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mirror of https://git.FreeBSD.org/src.git synced 2024-12-01 08:27:59 +00:00
freebsd/contrib/less/os.c
Robert Watson 1ea316270f Currently, less(1) uses K&R prototypes, which both fails to provide useful
compiler-time type checking, and also causes problems for targets where
multiple incompatible calling conventions may be selected based on argument
types.  This change switches less(1) to ANSI prototypes.

While there, we also remove use of "register", and attempt to use "const" a
bit better now that the compiler can check argument types.

Reviewed by:	cem, emaste
MFC after:	3 weeks
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D10152
2017-03-31 21:29:43 +00:00

346 lines
6.1 KiB
C

/*
* Copyright (C) 1984-2015 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, 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
/*
* 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(int fd, char *buf, unsigned int len)
{
int n;
start:
#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)
{
#if HAVE_ERRNO
/*
* Certain values of errno indicate we should just retry the read.
*/
#if MUST_DEFINE_ERRNO
extern int errno;
#endif
#ifdef EINTR
if (errno == EINTR)
goto start;
#endif
#ifdef EAGAIN
if (errno == EAGAIN)
goto start;
#endif
#endif
return (-1);
}
return (n);
}
/*
* Interrupt a pending iread().
*/
public void
intread(void)
{
LONG_JUMP(read_label, 1);
}
/*
* Return the current time.
*/
#if HAVE_TIME
public time_type
get_time(void)
{
time_type t;
time(&t);
return (t);
}
#endif
#if !HAVE_STRERROR
/*
* Local version of strerror, if not available from the system.
*/
static char *
strerror(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(char *filename)
{
char *p;
char *m;
int len;
#if HAVE_ERRNO
#if MUST_DEFINE_ERRNO
extern int errno;
#endif
p = strerror(errno);
#else
p = "cannot open";
#endif
len = (int) (strlen(filename) + strlen(p) + 3);
m = (char *) ecalloc(len, sizeof(char));
SNPRINTF2(m, len, "%s: %s", filename, p);
return (m);
}
/* #define HAVE_FLOAT 0 */
static POSITION
muldiv(POSITION val, POSITION num, POSITION den)
{
#if HAVE_FLOAT
double v = (((double) val) * num) / den;
return ((POSITION) (v + 0.5));
#else
POSITION v = ((POSITION) val) * num;
if (v / num == val)
/* No overflow */
return (POSITION) (v / den);
else
/* Above calculation overflows;
* use a method that is less precise but won't overflow. */
return (POSITION) (val / (den / num));
#endif
}
/*
* Return the ratio of two POSITIONS, as a percentage.
* {{ Assumes a POSITION is a long int. }}
*/
public int
percentage(POSITION num, POSITION den)
{
return (int) muldiv(num, (POSITION) 100, den);
}
/*
* Return the specified percentage of a POSITION.
*/
public POSITION
percent_pos(POSITION pos, int percent, long fraction)
{
/* Change percent (parts per 100) to perden (parts per NUM_FRAC_DENOM). */
POSITION perden = (percent * (NUM_FRAC_DENOM / 100)) + (fraction / 100);
if (perden == 0)
return (0);
return (POSITION) muldiv(pos, perden, (POSITION) NUM_FRAC_DENOM);
}
#if !HAVE_STRCHR
/*
* strchr is used by regexp.c.
*/
char *
strchr(s, c)
char *s;
int c;
{
for ( ; *s != '\0'; s++)
if (*s == c)
return (s);
if (c == '\0')
return (s);
return (NULL);
}
#endif
#if !HAVE_MEMCPY
VOID_POINTER
memcpy(dst, src, len)
VOID_POINTER dst;
VOID_POINTER src;
int len;
{
char *dstp = (char *) dst;
char *srcp = (char *) src;
int i;
for (i = 0; i < len; i++)
dstp[i] = srcp[i];
return (dst);
}
#endif
#ifdef _OSK_MWC32
/*
* This implements an ANSI-style intercept setup for Microware C 3.2
*/
public int
os9_signal(int type, RETSIGTYPE (*handler)())
{
intercept(handler);
}
#include <sgstat.h>
int
isatty(f)
int f;
{
struct sgbuf sgbuf;
if (_gs_opt(f, &sgbuf) < 0)
return -1;
return (sgbuf.sg_class == 0);
}
#endif