1/* $NetBSD: os.c,v 1.6 2023/10/06 07:31:30 simonb Exp $ */ 2 3/* 4 * Copyright (C) 1984-2023 Mark Nudelman 5 * 6 * You may distribute under the terms of either the GNU General Public 7 * License or the Less License, as specified in the README file. 8 * 9 * For more information, see the README file. 10 */ 11 12 13/* 14 * Operating system dependent routines. 15 * 16 * Most of the stuff in here is based on Unix, but an attempt 17 * has been made to make things work on other operating systems. 18 * This will sometimes result in a loss of functionality, unless 19 * someone rewrites code specifically for the new operating system. 20 * 21 * The makefile provides defines to decide whether various 22 * Unix features are present. 23 */ 24 25#include "less.h" 26#include <signal.h> 27#include <setjmp.h> 28#if MSDOS_COMPILER==WIN32C 29#include <windows.h> 30#endif 31#if HAVE_TIME_H 32#include <time.h> 33#endif 34#if HAVE_ERRNO_H 35#include <errno.h> 36#endif 37#if HAVE_VALUES_H 38#include <values.h> 39#endif 40 41#if defined(__APPLE__) 42#include <sys/utsname.h> 43#endif 44 45#if HAVE_POLL && !MSDOS_COMPILER 46#define USE_POLL 1 47static int use_poll = TRUE; 48#else 49#define USE_POLL 0 50#endif 51#if USE_POLL 52#include <poll.h> 53static int any_data = FALSE; 54#endif 55 56/* 57 * BSD setjmp() saves (and longjmp() restores) the signal mask. 58 * This costs a system call or two per setjmp(), so if possible we clear the 59 * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead. 60 * On other systems, setjmp() doesn't affect the signal mask and so 61 * _setjmp() does not exist; we just use setjmp(). 62 */ 63#if HAVE__SETJMP && HAVE_SIGSETMASK 64#define SET_JUMP _setjmp 65#define LONG_JUMP _longjmp 66#else 67#define SET_JUMP setjmp 68#define LONG_JUMP longjmp 69#endif 70 71public int reading; 72public int waiting_for_data; 73public int consecutive_nulls = 0; 74 75/* Milliseconds to wait for data before displaying "waiting for data" message. */ 76static int waiting_for_data_delay = 4000; 77static jmp_buf read_label; 78 79extern int sigs; 80extern int ignore_eoi; 81extern int exit_F_on_close; 82extern int follow_mode; 83extern int scanning_eof; 84extern char intr_char; 85#if !MSDOS_COMPILER 86extern int tty; 87#endif 88#if LESSTEST 89extern char *ttyin_name; 90#endif /*LESSTEST*/ 91 92public void init_poll(void) 93{ 94 char *delay = lgetenv("LESS_DATA_DELAY"); 95 int idelay = (delay == NULL) ? 0 : atoi(delay); 96 if (idelay > 0) 97 waiting_for_data_delay = idelay; 98#if USE_POLL 99#if defined(__APPLE__) 100 /* In old versions of MacOS, poll() does not work with /dev/tty. */ 101 struct utsname uts; 102 if (uname(&uts) < 0 || lstrtoi(uts.release, NULL, 10) < 20) 103 use_poll = FALSE; 104#endif 105#endif 106} 107 108#if USE_POLL 109/* 110 * Check whether data is available, either from a file/pipe or from the tty. 111 * Return READ_AGAIN if no data currently available, but caller should retry later. 112 * Return READ_INTR to abort F command (forw_loop). 113 * Return 0 if safe to read from fd. 114 */ 115static int check_poll(int fd, int tty) 116{ 117 struct pollfd poller[2] = { { fd, POLLIN, 0 }, { tty, POLLIN, 0 } }; 118 int timeout = (waiting_for_data && !(scanning_eof && follow_mode == FOLLOW_NAME)) ? -1 : waiting_for_data_delay; 119 if (!any_data) 120 { 121 /* 122 * Don't do polling if no data has yet been received, 123 * to allow a program piping data into less to have temporary 124 * access to the tty (like sudo asking for a password). 125 */ 126 return (0); 127 } 128 poll(poller, 2, timeout); 129#if LESSTEST 130 if (ttyin_name == NULL) /* Check for ^X only on a real tty. */ 131#endif /*LESSTEST*/ 132 { 133 if (poller[1].revents & POLLIN) 134 { 135 LWCHAR ch = getchr(); 136 if (ch == intr_char) 137 /* Break out of "waiting for data". */ 138 return (READ_INTR); 139 ungetcc_back(ch); 140 } 141 } 142 if (ignore_eoi && exit_F_on_close && (poller[0].revents & (POLLHUP|POLLIN)) == POLLHUP) 143 /* Break out of F loop on HUP due to --exit-follow-on-close. */ 144 return (READ_INTR); 145 if ((poller[0].revents & (POLLIN|POLLHUP|POLLERR)) == 0) 146 /* No data available; let caller take action, then try again. */ 147 return (READ_AGAIN); 148 /* There is data (or HUP/ERR) available. Safe to call read() without blocking. */ 149 return (0); 150} 151#endif /* USE_POLL */ 152 153public int supports_ctrl_x(void) 154{ 155#if USE_POLL 156 return (use_poll); 157#else 158 return (FALSE); 159#endif /* USE_POLL */ 160} 161 162/* 163 * Like read() system call, but is deliberately interruptible. 164 * A call to intread() from a signal handler will interrupt 165 * any pending iread(). 166 */ 167public int iread(int fd, unsigned char *buf, unsigned int len) 168{ 169 int n; 170 171start: 172#if MSDOS_COMPILER==WIN32C 173 if (ABORT_SIGS()) 174 return (READ_INTR); 175#else 176#if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC 177 if (kbhit()) 178 { 179 int c; 180 181 c = getch(); 182 if (c == '\003') 183 return (READ_INTR); 184 ungetch(c); 185 } 186#endif 187#endif 188 if (!reading && SET_JUMP(read_label)) 189 { 190 /* 191 * We jumped here from intread. 192 */ 193 reading = 0; 194#if HAVE_SIGPROCMASK 195 { 196 sigset_t mask; 197 sigemptyset(&mask); 198 sigprocmask(SIG_SETMASK, &mask, NULL); 199 } 200#else 201#if HAVE_SIGSETMASK 202 sigsetmask(0); 203#else 204#ifdef _OSK 205 sigmask(~0); 206#endif 207#endif 208#endif 209#if !MSDOS_COMPILER 210 if (fd != tty && !ABORT_SIGS()) 211 /* Non-interrupt signal like SIGWINCH. */ 212 return (READ_AGAIN); 213#endif 214 return (READ_INTR); 215 } 216 217 flush(); 218 reading = 1; 219#if MSDOS_COMPILER==DJGPPC 220 if (isatty(fd)) 221 { 222 /* 223 * Don't try reading from a TTY until a character is 224 * available, because that makes some background programs 225 * believe DOS is busy in a way that prevents those 226 * programs from working while "less" waits. 227 * {{ This code was added 12 Jan 2007; still needed? }} 228 */ 229 fd_set readfds; 230 231 FD_ZERO(&readfds); 232 FD_SET(fd, &readfds); 233 if (select(fd+1, &readfds, 0, 0, 0) == -1) 234 { 235 reading = 0; 236 return (READ_ERR); 237 } 238 } 239#endif 240#if USE_POLL 241 if (fd != tty && use_poll) 242 { 243 int ret = check_poll(fd, tty); 244 if (ret != 0) 245 { 246 if (ret == READ_INTR) 247 sigs |= S_INTERRUPT; 248 reading = 0; 249 return (ret); 250 } 251 } 252#else 253#if MSDOS_COMPILER==WIN32C 254 if (win32_kbhit()) 255 { 256 int c; 257 258 c = WIN32getch(); 259 if (c == intr_char) 260 { 261 sigs |= S_INTERRUPT; 262 reading = 0; 263 return (READ_INTR); 264 } 265 WIN32ungetch(c); 266 } 267#endif 268#endif 269 n = read(fd, buf, len); 270 reading = 0; 271#if 1 272 /* 273 * This is a kludge to workaround a problem on some systems 274 * where terminating a remote tty connection causes read() to 275 * start returning 0 forever, instead of -1. 276 */ 277 { 278 if (!ignore_eoi) 279 { 280 if (n == 0) 281 consecutive_nulls++; 282 else 283 consecutive_nulls = 0; 284 if (consecutive_nulls > 20) 285 quit(QUIT_ERROR); 286 } 287 } 288#endif 289 if (n < 0) 290 { 291#if HAVE_ERRNO 292 /* 293 * Certain values of errno indicate we should just retry the read. 294 */ 295#if MUST_DEFINE_ERRNO 296 extern int errno; 297#endif 298#ifdef EINTR 299 if (errno == EINTR) 300 goto start; 301#endif 302#ifdef EAGAIN 303 if (errno == EAGAIN) 304 goto start; 305#endif 306#endif 307 return (READ_ERR); 308 } 309#if USE_POLL 310 if (fd != tty && n > 0) 311 any_data = TRUE; 312#endif 313 return (n); 314} 315 316/* 317 * Interrupt a pending iread(). 318 */ 319public void intread(void) 320{ 321 LONG_JUMP(read_label, 1); 322} 323 324/* 325 * Return the current time. 326 */ 327#if HAVE_TIME 328public time_type get_time(void) 329{ 330 time_type t; 331 332 time(&t); 333 return (t); 334} 335#endif 336 337 338#if !HAVE_STRERROR 339/* 340 * Local version of strerror, if not available from the system. 341 */ 342static char * strerror(int err) 343{ 344 static char buf[INT_STRLEN_BOUND(int)+12]; 345#if HAVE_SYS_ERRLIST 346 extern char *sys_errlist[]; 347 extern int sys_nerr; 348 349 if (err < sys_nerr) 350 return sys_errlist[err]; 351#endif 352 sprintf(buf, "Error %d", err); 353 return buf; 354} 355#endif 356 357/* 358 * errno_message: Return an error message based on the value of "errno". 359 */ 360public char * errno_message(char *filename) 361{ 362 char *p; 363 char *m; 364 int len; 365#if HAVE_ERRNO 366#if MUST_DEFINE_ERRNO 367 extern int errno; 368#endif 369 p = strerror(errno); 370#else 371 p = "cannot open"; 372#endif 373 len = (int) (strlen(filename) + strlen(p) + 3); 374 m = (char *) ecalloc(len, sizeof(char)); 375 SNPRINTF2(m, len, "%s: %s", filename, p); 376 return (m); 377} 378 379/* 380 * Return a description of a signal. 381 * The return value is good until the next call to this function. 382 */ 383public char * signal_message(int sig) 384{ 385 static char sigbuf[sizeof("Signal ") + INT_STRLEN_BOUND(sig) + 1]; 386#if HAVE_STRSIGNAL 387 char *description = strsignal(sig); 388 if (description) 389 return description; 390#endif 391 sprintf(sigbuf, "Signal %d", sig); 392 return sigbuf; 393} 394 395/* 396 * Return (VAL * NUM) / DEN, where DEN is positive 397 * and min(VAL, NUM) <= DEN so the result cannot overflow. 398 * Round to the nearest integer, breaking ties by rounding to even. 399 */ 400public uintmax muldiv(uintmax val, uintmax num, uintmax den) 401{ 402 /* 403 * Like round(val * (double) num / den), but without rounding error. 404 * Overflow cannot occur, so there is no need for floating point. 405 */ 406 uintmax q = val / den; 407 uintmax r = val % den; 408 uintmax qnum = q * num; 409 uintmax rnum = r * num; 410 uintmax quot = qnum + rnum / den; 411 uintmax rem = rnum % den; 412 return quot + (den / 2 < rem + (quot & ~den & 1)); 413} 414 415/* 416 * Return the ratio of two POSITIONS, as a percentage. 417 * {{ Assumes a POSITION is a long int. }} 418 */ 419public int percentage(POSITION num, POSITION den) 420{ 421 return (int) muldiv(num, (POSITION) 100, den); 422} 423 424/* 425 * Return the specified percentage of a POSITION. 426 * Assume (0 <= POS && 0 <= PERCENT <= 100 427 * && 0 <= FRACTION < (PERCENT == 100 ? 1 : NUM_FRAC_DENOM)), 428 * so the result cannot overflow. Round to even. 429 */ 430public POSITION percent_pos(POSITION pos, int percent, long fraction) 431{ 432 /* 433 * Change from percent (parts per 100) 434 * to pctden (parts per 100 * NUM_FRAC_DENOM). 435 */ 436 POSITION pctden = (percent * NUM_FRAC_DENOM) + fraction; 437 438 return (POSITION) muldiv(pos, pctden, 100 * (POSITION) NUM_FRAC_DENOM); 439} 440 441#if !HAVE_STRCHR 442/* 443 * strchr is used by regexp.c. 444 */ 445char * strchr(char *s, char c) 446{ 447 for ( ; *s != '\0'; s++) 448 if (*s == c) 449 return (s); 450 if (c == '\0') 451 return (s); 452 return (NULL); 453} 454#endif 455 456#if !HAVE_MEMCPY 457void * memcpy(void *dst, void *src, int len) 458{ 459 char *dstp = (char *) dst; 460 char *srcp = (char *) src; 461 int i; 462 463 for (i = 0; i < len; i++) 464 dstp[i] = srcp[i]; 465 return (dst); 466} 467#endif 468 469#ifdef _OSK_MWC32 470 471/* 472 * This implements an ANSI-style intercept setup for Microware C 3.2 473 */ 474public int os9_signal(int type, RETSIGTYPE (*handler)()) 475{ 476 intercept(handler); 477} 478 479#include <sgstat.h> 480 481int isatty(int f) 482{ 483 struct sgbuf sgbuf; 484 485 if (_gs_opt(f, &sgbuf) < 0) 486 return -1; 487 return (sgbuf.sg_class == 0); 488} 489 490#endif 491 492public void sleep_ms(int ms) 493{ 494#if MSDOS_COMPILER==WIN32C 495 Sleep(ms); 496#else 497#if HAVE_NANOSLEEP 498 int sec = ms / 1000; 499 struct timespec t = { sec, (ms - sec*1000) * 1000000 }; 500 nanosleep(&t, NULL); 501#else 502#if HAVE_USLEEP 503 usleep(ms); 504#else 505 sleep(ms / 1000 + (ms % 1000 != 0)); 506#endif 507#endif 508#endif 509} 510