summaryrefslogtreecommitdiffstats
path: root/contrib/less/os.c
blob: 6e37bb2aaf5700bb3a9534c813c7e67915ae4c8d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
/*
 * Copyright (C) 1984-2000  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


/*
 * Operating system dependent routines.
 *
 * Most of the stuff in here is based on Unix, but an attempt
 * has been made to make things work on other operating systems.
 * This will sometimes result in a loss of functionality, unless
 * someone rewrites code specifically for the new operating system.
 *
 * The makefile provides defines to decide whether various
 * Unix features are present.
 */

#include "less.h"
#include <signal.h>
#include <setjmp.h>
#if HAVE_TIME_H
#include <time.h>
#endif
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#if HAVE_VALUES_H
#include <values.h>
#endif
#if HAVE_LIMITS_H
#include <limits.h>
#endif

#if HAVE_TIME_T
#define time_type	time_t
#else
#define	time_type	long
#endif

/*
 * BSD setjmp() saves (and longjmp() restores) the signal mask.
 * This costs a system call or two per setjmp(), so if possible we clear the
 * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
 * On other systems, setjmp() doesn't affect the signal mask and so
 * _setjmp() does not exist; we just use setjmp().
 */
#if HAVE__SETJMP && HAVE_SIGSETMASK
#define SET_JUMP	_setjmp
#define LONG_JUMP	_longjmp
#else
#define SET_JUMP	setjmp
#define LONG_JUMP	longjmp
#endif

public int reading;

static jmp_buf read_label;

extern int sigs;

/*
 * Like read() system call, but is deliberately interruptible.
 * A call to intread() from a signal handler will interrupt
 * any pending iread().
 */
	public int
iread(fd, buf, len)
	int fd;
	char *buf;
	unsigned int len;
{
	register int n;

#if MSDOS_COMPILER==WIN32C
	if (ABORT_SIGS())
		return (READ_INTR);
#else
#if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
	if (kbhit())
	{
		int c;
		
		c = getch();
		if (c == '\003')
			return (READ_INTR);
		ungetch(c);
	}
#endif
#endif
	if (SET_JUMP(read_label))
	{
		/*
		 * We jumped here from intread.
		 */
		reading = 0;
#if HAVE_SIGPROCMASK
		{
		  sigset_t mask;
		  sigemptyset(&mask);
		  sigprocmask(SIG_SETMASK, &mask, NULL);
		}
#else
#if HAVE_SIGSETMASK
		sigsetmask(0);
#else
#ifdef _OSK
		sigmask(~0);
#endif
#endif
#endif
		return (READ_INTR);
	}

	flush();
	reading = 1;
#if MSDOS_COMPILER==DJGPPC
	if (isatty(fd))
	{
		/*
		 * Don't try reading from a TTY until a character is
		 * available, because that makes some background programs
		 * believe DOS is busy in a way that prevents those
		 * programs from working while "less" waits.
		 */
		fd_set readfds;

		FD_ZERO(&readfds);
		FD_SET(fd, &readfds);
		if (select(fd+1, &readfds, 0, 0, 0) == -1)
			return (-1);
	}
#endif
	n = read(fd, buf, len);
#if 1
	/*
	 * This is a kludge to workaround a problem on some systems
	 * where terminating a remote tty connection causes read() to
	 * start returning 0 forever, instead of -1.
	 */
	{
		extern int ignore_eoi;
		if (!ignore_eoi)
		{
			static int consecutive_nulls = 0;
			if (n == 0)
				consecutive_nulls++;
			else
				consecutive_nulls = 0;
			if (consecutive_nulls > 20)
				quit(QUIT_ERROR);
		}
	}
#endif
	reading = 0;
	if (n < 0)
		return (-1);
	return (n);
}

/*
 * Interrupt a pending iread().
 */
	public void
intread()
{
	LONG_JUMP(read_label, 1);
}

/*
 * Return the current time.
 */
#if HAVE_TIME
	public long
get_time()
{
	time_type t;

	time(&t);
	return (t);
}
#endif


#if !HAVE_STRERROR
/*
 * Local version of strerror, if not available from the system.
 */
	static char *
strerror(err)
	int err;
{
#if HAVE_SYS_ERRLIST
	static char buf[16];
	extern char *sys_errlist[];
	extern int sys_nerr;
  
	if (err < sys_nerr)
		return sys_errlist[err];
	sprintf(buf, "Error %d", err);
	return buf;
#else
	return ("cannot open");
#endif
}
#endif

/*
 * errno_message: Return an error message based on the value of "errno".
 */
	public char *
errno_message(filename)
	char *filename;
{
	register char *p;
	register char *m;
#if HAVE_ERRNO
#if MUST_DEFINE_ERRNO
	extern int errno;
#endif
	p = strerror(errno);
#else
	p = "cannot open";
#endif
	m = (char *) ecalloc(strlen(filename) + strlen(p) + 3, sizeof(char));
	sprintf(m, "%s: %s", filename, p);
	return (m);
}

/*
 * Return the largest possible number that can fit in a long.
 */
	static long
get_maxlong()
{
#ifdef LONG_MAX
	return (LONG_MAX);
#else
#ifdef MAXLONG
	return (MAXLONG);
#else
	long n, n2;

	/*
	 * Keep doubling n until we overflow.
	 * {{ This actually only returns the largest power of two that
	 *    can fit in a long, but percentage() doesn't really need
	 *    it any more accurate than that. }}
	 */
	n2 = 128;  /* Hopefully no maxlong is less than 128! */
	do {
		n = n2;
		n2 *= 2;
	} while (n2 / 2 == n);
	return (n);
#endif
#endif
}

/*
 * Return the ratio of two POSITIONS, as a percentage.
 * {{ Assumes a POSITION is a long int. }}
 */
	public int
percentage(num, den)
	POSITION num, den;
{
	if (num <= get_maxlong() / 100)
		return ((100 * num) / den);
	else
		return (num / (den / 100));
}

/*
 * Return the specified percentage of a POSITION.
 * {{ Assumes a POSITION is a long int. }}
 */
	public POSITION
percent_pos(pos, percent)
	POSITION pos;
	int percent;
{
	if (pos <= get_maxlong() / 100)
		return ((percent * pos) / 100);
	else
		return (percent * (pos / 100));
}

#ifdef _OSK_MWC32

/*
 * This implements an ANSI-style intercept setup for Microware C 3.2
 */
	public int 
os9_signal(type, handler)
	int type;
	RETSIGTYPE (*handler)();
{
	intercept(handler);
}

#include <sgstat.h>

	public int 
isatty(f)
	int f;
{
	struct sgbuf sgbuf;

	if (_gs_opt(f, &sgbuf) < 0)
		return -1;
	return (sgbuf.sg_class == 0);
}
	
#endif
OpenPOWER on IntegriCloud