96 lines
4.2 KiB
C
96 lines
4.2 KiB
C
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/* Definitions used by the GDB event loop.
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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,
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Boston, MA 02111-1307, USA. */
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/* An event loop listens for events from multiple event sources. When
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an event arrives, it is queued and processed by calling the
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appropriate event handler. The event loop then continues to listen
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for more events. An event loop completes when there are no event
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sources to listen on. External event sources can be plugged into
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the loop.
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There are 3 main components:
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- a list of file descriptors to be monitored, GDB_NOTIFIER.
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- a list of events that have occurred, EVENT_QUEUE.
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- a list of signal handling functions, SIGHANDLER_LIST.
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GDB_NOTIFIER keeps track of the event sources. Event sources for
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gdb are currently the UI and the target. Gdb communicates with the
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command line user interface via the readline library and usually
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communicates with remote targets via a serial port. Serial ports
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are represented in GDB as file descriptors and select/poll calls.
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For native targets instead, the communication consists of calls to
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ptrace and waits (via signals) or calls to poll/select (via file
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descriptors). In the current gdb, the code handling events related
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to the target resides in the wait_for_inferior function and in
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various target specific files (*-tdep.c).
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EVENT_QUEUE keeps track of the events that have happened during the
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last iteration of the event loop, and need to be processed. An
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event is represented by a procedure to be invoked in order to
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process the event. The queue is scanned head to tail. If the
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event of interest is a change of state in a file descriptor, then a
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call to poll or select will be made to detect it.
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If the events generate signals, they are also queued by special
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functions that are invoked through traditional signal handlers.
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The actions to be taken is response to such events will be executed
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when the SIGHANDLER_LIST is scanned, the next time through the
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infinite loop.
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Corollary tasks are the creation and deletion of event sources. */
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typedef void *gdb_client_data;
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struct async_signal_handler;
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typedef void (handler_func) (int, gdb_client_data);
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typedef void (sig_handler_func) (gdb_client_data);
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typedef void (timer_handler_func) (gdb_client_data);
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/* Where to add an event onto the event queue, by queue_event. */
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typedef enum
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{
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/* Add at tail of queue. It will be processed in first in first
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out order. */
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TAIL,
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/* Add at head of queue. It will be processed in last in first out
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order. */
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HEAD
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}
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queue_position;
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/* Tell create_file_handler what events we are interested in.
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This is used by the select version of the event loop. */
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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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/* Exported functions from event-loop.c */
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extern void start_event_loop (void);
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extern void delete_file_handler (int fd);
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extern void add_file_handler (int fd, handler_func * proc, gdb_client_data client_data);
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extern void mark_async_signal_handler (struct async_signal_handler *async_handler_ptr);
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extern struct async_signal_handler *
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create_async_signal_handler (sig_handler_func * proc, gdb_client_data client_data);
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extern void delete_async_signal_handler (struct async_signal_handler **async_handler_ptr);
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extern int create_timer (int milliseconds, timer_handler_func * proc, gdb_client_data client_data);
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extern void delete_timer (int id);
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