| 1 | /* tty.c 4.23 82/07/15 */ |
| 2 | |
| 3 | /* |
| 4 | * TTY subroutines common to more than one line discipline |
| 5 | */ |
| 6 | #include "../h/param.h" |
| 7 | #include "../h/systm.h" |
| 8 | #include "../h/dir.h" |
| 9 | #include "../h/user.h" |
| 10 | #include "../h/tty.h" |
| 11 | #include "../h/proc.h" |
| 12 | #include "../h/inode.h" |
| 13 | #include "../h/file.h" |
| 14 | #include "../h/reg.h" |
| 15 | #include "../h/conf.h" |
| 16 | #include "../h/buf.h" |
| 17 | #include "../h/dk.h" |
| 18 | |
| 19 | /* |
| 20 | * Table giving parity for characters and indicating |
| 21 | * character classes to tty driver. In particular, |
| 22 | * if the low 6 bits are 0, then the character needs |
| 23 | * no special processing on output. |
| 24 | */ |
| 25 | |
| 26 | char partab[] = { |
| 27 | 0001,0201,0201,0001,0201,0001,0001,0201, |
| 28 | 0202,0004,0003,0201,0005,0206,0201,0001, |
| 29 | 0201,0001,0001,0201,0001,0201,0201,0001, |
| 30 | 0001,0201,0201,0001,0201,0001,0001,0201, |
| 31 | 0200,0000,0000,0200,0000,0200,0200,0000, |
| 32 | 0000,0200,0200,0000,0200,0000,0000,0200, |
| 33 | 0000,0200,0200,0000,0200,0000,0000,0200, |
| 34 | 0200,0000,0000,0200,0000,0200,0200,0000, |
| 35 | 0200,0000,0000,0200,0000,0200,0200,0000, |
| 36 | 0000,0200,0200,0000,0200,0000,0000,0200, |
| 37 | 0000,0200,0200,0000,0200,0000,0000,0200, |
| 38 | 0200,0000,0000,0200,0000,0200,0200,0000, |
| 39 | 0000,0200,0200,0000,0200,0000,0000,0200, |
| 40 | 0200,0000,0000,0200,0000,0200,0200,0000, |
| 41 | 0200,0000,0000,0200,0000,0200,0200,0000, |
| 42 | 0000,0200,0200,0000,0200,0000,0000,0201, |
| 43 | |
| 44 | /* |
| 45 | * 7 bit ascii ends with the last character above, |
| 46 | * but we contine through all 256 codes for the sake |
| 47 | * of the tty output routines which use special vax |
| 48 | * instructions which need a 256 character trt table. |
| 49 | */ |
| 50 | |
| 51 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 52 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 53 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 54 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 55 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 56 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 57 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 58 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 59 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 60 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 61 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 62 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 63 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 64 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 65 | 0007,0007,0007,0007,0007,0007,0007,0007, |
| 66 | 0007,0007,0007,0007,0007,0007,0007,0007 |
| 67 | }; |
| 68 | |
| 69 | /* |
| 70 | * Input mapping table-- if an entry is non-zero, when the |
| 71 | * corresponding character is typed preceded by "\" the escape |
| 72 | * sequence is replaced by the table value. Mostly used for |
| 73 | * upper-case only terminals. |
| 74 | */ |
| 75 | |
| 76 | char maptab[] ={ |
| 77 | 000,000,000,000,000,000,000,000, |
| 78 | 000,000,000,000,000,000,000,000, |
| 79 | 000,000,000,000,000,000,000,000, |
| 80 | 000,000,000,000,000,000,000,000, |
| 81 | 000,'|',000,000,000,000,000,'`', |
| 82 | '{','}',000,000,000,000,000,000, |
| 83 | 000,000,000,000,000,000,000,000, |
| 84 | 000,000,000,000,000,000,000,000, |
| 85 | 000,000,000,000,000,000,000,000, |
| 86 | 000,000,000,000,000,000,000,000, |
| 87 | 000,000,000,000,000,000,000,000, |
| 88 | 000,000,000,000,000,000,'~',000, |
| 89 | 000,'A','B','C','D','E','F','G', |
| 90 | 'H','I','J','K','L','M','N','O', |
| 91 | 'P','Q','R','S','T','U','V','W', |
| 92 | 'X','Y','Z',000,000,000,000,000, |
| 93 | }; |
| 94 | |
| 95 | short tthiwat[16] = |
| 96 | { 100,100,100,100,100,100,100,200,200,400,400,400,650,650,650,650 }; |
| 97 | short ttlowat[16] = |
| 98 | { 30, 30, 30, 30, 30, 30, 30, 50, 50,120,120,120,125,125,125,125 }; |
| 99 | |
| 100 | #define OBUFSIZ 100 |
| 101 | |
| 102 | /* |
| 103 | * set default control characters. |
| 104 | */ |
| 105 | ttychars(tp) |
| 106 | register struct tty *tp; |
| 107 | { |
| 108 | |
| 109 | tun.t_intrc = CINTR; |
| 110 | tun.t_quitc = CQUIT; |
| 111 | tun.t_startc = CSTART; |
| 112 | tun.t_stopc = CSTOP; |
| 113 | tun.t_eofc = CEOT; |
| 114 | tun.t_brkc = CBRK; |
| 115 | tp->t_erase = CERASE; |
| 116 | tp->t_kill = CKILL; |
| 117 | /* begin local */ |
| 118 | tlun.t_suspc = CTRL(z); |
| 119 | tlun.t_dsuspc = CTRL(y); |
| 120 | tlun.t_rprntc = CTRL(r); |
| 121 | tlun.t_flushc = CTRL(o); |
| 122 | tlun.t_werasc = CTRL(w); |
| 123 | tlun.t_lnextc = CTRL(v); |
| 124 | tp->t_local = 0; |
| 125 | tp->t_lstate = 0; |
| 126 | /* end local */ |
| 127 | } |
| 128 | |
| 129 | /* |
| 130 | * Wait for output to drain, then flush input waiting. |
| 131 | */ |
| 132 | wflushtty(tp) |
| 133 | register struct tty *tp; |
| 134 | { |
| 135 | |
| 136 | (void) spl5(); |
| 137 | while (tp->t_outq.c_cc && tp->t_state&TS_CARR_ON |
| 138 | && tp->t_oproc) { /* kludge for pty */ |
| 139 | (*tp->t_oproc)(tp); |
| 140 | tp->t_state |= TS_ASLEEP; |
| 141 | sleep((caddr_t)&tp->t_outq, TTOPRI); |
| 142 | } |
| 143 | flushtty(tp, FREAD); |
| 144 | (void) spl0(); |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * flush all TTY queues |
| 149 | */ |
| 150 | flushtty(tp, rw) |
| 151 | register struct tty *tp; |
| 152 | { |
| 153 | register s; |
| 154 | |
| 155 | s = spl6(); |
| 156 | if (rw & FREAD) { |
| 157 | while (getc(&tp->t_canq) >= 0) |
| 158 | ; |
| 159 | wakeup((caddr_t)&tp->t_rawq); |
| 160 | } |
| 161 | if (rw & FWRITE) { |
| 162 | wakeup((caddr_t)&tp->t_outq); |
| 163 | tp->t_state &= ~TS_TTSTOP; |
| 164 | (*cdevsw[major(tp->t_dev)].d_stop)(tp, rw); |
| 165 | while (getc(&tp->t_outq) >= 0) |
| 166 | ; |
| 167 | } |
| 168 | if (rw & FREAD) { |
| 169 | while (getc(&tp->t_rawq) >= 0) |
| 170 | ; |
| 171 | tp->t_delct = 0; |
| 172 | tp->t_rocount = 0; /* local */ |
| 173 | tp->t_rocol = 0; |
| 174 | tp->t_lstate = 0; |
| 175 | } |
| 176 | splx(s); |
| 177 | } |
| 178 | |
| 179 | /* |
| 180 | * Send stop character on input overflow. |
| 181 | */ |
| 182 | ttyblock(tp) |
| 183 | register struct tty *tp; |
| 184 | { |
| 185 | register x; |
| 186 | x = tp->t_rawq.c_cc + tp->t_canq.c_cc; |
| 187 | if (tp->t_rawq.c_cc > TTYHOG) { |
| 188 | flushtty(tp, FREAD|FWRITE); |
| 189 | tp->t_state &= ~TS_TBLOCK; |
| 190 | } |
| 191 | if (x >= TTYHOG/2) { |
| 192 | if (putc(tun.t_stopc, &tp->t_outq)==0) { |
| 193 | tp->t_state |= TS_TBLOCK; |
| 194 | tp->t_char++; |
| 195 | ttstart(tp); |
| 196 | } |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | /* |
| 201 | * Restart typewriter output following a delay |
| 202 | * timeout. |
| 203 | * The name of the routine is passed to the timeout |
| 204 | * subroutine and it is called during a clock interrupt. |
| 205 | */ |
| 206 | ttrstrt(tp) |
| 207 | register struct tty *tp; |
| 208 | { |
| 209 | |
| 210 | if (tp == 0) { |
| 211 | printf("ttrstrt: arg was 0!\n"); |
| 212 | return; |
| 213 | } |
| 214 | tp->t_state &= ~TS_TIMEOUT; |
| 215 | ttstart(tp); |
| 216 | } |
| 217 | |
| 218 | /* |
| 219 | * Start output on the typewriter. It is used from the top half |
| 220 | * after some characters have been put on the output queue, |
| 221 | * from the interrupt routine to transmit the next |
| 222 | * character, and after a timeout has finished. |
| 223 | */ |
| 224 | ttstart(tp) |
| 225 | register struct tty *tp; |
| 226 | { |
| 227 | register s; |
| 228 | |
| 229 | s = spl5(); |
| 230 | if((tp->t_state&(TS_TIMEOUT|TS_TTSTOP|TS_BUSY)) == 0 && |
| 231 | tp->t_oproc) /* kludge for pty */ |
| 232 | (*tp->t_oproc)(tp); |
| 233 | splx(s); |
| 234 | } |
| 235 | |
| 236 | /* |
| 237 | * Common code for tty ioctls. |
| 238 | */ |
| 239 | /*ARGSUSED*/ |
| 240 | ttioctl(tp, com, addr, flag) |
| 241 | register struct tty *tp; |
| 242 | caddr_t addr; |
| 243 | { |
| 244 | int dev; |
| 245 | unsigned t; |
| 246 | struct sgttyb iocb; |
| 247 | struct clist tq; |
| 248 | extern int nldisp; |
| 249 | register c; |
| 250 | int temp; |
| 251 | |
| 252 | /* |
| 253 | * This is especially so that isatty() will |
| 254 | * fail when carrier is gone. |
| 255 | */ |
| 256 | if ((tp->t_state&TS_CARR_ON) == 0) { |
| 257 | u.u_error = EBADF; |
| 258 | return (1); |
| 259 | } |
| 260 | |
| 261 | dev = tp->t_dev; |
| 262 | /* |
| 263 | * If the ioctl involves modification, |
| 264 | * insist on being able to write the device, |
| 265 | * and hang if in the background. |
| 266 | */ |
| 267 | switch(com) { |
| 268 | |
| 269 | case TIOCSETD: |
| 270 | case TIOCSETP: |
| 271 | case TIOCSETN: |
| 272 | case TIOCFLUSH: |
| 273 | case TIOCSETC: |
| 274 | case TIOCSLTC: |
| 275 | case TIOCSPGRP: |
| 276 | case TIOCLBIS: |
| 277 | case TIOCLBIC: |
| 278 | case TIOCLSET: |
| 279 | case TIOCSTI: |
| 280 | /* this is reasonable, but impractical... |
| 281 | if ((flag & FWRITE) == 0) { |
| 282 | u.u_error = EBADF; |
| 283 | return (1); |
| 284 | } |
| 285 | */ |
| 286 | while (tp->t_line == NTTYDISC && |
| 287 | u.u_procp->p_pgrp != tp->t_pgrp && tp == u.u_ttyp && |
| 288 | (u.u_procp->p_flag&SVFORK) == 0 && |
| 289 | u.u_signal[SIGTTOU] != SIG_IGN && |
| 290 | u.u_signal[SIGTTOU] != SIG_HOLD |
| 291 | /* |
| 292 | && |
| 293 | (u.u_procp->p_flag&SDETACH)==0) { |
| 294 | */ |
| 295 | ) { |
| 296 | gsignal(u.u_procp->p_pgrp, SIGTTOU); |
| 297 | sleep((caddr_t)&lbolt, TTOPRI); |
| 298 | } |
| 299 | break; |
| 300 | } |
| 301 | |
| 302 | /* |
| 303 | * Process the ioctl. |
| 304 | */ |
| 305 | switch(com) { |
| 306 | |
| 307 | /* |
| 308 | * Get discipline number |
| 309 | */ |
| 310 | case TIOCGETD: |
| 311 | t = tp->t_line; |
| 312 | if (copyout((caddr_t)&t, addr, sizeof(t))) |
| 313 | u.u_error = EFAULT; |
| 314 | break; |
| 315 | |
| 316 | /* |
| 317 | * Set line discipline |
| 318 | */ |
| 319 | case TIOCSETD: |
| 320 | if (copyin(addr, (caddr_t)&t, sizeof(t))) { |
| 321 | u.u_error = EFAULT; |
| 322 | break; |
| 323 | } |
| 324 | if (t >= nldisp) { |
| 325 | u.u_error = ENXIO; |
| 326 | break; |
| 327 | } |
| 328 | (void) spl5(); |
| 329 | if (tp->t_line) |
| 330 | (*linesw[tp->t_line].l_close)(tp); |
| 331 | if (t) |
| 332 | (*linesw[t].l_open)(dev, tp, addr); |
| 333 | if (u.u_error==0) |
| 334 | tp->t_line = t; |
| 335 | (void) spl0(); |
| 336 | break; |
| 337 | |
| 338 | /* |
| 339 | * Prevent more opens on channel |
| 340 | */ |
| 341 | case TIOCEXCL: |
| 342 | tp->t_state |= TS_XCLUDE; |
| 343 | break; |
| 344 | |
| 345 | case TIOCNXCL: |
| 346 | tp->t_state &= ~TS_XCLUDE; |
| 347 | break; |
| 348 | |
| 349 | /* |
| 350 | * Set new parameters |
| 351 | */ |
| 352 | case TIOCSETP: |
| 353 | case TIOCSETN: |
| 354 | if (copyin(addr, (caddr_t)&iocb, sizeof(iocb))) { |
| 355 | u.u_error = EFAULT; |
| 356 | return(1); |
| 357 | } |
| 358 | (void) spl5(); |
| 359 | if (tp->t_flags&RAW || iocb.sg_flags&RAW || |
| 360 | com == TIOCSETP) |
| 361 | wflushtty(tp); |
| 362 | else if ((tp->t_flags&CBREAK) != (iocb.sg_flags&CBREAK)) { |
| 363 | if (iocb.sg_flags & CBREAK) { |
| 364 | catq(&tp->t_rawq, &tp->t_canq); |
| 365 | tq = tp->t_rawq; |
| 366 | tp->t_rawq = tp->t_canq; |
| 367 | tp->t_canq = tq; |
| 368 | } else { |
| 369 | tp->t_local |= LPENDIN; |
| 370 | ttwakeup(tp); |
| 371 | } |
| 372 | } |
| 373 | tp->t_ispeed = iocb.sg_ispeed; |
| 374 | tp->t_ospeed = iocb.sg_ospeed; |
| 375 | tp->t_erase = iocb.sg_erase; |
| 376 | tp->t_kill = iocb.sg_kill; |
| 377 | tp->t_flags = iocb.sg_flags; |
| 378 | if (tp->t_flags & RAW) { |
| 379 | tp->t_state &= ~TS_TTSTOP; |
| 380 | ttstart(tp); |
| 381 | } |
| 382 | (void) spl0(); |
| 383 | break; |
| 384 | |
| 385 | /* |
| 386 | * Send current parameters to user |
| 387 | */ |
| 388 | case TIOCGETP: |
| 389 | iocb.sg_ispeed = tp->t_ispeed; |
| 390 | iocb.sg_ospeed = tp->t_ospeed; |
| 391 | iocb.sg_erase = tp->t_erase; |
| 392 | iocb.sg_kill = tp->t_kill; |
| 393 | iocb.sg_flags = tp->t_flags; |
| 394 | if (copyout((caddr_t)&iocb, addr, sizeof(iocb))) |
| 395 | u.u_error = EFAULT; |
| 396 | break; |
| 397 | |
| 398 | /* |
| 399 | * Hang up line on last close |
| 400 | */ |
| 401 | case TIOCHPCL: |
| 402 | tp->t_state |= TS_HUPCLS; |
| 403 | break; |
| 404 | |
| 405 | case TIOCFLUSH: { |
| 406 | int flags; |
| 407 | if (addr == 0) |
| 408 | flags = FREAD|FWRITE; |
| 409 | else if (copyin(addr, (caddr_t)&flags, sizeof (flags))) { |
| 410 | u.u_error = EFAULT; |
| 411 | return(1); |
| 412 | } |
| 413 | flushtty(tp, flags); |
| 414 | break; |
| 415 | } |
| 416 | |
| 417 | case FIONBIO: { |
| 418 | int nbio; |
| 419 | if (copyin(addr, (caddr_t)&nbio, sizeof (nbio))) { |
| 420 | u.u_error = EFAULT; |
| 421 | return(1); |
| 422 | } |
| 423 | if (nbio) |
| 424 | tp->t_state |= TS_NBIO; |
| 425 | else |
| 426 | tp->t_state &= ~TS_NBIO; |
| 427 | break; |
| 428 | } |
| 429 | |
| 430 | case FIOASYNC: { |
| 431 | int async; |
| 432 | if (copyin(addr, (caddr_t)&async, sizeof (async))) { |
| 433 | u.u_error = EFAULT; |
| 434 | return(1); |
| 435 | } |
| 436 | if (async) |
| 437 | tp->t_state |= TS_ASYNC; |
| 438 | else |
| 439 | tp->t_state &= ~TS_ASYNC; |
| 440 | break; |
| 441 | } |
| 442 | |
| 443 | /* |
| 444 | * Set and fetch special characters |
| 445 | */ |
| 446 | case TIOCSETC: |
| 447 | if (copyin(addr, (caddr_t)&tun, sizeof(struct tchars))) |
| 448 | u.u_error = EFAULT; |
| 449 | break; |
| 450 | |
| 451 | case TIOCGETC: |
| 452 | if (copyout((caddr_t)&tun, addr, sizeof(struct tchars))) |
| 453 | u.u_error = EFAULT; |
| 454 | break; |
| 455 | |
| 456 | /* local ioctls */ |
| 457 | /* |
| 458 | * Set/get local special characters. |
| 459 | */ |
| 460 | case TIOCSLTC: |
| 461 | if (copyin(addr, (caddr_t)&tlun, sizeof (struct ltchars))) |
| 462 | u.u_error = EFAULT; |
| 463 | break; |
| 464 | |
| 465 | case TIOCGLTC: |
| 466 | if (copyout((caddr_t)&tlun, addr, sizeof (struct ltchars))) |
| 467 | u.u_error = EFAULT; |
| 468 | break; |
| 469 | |
| 470 | /* |
| 471 | * Return number of characters immediately available. |
| 472 | */ |
| 473 | case FIONREAD: { |
| 474 | off_t nread = ttnread(tp); |
| 475 | if (copyout((caddr_t)&nread, addr, sizeof (off_t))) |
| 476 | u.u_error = EFAULT; |
| 477 | break; |
| 478 | } |
| 479 | |
| 480 | /* |
| 481 | * Should allow SPGRP and GPGRP only if tty open for reading. |
| 482 | */ |
| 483 | case TIOCSPGRP: |
| 484 | if (copyin(addr, (caddr_t)&tp->t_pgrp, sizeof (tp->t_pgrp))) |
| 485 | u.u_error = EFAULT; |
| 486 | break; |
| 487 | |
| 488 | case TIOCGPGRP: |
| 489 | if (copyout((caddr_t)&tp->t_pgrp, addr, sizeof(tp->t_pgrp))) |
| 490 | u.u_error = EFAULT; |
| 491 | break; |
| 492 | |
| 493 | /* |
| 494 | * Modify local mode word. |
| 495 | */ |
| 496 | case TIOCLBIS: |
| 497 | if (copyin(addr, (caddr_t)&temp, sizeof (tp->t_local))) |
| 498 | u.u_error = EFAULT; |
| 499 | else |
| 500 | tp->t_local |= temp; |
| 501 | break; |
| 502 | |
| 503 | case TIOCLBIC: |
| 504 | if (copyin(addr, (caddr_t)&temp, sizeof (tp->t_local))) |
| 505 | u.u_error = EFAULT; |
| 506 | else |
| 507 | tp->t_local &= ~temp; |
| 508 | break; |
| 509 | |
| 510 | case TIOCLSET: |
| 511 | if (copyin(addr, (caddr_t)&temp, sizeof (tp->t_local))) |
| 512 | u.u_error = EFAULT; |
| 513 | else |
| 514 | tp->t_local = temp; |
| 515 | break; |
| 516 | |
| 517 | case TIOCLGET: |
| 518 | if (copyout((caddr_t)&tp->t_local, addr, sizeof(tp->t_local))) |
| 519 | u.u_error = EFAULT; |
| 520 | break; |
| 521 | |
| 522 | /* |
| 523 | * Return number of characters in |
| 524 | * the output. |
| 525 | */ |
| 526 | case TIOCOUTQ: |
| 527 | if (copyout((caddr_t)&tp->t_outq.c_cc, addr, sizeof(tp->t_outq.c_cc))) |
| 528 | u.u_error = EFAULT; |
| 529 | break; |
| 530 | |
| 531 | /* |
| 532 | * Simulate typing of a character at the terminal. |
| 533 | */ |
| 534 | case TIOCSTI: |
| 535 | c = fubyte(addr); |
| 536 | if (u.u_uid && u.u_ttyp != tp || c < 0) |
| 537 | u.u_error = EFAULT; |
| 538 | else |
| 539 | (*linesw[tp->t_line].l_rint)(c, tp); |
| 540 | break; |
| 541 | |
| 542 | case TIOCSTOP: |
| 543 | c = spl5(); |
| 544 | if ((tp->t_state & TS_TTSTOP) == 0) { |
| 545 | tp->t_state |= TS_TTSTOP; |
| 546 | (*cdevsw[major(tp->t_dev)].d_stop)(tp, 0); |
| 547 | } |
| 548 | splx(c); |
| 549 | break; |
| 550 | |
| 551 | case TIOCSTART: |
| 552 | c = spl5(); |
| 553 | if ((tp->t_state & TS_TTSTOP) || (tp->t_local & LFLUSHO)) { |
| 554 | tp->t_state &= ~TS_TTSTOP; |
| 555 | tp->t_local &= ~LFLUSHO; |
| 556 | ttstart(tp); |
| 557 | } |
| 558 | splx(c); |
| 559 | break; |
| 560 | |
| 561 | /* end of locals */ |
| 562 | |
| 563 | default: |
| 564 | return(0); |
| 565 | } |
| 566 | return(1); |
| 567 | } |
| 568 | |
| 569 | ttnread(tp) |
| 570 | struct tty *tp; |
| 571 | { |
| 572 | int nread = 0; |
| 573 | |
| 574 | if (tp->t_local & LPENDIN) |
| 575 | ttypend(tp); |
| 576 | nread = tp->t_canq.c_cc; |
| 577 | if (tp->t_flags & (RAW|CBREAK)) |
| 578 | nread += tp->t_rawq.c_cc; |
| 579 | return (nread); |
| 580 | } |
| 581 | |
| 582 | ttselect(dev, rw) |
| 583 | dev_t dev; |
| 584 | int rw; |
| 585 | { |
| 586 | register struct tty *tp = &cdevsw[major(dev)].d_ttys[minor(dev)]; |
| 587 | int nread; |
| 588 | int s = spl5(); |
| 589 | |
| 590 | switch (rw) { |
| 591 | |
| 592 | case FREAD: |
| 593 | nread = ttnread(tp); |
| 594 | if (nread > 0) |
| 595 | goto win; |
| 596 | if (tp->t_rsel && tp->t_rsel->p_wchan == (caddr_t)&selwait) |
| 597 | tp->t_state |= TS_RCOLL; |
| 598 | else |
| 599 | tp->t_rsel = u.u_procp; |
| 600 | break; |
| 601 | |
| 602 | case FWRITE: |
| 603 | if (tp->t_outq.c_cc <= TTLOWAT(tp)) |
| 604 | goto win; |
| 605 | if (tp->t_wsel && tp->t_wsel->p_wchan == (caddr_t)&selwait) |
| 606 | tp->t_state |= TS_WCOLL; |
| 607 | else |
| 608 | tp->t_wsel = u.u_procp; |
| 609 | break; |
| 610 | } |
| 611 | splx(s); |
| 612 | return (0); |
| 613 | win: |
| 614 | splx(s); |
| 615 | return (1); |
| 616 | } |
| 617 | |