scsh-0.6/c/unix/event.c

/* Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees.
   See file COPYING. */

#include <signal.h>		/* for sigaction() (POSIX.1) */
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/times.h>
#include <errno.h>              /* for errno, (POSIX?/ANSI) */
#include "sysdep.h"
#include "c-mods.h"
#include "scheme48vm.h"
#include "event.h"
#include "../scsh/scsh_aux.h"
#include "../scsh/signals1.h"

/* turning interrupts and I/O readiness into events */
sigset_t full_sigset;

#define block_interrupts(){sigprocmask (SIG_BLOCK, &full_sigset, 0);}
#define allow_interrupts(){sigprocmask (SIG_UNBLOCK, &full_sigset, 0);}


static void	when_keyboard_interrupt();
static void	when_alarm_interrupt();
static void     when_sigpipe_interrupt();

/* JMG:*/
static void     when_scsh_interrupt();
/* JMG: for scsh */
#define INTERRUPT_QUEUE_LENGTH 32

static int      interrupt_queue [INTERRUPT_QUEUE_LENGTH];
static int	next_interrupt = 0;
static int s48_os_signal_pending(void);
static bool s48_os_signal_happend(void);


bool		s48_setcatcher(int signum, void (*catcher)(int));
void		s48_start_alarm_interrupts(void);


void
s48_sysdep_init(void)
{
  if (!s48_setcatcher(SIGINT, when_keyboard_interrupt)
      || !s48_setcatcher(SIGALRM, when_alarm_interrupt)
      || !s48_setcatcher(SIGPIPE, when_sigpipe_interrupt)) {
    fprintf(stderr,
	    "Failed to install signal handlers, errno = %d\n",
	    errno);
    exit(1);
  }

  sigfillset (&full_sigset);
      
  /* JMG: for scsh */
  s48_setcatcher(SIGCHLD,   when_scsh_interrupt);
  s48_setcatcher(SIGCONT,   when_scsh_interrupt);
  s48_setcatcher(SIGHUP,    when_scsh_interrupt);
  s48_setcatcher(SIGQUIT,   when_scsh_interrupt);
  s48_setcatcher(SIGTERM,   when_scsh_interrupt);
  s48_setcatcher(SIGTSTP,   when_scsh_interrupt);
  s48_setcatcher(SIGUSR1,   when_scsh_interrupt);
  s48_setcatcher(SIGUSR2,   when_scsh_interrupt);
#ifdef SIGINFO		     
  s48_setcatcher(SIGINFO,   when_scsh_interrupt);
#endif			     
#ifdef SIGIO		     
  s48_setcatcher(SIGIO,     when_scsh_interrupt);
#endif
#if defined SIGPOLL && ((defined SIGIO && SIGPOLL != SIGIO) ||	\
			 !defined SIGIO)
  s48_setcatcher(SIGPOLL,   when_scsh_interrupt);
#endif
#ifdef SIGPROF	   
  s48_setcatcher(SIGPROF,   when_scsh_interrupt);
#endif			     
#ifdef SIGPWR		     
  s48_setcatcher(SIGPWR,    when_scsh_interrupt);
#endif
#ifdef SIGVTALRM
  s48_setcatcher(SIGVTALRM, when_scsh_interrupt);
#endif
#ifdef SIGWINCH
  s48_setcatcher(SIGWINCH,  when_scsh_interrupt);
#endif
#ifdef SIGXCPU
  s48_setcatcher(SIGXCPU,   when_scsh_interrupt);
#endif
#ifdef SIGXFSZ
  s48_setcatcher(SIGXFSZ,   when_scsh_interrupt);
#endif
  
  s48_start_alarm_interrupts();
}


/*
 * Unless a signal is being ignored, set up the handler.
 * If we return FALSE, something went wrong and errno is set to what.
 */
bool
s48_setcatcher(int signum, void (*catcher)(int))
{
  struct sigaction	sa;

  if (sigaction(signum, (struct sigaction *)NULL, &sa) != 0){
    fprintf(stderr, "Failed to get sigaction for signal %d\n", signum);
    exit(1);
  }
  /*  JMG: what's the point of not setting the handler in this case?
      if (sa.sa_handler == SIG_IGN)
      return (TRUE);*/
  sa.sa_handler = catcher;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  if (sigaction(signum, &sa, (struct sigaction *)NULL) != 0){
    fprintf(stderr, "Failed to define handler for signal %d\n", signum);
    exit(1);
  }
   
  return (TRUE);
}

static long	keyboard_interrupt_count = 0;

static void
when_keyboard_interrupt(int ign)
{
  keyboard_interrupt_count += 1;
  NOTE_EVENT;
  return;
}

/*
   We turn off SIGPIPE interrupts by installing a handler that does nothing.
   Turning them off affects exec()'ed programs, so we don't want to do that.
   Any actual pipe problems are caught when we try to read or write to them.

   We thank Olin Shivers for this hack.
*/

static void
when_sigpipe_interrupt(int ign)
{
  return;
}

/* ticks since last timer-interrupt request */
long		s48_current_time = 0;

static long	alarm_time = -1;
static long	poll_time = -1;
static long	poll_interval = 5;

static void
when_alarm_interrupt(int ign)
{
  s48_current_time += 1;
  /* fprintf(stderr, "[tick]"); */
  if ((alarm_time >= 0 && alarm_time <= s48_current_time) ||
      (poll_time >= 0 && poll_time <= s48_current_time)) {
    NOTE_EVENT;
  };
  return;
}



#define USEC_PER_POLL   (1000000 / POLLS_PER_SECOND)

/* delta is in ticks, 0 cancels current alarm */

long
s48_schedule_alarm_interrupt(long delta)
{
  long old;
  /*
  fprintf(stderr, "<scheduling alarm for %ld + %ld>\n", s48_current_time,
	  delta/TICKS_PER_POLL);
	  */
  /* get remaining time */
  if (alarm_time == -1)
    old = -1;
  else
    old = (alarm_time - s48_current_time) * TICKS_PER_POLL;

  /* decrement poll_time and reset current_time */
  if (poll_time != -1)
    poll_time -= s48_current_time;
  s48_current_time = 0;

  /* set alarm_time */
  if (delta == 0) {
    NOTE_EVENT;
    alarm_time = 0; }
  else
    alarm_time = delta / TICKS_PER_POLL;

  return old;
}

/* The next two procedures return times in seconds and ticks */

long
s48_real_time(long *ticks)
{
  struct timeval tv;
  static struct timeval tv_orig;
  static int initp = 0;
  if (!initp) {
    gettimeofday(&tv_orig, NULL);
    initp = 1;
  };
  gettimeofday(&tv, NULL);
  *ticks = (tv.tv_usec - tv_orig.tv_usec)/(1000000/TICKS_PER_SECOND);
  return tv.tv_sec - tv_orig.tv_sec;
}

long
s48_run_time(long *ticks)
{
  struct tms time_buffer;
  static long clock_tick = 0;
  long cpu_time;

  if (clock_tick == 0)
    clock_tick = sysconf(_SC_CLK_TCK); /* POSIX.1, POSIX.2 */
  times(&time_buffer);		/* On Sun, getrusage() would be better */

  cpu_time = time_buffer.tms_utime + time_buffer.tms_stime;

  *ticks = (cpu_time % clock_tick) * TICKS_PER_SECOND / clock_tick;
  return cpu_time / clock_tick;
}

void
s48_start_alarm_interrupts(void)
{
  struct itimerval new, old;

  new.it_value.tv_sec = 0;
  new.it_value.tv_usec = USEC_PER_POLL;
  new.it_interval.tv_sec = 0;
  new.it_interval.tv_usec = USEC_PER_POLL;
  if (0 != setitimer(ITIMER_REAL, &new, &old)) {
    perror("setitimer");
    exit(-1); }
}

void
s48_stop_alarm_interrupts(void)
{
  struct itimerval new, old;

  new.it_value.tv_sec = 0;
  new.it_value.tv_usec = 0;
  new.it_interval.tv_sec = 0;
  new.it_interval.tv_usec = 0;
  if (0 != setitimer(ITIMER_REAL, &new, &old)) {
    perror("setitimer");
    exit(-1); }
}


/*
 *  ; Scheme version of the get-next-event procedure
 *  ;
 *  ; 1. If there has been a keyboard interrupt, return it.
 *  ; 2. Check for ready ports if enough time has passed since the last check.
 *  ; 3. If there is a ready port, return it.
 *  ; 4. If an alarm is due, return it.
 *  ; 5. If no events are pending, clear the event flags.
 *  (define (get-next-event)
 *    (cond ((> *keyboard-interrupt-count* 0)
 *           (without-interrupts
 *             (lambda ()
 *              (set! *keyboard-interrupt-count*
 *                    (- *keyboard-interrupt-count* 1))))
 *           (values (enum event-type keyboard-interrupt) #f #f))
 *          (else
 *           (cond ((>= *current_time* *poll-time*)
 *                  (queue-ready-ports)
 *                  (set! *poll-time* (+ *time* *poll-interval*))))
 *           (cond ((not (queue-empty? ready-ports))
 *                  (values (enum event-type i/o-{read/write}-completion)
 *                          (dequeue! ready-ports)))
 *                 ((>= *current_time* *alarm-time*)
 *                  (set! *alarm-time* max-integer)
 *                  (values (enum event-type alarm-interrupt) #f))
 *                 (else
 *                  (without-interrupts
 *                    (lambda ()
 *                      (if (and (= *keyboard-interrupt-count* 0)
 *                               (> *alarm-time* *current_time*)
 *                               (> *poll-time* *current_time*))
 *                          (set! *pending-event?* #f))))
 *                  (values (enum event-type no-event) #f))))))
 */

#define FD_QUIESCENT 0			/* idle */
#define FD_READY     1			/* I/O ready to be performed */
#define FD_PENDING   2			/* waiting */

typedef struct fd_struct {
 int	fd,			/* file descriptor */
	status;			/* one of the FD_* constants */
 bool	is_input;		/* iff input */
 struct fd_struct	*next;	/* next on same queue */
} fd_struct;

static bool	 there_are_ready_ports(void);
static fd_struct *next_ready_fd_struct(void);
static int	 queue_ready_ports(bool wait, long seconds, long ticks);

int
s48_get_next_event(long *ready_fd, long *status)
{
  /*
  extern int s48_os_signal_pending(void);
  */

  int io_poll_status;
  fd_struct *f;

  /*
    fprintf(stderr, "[poll at %d (waiting for %d)]\n", s48_current_time, alarm_time);
    */
  if (keyboard_interrupt_count > 0) {
    block_interrupts();
    --keyboard_interrupt_count;
    allow_interrupts();
    /* fprintf(stderr, "[keyboard interrupt]\n"); */
    return (KEYBOARD_INTERRUPT_EVENT);
  }
  if (poll_time != -1 && s48_current_time >= poll_time) {
    io_poll_status = queue_ready_ports(FALSE, 0, 0);
    if (io_poll_status == NO_ERRORS)
      poll_time = s48_current_time + poll_interval;
    else {
      *status = io_poll_status;
      return (ERROR_EVENT);
    }
  }
  if (there_are_ready_ports()) {
    f = next_ready_fd_struct();
    *ready_fd = f->fd;
    *status = 0;   /* chars read or written */
    /* fprintf(stderr, "[i/o completion]\n"); */
    if (f->is_input)
      return (IO_READ_COMPLETION_EVENT);
    else
      return (IO_WRITE_COMPLETION_EVENT);
  }
  if (alarm_time != -1 && s48_current_time >= alarm_time) {
    alarm_time = -1;
    /* fprintf(stderr, "[alarm]\n"); */
    return (ALARM_EVENT);
  }
  block_interrupts();
  /* JMG: scsh should handle this */
  if (s48_os_signal_pending())
    return (OS_SIGNAL_EVENT);
    
  if ((keyboard_interrupt_count == 0)
      &&  (alarm_time == -1 || s48_current_time < alarm_time)
      &&  (poll_time == -1 || s48_current_time < poll_time))
    s48_Spending_eventsPS = FALSE;
  allow_interrupts();
  return (NO_EVENT);
}


/*
 * We keep two queues of ports: those that have a pending operation, and
 * those whose operation has completed.  Periodically, we call select() on
 * the pending ports and move any that are ready onto the other queue and
 * signal an event.
 */

/*
 * A queue of fd_structs is empty iff the first field is NULL.  In
 * that case, lastp points to first.
 */
typedef struct fdque {
  fd_struct	*first,
		**lastp;
} fdque;


static fd_struct	*fds[FD_SETSIZE];
static fdque	ready = {
			 NULL,
			 &ready.first
			},
		pending = {
			   NULL,
			   &pending.first
			  };


static void		findrm(fd_struct *entry, fdque *que);
static fd_struct	*rmque(fd_struct **link, fdque *que);
static void		addque(fd_struct *entry, fdque *que);
static fd_struct	*add_fd(int fd, bool is_input);


/*
 * Find a fd_struct in a queue, and remove it.
 */
static void
findrm(fd_struct *entry, fdque *que)
{
  fd_struct	**fp,
    *f;

  for (fp = &que->first; (f = *fp) != entry; fp = &f->next)
    if (f == NULL) {
      fprintf(stderr, "ERROR: findrm fd %d, status %d not on queue.\n",
	      entry->fd, entry->status);
      return;
    }
  rmque(fp, que);
}


/*
 * Given a pointer to the link of a fd_struct, and a pointer to
 * the queue it is on, remove the entry from the queue.
 * The entry removed is returned.
 */
static fd_struct	*
rmque(fd_struct **link, fdque *que)
{
  fd_struct	*res;

  res = *link;
  *link = res->next;
  if (res->next == NULL)
    que->lastp = link;
  return (res);
}


/*
 * Add a fd_struct to a queue.
 */
static void
addque(fd_struct *entry, fdque *que)
{
  *que->lastp = entry;
  entry->next = NULL;
  que->lastp = &entry->next;
}


static bool
there_are_ready_ports(void)
{
  return (ready.first != NULL);
}


static fd_struct *
next_ready_fd_struct(void)
{
  fd_struct	*p;

  p = rmque(&ready.first, &ready);
  p->status = FD_QUIESCENT;
  return (p);
}


/*
 * Put fd on to the queue of ports with pending operations.
 * Return TRUE if successful, and FALSE otherwise.
 */
bool
s48_add_pending_fd(int fd, bool is_input)
{
  fd_struct	*data;

  if (! (0 <= fd && fd < FD_SETSIZE)) {
    fprintf(stderr, "ERROR: add_pending fd %d not in [0, %d)\n",
	    fd,
	    FD_SETSIZE);
    return (FALSE);
  }
  data = fds[fd];
  if (data == NULL) {
    data = add_fd(fd, is_input);
    if (data == NULL)
      return (FALSE);		/* no more memory */
  } else if (data->status == FD_PENDING)
    return (TRUE);			/* fd is already pending */
  else if (data->status == FD_READY)
    findrm(data, &ready);
  data->status = FD_PENDING;
  addque(data, &pending);
  if (poll_time == -1)
    poll_time = s48_current_time + poll_interval;
  return TRUE;
}


/*
 * Add a new fd_struct for fd.
 */
static fd_struct	*
add_fd(int fd, bool is_input)
{
  struct fd_struct	*new;

  new = (struct fd_struct *)malloc(sizeof(*new));
  if (new != NULL) {
    new->fd = fd;
    new->status = FD_QUIESCENT;
    new->is_input = is_input;
    new->next = NULL;
    fds[fd] = new;
  }
  return (new);
}


/*
 * Remove fd from any queues it is on.  Returns true if the FD was on a queue
 * and false if it wasn't.
 */
bool
s48_remove_fd(int fd)
{
  struct fd_struct	*data;

  if (! (0 <= fd && fd < FD_SETSIZE)) {
    fprintf(stderr, "ERROR: s48_remove_fd fd %d not in [0, %d)\n",
	    fd,
	    FD_SETSIZE);
    return FALSE;
  }
  data = fds[fd];
  if (data == NULL)
    return FALSE;
  if (data->status == FD_PENDING) {
    findrm(data, &pending);
    if (pending.first == NULL)
      poll_time = -1;
  } else if (data->status == FD_READY)
    findrm(data, &ready);
  free((void *)data);
  fds[fd] = NULL;
  return TRUE;
}


int
s48_wait_for_event(long max_wait, bool is_minutes)
{
  int	status;
  long	seconds,
	ticks;

  /* fprintf(stderr, "[waiting]\n"); */

  s48_stop_alarm_interrupts();
  ticks = 0;
  if (max_wait == -1)
    seconds = -1;
  else if (is_minutes)
    seconds = max_wait * 60;
  else {
    seconds = max_wait / TICKS_PER_SECOND;
    ticks = max_wait % TICKS_PER_SECOND;
  }
  if (keyboard_interrupt_count > 0)
    status = NO_ERRORS;
  else if (s48_os_signal_happend ())
    status = NO_ERRORS;
  else {
    status = queue_ready_ports(TRUE, seconds, ticks);
    if (there_are_ready_ports())
      NOTE_EVENT;
  }
  s48_start_alarm_interrupts();
  return (status);
}


/*
 * Call select() on the pending ports and move any ready ones to the ready
 * queue.  If wait is true, seconds is either -1 (wait forever) or the
 * maximum number of seconds to wait (with ticks any additional ticks).
 * The returned value is a status code.
 */
static int
queue_ready_ports(bool wait, long seconds, long ticks)
{
  fd_set	reads,
    		writes,
    		alls;
  int		limfd;
  fd_struct	*fdp,
    		**fdpp;
  int		left;
  struct timeval	tv,
    			*tvp;

  if ((! wait)
      &&  (pending.first == NULL))
    return (NO_ERRORS);
  FD_ZERO(&reads);
  FD_ZERO(&writes);
  FD_ZERO(&alls);
  limfd = 0;
  for (fdp = pending.first; fdp != NULL; fdp = fdp->next) {
    FD_SET(fdp->fd, fdp->is_input ? &reads : &writes);
    FD_SET(fdp->fd, &alls);
    if (limfd <= fdp->fd)
      limfd = fdp->fd + 1;
  }
  tvp = &tv;
  if (wait)
    if (seconds == -1){
      tvp = NULL;
    }
    else {
      tv.tv_sec = seconds;
      tv.tv_usec = ticks * (1000000 / TICKS_PER_SECOND);
    }
  else
    timerclear(&tv);
  while(TRUE) {
    if ((keyboard_interrupt_count > 0) || s48_os_signal_happend ())
      return NO_ERRORS;
    /* time gap */
    left = select(limfd, &reads, &writes, &alls, tvp);
    if (left > 0) {
      fdpp = &pending.first;
      while (left > 0 && (fdp = *fdpp) != NULL)
	if ((FD_ISSET(fdp->fd, &alls))
	    ||  (FD_ISSET(fdp->fd, fdp->is_input ? &reads : &writes))) {
	  --left;
	  rmque(fdpp, &pending);
	  fdp->status = FD_READY;
	  addque(fdp, &ready);
	} else
	  fdpp = &fdp->next;
      if (pending.first == NULL)
	poll_time = -1;
      return NO_ERRORS;
    }
    else if (left == 0)
      return NO_ERRORS;
    else if (errno == EINTR) {
      tvp = &tv;		/* turn off blocking and try again */
      timerclear(tvp);
    }	      
    else
      return errno;
  }
}

/*
 * Adds `signum' to the queue of received signals.
 */

static void
queue_interrupt(int signum)
{
  if (next_interrupt == INTERRUPT_QUEUE_LENGTH){
    perror("Interrupt queue overflow -- report to Scheme 48 maintainers.");
    exit(-1); 
  }
  interrupt_queue[next_interrupt] = signum;
  next_interrupt++;
}

/* JMG: for scsh */
static void when_scsh_interrupt(int signo)
{
  queue_interrupt(sig2int[signo]);
  NOTE_EVENT;
  return;
}


/*
 * This procedure is called periodically by the VM .
 *
 * s48_set_os_signal() is a VM procedure.  The two arguments are the type
 * of interrupt and one other value which can be used to return whatever
 * associated information is desired.  The two values, along with the
 * current enabled-interrupts mask, are passed to the handler for os-signal
 * interrupts.
 *
 * A handler can be installed by doing
    (set-interrupt-handler! (enum interrupt os-signal)
 			     (lambda (type arg enabled-interrupts)
                              (display type)
			      (newline)
			      (display arg)
			      (newline)
			      (display enabled-interrupts)
			      (newline)))
 * The handler is called with all interrupts disabled.  They are
 * reenabled when the handler returns (or if done by hand).
 */

/*
 * Returns TRUE if there is a signal to be delivered up to Scheme.
 * Needs no be called with interrupts blocked.
 */

int
s48_os_signal_pending(void) {
  int i;
  s48_value interrupt_list = S48_NULL;
  block_interrupts();

  if (next_interrupt == 0) {
    allow_interrupts();
    return FALSE; }
  else {
    /* turn the queue into a scheme list and preserve the order */
    for (i = next_interrupt; i > 0 ; i--)
      interrupt_list = s48_cons (s48_enter_fixnum (interrupt_queue  [i - 1]),
				 interrupt_list);
    s48_set_os_signals(interrupt_list);
		      
    next_interrupt = 0;
    allow_interrupts();
    return TRUE; }
}

bool 
s48_os_signal_happend(void) {
  return (next_interrupt != 0);
}