/*
* Copyright (C) 1984-2023 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 MSDOS_COMPILER==WIN32C
#include <windows.h>
#endif
#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 defined(__APPLE__)
#include <sys/utsname.h>
#endif
#if HAVE_POLL && !MSDOS_COMPILER
#define USE_POLL 1
static int use_poll = TRUE;
#else
#define USE_POLL 0
#endif
#if USE_POLL
#include <poll.h>
static int any_data = FALSE;
#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;
public int waiting_for_data;
public int consecutive_nulls = 0;
/* Milliseconds to wait for data before displaying "waiting for data" message. */
static int waiting_for_data_delay = 4000;
static jmp_buf read_label;
extern int sigs;
extern int ignore_eoi;
extern int exit_F_on_close;
extern int follow_mode;
extern int scanning_eof;
extern char intr_char;
#if !MSDOS_COMPILER
extern int tty;
#endif
#if LESSTEST
extern char *ttyin_name;
#endif /*LESSTEST*/
public void init_poll(void)
{
char *delay = lgetenv("LESS_DATA_DELAY");
int idelay = (delay == NULL) ? 0 : atoi(delay);
if (idelay > 0)
waiting_for_data_delay = idelay;
#if USE_POLL
#if defined(__APPLE__)
/* In old versions of MacOS, poll() does not work with /dev/tty. */
struct utsname uts;
if (uname(&uts) < 0 || lstrtoi(uts.release, NULL, 10) < 20)
use_poll = FALSE;
#endif
#endif
}
#if USE_POLL
/*
* Check whether data is available, either from a file/pipe or from the tty.
* Return READ_AGAIN if no data currently available, but caller should retry later.
* Return READ_INTR to abort F command (forw_loop).
* Return 0 if safe to read from fd.
*/
static int check_poll(int fd, int tty)
{
struct pollfd poller[2] = { { fd, POLLIN, 0 }, { tty, POLLIN, 0 } };
int timeout = (waiting_for_data && !(scanning_eof && follow_mode == FOLLOW_NAME)) ? -1 : waiting_for_data_delay;
if (!any_data)
{
/*
* Don't do polling if no data has yet been received,
* to allow a program piping data into less to have temporary
* access to the tty (like sudo asking for a password).
*/
return (0);
}
poll(poller, 2, timeout);
#if LESSTEST
if (ttyin_name == NULL) /* Check for ^X only on a real tty. */
#endif /*LESSTEST*/
{
if (poller[1].revents & POLLIN)
{
LWCHAR ch = getchr();
if (ch == intr_char)
/* Break out of "waiting for data". */
return (READ_INTR);
ungetcc_back(ch);
}
}
if (ignore_eoi && exit_F_on_close && (poller[0].revents & (POLLHUP|POLLIN)) == POLLHUP)
/* Break out of F loop on HUP due to --exit-follow-on-close. */
return (READ_INTR);
if ((poller[0].revents & (POLLIN|POLLHUP|POLLERR)) == 0)
/* No data available; let caller take action, then try again. */
return (READ_AGAIN);
/* There is data (or HUP/ERR) available. Safe to call read() without blocking. */
return (0);
}
#endif /* USE_POLL */
public int supports_ctrl_x(void)
{
#if USE_POLL
return (use_poll);
#else
return (FALSE);
#endif /* USE_POLL */
}
/*
* 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, unsigned 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 (!reading && 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
#if !MSDOS_COMPILER
if (fd != tty && !ABORT_SIGS())
/* Non-interrupt signal like SIGWINCH. */
return (READ_AGAIN);
#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.
* {{ This code was added 12 Jan 2007; still needed? }}
*/
fd_set readfds;
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
if (select(fd+1, &readfds, 0, 0, 0) == -1)
{
reading = 0;
return (READ_ERR);
}
}
#endif
#if USE_POLL
if (fd != tty && use_poll)
{
int ret = check_poll(fd, tty);
if (ret != 0)
{
if (ret == READ_INTR)
sigs |= S_INTERRUPT;
reading = 0;
return (ret);
}
}
#else
#if MSDOS_COMPILER==WIN32C
if (win32_kbhit())
{
int c;
c = WIN32getch();
if (c == intr_char)
{
sigs |= S_INTERRUPT;
reading = 0;
return (READ_INTR);
}
WIN32ungetch(c);
}
#endif
#endif
n = read(fd, buf, len);
reading = 0;
#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.
*/
{
if (!ignore_eoi)
{
if (n == 0)
consecutive_nulls++;
else
consecutive_nulls = 0;
if (consecutive_nulls > 20)
quit(QUIT_ERROR);
}
}
#endif
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 (READ_ERR);
}
#if USE_POLL
if (fd != tty && n > 0)
any_data = TRUE;
#endif
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)
{
static char buf[INT_STRLEN_BOUND(int)+12];
#if HAVE_SYS_ERRLIST
extern char *sys_errlist[];
extern int sys_nerr;
if (err < sys_nerr)
return sys_errlist[err];
#endif
sprintf(buf, "Error %d", err);
return buf;
}
#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);
}
/*
* Return a description of a signal.
* The return value is good until the next call to this function.
*/
public char * signal_message(int sig)
{
static char sigbuf[sizeof("Signal ") + INT_STRLEN_BOUND(sig) + 1];
#if HAVE_STRSIGNAL
char *description = strsignal(sig);
if (description)
return description;
#endif
sprintf(sigbuf, "Signal %d", sig);
return sigbuf;
}
/*
* Return (VAL * NUM) / DEN, where DEN is positive
* and min(VAL, NUM) <= DEN so the result cannot overflow.
* Round to the nearest integer, breaking ties by rounding to even.
*/
public uintmax muldiv(uintmax val, uintmax num, uintmax den)
{
/*
* Like round(val * (double) num / den), but without rounding error.
* Overflow cannot occur, so there is no need for floating point.
*/
uintmax q = val / den;
uintmax r = val % den;
uintmax qnum = q * num;
uintmax rnum = r * num;
uintmax quot = qnum + rnum / den;
uintmax rem = rnum % den;
return quot + (den / 2 < rem + (quot & ~den & 1));
}
/*
* 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.
* Assume (0 <= POS && 0 <= PERCENT <= 100
* && 0 <= FRACTION < (PERCENT == 100 ? 1 : NUM_FRAC_DENOM)),
* so the result cannot overflow. Round to even.
*/
public POSITION percent_pos(POSITION pos, int percent, long fraction)
{
/*
* Change from percent (parts per 100)
* to pctden (parts per 100 * NUM_FRAC_DENOM).
*/
POSITION pctden = (percent * NUM_FRAC_DENOM) + fraction;
return (POSITION) muldiv(pos, pctden, 100 * (POSITION) NUM_FRAC_DENOM);
}
#if !HAVE_STRCHR
/*
* strchr is used by regexp.c.
*/
char * strchr(char *s, char c)
{
for ( ; *s != '\0'; s++)
if (*s == c)
return (s);
if (c == '\0')
return (s);
return (NULL);
}
#endif
#if !HAVE_MEMCPY
void * memcpy(void *dst, void *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(int f)
{
struct sgbuf sgbuf;
if (_gs_opt(f, &sgbuf) < 0)
return -1;
return (sgbuf.sg_class == 0);
}
#endif
public void sleep_ms(int ms)
{
#if MSDOS_COMPILER==WIN32C
Sleep(ms);
#else
#if HAVE_NANOSLEEP
int sec = ms / 1000;
struct timespec t = { sec, (ms - sec*1000) * 1000000 };
nanosleep(&t, NULL);
#else
#if HAVE_USLEEP
usleep(ms);
#else
sleep(ms / 1000 + (ms % 1000 != 0));
#endif
#endif
#endif
}
