1/*
2 * Copyright (C) 1984-2000 Mark Nudelman
3 *
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.
6 *
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
9 */
10
11
12/*
13 * Operating system dependent routines.
14 *
15 * Most of the stuff in here is based on Unix, but an attempt
16 * has been made to make things work on other operating systems.
17 * This will sometimes result in a loss of functionality, unless
18 * someone rewrites code specifically for the new operating system.
19 *
20 * The makefile provides defines to decide whether various
21 * Unix features are present.
22 */
23
24#include "less.h"
25#include <signal.h>
26#include <setjmp.h>
27#if HAVE_TIME_H
28#include <time.h>
29#endif
30#if HAVE_ERRNO_H
31#include <errno.h>
32#endif
33#if HAVE_VALUES_H
34#include <values.h>
35#endif
36#if HAVE_LIMITS_H
37#include <limits.h>
38#endif
39
40#if HAVE_TIME_T
41#define time_type time_t
42#else
43#define time_type long
44#endif
45
46/*
47 * BSD setjmp() saves (and longjmp() restores) the signal mask.
48 * This costs a system call or two per setjmp(), so if possible we clear the
49 * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
50 * On other systems, setjmp() doesn't affect the signal mask and so
51 * _setjmp() does not exist; we just use setjmp().
52 */
53#if HAVE__SETJMP && HAVE_SIGSETMASK
54#define SET_JUMP _setjmp
55#define LONG_JUMP _longjmp
56#else
57#define SET_JUMP setjmp
58#define LONG_JUMP longjmp
59#endif
60
61public int reading;
62
63static jmp_buf read_label;
64
65extern int sigs;
66
67/*
68 * Like read() system call, but is deliberately interruptible.
69 * A call to intread() from a signal handler will interrupt
70 * any pending iread().
71 */
72 public int
73iread(fd, buf, len)
74 int fd;
75 char *buf;
76 unsigned int len;
77{
78 register int n;
79
80#if MSDOS_COMPILER==WIN32C
81 if (ABORT_SIGS())
82 return (READ_INTR);
83#else
84#if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
85 if (kbhit())
86 {
87 int c;
88
89 c = getch();
90 if (c == '\003')
91 return (READ_INTR);
92 ungetch(c);
93 }
94#endif
95#endif
96 if (SET_JUMP(read_label))
97 {
98 /*
99 * We jumped here from intread.
100 */
101 reading = 0;
102#if HAVE_SIGPROCMASK
103 {
104 sigset_t mask;
105 sigemptyset(&mask);
106 sigprocmask(SIG_SETMASK, &mask, NULL);
107 }
108#else
109#if HAVE_SIGSETMASK
110 sigsetmask(0);
111#else
112#ifdef _OSK
113 sigmask(~0);
114#endif
115#endif
116#endif
117 return (READ_INTR);
118 }
119
120 flush();
121 reading = 1;
122#if MSDOS_COMPILER==DJGPPC
123 if (isatty(fd))
124 {
125 /*
126 * Don't try reading from a TTY until a character is
127 * available, because that makes some background programs
128 * believe DOS is busy in a way that prevents those
129 * programs from working while "less" waits.
130 */
131 fd_set readfds;
132
133 FD_ZERO(&readfds);
134 FD_SET(fd, &readfds);
135 if (select(fd+1, &readfds, 0, 0, 0) == -1)
136 return (-1);
137 }
138#endif
139 n = read(fd, buf, len);
140#if 1
141 /*
142 * This is a kludge to workaround a problem on some systems
143 * where terminating a remote tty connection causes read() to
144 * start returning 0 forever, instead of -1.
145 */
146 {
147 extern int ignore_eoi;
148 if (!ignore_eoi)
149 {
150 static int consecutive_nulls = 0;
151 if (n == 0)
152 consecutive_nulls++;
153 else
154 consecutive_nulls = 0;
155 if (consecutive_nulls > 20)
156 quit(QUIT_ERROR);
157 }
158 }
159#endif
160 reading = 0;
161 if (n < 0)
162 return (-1);
163 return (n);
164}
165
166/*
167 * Interrupt a pending iread().
168 */
169 public void
170intread()
171{
172 LONG_JUMP(read_label, 1);
173}
174
175/*
176 * Return the current time.
177 */
178#if HAVE_TIME
179 public long
180get_time()
181{
182 time_type t;
183
184 time(&t);
185 return (t);
186}
187#endif
188
189
190#if !HAVE_STRERROR
191/*
192 * Local version of strerror, if not available from the system.
193 */
194 static char *
195strerror(err)
196 int err;
197{
198#if HAVE_SYS_ERRLIST
199 static char buf[16];
200 extern char *sys_errlist[];
201 extern int sys_nerr;
202
203 if (err < sys_nerr)
204 return sys_errlist[err];
205 sprintf(buf, "Error %d", err);
206 return buf;
207#else
208 return ("cannot open");
209#endif
210}
211#endif
212
213/*
214 * errno_message: Return an error message based on the value of "errno".
215 */
216 public char *
217errno_message(filename)
218 char *filename;
219{
220 register char *p;
221 register char *m;
222#if HAVE_ERRNO
223#if MUST_DEFINE_ERRNO
224 extern int errno;
225#endif
226 p = strerror(errno);
227#else
228 p = "cannot open";
229#endif
230 m = (char *) ecalloc(strlen(filename) + strlen(p) + 3, sizeof(char));
231 sprintf(m, "%s: %s", filename, p);
232 return (m);
233}
234
235/*
236 * Return the largest possible number that can fit in a long.
237 */
238 static long
239get_maxlong()
240{
241#ifdef LONG_MAX
242 return (LONG_MAX);
243#else
244#ifdef MAXLONG
245 return (MAXLONG);
246#else
247 long n, n2;
248
249 /*
250 * Keep doubling n until we overflow.
251 * {{ This actually only returns the largest power of two that
252 * can fit in a long, but percentage() doesn't really need
253 * it any more accurate than that. }}
254 */
255 n2 = 128; /* Hopefully no maxlong is less than 128! */
256 do {
257 n = n2;
258 n2 *= 2;
259 } while (n2 / 2 == n);
260 return (n);
261#endif
262#endif
263}
264
265/*
266 * Return the ratio of two POSITIONS, as a percentage.
267 * {{ Assumes a POSITION is a long int. }}
268 */
269 public int
270percentage(num, den)
271 POSITION num, den;
272{
273 if (num <= get_maxlong() / 100)
274 return ((100 * num) / den);
275 else
276 return (num / (den / 100));
277}
278
279/*
280 * Return the specified percentage of a POSITION.
281 * {{ Assumes a POSITION is a long int. }}
282 */
283 public POSITION
284percent_pos(pos, percent)
285 POSITION pos;
286 int percent;
287{
288 if (pos <= get_maxlong() / 100)
289 return ((percent * pos) / 100);
290 else
291 return (percent * (pos / 100));
292}
293
294#ifdef _OSK_MWC32
295
296/*
297 * This implements an ANSI-style intercept setup for Microware C 3.2
298 */
299 public int
300os9_signal(type, handler)
301 int type;
302 RETSIGTYPE (*handler)();
303{
304 intercept(handler);
305}
306
307#include <sgstat.h>
308
309 public int
310isatty(f)
311 int f;
312{
313 struct sgbuf sgbuf;
314
315 if (_gs_opt(f, &sgbuf) < 0)
316 return -1;
317 return (sgbuf.sg_class == 0);
318}
319
320#endif