf->data += len;
 360                         break;
 361                 }
 362
 363                 ustream_free_buf(&s->w, buf);
 364                 buf = next;
 365         }
 366
 367         if (s->notify_write)
 368                 s->notify_write(s, wr);
 369
 370         if (s->eof && wr && !s->w.data_bytes)
 371                 ustream_state_change(s);
 372
 373         return !s->w.data_bytes;
 374 }
 375
 376 static int ustream_write_buffered(struct ustream *s, const char *data, int len, int wr)
 377 {
 378         struct ustream_buf_list *l = &s->w;
 379         struct ustream_buf *buf;
 380         int maxlen;
 381
 382         while (len) {
 383                 if (!ustream_prepare_buf(s, &s->w, len))
 384                         break;
 385
 386                 buf = l->data_tail;
 387
 388                 maxlen = buf->end - buf->tail;
 389                 if (maxlen > len)
 390                         maxlen = len;
 391
 392                 memcpy(buf->tail, data, maxlen);
 393                 buf->tail += maxlen;
 394                 data += maxlen;
 395                 len -= maxlen;
 396                 wr += maxlen;
 397                 l->data_bytes += maxlen;
 398         }
 399
 400         return wr;
 401 }
 402
 403 int ustream_write(struct ustream *s, const char *data, int len, bool more)
 404 {
 405         struct ustream_buf_list *l = &s->w;
 406         int wr;
 407
 408         if (s->write_error)
 409                 return 0;
 410
 411         if (!l->data_bytes) {
 412                 wr = s->write(s, data, len, more);
 413                 if (wr == len)
 414                         return wr;
 415
 416                 if (wr < 0) {
 417                         ustream_write_error(s);
 418                         return wr;
 419                 }
 420
 421                 data += wr;
 422                 len -= wr;
 423         }
 424
 425         return ustream_write_buffered(s, data, len, wr);
 426 }
 427
 428 #define MAX_STACK_BUFLEN        256
 429
 430 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
 431 {
 432         struct ustream_buf_list *l = &s->w;
 433         char *buf;
 434         va_list arg2;
 435         int wr, maxlen, buflen;
 436
 437         if (!l->data_bytes) {
 438                 buf = alloca(MAX_STACK_BUFLEN);
 439                 va_copy(arg2, arg);
 440                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
 441                 va_end(arg2);
 442                 if (maxlen < MAX_STACK_BUFLEN) {
 443                         wr = s->write(s, buf, maxlen, false);
 444                         if (wr < 0) {
 445                                 ustream_write_error(s);
 446                                 return wr;
 447                         }
 448                         if (wr == maxlen)
 449                                 return wr;
 450
 451                         buf += wr;
 452                         maxlen -= wr;
 453                         return ustream_write_buffered(s, buf, maxlen, wr);
 454                 } else {
 455                         buf = malloc(maxlen + 1);
 456                         wr = vsnprintf(buf, maxlen + 1, format, arg);
 457                         wr = ustream_write(s, buf, wr, false);
 458                         free(buf);
 459                         return wr;
 460                 }
 461         }
 462
 463         if (!ustream_prepare_buf(s, l, 1))
 464                 return 0;
 465
 466         buf = l->data_tail->tail;
 467         buflen = l->data_tail->end - buf;
 468
 469         va_copy(arg2, arg);
 470         maxlen = vsnprintf(buf, buflen, format, arg2);
 471         va_end(arg2);
 472
 473         wr = maxlen;
 474         if (wr >= buflen)
 475                 wr = buflen - 1;
 476
 477         l->data_tail->tail += wr;
 478         l->data_bytes += wr;
 479         if (maxlen < buflen)
 480                 return wr;
 481
 482         buf = malloc(maxlen + 1);
 483         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
 484         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
 485         free(buf);
 486
 487         return wr;
 488 }
 489
 490 int ustream_printf(struct ustream *s, const char *format, ...)
 491 {
 492         va_list arg;
 493         int ret;
 494
 495         va_start(arg, format);
 496         ret = ustream_vprintf(s, format, arg);
 497         va_end(arg);
 498
 499         return ret;
 500 }