Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/dev/snp/snp.c
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1 /*- 2 * Copyright (c) 1995 Ugen J.S.Antsilevich 3 * 4 * Redistribution and use in source forms, with and without modification, 5 * are permitted provided that this entire comment appears intact. 6 * 7 * Redistribution in binary form may occur without any restrictions. 8 * Obviously, it would be nice if you gave credit where credit is due 9 * but requiring it would be too onerous. 10 * 11 * This software is provided ``AS IS'' without any warranties of any kind. 12 * 13 * Snoop stuff. 14 * 15 */ 16 17 #include <sys/cdefs.h> 18 __FBSDID("$FreeBSD$"); 19 20 #include <sys/param.h> 21 #include <sys/systm.h> 22 #include <sys/fcntl.h> 23 #include <sys/filio.h> 24 #include <sys/malloc.h> 25 #include <sys/tty.h> 26 #include <sys/conf.h> 27 #include <sys/poll.h> 28 #include <sys/kernel.h> 29 #include <sys/module.h> 30 #include <sys/queue.h> 31 #include <sys/snoop.h> 32 #include <sys/uio.h> 33 #include <sys/file.h> 34 #include <sys/vnode.h> 35 36 static l_close_t snplclose; 37 static l_write_t snplwrite; 38 static d_open_t snpopen; 39 static d_close_t snpclose; 40 static d_read_t snpread; 41 static d_write_t snpwrite; 42 static d_ioctl_t snpioctl; 43 static d_poll_t snppoll; 44 45 static struct cdevsw snp_cdevsw = { 46 .d_version = D_VERSION, 47 .d_flags = D_PSEUDO | D_NEEDGIANT, 48 .d_open = snpopen, 49 .d_close = snpclose, 50 .d_read = snpread, 51 .d_write = snpwrite, 52 .d_ioctl = snpioctl, 53 .d_poll = snppoll, 54 .d_name = "snp", 55 }; 56 57 static struct linesw snpdisc = { 58 .l_open = tty_open, 59 .l_close = snplclose, 60 .l_read = ttread, 61 .l_write = snplwrite, 62 .l_ioctl = l_nullioctl, 63 .l_rint = ttyinput, 64 .l_start = ttstart, 65 .l_modem = ttymodem 66 }; 67 68 /* 69 * This is the main snoop per-device structure. 70 */ 71 struct snoop { 72 LIST_ENTRY(snoop) snp_list; /* List glue. */ 73 int snp_unit; /* Device number. */ 74 struct cdev *snp_target; /* Target tty device. */ 75 struct tty *snp_tty; /* Target tty pointer. */ 76 u_long snp_len; /* Possible length. */ 77 u_long snp_base; /* Data base. */ 78 u_long snp_blen; /* Used length. */ 79 caddr_t snp_buf; /* Allocation pointer. */ 80 int snp_flags; /* Flags. */ 81 struct selinfo snp_sel; /* Select info. */ 82 int snp_olddisc; /* Old line discipline. */ 83 }; 84 85 /* 86 * Possible flags. 87 */ 88 #define SNOOP_ASYNC 0x0002 89 #define SNOOP_OPEN 0x0004 90 #define SNOOP_RWAIT 0x0008 91 #define SNOOP_OFLOW 0x0010 92 #define SNOOP_DOWN 0x0020 93 94 /* 95 * Other constants. 96 */ 97 #define SNOOP_MINLEN (4*1024) /* This should be power of 2. 98 * 4K tested to be the minimum 99 * for which on normal tty 100 * usage there is no need to 101 * allocate more. 102 */ 103 #define SNOOP_MAXLEN (64*1024) /* This one also,64K enough 104 * If we grow more,something 105 * really bad in this world.. 106 */ 107 108 static MALLOC_DEFINE(M_SNP, "snp", "Snoop device data"); 109 /* 110 * The number of the "snoop" line discipline. This gets determined at 111 * module load time. 112 */ 113 static int snooplinedisc; 114 115 static LIST_HEAD(, snoop) snp_sclist = LIST_HEAD_INITIALIZER(&snp_sclist); 116 static struct clonedevs *snpclones; 117 118 static struct tty *snpdevtotty(struct cdev *dev); 119 static void snp_clone(void *arg, struct ucred *cred, char *name, 120 int namelen, struct cdev **dev); 121 static void snp_detach(void *arg); 122 static int snp_down(struct snoop *snp); 123 static int snp_in(struct snoop *snp, char *buf, int n); 124 static int snp_modevent(module_t mod, int what, void *arg); 125 static struct snoop *ttytosnp(struct tty *); 126 127 static struct snoop * 128 ttytosnp(struct tty *tp) 129 { 130 struct snoop *snp; 131 132 LIST_FOREACH(snp, &snp_sclist, snp_list) { 133 if (snp->snp_tty == tp) 134 return (snp); 135 } 136 return (NULL); 137 } 138 139 static int 140 snplclose(struct tty *tp, int flag) 141 { 142 struct snoop *snp; 143 int error; 144 145 snp = ttytosnp(tp); 146 error = snp_down(snp); 147 if (error != 0) 148 return (error); 149 error = ttylclose(tp, flag); 150 return (error); 151 } 152 153 static int 154 snplwrite(struct tty *tp, struct uio *uio, int flag) 155 { 156 struct iovec iov; 157 struct uio uio2; 158 struct snoop *snp; 159 int error, ilen; 160 char *ibuf; 161 162 error = 0; 163 ibuf = NULL; 164 snp = ttytosnp(tp); 165 while (uio->uio_resid > 0) { 166 ilen = imin(512, uio->uio_resid); 167 ibuf = malloc(ilen, M_SNP, M_WAITOK); 168 error = uiomove(ibuf, ilen, uio); 169 if (error != 0) 170 break; 171 snp_in(snp, ibuf, ilen); 172 /* Hackish, but probably the least of all evils. */ 173 iov.iov_base = ibuf; 174 iov.iov_len = ilen; 175 uio2.uio_iov = &iov; 176 uio2.uio_iovcnt = 1; 177 uio2.uio_offset = 0; 178 uio2.uio_resid = ilen; 179 uio2.uio_segflg = UIO_SYSSPACE; 180 uio2.uio_rw = UIO_WRITE; 181 uio2.uio_td = uio->uio_td; 182 error = ttwrite(tp, &uio2, flag); 183 if (error != 0) 184 break; 185 free(ibuf, M_SNP); 186 ibuf = NULL; 187 } 188 if (ibuf != NULL) 189 free(ibuf, M_SNP); 190 return (error); 191 } 192 193 static struct tty * 194 snpdevtotty(struct cdev *dev) 195 { 196 struct cdevsw *cdp; 197 struct tty *tp; 198 199 cdp = dev_refthread(dev); 200 if (cdp == NULL) 201 return (NULL); 202 if (!(cdp->d_flags & D_TTY)) 203 tp = NULL; 204 else 205 tp = dev->si_tty; 206 dev_relthread(dev); 207 return (tp); 208 } 209 210 #define SNP_INPUT_BUF 5 /* This is even too much, the maximal 211 * interactive mode write is 3 bytes 212 * length for function keys... 213 */ 214 215 static int 216 snpwrite(struct cdev *dev, struct uio *uio, int flag) 217 { 218 struct snoop *snp; 219 struct tty *tp; 220 int error, i, len; 221 unsigned char c[SNP_INPUT_BUF]; 222 223 snp = dev->si_drv1; 224 tp = snp->snp_tty; 225 if (tp == NULL) 226 return (EIO); 227 if ((tp->t_state & TS_SNOOP) && tp->t_line == snooplinedisc) 228 goto tty_input; 229 230 printf("snp%d: attempt to write to bad tty\n", snp->snp_unit); 231 return (EIO); 232 233 tty_input: 234 if (!(tp->t_state & TS_ISOPEN)) 235 return (EIO); 236 237 while (uio->uio_resid > 0) { 238 len = imin(uio->uio_resid, SNP_INPUT_BUF); 239 if ((error = uiomove(c, len, uio)) != 0) 240 return (error); 241 for (i=0; i < len; i++) { 242 if (ttyinput(c[i], tp)) 243 return (EIO); 244 } 245 } 246 return (0); 247 } 248 249 250 static int 251 snpread(struct cdev *dev, struct uio *uio, int flag) 252 { 253 struct snoop *snp; 254 int error, len, n, nblen, s; 255 caddr_t from; 256 char *nbuf; 257 258 snp = dev->si_drv1; 259 KASSERT(snp->snp_len + snp->snp_base <= snp->snp_blen, 260 ("snoop buffer error")); 261 262 if (snp->snp_tty == NULL) 263 return (EIO); 264 265 snp->snp_flags &= ~SNOOP_RWAIT; 266 267 do { 268 if (snp->snp_len == 0) { 269 if (flag & O_NONBLOCK) 270 return (EWOULDBLOCK); 271 snp->snp_flags |= SNOOP_RWAIT; 272 error = tsleep(snp, (PZERO + 1) | PCATCH, 273 "snprd", 0); 274 if (error != 0) 275 return (error); 276 } 277 } while (snp->snp_len == 0); 278 279 n = snp->snp_len; 280 281 error = 0; 282 while (snp->snp_len > 0 && uio->uio_resid > 0 && error == 0) { 283 len = min((unsigned)uio->uio_resid, snp->snp_len); 284 from = (caddr_t)(snp->snp_buf + snp->snp_base); 285 if (len == 0) 286 break; 287 288 error = uiomove(from, len, uio); 289 snp->snp_base += len; 290 snp->snp_len -= len; 291 } 292 if ((snp->snp_flags & SNOOP_OFLOW) && (n < snp->snp_len)) { 293 snp->snp_flags &= ~SNOOP_OFLOW; 294 } 295 s = spltty(); 296 nblen = snp->snp_blen; 297 if (((nblen / 2) >= SNOOP_MINLEN) && (nblen / 2) >= snp->snp_len) { 298 while (nblen / 2 >= snp->snp_len && nblen / 2 >= SNOOP_MINLEN) 299 nblen = nblen / 2; 300 if ((nbuf = malloc(nblen, M_SNP, M_NOWAIT)) != NULL) { 301 bcopy(snp->snp_buf + snp->snp_base, nbuf, snp->snp_len); 302 free(snp->snp_buf, M_SNP); 303 snp->snp_buf = nbuf; 304 snp->snp_blen = nblen; 305 snp->snp_base = 0; 306 } 307 } 308 splx(s); 309 310 return (error); 311 } 312 313 static int 314 snp_in(struct snoop *snp, char *buf, int n) 315 { 316 int s_free, s_tail; 317 int s, len, nblen; 318 caddr_t from, to; 319 char *nbuf; 320 321 KASSERT(n >= 0, ("negative snoop char count")); 322 323 if (n == 0) 324 return (0); 325 326 if (snp->snp_flags & SNOOP_DOWN) { 327 printf("snp%d: more data to down interface\n", snp->snp_unit); 328 return (0); 329 } 330 331 if (snp->snp_flags & SNOOP_OFLOW) { 332 printf("snp%d: buffer overflow\n", snp->snp_unit); 333 /* 334 * On overflow we just repeat the standart close 335 * procedure...yes , this is waste of space but.. Then next 336 * read from device will fail if one would recall he is 337 * snooping and retry... 338 */ 339 340 return (snp_down(snp)); 341 } 342 s_tail = snp->snp_blen - (snp->snp_len + snp->snp_base); 343 s_free = snp->snp_blen - snp->snp_len; 344 345 346 if (n > s_free) { 347 s = spltty(); 348 nblen = snp->snp_blen; 349 while ((n > s_free) && ((nblen * 2) <= SNOOP_MAXLEN)) { 350 nblen = snp->snp_blen * 2; 351 s_free = nblen - (snp->snp_len + snp->snp_base); 352 } 353 if ((n <= s_free) && (nbuf = malloc(nblen, M_SNP, M_NOWAIT))) { 354 bcopy(snp->snp_buf + snp->snp_base, nbuf, snp->snp_len); 355 free(snp->snp_buf, M_SNP); 356 snp->snp_buf = nbuf; 357 snp->snp_blen = nblen; 358 snp->snp_base = 0; 359 } else { 360 snp->snp_flags |= SNOOP_OFLOW; 361 if (snp->snp_flags & SNOOP_RWAIT) { 362 snp->snp_flags &= ~SNOOP_RWAIT; 363 wakeup(snp); 364 } 365 splx(s); 366 return (0); 367 } 368 splx(s); 369 } 370 if (n > s_tail) { 371 from = (caddr_t)(snp->snp_buf + snp->snp_base); 372 to = (caddr_t)(snp->snp_buf); 373 len = snp->snp_len; 374 bcopy(from, to, len); 375 snp->snp_base = 0; 376 } 377 to = (caddr_t)(snp->snp_buf + snp->snp_base + snp->snp_len); 378 bcopy(buf, to, n); 379 snp->snp_len += n; 380 381 if (snp->snp_flags & SNOOP_RWAIT) { 382 snp->snp_flags &= ~SNOOP_RWAIT; 383 wakeup(snp); 384 } 385 selwakeuppri(&snp->snp_sel, PZERO + 1); 386 387 return (n); 388 } 389 390 static int 391 snpopen(struct cdev *dev, int flag, int mode, struct thread *td) 392 { 393 struct snoop *snp; 394 395 if (dev->si_drv1 == NULL) { 396 dev->si_flags &= ~SI_CHEAPCLONE; 397 dev->si_drv1 = snp = malloc(sizeof(*snp), M_SNP, 398 M_WAITOK | M_ZERO); 399 snp->snp_unit = dev2unit(dev); 400 } else 401 return (EBUSY); 402 403 /* 404 * We intentionally do not OR flags with SNOOP_OPEN, but set them so 405 * all previous settings (especially SNOOP_OFLOW) will be cleared. 406 */ 407 snp->snp_flags = SNOOP_OPEN; 408 409 snp->snp_buf = malloc(SNOOP_MINLEN, M_SNP, M_WAITOK); 410 snp->snp_blen = SNOOP_MINLEN; 411 snp->snp_base = 0; 412 snp->snp_len = 0; 413 414 /* 415 * snp_tty == NULL is for inactive snoop devices. 416 */ 417 snp->snp_tty = NULL; 418 snp->snp_target = NULL; 419 420 LIST_INSERT_HEAD(&snp_sclist, snp, snp_list); 421 return (0); 422 } 423 424 425 static void 426 snp_detach(void *arg) 427 { 428 struct snoop *snp; 429 struct tty *tp; 430 431 snp = (struct snoop *)arg; 432 snp->snp_base = 0; 433 snp->snp_len = 0; 434 435 /* 436 * If line disc. changed we do not touch this pointer, SLIP/PPP will 437 * change it anyway. 438 */ 439 tp = snp->snp_tty; 440 if (tp == NULL) 441 goto detach_notty; 442 443 if ((tp->t_state & TS_SNOOP) && tp->t_line == snooplinedisc) { 444 tp->t_state &= ~TS_SNOOP; 445 tp->t_line = snp->snp_olddisc; 446 } else 447 printf("snp%d: bad attached tty data\n", snp->snp_unit); 448 449 snp->snp_tty = NULL; 450 snp->snp_target = NULL; 451 452 detach_notty: 453 selwakeuppri(&snp->snp_sel, PZERO + 1); 454 if ((snp->snp_flags & SNOOP_OPEN) == 0) 455 free(snp, M_SNP); 456 } 457 458 static int 459 snpclose(struct cdev *dev, int flags, int fmt, struct thread *td) 460 { 461 struct snoop *snp; 462 463 snp = dev->si_drv1; 464 snp->snp_blen = 0; 465 LIST_REMOVE(snp, snp_list); 466 free(snp->snp_buf, M_SNP); 467 snp->snp_flags &= ~SNOOP_OPEN; 468 dev->si_drv1 = NULL; 469 snp_detach(snp); 470 destroy_dev_sched(dev); 471 472 return (0); 473 } 474 475 static int 476 snp_down(struct snoop *snp) 477 { 478 479 if (snp->snp_blen != SNOOP_MINLEN) { 480 free(snp->snp_buf, M_SNP); 481 snp->snp_buf = malloc(SNOOP_MINLEN, M_SNP, M_WAITOK); 482 snp->snp_blen = SNOOP_MINLEN; 483 } 484 snp->snp_flags |= SNOOP_DOWN; 485 snp_detach(snp); 486 487 return (0); 488 } 489 490 static int 491 snpioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, 492 struct thread *td) 493 { 494 struct snoop *snp; 495 struct tty *tp; 496 struct cdev *tdev; 497 struct file *fp; 498 int s; 499 500 snp = dev->si_drv1; 501 switch (cmd) { 502 case SNPSTTY: 503 s = *(int *)data; 504 if (s < 0) 505 return (snp_down(snp)); 506 507 if (fget(td, s, &fp) != 0) 508 return (EINVAL); 509 if (fp->f_type != DTYPE_VNODE || 510 fp->f_vnode->v_type != VCHR || 511 fp->f_vnode->v_rdev == NULL) { 512 fdrop(fp, td); 513 return (EINVAL); 514 } 515 tdev = fp->f_vnode->v_rdev; 516 fdrop(fp, td); 517 518 if (snp->snp_tty != NULL) 519 return (EBUSY); 520 521 tp = snpdevtotty(tdev); 522 if (!tp) 523 return (EINVAL); 524 if (tp->t_state & TS_SNOOP) 525 return (EBUSY); 526 527 s = spltty(); 528 tp->t_state |= TS_SNOOP; 529 snp->snp_olddisc = tp->t_line; 530 tp->t_line = snooplinedisc; 531 snp->snp_tty = tp; 532 snp->snp_target = tdev; 533 534 /* 535 * Clean overflow and down flags - 536 * we'll have a chance to get them in the future :))) 537 */ 538 snp->snp_flags &= ~SNOOP_OFLOW; 539 snp->snp_flags &= ~SNOOP_DOWN; 540 splx(s); 541 break; 542 543 case SNPGTTY: 544 /* 545 * We keep snp_target field specially to make 546 * SNPGTTY happy, else we can't know what is device 547 * major/minor for tty. 548 */ 549 *((dev_t *)data) = dev2udev(snp->snp_target); 550 break; 551 552 case FIONBIO: 553 break; 554 555 case FIOASYNC: 556 if (*(int *)data) 557 snp->snp_flags |= SNOOP_ASYNC; 558 else 559 snp->snp_flags &= ~SNOOP_ASYNC; 560 break; 561 562 case FIONREAD: 563 s = spltty(); 564 if (snp->snp_tty != NULL) 565 *(int *)data = snp->snp_len; 566 else 567 if (snp->snp_flags & SNOOP_DOWN) { 568 if (snp->snp_flags & SNOOP_OFLOW) 569 *(int *)data = SNP_OFLOW; 570 else 571 *(int *)data = SNP_TTYCLOSE; 572 } else { 573 *(int *)data = SNP_DETACH; 574 } 575 splx(s); 576 break; 577 578 default: 579 return (ENOTTY); 580 } 581 return (0); 582 } 583 584 static int 585 snppoll(struct cdev *dev, int events, struct thread *td) 586 { 587 struct snoop *snp; 588 int revents; 589 590 snp = dev->si_drv1; 591 revents = 0; 592 /* 593 * If snoop is down, we don't want to poll() forever so we return 1. 594 * Caller should see if we down via FIONREAD ioctl(). The last should 595 * return -1 to indicate down state. 596 */ 597 if (events & (POLLIN | POLLRDNORM)) { 598 if (snp->snp_flags & SNOOP_DOWN || snp->snp_len > 0) 599 revents |= events & (POLLIN | POLLRDNORM); 600 else 601 selrecord(td, &snp->snp_sel); 602 } 603 return (revents); 604 } 605 606 static void 607 snp_clone(void *arg, struct ucred *cred, char *name, int namelen, 608 struct cdev **dev) 609 { 610 int u, i; 611 612 if (*dev != NULL) 613 return; 614 if (dev_stdclone(name, NULL, "snp", &u) != 1) 615 return; 616 i = clone_create(&snpclones, &snp_cdevsw, &u, dev, 0); 617 if (i) 618 *dev = make_dev_credf(MAKEDEV_REF, &snp_cdevsw, unit2minor(u), 619 NULL, UID_ROOT, GID_WHEEL, 0600, "snp%d", u); 620 if (*dev != NULL) { 621 (*dev)->si_flags |= SI_CHEAPCLONE; 622 } 623 } 624 625 static int 626 snp_modevent(module_t mod, int type, void *data) 627 { 628 static eventhandler_tag eh_tag; 629 630 switch (type) { 631 case MOD_LOAD: 632 /* XXX error checking. */ 633 clone_setup(&snpclones); 634 eh_tag = EVENTHANDLER_REGISTER(dev_clone, snp_clone, 0, 1000); 635 snooplinedisc = ldisc_register(LDISC_LOAD, &snpdisc); 636 break; 637 case MOD_UNLOAD: 638 if (!LIST_EMPTY(&snp_sclist)) 639 return (EBUSY); 640 EVENTHANDLER_DEREGISTER(dev_clone, eh_tag); 641 drain_dev_clone_events(); 642 clone_cleanup(&snpclones); 643 destroy_dev_drain(&snp_cdevsw); 644 ldisc_deregister(snooplinedisc); 645 break; 646 default: 647 return (EOPNOTSUPP); 648 break; 649 } 650 return (0); 651 } 652 653 static moduledata_t snp_mod = { 654 "snp", 655 snp_modevent, 656 NULL 657 }; 658 DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
Cache object: 20e4a925ec2f6b89044affb3b98dce99
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