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         if (s->notify_state)
 108                 s->notify_state(s);
 109 }
 110
 111 void ustream_init_defaults(struct ustream *s)
 112 {
 113 #define DEFAULT_SET(_f, _default)       \
 114         do {                            \
 115                 if (!_f)                \
 116                         _f = _default;  \
 117         } while(0)
 118
 119         DEFAULT_SET(s->r.alloc, ustream_alloc_default);
 120         DEFAULT_SET(s->w.alloc, ustream_alloc_default);
 121
 122         DEFAULT_SET(s->r.min_buffers, 1);
 123         DEFAULT_SET(s->r.max_buffers, 1);
 124         DEFAULT_SET(s->r.buffer_len, 4096);
 125
 126         DEFAULT_SET(s->w.min_buffers, 2);
 127         DEFAULT_SET(s->w.max_buffers, -1);
 128         DEFAULT_SET(s->w.buffer_len, 256);
 129
 130 #undef DEFAULT_SET
 131
 132         s->state_change.cb = ustream_state_change_cb;
 133 }
 134
 135 static bool ustream_should_move(struct ustream_buf_list *l, struct ustream_buf *buf, int len)
 136 {
 137         int maxlen;
 138         int offset;
 139
 140         if (buf->data == buf->head)
 141                 return false;
 142
 143         maxlen = buf->end - buf->head;
 144         offset = buf->data - buf->head;
 145
 146         if (offset > maxlen / 2)
 147                 return true;
 148
 149         if (buf->tail - buf->data < 32 && offset > maxlen / 4)
 150                 return true;
 151
 152         if (buf != l->tail || ustream_can_alloc(l))
 153                 return false;
 154
 155         return (buf->end - buf->tail < len);
 156 }
 157
 158 static void ustream_free_buf(struct ustream_buf_list *l, struct ustream_buf *buf)
 159 {
 160         if (buf == l->head)
 161                 l->head = buf->next;
 162
 163         if (buf == l->data_tail)
 164                 l->data_tail = buf->next;
 165
 166         if (buf == l->tail)
 167                 l->tail = NULL;
 168
 169         if (--l->buffers >= l->min_buffers) {
 170                 free(buf);
 171                 return;
 172         }
 173
 174         /* recycle */
 175         ustream_init_buf(buf, buf->end - buf->head);
 176         ustream_add_buf(l, buf);
 177 }
 178
 179 static void __ustream_set_read_blocked(struct ustream *s, unsigned char val)
 180 {
 181         bool changed = !!s->read_blocked != !!val;
 182
 183         s->read_blocked = val;
 184         if (changed)
 185                 s->set_read_blocked(s);
 186 }
 187
 188 void ustream_set_read_blocked(struct ustream *s, bool set)
 189 {
 190         unsigned char val = s->read_blocked & ~READ_BLOCKED_USER;
 191
 192         if (set)
 193                 val |= READ_BLOCKED_USER;
 194
 195         __ustream_set_read_blocked(s, val);
 196 }
 197
 198 void ustream_consume(struct ustream *s, int len)
 199 {
 200         struct ustream_buf *buf = s->r.head;
 201
 202         if (!len)
 203                 return;
 204
 205         s->r.data_bytes -= len;
 206         if (s->r.data_bytes < 0)
 207                 abort();
 208
 209         do {
 210                 struct ustream_buf *next = buf->next;
 211                 int buf_len = buf->tail - buf->data;
 212
 213                 if (len < buf_len) {
 214                         buf->data += len;
 215                         break;
 216                 }
 217
 218                 len -= buf_len;
 219                 ustream_free_buf(&s->r, buf);
 220                 buf = next;
 221         } while(len);
 222
 223         __ustream_set_read_blocked(s, s->read_blocked & ~READ_BLOCKED_FULL);
 224 }
 225
 226 static void ustream_fixup_string(struct ustream *s, struct ustream_buf *buf)
 227 {
 228         if (!s->string_data)
 229                 return;
 230
 231         *buf->tail = 0;
 232 }
 233
 234 static bool ustream_prepare_buf(struct ustream *s, struct ustream_buf_list *l, int len)
 235 {
 236         struct ustream_buf *buf;
 237
 238         buf = l->data_tail;
 239         if (buf) {
 240                 if (ustream_should_move(l, buf, len)) {
 241                         int len = buf->tail - buf->data;
 242
 243                         memmove(buf->head, buf->data, len);
 244                         buf->data = buf->head;
 245                         buf->tail = buf->data + len;
 246
 247                         if (l == &s->r)
 248                                 ustream_fixup_string(s, buf);
 249                 }
 250                 if (buf->tail != buf->end)
 251                         return true;
 252         }
 253
 254         if (buf && buf->next) {
 255                 l->data_tail = buf->next;
 256                 return true;
 257         }
 258
 259         if (!ustream_can_alloc(l))
 260                 return false;
 261
 262         if (l->alloc(s, l) < 0)
 263                 return false;
 264
 265         l->data_tail = l->tail;
 266         return true;
 267 }
 268
 269 char *ustream_reserve(struct ustream *s, int len, int *maxlen)
 270 {
 271         struct ustream_buf *buf = s->r.head;
 272
 273         if (!ustream_prepare_buf(s, &s->r, len)) {
 274                 __ustream_set_read_blocked(s, s->read_blocked | READ_BLOCKED_FULL);
 275                 *maxlen = 0;
 276                 return NULL;
 277         }
 278
 279         buf = s->r.data_tail;
 280         *maxlen = buf->end - buf->tail;
 281         return buf->tail;
 282 }
 283
 284 void ustream_fill_read(struct ustream *s, int len)
 285 {
 286         struct ustream_buf *buf = s->r.data_tail;
 287         int n = len;
 288         int maxlen;
 289
 290         s->r.data_bytes += len;
 291         do {
 292                 if (!buf)
 293                         abort();
 294
 295                 maxlen = buf->end - buf->tail;
 296                 if (len < maxlen)
 297                         maxlen = len;
 298
 299                 len -= maxlen;
 300                 buf->tail += maxlen;
 301                 ustream_fixup_string(s, buf);
 302
 303                 s->r.data_tail = buf;
 304                 buf = buf->next;
 305         } while (len);
 306
 307         if (s->notify_read)
 308                 s->notify_read(s, n);
 309 }
 310
 311 char *ustream_get_read_buf(struct ustream *s, int *buflen)
 312 {
 313         char *data;
 314         int len;
 315
 316         if (s->r.head) {
 317                 len = s->r.head->tail - s->r.head->data;
 318                 data = s->r.head->data;
 319         } else {
 320                 len = 0;
 321                 data = NULL;
 322         }
 323
 324         if (buflen)
 325                 *buflen = len;
 326
 327         return data;
 328 }
 329
 330 static void ustream_write_error(struct ustream *s)
 331 {
 332         s->write_error = true;
 333         ustream_state_change(s);
 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         bool has_data = !!s->w.data_bytes;
 383
 384         while (len) {
 385                 if (!ustream_prepare_buf(s, &s->w, len))
 386                         break;
 387
 388                 buf = l->data_tail;
 389
 390                 maxlen = buf->end - buf->tail;
 391                 if (maxlen > len)
 392                         maxlen = len;
 393
 394                 memcpy(buf->tail, data, maxlen);
 395                 buf->tail += maxlen;
 396                 data += maxlen;
 397                 len -= maxlen;
 398                 wr += maxlen;
 399                 l->data_bytes += maxlen;
 400         }
 401
 402         if (s->poll && !has_data)
 403                 s->poll(s);
 404
 405         return wr;
 406 }
 407
 408 int ustream_write(struct ustream *s, const char *data, int len, bool more)
 409 {
 410         struct ustream_buf_list *l = &s->w;
 411         int wr = 0;
 412
 413         if (s->write_error)
 414                 return 0;
 415
 416         if (!l->data_bytes) {
 417                 wr = s->write(s, data, len, more);
 418                 if (wr == len)
 419                         return wr;
 420
 421                 if (wr < 0) {
 422                         ustream_write_error(s);
 423                         return wr;
 424                 }
 425
 426                 data += wr;
 427                 len -= wr;
 428         }
 429
 430         return ustream_write_buffered(s, data, len, wr);
 431 }
 432
 433 #define MAX_STACK_BUFLEN        256
 434
 435 int ustream_vprintf(struct ustream *s, const char *format, va_list arg)
 436 {
 437         struct ustream_buf_list *l = &s->w;
 438         char *buf;
 439         va_list arg2;
 440         int wr, maxlen, buflen;
 441
 442         if (s->write_error)
 443                 return 0;
 444
 445         if (!l->data_bytes) {
 446                 buf = alloca(MAX_STACK_BUFLEN);
 447                 va_copy(arg2, arg);
 448                 maxlen = vsnprintf(buf, MAX_STACK_BUFLEN, format, arg2);
 449                 va_end(arg2);
 450                 if (maxlen < MAX_STACK_BUFLEN) {
 451                         wr = s->write(s, buf, maxlen, false);
 452                         if (wr < 0) {
 453                                 ustream_write_error(s);
 454                                 return wr;
 455                         }
 456                         if (wr == maxlen)
 457                                 return wr;
 458
 459                         buf += wr;
 460                         maxlen -= wr;
 461                         return ustream_write_buffered(s, buf, maxlen, wr);
 462                 } else {
 463                         buf = malloc(maxlen + 1);
 464                         wr = vsnprintf(buf, maxlen + 1, format, arg);
 465                         wr = ustream_write(s, buf, wr, false);
 466                         free(buf);
 467                         return wr;
 468                 }
 469         }
 470
 471         if (!ustream_prepare_buf(s, l, 1))
 472                 return 0;
 473
 474         buf = l->data_tail->tail;
 475         buflen = l->data_tail->end - buf;
 476
 477         va_copy(arg2, arg);
 478         maxlen = vsnprintf(buf, buflen, format, arg2);
 479         va_end(arg2);
 480
 481         wr = maxlen;
 482         if (wr >= buflen)
 483                 wr = buflen - 1;
 484
 485         l->data_tail->tail += wr;
 486         l->data_bytes += wr;
 487         if (maxlen < buflen)
 488                 return wr;
 489
 490         buf = malloc(maxlen + 1);
 491         maxlen = vsnprintf(buf, maxlen + 1, format, arg);
 492         wr = ustream_write_buffered(s, buf + wr, maxlen - wr, wr);
 493         free(buf);
 494
 495         return wr;
 496 }
 497
 498 int ustream_printf(struct ustream *s, const char *format, ...)
 499 {
 500         va_list arg;
 501         int ret;
 502
 503         if (s->write_error)
 504                 return 0;
 505
 506         va_start(arg, format);
 507         ret = ustream_vprintf(s, format, arg);
 508         va_end(arg);
 509
 510         return ret;
 511 }