2 * Copyright (C) 1984-2015 Mark Nudelman
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
7 * For more information, see the README file.
12 * Operating system dependent routines.
14 * Most of the stuff in here is based on Unix, but an attempt
15 * has been made to make things work on other operating systems.
16 * This will sometimes result in a loss of functionality, unless
17 * someone rewrites code specifically for the new operating system.
19 * The makefile provides defines to decide whether various
20 * Unix features are present.
37 * BSD setjmp() saves (and longjmp() restores) the signal mask.
38 * This costs a system call or two per setjmp(), so if possible we clear the
39 * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
40 * On other systems, setjmp() doesn't affect the signal mask and so
41 * _setjmp() does not exist; we just use setjmp().
43 #if HAVE__SETJMP && HAVE_SIGSETMASK
44 #define SET_JUMP _setjmp
45 #define LONG_JUMP _longjmp
47 #define SET_JUMP setjmp
48 #define LONG_JUMP longjmp
53 static jmp_buf read_label;
58 * Like read() system call, but is deliberately interruptible.
59 * A call to intread() from a signal handler will interrupt
60 * any pending iread().
63 iread(int fd, char *buf, unsigned int len)
68 #if MSDOS_COMPILER==WIN32C
72 #if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
84 if (SET_JUMP(read_label))
87 * We jumped here from intread.
94 sigprocmask(SIG_SETMASK, &mask, NULL);
110 #if MSDOS_COMPILER==DJGPPC
114 * Don't try reading from a TTY until a character is
115 * available, because that makes some background programs
116 * believe DOS is busy in a way that prevents those
117 * programs from working while "less" waits.
122 FD_SET(fd, &readfds);
123 if (select(fd+1, &readfds, 0, 0, 0) == -1)
127 n = read(fd, buf, len);
130 * This is a kludge to workaround a problem on some systems
131 * where terminating a remote tty connection causes read() to
132 * start returning 0 forever, instead of -1.
135 extern int ignore_eoi;
138 static int consecutive_nulls = 0;
142 consecutive_nulls = 0;
143 if (consecutive_nulls > 20)
153 * Certain values of errno indicate we should just retry the read.
155 #if MUST_DEFINE_ERRNO
173 * Interrupt a pending iread().
178 LONG_JUMP(read_label, 1);
182 * Return the current time.
198 * Local version of strerror, if not available from the system.
205 extern char *sys_errlist[];
209 return sys_errlist[err];
210 sprintf(buf, "Error %d", err);
213 return ("cannot open");
219 * errno_message: Return an error message based on the value of "errno".
222 errno_message(char *filename)
228 #if MUST_DEFINE_ERRNO
235 len = (int) (strlen(filename) + strlen(p) + 3);
236 m = (char *) ecalloc(len, sizeof(char));
237 SNPRINTF2(m, len, "%s: %s", filename, p);
241 /* #define HAVE_FLOAT 0 */
244 muldiv(POSITION val, POSITION num, POSITION den)
247 double v = (((double) val) * num) / den;
248 return ((POSITION) (v + 0.5));
250 POSITION v = ((POSITION) val) * num;
254 return (POSITION) (v / den);
256 /* Above calculation overflows;
257 * use a method that is less precise but won't overflow. */
258 return (POSITION) (val / (den / num));
263 * Return the ratio of two POSITIONS, as a percentage.
264 * {{ Assumes a POSITION is a long int. }}
267 percentage(POSITION num, POSITION den)
269 return (int) muldiv(num, (POSITION) 100, den);
273 * Return the specified percentage of a POSITION.
276 percent_pos(POSITION pos, int percent, long fraction)
278 /* Change percent (parts per 100) to perden (parts per NUM_FRAC_DENOM). */
279 POSITION perden = (percent * (NUM_FRAC_DENOM / 100)) + (fraction / 100);
283 return (POSITION) muldiv(pos, perden, (POSITION) NUM_FRAC_DENOM);
288 * strchr is used by regexp.c.
295 for ( ; *s != '\0'; s++)
306 memcpy(dst, src, len)
311 char *dstp = (char *) dst;
312 char *srcp = (char *) src;
315 for (i = 0; i < len; i++)
324 * This implements an ANSI-style intercept setup for Microware C 3.2
327 os9_signal(int type, RETSIGTYPE (*handler)())
340 if (_gs_opt(f, &sgbuf) < 0)
342 return (sgbuf.sg_class == 0);