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Diffstat (limited to 'gdb/async-event.c')
| -rw-r--r-- | gdb/async-event.c | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/gdb/async-event.c b/gdb/async-event.c new file mode 100644 index 0000000..dd65c17 --- /dev/null +++ b/gdb/async-event.c @@ -0,0 +1,325 @@ +/* Async events for the GDB event loop. + Copyright (C) 1999-2019 Free Software Foundation, Inc. + + 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 3 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, see <http://www.gnu.org/licenses/>. */ + +#include "defs.h" +#include "async-event.h" + +#include "ser-event.h" +#include "top.h" + +/* PROC is a function to be invoked when the READY flag is set. This + happens when there has been a signal and the corresponding signal + handler has 'triggered' this async_signal_handler for execution. + The actual work to be done in response to a signal will be carried + out by PROC at a later time, within process_event. This provides a + deferred execution of signal handlers. + + Async_init_signals takes care of setting up such an + async_signal_handler for each interesting signal. */ + +typedef struct async_signal_handler + { + int ready; /* If ready, call this handler + from the main event loop, using + invoke_async_handler. */ + struct async_signal_handler *next_handler; /* Ptr to next handler. */ + sig_handler_func *proc; /* Function to call to do the work. */ + gdb_client_data client_data; /* Argument to async_handler_func. */ + } +async_signal_handler; + +/* PROC is a function to be invoked when the READY flag is set. This + happens when the event has been marked with + MARK_ASYNC_EVENT_HANDLER. The actual work to be done in response + to an event will be carried out by PROC at a later time, within + process_event. This provides a deferred execution of event + handlers. */ +typedef struct async_event_handler + { + /* If ready, call this handler from the main event loop, using + invoke_event_handler. */ + int ready; + + /* Point to next handler. */ + struct async_event_handler *next_handler; + + /* Function to call to do the work. */ + async_event_handler_func *proc; + + /* Argument to PROC. */ + gdb_client_data client_data; + } +async_event_handler; + +/* 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; + +/* All the async_event_handlers gdb is interested in are kept onto + this list. */ +static struct + { + /* Pointer to first in handler list. */ + async_event_handler *first_handler; + + /* Pointer to last in handler list. */ + async_event_handler *last_handler; + } +async_event_handler_list; + + +/* This event is signalled whenever an asynchronous handler needs to + defer an action to the event loop. */ +static struct serial_event *async_signal_handlers_serial_event; + +/* Callback registered with ASYNC_SIGNAL_HANDLERS_SERIAL_EVENT. */ + +static void +async_signals_handler (int error, gdb_client_data client_data) +{ + /* Do nothing. Handlers are run by invoke_async_signal_handlers + from instead. */ +} + +void +initialize_async_signal_handlers (void) +{ + async_signal_handlers_serial_event = make_serial_event (); + + add_file_handler (serial_event_fd (async_signal_handlers_serial_event), + async_signals_handler, NULL); +} + + + +/* 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 (sig_handler_func * proc, + gdb_client_data client_data) +{ + async_signal_handler *async_handler_ptr; + + async_handler_ptr = XNEW (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_signal_handler * async_handler_ptr) +{ + async_handler_ptr->ready = 1; + serial_event_set (async_signal_handlers_serial_event); +} + +/* See event-loop.h. */ + +void +clear_async_signal_handler (async_signal_handler *async_handler_ptr) +{ + async_handler_ptr->ready = 0; +} + +/* See event-loop.h. */ + +int +async_signal_handler_is_marked (async_signal_handler *async_handler_ptr) +{ + return async_handler_ptr->ready; +} + +/* Call all the handlers that are ready. Returns true if any was + indeed ready. */ + +int +invoke_async_signal_handlers (void) +{ + async_signal_handler *async_handler_ptr; + int any_ready = 0; + + /* We're going to handle all pending signals, so no need to wake up + the event loop again the next time around. Note this must be + cleared _before_ calling the callbacks, to avoid races. */ + serial_event_clear (async_signal_handlers_serial_event); + + /* Invoke all 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; + any_ready = 1; + async_handler_ptr->ready = 0; + /* Async signal handlers have no connection to whichever was the + current UI, and thus always run on the main one. */ + current_ui = main_ui; + (*async_handler_ptr->proc) (async_handler_ptr->client_data); + } + + return any_ready; +} + +/* Delete an asynchronous handler (ASYNC_HANDLER_PTR). + Free the space allocated for it. */ +void +delete_async_signal_handler (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 && prev_ptr->next_handler != (*async_handler_ptr)) + prev_ptr = prev_ptr->next_handler; + gdb_assert (prev_ptr); + prev_ptr->next_handler = (*async_handler_ptr)->next_handler; + if (sighandler_list.last_handler == (*async_handler_ptr)) + sighandler_list.last_handler = prev_ptr; + } + xfree ((*async_handler_ptr)); + (*async_handler_ptr) = NULL; +} + +/* Create an asynchronous event handler, allocating memory for it. + Return a pointer to the newly created handler. PROC is the + function to call with CLIENT_DATA argument whenever the handler is + invoked. */ +async_event_handler * +create_async_event_handler (async_event_handler_func *proc, + gdb_client_data client_data) +{ + async_event_handler *h; + + h = XNEW (struct async_event_handler); + h->ready = 0; + h->next_handler = NULL; + h->proc = proc; + h->client_data = client_data; + if (async_event_handler_list.first_handler == NULL) + async_event_handler_list.first_handler = h; + else + async_event_handler_list.last_handler->next_handler = h; + async_event_handler_list.last_handler = h; + return h; +} + +/* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information + will be used by gdb_do_one_event. The caller will be whoever + created the event source, and wants to signal that the event is + ready to be handled. */ +void +mark_async_event_handler (async_event_handler *async_handler_ptr) +{ + async_handler_ptr->ready = 1; +} + +/* See event-loop.h. */ + +void +clear_async_event_handler (async_event_handler *async_handler_ptr) +{ + async_handler_ptr->ready = 0; +} + +/* Check if asynchronous event handlers are ready, and call the + handler function for one that is. */ + +int +check_async_event_handlers () +{ + async_event_handler *async_handler_ptr; + + for (async_handler_ptr = async_event_handler_list.first_handler; + async_handler_ptr != NULL; + async_handler_ptr = async_handler_ptr->next_handler) + { + if (async_handler_ptr->ready) + { + async_handler_ptr->ready = 0; + (*async_handler_ptr->proc) (async_handler_ptr->client_data); + return 1; + } + } + + return 0; +} + +/* Delete an asynchronous handler (ASYNC_HANDLER_PTR). + Free the space allocated for it. */ +void +delete_async_event_handler (async_event_handler **async_handler_ptr) +{ + async_event_handler *prev_ptr; + + if (async_event_handler_list.first_handler == *async_handler_ptr) + { + async_event_handler_list.first_handler + = (*async_handler_ptr)->next_handler; + if (async_event_handler_list.first_handler == NULL) + async_event_handler_list.last_handler = NULL; + } + else + { + prev_ptr = async_event_handler_list.first_handler; + while (prev_ptr && prev_ptr->next_handler != *async_handler_ptr) + prev_ptr = prev_ptr->next_handler; + gdb_assert (prev_ptr); + prev_ptr->next_handler = (*async_handler_ptr)->next_handler; + if (async_event_handler_list.last_handler == (*async_handler_ptr)) + async_event_handler_list.last_handler = prev_ptr; + } + xfree (*async_handler_ptr); + *async_handler_ptr = NULL; +} |