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b5a0ac70 | 1 | /* Definitions used by the GDB event loop. |
6aba47ca | 2 | Copyright (C) 1999, 2000, 2007 Free Software Foundation, Inc. |
b5a0ac70 SS |
3 | Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions. |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
a9762ec7 | 9 | the Free Software Foundation; either version 3 of the License, or |
b5a0ac70 SS |
10 | (at your option) any later version. |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
b5a0ac70 | 19 | |
b5a0ac70 SS |
20 | /* An event loop listens for events from multiple event sources. When |
21 | an event arrives, it is queued and processed by calling the | |
22 | appropriate event handler. The event loop then continues to listen | |
23 | for more events. An event loop completes when there are no event | |
24 | sources to listen on. External event sources can be plugged into | |
25 | the loop. | |
26 | ||
27 | There are 3 main components: | |
28 | - a list of file descriptors to be monitored, GDB_NOTIFIER. | |
29 | - a list of events that have occurred, EVENT_QUEUE. | |
30 | - a list of signal handling functions, SIGHANDLER_LIST. | |
31 | ||
32 | GDB_NOTIFIER keeps track of the event sources. Event sources for | |
33 | gdb are currently the UI and the target. Gdb communicates with the | |
34 | command line user interface via the readline library and usually | |
35 | communicates with remote targets via a serial port. Serial ports | |
36 | are represented in GDB as file descriptors and select/poll calls. | |
37 | For native targets instead, the communication consists of calls to | |
38 | ptrace and waits (via signals) or calls to poll/select (via file | |
39 | descriptors). In the current gdb, the code handling events related | |
40 | to the target resides in the wait_for_inferior function and in | |
41 | various target specific files (*-tdep.c). | |
42 | ||
43 | EVENT_QUEUE keeps track of the events that have happened during the | |
44 | last iteration of the event loop, and need to be processed. An | |
45 | event is represented by a procedure to be invoked in order to | |
46 | process the event. The queue is scanned head to tail. If the | |
47 | event of interest is a change of state in a file descriptor, then a | |
48 | call to poll or select will be made to detect it. | |
49 | ||
50 | If the events generate signals, they are also queued by special | |
51 | functions that are invoked through traditional signal handlers. | |
52 | The actions to be taken is response to such events will be executed | |
53 | when the SIGHANDLER_LIST is scanned, the next time through the | |
54 | infinite loop. | |
55 | ||
56 | Corollary tasks are the creation and deletion of event sources. */ | |
57 | ||
97bb9d91 | 58 | typedef void *gdb_client_data; |
c2c6d25f | 59 | struct async_signal_handler; |
2acceee2 | 60 | typedef void (handler_func) (int, gdb_client_data); |
c2c6d25f JM |
61 | typedef void (sig_handler_func) (gdb_client_data); |
62 | typedef void (timer_handler_func) (gdb_client_data); | |
b5a0ac70 SS |
63 | |
64 | /* Where to add an event onto the event queue, by queue_event. */ | |
65 | typedef enum | |
66 | { | |
67 | /* Add at tail of queue. It will be processed in first in first | |
68 | out order. */ | |
69 | TAIL, | |
70 | /* Add at head of queue. It will be processed in last in first out | |
71 | order. */ | |
c5aa993b | 72 | HEAD |
b5a0ac70 SS |
73 | } |
74 | queue_position; | |
75 | ||
76 | /* Tell create_file_handler what events we are interested in. | |
77 | This is used by the select version of the event loop. */ | |
78 | ||
79 | #define GDB_READABLE (1<<1) | |
80 | #define GDB_WRITABLE (1<<2) | |
81 | #define GDB_EXCEPTION (1<<3) | |
82 | ||
085dd6e6 | 83 | /* Exported functions from event-loop.c */ |
0f71a2f6 | 84 | |
c2c6d25f | 85 | extern void start_event_loop (void); |
99656a61 | 86 | extern int gdb_do_one_event (void *data); |
c2c6d25f | 87 | extern void delete_file_handler (int fd); |
6426a772 | 88 | extern void add_file_handler (int fd, handler_func * proc, gdb_client_data client_data); |
c2c6d25f | 89 | extern void mark_async_signal_handler (struct async_signal_handler *async_handler_ptr); |
6426a772 JM |
90 | extern struct async_signal_handler * |
91 | create_async_signal_handler (sig_handler_func * proc, gdb_client_data client_data); | |
92 | extern void delete_async_signal_handler (struct async_signal_handler **async_handler_ptr); | |
6426a772 | 93 | extern int create_timer (int milliseconds, timer_handler_func * proc, gdb_client_data client_data); |
c2c6d25f | 94 | extern void delete_timer (int id); |