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505 lines
14 KiB
C
505 lines
14 KiB
C
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/* Event loop machinery for the remote server for GDB.
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Copyright (C) 1999, 2000, 2001, 2002, 2005, 2006, 2007, 2008
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Free Software Foundation, Inc.
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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 3 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, see <http://www.gnu.org/licenses/>. */
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/* Based on src/gdb/event-loop.c. */
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#include "server.h"
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#include <sys/types.h>
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#include <string.h>
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#include <sys/time.h>
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#ifdef USE_WIN32API
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#include <windows.h>
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#include <io.h>
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#endif
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#ifdef HAVE_ERRNO_H
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#include <errno.h>
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#endif
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typedef struct gdb_event gdb_event;
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typedef void (event_handler_func) (int);
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/* Tell create_file_handler what events we are interested in. */
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#define GDB_READABLE (1<<1)
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#define GDB_WRITABLE (1<<2)
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#define GDB_EXCEPTION (1<<3)
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/* Events are queued by calling async_queue_event and serviced later
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on by do_one_event. An event can be, for instance, a file
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descriptor becoming ready to be read. Servicing an event simply
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means that the procedure PROC will be called. We have 2 queues,
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one for file handlers that we listen to in the event loop, and one
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for the file handlers+events that are ready. The procedure PROC
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associated with each event is always the same (handle_file_event).
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Its duty is to invoke the handler associated with the file
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descriptor whose state change generated the event, plus doing other
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cleanups and such. */
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struct gdb_event
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{
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/* Procedure to call to service this event. */
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event_handler_func *proc;
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/* File descriptor that is ready. */
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int fd;
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/* Next in list of events or NULL. */
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struct gdb_event *next_event;
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};
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/* Information about each file descriptor we register with the event
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loop. */
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typedef struct file_handler
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{
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/* File descriptor. */
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int fd;
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/* Events we want to monitor. */
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int mask;
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/* Events that have been seen since the last time. */
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int ready_mask;
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/* Procedure to call when fd is ready. */
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handler_func *proc;
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/* Argument to pass to proc. */
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gdb_client_data client_data;
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/* Was an error detected on this fd? */
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int error;
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/* Next registered file descriptor. */
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struct file_handler *next_file;
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}
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file_handler;
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/* Event 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 fashion, while
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those inserted at the tail of the queue will be processed in a
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first 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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/* The first pending event. */
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gdb_event *first_event;
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/* The last pending event. */
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gdb_event *last_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
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in. These are the input file descriptor, and the target file
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descriptor. 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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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. Bits are set in
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response to calls to create_file_handler. */
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fd_set check_masks[3];
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/* What file descriptors were found ready by select. */
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fd_set ready_masks[3];
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/* Number of valid bits (highest fd value + 1). (for select) */
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int num_fds;
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}
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gdb_notifier;
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/* Insert an event object into the gdb event queue.
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EVENT_PTR points to the event to be inserted into the queue. The
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caller must allocate memory for the event. It is freed after the
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event has ben handled. Events in the queue will be processed head
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to tail, therefore, events will be processed first in first
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out. */
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static void
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async_queue_event (gdb_event *event_ptr)
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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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/* Process one event. If an event was processed, 1 is returned
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otherwise 0 is returned. Scan the queue from head to tail,
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processing therefore the high priority events first, by invoking
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the associated event handler procedure. */
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static int
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process_event (void)
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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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/* 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;
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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, since the
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proc function could end up jumping out to the caller of this
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function. In that case, we would have on the event queue an
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event which has been 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 (event_ptr);
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/* Now call the procedure associated 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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/* Add a file handler/descriptor to the list of descriptors we are
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interested in. FD is the file descriptor for the file/stream to be
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listened to. MASK is a combination of READABLE, WRITABLE,
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EXCEPTION. PROC is the procedure that will be called when an event
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occurs for FD. CLIENT_DATA is the argument to pass to PROC. */
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static void
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create_file_handler (int fd, int mask, 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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/* 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;
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file_ptr != NULL;
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file_ptr = file_ptr->next_file)
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if (file_ptr->fd == fd)
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break;
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/* It is a new file descriptor. Add it to the list. Otherwise,
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just change the data associated with it. */
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if (file_ptr == NULL)
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{
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file_ptr = xmalloc (sizeof (*file_ptr));
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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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if (mask & GDB_READABLE)
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FD_SET (fd, &gdb_notifier.check_masks[0]);
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else
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FD_CLR (fd, &gdb_notifier.check_masks[0]);
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if (mask & GDB_WRITABLE)
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FD_SET (fd, &gdb_notifier.check_masks[1]);
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else
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FD_CLR (fd, &gdb_notifier.check_masks[1]);
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if (mask & GDB_EXCEPTION)
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FD_SET (fd, &gdb_notifier.check_masks[2]);
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else
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FD_CLR (fd, &gdb_notifier.check_masks[2]);
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if (gdb_notifier.num_fds <= fd)
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gdb_notifier.num_fds = fd + 1;
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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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}
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/* Wrapper function for create_file_handler. */
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void
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add_file_handler (int fd, handler_func *proc, gdb_client_data client_data)
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{
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create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION, proc, client_data);
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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 (int fd)
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{
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file_handler *file_ptr, *prev_ptr = NULL;
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int i;
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/* Find the entry for the given file. */
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for (file_ptr = gdb_notifier.first_file_handler;
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file_ptr != NULL;
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file_ptr = file_ptr->next_file)
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if (file_ptr->fd == fd)
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break;
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if (file_ptr == NULL)
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return;
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if (file_ptr->mask & GDB_READABLE)
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FD_CLR (fd, &gdb_notifier.check_masks[0]);
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if (file_ptr->mask & GDB_WRITABLE)
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FD_CLR (fd, &gdb_notifier.check_masks[1]);
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if (file_ptr->mask & GDB_EXCEPTION)
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FD_CLR (fd, &gdb_notifier.check_masks[2]);
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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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gdb_notifier.num_fds--;
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for (i = gdb_notifier.num_fds; i; i--)
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{
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if (FD_ISSET (i - 1, &gdb_notifier.check_masks[0])
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|| FD_ISSET (i - 1, &gdb_notifier.check_masks[1])
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|| FD_ISSET (i - 1, &gdb_notifier.check_masks[2]))
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break;
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}
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gdb_notifier.num_fds = i;
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}
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/* Deactivate the file descriptor, by clearing its mask, so that it
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will not fire again. */
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file_ptr->mask = 0;
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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 (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 (int event_file_desc)
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{
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file_handler *file_ptr;
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int 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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/* See if the desired events (mask) match the received
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events (ready_mask). */
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if (file_ptr->ready_mask & GDB_EXCEPTION)
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{
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fprintf (stderr, "Exception condition detected on fd %d\n",
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file_ptr->fd);
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file_ptr->error = 1;
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}
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else
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file_ptr->error = 0;
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mask = file_ptr->ready_mask & file_ptr->mask;
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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. */
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if (mask != 0)
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(*file_ptr->proc) (file_ptr->error, file_ptr->client_data);
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break;
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}
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}
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}
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/* Create a file event, to be enqueued in the event queue for
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processing. The procedure associated to this event is always
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handle_file_event, which will in turn invoke the one that was
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associated to FD when it was registered with the event loop. */
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static gdb_event *
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create_file_event (int fd)
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{
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gdb_event *file_event_ptr;
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file_event_ptr = xmalloc (sizeof (gdb_event));
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file_event_ptr->proc = handle_file_event;
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file_event_ptr->fd = fd;
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return file_event_ptr;
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}
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/* Called by do_one_event to wait for new events on the monitored file
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descriptors. Queue file events as they are detected by the poll.
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If there are no events, this function will block in the call to
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select. Return -1 if there are no files descriptors to monitor,
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otherwise return 0. */
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static int
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wait_for_event (void)
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{
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file_handler *file_ptr;
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gdb_event *file_event_ptr;
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int num_found = 0;
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/* Make sure all output is done before getting another event. */
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fflush (stdout);
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fflush (stderr);
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if (gdb_notifier.num_fds == 0)
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return -1;
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gdb_notifier.ready_masks[0] = gdb_notifier.check_masks[0];
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gdb_notifier.ready_masks[1] = gdb_notifier.check_masks[1];
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gdb_notifier.ready_masks[2] = gdb_notifier.check_masks[2];
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num_found = select (gdb_notifier.num_fds,
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&gdb_notifier.ready_masks[0],
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&gdb_notifier.ready_masks[1],
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&gdb_notifier.ready_masks[2],
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NULL);
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/* Clear the masks after an error from select. */
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if (num_found == -1)
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{
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FD_ZERO (&gdb_notifier.ready_masks[0]);
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FD_ZERO (&gdb_notifier.ready_masks[1]);
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FD_ZERO (&gdb_notifier.ready_masks[2]);
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#ifdef EINTR
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/* Dont print anything if we got a signal, let gdb handle
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it. */
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if (errno != EINTR)
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perror_with_name ("select");
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#endif
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||
|
}
|
||
|
|
||
|
/* Enqueue all detected file events. */
|
||
|
|
||
|
for (file_ptr = gdb_notifier.first_file_handler;
|
||
|
file_ptr != NULL && num_found > 0;
|
||
|
file_ptr = file_ptr->next_file)
|
||
|
{
|
||
|
int mask = 0;
|
||
|
|
||
|
if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[0]))
|
||
|
mask |= GDB_READABLE;
|
||
|
if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[1]))
|
||
|
mask |= GDB_WRITABLE;
|
||
|
if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[2]))
|
||
|
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 = create_file_event (file_ptr->fd);
|
||
|
async_queue_event (file_event_ptr);
|
||
|
}
|
||
|
file_ptr->ready_mask = mask;
|
||
|
}
|
||
|
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
/* Start up the event loop. This is the entry point to the event
|
||
|
loop. */
|
||
|
|
||
|
void
|
||
|
start_event_loop (void)
|
||
|
{
|
||
|
/* Loop until there is nothing to do. This is the entry point to
|
||
|
the event loop engine. If nothing is ready at this time, wait
|
||
|
for something to happen (via wait_for_event), then process it.
|
||
|
Return when there are no longer event sources to wait for. */
|
||
|
|
||
|
while (1)
|
||
|
{
|
||
|
/* Any events already waiting in the queue? */
|
||
|
if (process_event ())
|
||
|
continue;
|
||
|
|
||
|
/* Wait for a new event. If 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. */
|
||
|
|
||
|
if (wait_for_event () < 0)
|
||
|
return;
|
||
|
}
|
||
|
|
||
|
/* We are done with the event loop. There are no more event sources
|
||
|
to listen to. So we exit gdbserver. */
|
||
|
}
|