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