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os.c
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1998-03-03
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/*
* Copyright (c) 1984,1985,1989,1994,1995,1996 Mark Nudelman
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice in the documentation and/or other materials provided with
* the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* 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_SIGSETMASK
sigsetmask(0);
#else
#ifdef _OSK
sigmask(~0);
#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);
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