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/* This file is part of the Project Athena Zephyr Notification System.
* It is one of the source files comprising zwgc, the Zephyr WindowGram
* client.
*
* Created by: Marc Horowitz <marc@athena.mit.edu>
*
* $Id$
*
* Copyright (c) 1989 by the Massachusetts Institute of Technology.
* For copying and distribution information, see the file
* "mit-copyright.h".
*/
#include <sysdep.h>
#if (!defined(lint) && !defined(SABER))
static const char rcsid_mux_c[] = "$Id$";
#endif
/****************************************************************************/
/* */
/* Module containing code to wait on multiple file descriptors: */
/* */
/****************************************************************************/
#include <zephyr/zephyr.h>
#include "main.h"
#include "mux.h"
#include "error.h"
#include "zwgc.h"
#include "pointer.h"
#ifdef CMU_ZWGCPLUS
#include "plus.h"
#endif
#ifdef _AIX
#include <sys/select.h>
#endif
/*
* mux_end_loop_p - Setting this to true during a mux_loop causes the mux_loop
* to be exited.
*/
int mux_end_loop_p;
/*
* have_tty - is defined to be true if there is a controlling tty for this
* process. When we can no longer access the controlling tty,
* the process will die.
*/
static int have_tty = 0;
/*
* max_source - the maximum file descriptor that a handler was ever
* registered for:
*/
static int max_source = -1;
/*
* Which file descriptors we're waiting on for input & the accompanying
* input handlers & their arguments:
*/
static fd_set input_sources;
static void (*input_handler[MAX_SOURCES])(void *);
static pointer input_handler_arg[MAX_SOURCES];
static int check_tty(void);
/*
* void mux_init()
* Requires: mux_init has never been called before
* Effects: Initializes the mux module. Must be called before
* any other mux call.
*/
void
mux_init(void)
{
int i;
FD_ZERO(&input_sources);
for (i=0; i<MAX_SOURCES; i++)
input_handler[i] = NULL;
have_tty = check_tty();
}
/*
* void mux_add_input_source(int descriptor; void (*handler)(); pointer arg)
* Requires: 0<=descriptor<MAX_SOURCES, mux_init has been called
* Modifies: Removes the previous input handler if any for descriptor
* Effects: Registers handler as the input handler for file descriptor
* descriptor. When mux_loop() is running and input is
* available on descriptor, handler will be called with
* argument arg.
*/
void
mux_add_input_source(int descriptor,
void (*handler)(void *),
pointer arg)
{
#ifdef DEBUG
if(descriptor < 0 || descriptor >= MAX_SOURCES)
abort(); /* <<<>>> */
#endif
input_handler[descriptor] = handler;
input_handler_arg[descriptor] = arg;
FD_SET(descriptor, &input_sources);
if(descriptor > max_source)
max_source = descriptor;
}
/*
* void mux_loop()
* Requires: mux_init has been called.
* Effects: Loops until mux_end_loop_p becomes true. (Sets
* mux_end_loop_p false to start). Whenever input is
* available on an input source which has a registered
* handler (see mux_add_input_source), that handler is
* called with its argument. It is guaranteed that if
* input is available on a source, its respective input
* handler, if any, will eventually be called. No other
* ordering guarantees are made. When some signal handler
* or input handler eventually sets mux_end_loop_p to
* true, we return.
*/
void
mux_loop(void)
{
int i, nfds;
fd_set inputs, outputs;
struct timeval tv, *tvp;
mux_end_loop_p = 0;
for (;;) {
/*
* Exit if mux_end_loop_p has been set to true by a handler:
*/
if (mux_end_loop_p)
break;
tvp = NULL;
tv.tv_sec = 0;
if (have_tty) {
#ifdef CMU_ZWGCPLUS
tv.tv_sec = plus_timequeue_events();
if (tv.tv_sec > 10) tv.tv_sec = 10;
#else
tv.tv_sec = 10;
#endif
tv.tv_usec = 0;
#ifdef CMU_ZWGCPLUS
} else {
tv.tv_sec = plus_timequeue_events();
tv.tv_usec = 0;
#endif
}
if (tv.tv_sec)
tvp = &tv;
/*
* Do a select on all the file descriptors we care about to
* wait until at least one of them has input available:
*/
inputs = input_sources;
FD_ZERO(&outputs);
#ifdef HAVE_ARES
nfds = ares_fds(achannel, &inputs, &outputs);
if (nfds < max_source + 1)
nfds = max_source + 1;
tvp = ares_timeout(achannel, tvp, &tv);
#else
nfds = max_source + 1;
#endif
i = select(nfds, &inputs, &outputs, NULL, tvp);
if (i == -1) {
if (errno == EINTR)
continue; /* on a signal restart checking mux_loop_end_p */
else
FATAL_TRAP( errno, "while selecting" );
}
else if (i == 0) {
if (have_tty && !check_tty()) {
mux_end_loop_p = 1;
continue;
}
}
#ifdef HAVE_ARES
ares_process(achannel, &inputs, &outputs);
#endif
/*
* Call all input handlers whose corresponding file descriptors have
* input:
*/
for(i=0; i<=max_source; i++)
if (FD_ISSET(i, &inputs) && input_handler[i]) {
#ifdef DEBUG
if (zwgc_debug)
fprintf(stderr,
"mux_loop...activity on fd %d, calling %lx(%lx)\n",
i, (unsigned long)input_handler[i],
(unsigned long)input_handler_arg[i]);
#endif
input_handler[i](input_handler_arg[i]);
}
}
}
static int
check_tty(void)
{
register int result;
int pgrp;
int tty = open("/dev/tty", O_RDONLY|O_NDELAY);
if (tty < 0) return 0;
#if defined(_POSIX_VERSION)
result = ( ((pgrp = tcgetpgrp(tty)) < 0) ? 0 : 1 );
#else
result = ( (ioctl(tty, TIOCGPGRP, &pgrp) < 0) ? 0 : 1 );
#endif
close(tty);
return(result);
}
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