binutils-gdb/gdb/event-loop.c

783 lines
22 KiB
C
Raw Normal View History

1999-05-12 04:29:07 +08:00
/* Event loop machinery for GDB, the GNU debugger.
Copyright 1999 Free Software Foundation, Inc.
Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#include "defs.h"
1999-06-21 21:27:42 +08:00
#include "top.h"
#include "event-loop.h"
1999-05-12 04:29:07 +08:00
#ifdef HAVE_POLL
1999-06-21 21:27:42 +08:00
#include <poll.h>
#else
#include <sys/types.h>
1999-05-12 04:29:07 +08:00
#endif
#include <errno.h>
1999-06-21 21:27:42 +08:00
#include <setjmp.h>
1999-05-12 04:29:07 +08:00
/* Event queue:
- the first event in the queue is the head of the queue.
It will be the next to be serviced.
- the last event in the queue
Events can be inserted at the front of the queue or at the end of
the queue. Events will be extracted from the queue for processing
starting from the head. Therefore, events inserted at the head of
the queue will be processed in a last in first out fashoin, while
those inserted at the tail of the queue will be processed in a first
in first out manner. All the fields are NULL if the queue is
empty. */
static struct
{
gdb_event *first_event; /* First pending event */
gdb_event *last_event; /* Last pending event */
}
event_queue;
/* Gdb_notifier is just a list of file descriptors gdb is interested in.
These are the input file descriptor, and the target file
descriptor. We have two flavors of the notifier, one for platforms
that have the POLL function, the other for those that don't, and
only support SELECT. Each of the elements in the gdb_notifier list is
basically a description of what kind of events gdb is interested
in, for each fd. */
1999-05-26 02:09:09 +08:00
/* As of 1999-04-30 only the input file descriptor is registered with the
1999-05-12 04:29:07 +08:00
event loop. */
#ifdef HAVE_POLL
/* Poll based implementation of the notifier. */
static struct
{
/* Ptr to head of file handler list. */
file_handler *first_file_handler;
/* Ptr to array of pollfd structures. */
struct pollfd *poll_fds;
/* Number of file descriptors to monitor. */
int num_fds;
}
gdb_notifier;
#else /* ! HAVE_POLL */
/* Select based implementation of the notifier. */
static struct
{
/* Ptr to head of file handler list. */
file_handler *first_file_handler;
/* Masks to be used in the next call to select.
Bits are set in response to calls to create_file_handler. */
fd_mask check_masks[3 * MASK_SIZE];
/* What file descriptors were found ready by select. */
fd_mask ready_masks[3 * MASK_SIZE];
/* Number of valid bits (highest fd value + 1). */
int num_fds;
}
gdb_notifier;
#endif /* HAVE_POLL */
/* All the async_signal_handlers gdb is interested in are kept onto
this list. */
static struct
{
/* Pointer to first in handler list. */
async_signal_handler *first_handler;
/* Pointer to last in handler list. */
async_signal_handler *last_handler;
}
sighandler_list;
/* Is any of the handlers ready? Check this variable using
check_async_ready. This is used by process_event, to determine
whether or not to invoke the invoke_async_signal_handler
function. */
static int async_handler_ready = 0;
1999-06-29 00:06:02 +08:00
static void create_file_handler PARAMS ((int, int, file_handler_func *, gdb_client_data));
1999-05-12 04:29:07 +08:00
static void invoke_async_signal_handler PARAMS ((void));
static int gdb_wait_for_event PARAMS ((void));
1999-06-29 00:06:02 +08:00
static int gdb_do_one_event PARAMS ((void));
1999-05-12 04:29:07 +08:00
static int check_async_ready PARAMS ((void));
/* Insert an event object into the gdb event queue at
the specified position.
POSITION can be head or tail, with values TAIL, HEAD.
EVENT_PTR points to the event to be inserted into the queue.
The caller must allocate memory for the event. It is freed
after the event has ben handled.
Events in the queue will be processed head to tail, therefore,
events inserted at the head of the queue will be processed
as last in first out. Event appended at the tail of the queue
will be processed first in first out. */
static void
async_queue_event (event_ptr, position)
gdb_event *event_ptr;
queue_position position;
{
if (position == TAIL)
{
/* The event will become the new last_event. */
event_ptr->next_event = NULL;
if (event_queue.first_event == NULL)
event_queue.first_event = event_ptr;
else
event_queue.last_event->next_event = event_ptr;
event_queue.last_event = event_ptr;
}
else if (position == HEAD)
{
/* The event becomes the new first_event. */
event_ptr->next_event = event_queue.first_event;
if (event_queue.first_event == NULL)
event_queue.last_event = event_ptr;
event_queue.first_event = event_ptr;
}
}
/* Process one event.
The event can be the next one to be serviced in the event queue,
or an asynchronous event handler can be invoked in response to
the reception of a signal.
If an event was processed (either way), 1 is returned otherwise
0 is returned.
Scan the queue from head to tail, processing therefore the high
priority events first, by invoking the associated event handler
procedure. */
static int
process_event ()
{
gdb_event *event_ptr, *prev_ptr;
event_handler_func *proc;
int fd;
/* First let's see if there are any asynchronous event handlers that
are ready. These would be the result of invoking any of the
signal handlers. */
if (check_async_ready ())
{
invoke_async_signal_handler ();
return 1;
}
/* Look in the event queue to find an event that is ready
to be processed. */
for (event_ptr = event_queue.first_event; event_ptr != NULL;
event_ptr = event_ptr->next_event)
{
/* Call the handler for the event. */
proc = event_ptr->proc;
fd = event_ptr->fd;
/* Let's get rid of the event from the event queue. We need to
do this now because while processing the event, the proc
function could end up calling 'error' and therefore jump out
to the caller of this function, gdb_do_one_event. In that
case, we would have on the event queue an event wich has been
processed, but not deleted. */
if (event_queue.first_event == event_ptr)
{
event_queue.first_event = event_ptr->next_event;
if (event_ptr->next_event == NULL)
event_queue.last_event = NULL;
}
else
{
prev_ptr = event_queue.first_event;
while (prev_ptr->next_event != event_ptr)
prev_ptr = prev_ptr->next_event;
prev_ptr->next_event = event_ptr->next_event;
if (event_ptr->next_event == NULL)
event_queue.last_event = prev_ptr;
}
free ((char *) event_ptr);
/* Now call the procedure associted with the event. */
(*proc) (fd);
return 1;
}
/* this is the case if there are no event on the event queue. */
return 0;
}
/* Process one high level event. If nothing is ready at this time,
wait for something to happen (via gdb_wait_for_event), then process
it. Returns 1 if something was done otherwise returns 0 (this can
happen if there are no event sources to wait for). */
1999-06-29 00:06:02 +08:00
static int
1999-05-12 04:29:07 +08:00
gdb_do_one_event ()
{
int result = 0;
while (1)
{
if (!SET_TOP_LEVEL ())
{
/* Any events already waiting in the queue? */
if (process_event ())
{
result = 1;
break;
}
/* Wait for a new event. If gdb_wait_for_event returns -1,
we should get out because this means that there are no
event sources left. This will make the event loop stop,
and the application exit. */
result = gdb_wait_for_event ();
if (result < 0)
{
result = 0;
break;
}
/* Handle any new events occurred while waiting. */
if (process_event ())
{
result = 1;
break;
}
/* If gdb_wait_for_event has returned 1, it means that one
event has been handled. We break out of the loop. */
if (result)
break;
} /* end of if !set_top_level */
else
{
1999-06-29 00:06:02 +08:00
/* FIXME: this should really be a call to a hook that is
interface specific, because interfaces can display the
prompt in their own way. */
1999-05-12 04:29:07 +08:00
display_gdb_prompt (0);
/* Maybe better to set a flag to be checked somewhere as to
whether display the prompt or not. */
}
}
return result;
}
1999-06-29 00:06:02 +08:00
/* Start up the event loop. This is the entry point to the event loop
from the command loop. */
void
start_event_loop ()
{
/* Loop until there is something to do. This is the entry point to
the event loop engine. gdb_do_one_event will process one event
for each invocation. It always returns 1, unless there are no
more event sources registered. In this case it returns 0. */
while (gdb_do_one_event () != 0)
;
/* We are done with the event loop. There are no more event sources
to listen to. So we exit GDB. */
return;
}
1999-05-12 04:29:07 +08:00
1999-06-29 00:06:02 +08:00
/* Wrapper function for create_file_handler, so that the caller
doesn't have to know implementation details about the use of poll
vs. select. */
void
add_file_handler (fd, proc, client_data)
int fd;
file_handler_func *proc;
gdb_client_data client_data;
{
#ifdef HAVE_POLL
create_file_handler (fd, POLLIN, (file_handler_func *) proc, client_data);
#else
create_file_handler (fd, GDB_READABLE, (file_handler_func *) proc, client_data);
#endif
}
1999-05-12 04:29:07 +08:00
/* Add a file handler/descriptor to the list of descriptors we are
interested in.
FD is the file descriptor for the file/stream to be listened to.
For the poll case, MASK is a combination (OR) of
POLLIN, POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM,
POLLWRBAND: these are the events we are interested in. If any of them
occurs, proc should be called.
For the select case, MASK is a combination of READABLE, WRITABLE, EXCEPTION.
PROC is the procedure that will be called when an event occurs for
FD. CLIENT_DATA is the argument to pass to PROC. */
1999-06-29 00:06:02 +08:00
static void
1999-05-12 04:29:07 +08:00
create_file_handler (fd, mask, proc, client_data)
int fd;
int mask;
file_handler_func *proc;
gdb_client_data client_data;
{
file_handler *file_ptr;
#ifndef HAVE_POLL
int index, bit;
#endif
/* Do we already have a file handler for this file? (We may be
changing its associated procedure). */
for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL;
file_ptr = file_ptr->next_file)
{
if (file_ptr->fd == fd)
break;
}
/* It is a new file descriptor. */
if (file_ptr == NULL)
{
file_ptr = (file_handler *) xmalloc (sizeof (file_handler));
file_ptr->fd = fd;
file_ptr->ready_mask = 0;
file_ptr->next_file = gdb_notifier.first_file_handler;
gdb_notifier.first_file_handler = file_ptr;
}
file_ptr->proc = proc;
file_ptr->client_data = client_data;
file_ptr->mask = mask;
#ifdef HAVE_POLL
gdb_notifier.num_fds++;
1999-06-21 21:27:42 +08:00
if (gdb_notifier.poll_fds)
gdb_notifier.poll_fds =
(struct pollfd *) realloc (gdb_notifier.poll_fds,
(gdb_notifier.num_fds) * sizeof (struct pollfd));
else
gdb_notifier.poll_fds =
(struct pollfd *) xmalloc (sizeof (struct pollfd));
1999-05-12 04:29:07 +08:00
(gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->fd = fd;
(gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->events = mask;
(gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->revents = 0;
#else /* ! HAVE_POLL */
index = fd / (NBBY * sizeof (fd_mask));
bit = 1 << (fd % (NBBY * sizeof (fd_mask)));
if (mask & GDB_READABLE)
gdb_notifier.check_masks[index] |= bit;
else
gdb_notifier.check_masks[index] &= ~bit;
if (mask & GDB_WRITABLE)
(gdb_notifier.check_masks + MASK_SIZE)[index] |= bit;
else
(gdb_notifier.check_masks + MASK_SIZE)[index] &= ~bit;
if (mask & GDB_EXCEPTION)
(gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] |= bit;
else
(gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] &= ~bit;
if (gdb_notifier.num_fds <= fd)
gdb_notifier.num_fds = fd + 1;
#endif /* HAVE_POLL */
}
/* Remove the file descriptor FD from the list of monitored fd's:
i.e. we don't care anymore about events on the FD. */
void
delete_file_handler (fd)
int fd;
{
file_handler *file_ptr, *prev_ptr = NULL;
int i, j;
struct pollfd *new_poll_fds;
#ifndef HAVE_POLL
int index, bit;
unsigned long flags;
#endif
/* Find the entry for the given file. */
for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL;
file_ptr = file_ptr->next_file)
{
if (file_ptr->fd == fd)
break;
}
if (file_ptr == NULL)
return;
/* Deactivate the file descriptor, by clearing its mask,
so that it will not fire again. */
file_ptr->mask = 0;
#ifdef HAVE_POLL
/* Create a new poll_fds array by copying every fd's information but the
one we want to get rid of. */
new_poll_fds =
(struct pollfd *) xmalloc ((gdb_notifier.num_fds - 1) * sizeof (struct pollfd));
for (i = 0, j = 0; i < gdb_notifier.num_fds; i++)
{
if ((gdb_notifier.poll_fds + i)->fd != fd)
{
(new_poll_fds + j)->fd = (gdb_notifier.poll_fds + i)->fd;
(new_poll_fds + j)->events = (gdb_notifier.poll_fds + i)->events;
(new_poll_fds + j)->revents = (gdb_notifier.poll_fds + i)->revents;
j++;
}
}
free (gdb_notifier.poll_fds);
gdb_notifier.poll_fds = new_poll_fds;
gdb_notifier.num_fds--;
#else /* ! HAVE_POLL */
index = fd / (NBBY * sizeof (fd_mask));
bit = 1 << (fd % (NBBY * sizeof (fd_mask)));
if (file_ptr->mask & GDB_READABLE)
gdb_notifier.check_masks[index] &= ~bit;
if (file_ptr->mask & GDB_WRITABLE)
(gdb_notifier.check_masks + MASK_SIZE)[index] &= ~bit;
if (file_ptr->mask & GDB_EXCEPTION)
(gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] &= ~bit;
/* Find current max fd. */
if ((fd + 1) == gdb_notifier.num_fds)
{
for (gdb_notifier.num_fds = 0; index >= 0; index--)
{
flags = gdb_notifier.check_masks[index]
| (gdb_notifier.check_masks + MASK_SIZE)[index]
| (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index];
if (flags)
{
for (i = (NBBY * sizeof (fd_mask)); i > 0; i--)
{
if (flags & (((unsigned long) 1) << (i - 1)))
break;
}
gdb_notifier.num_fds = index * (NBBY * sizeof (fd_mask)) + i;
break;
}
}
}
#endif /* HAVE_POLL */
/* Get rid of the file handler in the file handler list. */
if (file_ptr == gdb_notifier.first_file_handler)
gdb_notifier.first_file_handler = file_ptr->next_file;
else
{
for (prev_ptr = gdb_notifier.first_file_handler;
1999-06-21 21:27:42 +08:00
prev_ptr->next_file != file_ptr;
1999-05-12 04:29:07 +08:00
prev_ptr = prev_ptr->next_file)
;
prev_ptr->next_file = file_ptr->next_file;
}
free ((char *) file_ptr);
}
/* Handle the given event by calling the procedure associated to the
corresponding file handler. Called by process_event indirectly,
through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the
event in the front of the event queue. */
static void
handle_file_event (event_file_desc)
int event_file_desc;
{
file_handler *file_ptr;
int mask, error_mask;
/* Search the file handler list to find one that matches the fd in
the event. */
for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL;
file_ptr = file_ptr->next_file)
{
if (file_ptr->fd == event_file_desc)
{
/* With poll, the ready_mask could have any of three events
set to 1: POLLHUP, POLLERR, POLLNVAL. These events cannot
be used in the requested event mask (events), but they
can be returned in the return mask (revents). We need to
check for those event too, and add them to the mask which
will be passed to the handler. */
/* See if the desired events (mask) match the received
events (ready_mask). */
#ifdef HAVE_POLL
error_mask = POLLHUP | POLLERR | POLLNVAL;
mask = (file_ptr->ready_mask & file_ptr->mask) |
(file_ptr->ready_mask & error_mask);
#else /* ! HAVE_POLL */
mask = file_ptr->ready_mask & file_ptr->mask;
#endif /* HAVE_POLL */
/* Clear the received events for next time around. */
file_ptr->ready_mask = 0;
/* If there was a match, then call the handler. */
if (mask != 0)
(*file_ptr->proc) (file_ptr->client_data, mask);
break;
}
}
}
/* Called by gdb_do_one_event to wait for new events on the
monitored file descriptors. Queue file events as they are
detected by the poll.
If there are no events, this function will block in the
call to poll.
Return -1 if there are no files descriptors to monitor,
otherwise return 0. */
static int
gdb_wait_for_event ()
{
file_handler *file_ptr;
gdb_event *file_event_ptr;
1999-06-15 02:08:47 +08:00
int num_found = 0;
int i;
1999-05-12 04:29:07 +08:00
#ifndef HAVE_POLL
int mask, bit, index;
#endif
if (gdb_notifier.num_fds == 0)
return -1;
#ifdef HAVE_POLL
num_found =
poll (gdb_notifier.poll_fds, (unsigned long) gdb_notifier.num_fds, -1);
#else /* ! HAVE_POLL */
memcpy (gdb_notifier.ready_masks,
gdb_notifier.check_masks,
3 * MASK_SIZE * sizeof (fd_mask));
num_found = select (gdb_notifier.num_fds,
(SELECT_MASK *) & gdb_notifier.ready_masks[0],
(SELECT_MASK *) & gdb_notifier.ready_masks[MASK_SIZE],
(SELECT_MASK *) & gdb_notifier.ready_masks[2 * MASK_SIZE],
NULL);
/* Clear the masks after an error from select. */
if (num_found == -1)
memset (gdb_notifier.ready_masks,
0, 3 * MASK_SIZE * sizeof (fd_mask));
#endif /* HAVE_POLL */
/* Enqueue all detected file events. */
#ifdef HAVE_POLL
for (i = 0; (i < gdb_notifier.num_fds) && (num_found > 0); i++)
{
if ((gdb_notifier.poll_fds + i)->revents)
num_found--;
else
continue;
for (file_ptr = gdb_notifier.first_file_handler;
file_ptr != NULL;
file_ptr = file_ptr->next_file)
{
if (file_ptr->fd == (gdb_notifier.poll_fds + i)->fd)
break;
}
if (file_ptr)
{
/* Enqueue an event only if this is still a new event for
this fd. */
if (file_ptr->ready_mask == 0)
{
file_event_ptr =
(gdb_event *) xmalloc (sizeof (gdb_event));
file_event_ptr->proc = handle_file_event;
file_event_ptr->fd = file_ptr->fd;
async_queue_event (file_event_ptr, TAIL);
}
}
file_ptr->ready_mask = (gdb_notifier.poll_fds + i)->revents;
}
#else /* ! HAVE_POLL */
for (file_ptr = gdb_notifier.first_file_handler;
(file_ptr != NULL) && (num_found > 0);
file_ptr = file_ptr->next_file)
{
index = file_ptr->fd / (NBBY * sizeof (fd_mask));
bit = 1 << (file_ptr->fd % (NBBY * sizeof (fd_mask)));
mask = 0;
if (gdb_notifier.ready_masks[index] & bit)
mask |= GDB_READABLE;
if ((gdb_notifier.ready_masks + MASK_SIZE)[index] & bit)
mask |= GDB_WRITABLE;
if ((gdb_notifier.ready_masks + 2 * (MASK_SIZE))[index] & bit)
mask |= GDB_EXCEPTION;
if (!mask)
continue;
else
num_found--;
/* Enqueue an event only if this is still a new event for
this fd. */
if (file_ptr->ready_mask == 0)
{
file_event_ptr =
(gdb_event *) xmalloc (sizeof (gdb_event));
file_event_ptr->proc = handle_file_event;
file_event_ptr->fd = file_ptr->fd;
async_queue_event (file_event_ptr, TAIL);
}
file_ptr->ready_mask = mask;
}
#endif /* HAVE_POLL */
return 0;
}
/* Create an asynchronous handler, allocating memory for it.
Return a pointer to the newly created handler.
This pointer will be used to invoke the handler by
invoke_async_signal_handler.
PROC is the function to call with CLIENT_DATA argument
whenever the handler is invoked. */
async_signal_handler *
create_async_signal_handler (proc, client_data)
async_handler_func *proc;
gdb_client_data client_data;
{
async_signal_handler *async_handler_ptr;
async_handler_ptr =
(async_signal_handler *) xmalloc (sizeof (async_signal_handler));
async_handler_ptr->ready = 0;
async_handler_ptr->next_handler = NULL;
async_handler_ptr->proc = proc;
async_handler_ptr->client_data = client_data;
if (sighandler_list.first_handler == NULL)
sighandler_list.first_handler = async_handler_ptr;
else
sighandler_list.last_handler->next_handler = async_handler_ptr;
sighandler_list.last_handler = async_handler_ptr;
return async_handler_ptr;
}
/* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information will
be used when the handlers are invoked, after we have waited for
some event. The caller of this function is the interrupt handler
associated with a signal. */
void
mark_async_signal_handler (async_handler_ptr)
async_signal_handler *async_handler_ptr;
{
((async_signal_handler *) async_handler_ptr)->ready = 1;
async_handler_ready = 1;
}
/* Call all the handlers that are ready. */
static void
invoke_async_signal_handler ()
{
async_signal_handler *async_handler_ptr;
if (async_handler_ready == 0)
return;
async_handler_ready = 0;
/* Invoke ready handlers. */
while (1)
{
for (async_handler_ptr = sighandler_list.first_handler;
async_handler_ptr != NULL;
async_handler_ptr = async_handler_ptr->next_handler)
{
if (async_handler_ptr->ready)
break;
}
if (async_handler_ptr == NULL)
break;
async_handler_ptr->ready = 0;
(*async_handler_ptr->proc) (async_handler_ptr->client_data);
}
return;
}
/* Delete an asynchronous handler (ASYNC_HANDLER_PTR).
Free the space allocated for it. */
void
delete_async_signal_handler (async_handler_ptr)
async_signal_handler *async_handler_ptr;
{
async_signal_handler *prev_ptr;
if (sighandler_list.first_handler == async_handler_ptr)
{
sighandler_list.first_handler = async_handler_ptr->next_handler;
if (sighandler_list.first_handler == NULL)
sighandler_list.last_handler = NULL;
}
else
{
prev_ptr = sighandler_list.first_handler;
while (prev_ptr->next_handler != async_handler_ptr)
prev_ptr = prev_ptr->next_handler;
prev_ptr->next_handler = async_handler_ptr->next_handler;
if (sighandler_list.last_handler == async_handler_ptr)
sighandler_list.last_handler = prev_ptr;
}
free ((char *) async_handler_ptr);
}
/* Is it necessary to call invoke_async_signal_handler? */
static int
check_async_ready ()
{
return async_handler_ready;
}