diff options
author | Stan Shebs <shebs@codesourcery.com> | 1999-05-11 20:29:07 +0000 |
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committer | Stan Shebs <shebs@codesourcery.com> | 1999-05-11 20:29:07 +0000 |
commit | b5a0ac702997c90cbf520fe7b92f9ebb36423855 (patch) | |
tree | c78c770c944f96659b242f1bd457f86eaeb2d661 /gdb/event-loop.c | |
parent | 5c746d907d11ff88feb0786e82d33c102c4d4c5d (diff) | |
download | fsf-binutils-gdb-b5a0ac702997c90cbf520fe7b92f9ebb36423855.zip fsf-binutils-gdb-b5a0ac702997c90cbf520fe7b92f9ebb36423855.tar.gz fsf-binutils-gdb-b5a0ac702997c90cbf520fe7b92f9ebb36423855.tar.bz2 |
import gdb-1999-05-10
Diffstat (limited to 'gdb/event-loop.c')
-rw-r--r-- | gdb/event-loop.c | 741 |
1 files changed, 741 insertions, 0 deletions
diff --git a/gdb/event-loop.c b/gdb/event-loop.c new file mode 100644 index 0000000..fe1d0f5 --- /dev/null +++ b/gdb/event-loop.c @@ -0,0 +1,741 @@ +/* Event loop machinery for GDB, the GNU debugger. + Copyright 1999 Free Software Foundation, Inc. + Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions. + + 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 2 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, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include "event-loop.h" +#include <readline/readline.h> +#include <setjmp.h> +#include "top.h" + +/* For config.h which may define HAVE_POLL */ +#include "defs.h" + +#ifdef HAVE_POLL +#include <sys/poll.h> +#endif +#include <errno.h> + +/* Event queue: + - the first event in the queue is the head of the queue. + It will be the next to be serviced. + - the last event in the queue + + Events can be inserted at the front of the queue or at the end of + the queue. Events will be extracted from the queue for processing + starting from the head. Therefore, events inserted at the head of + the queue will be processed in a last in first out fashoin, while + those inserted at the tail of the queue will be processed in a first + in first out manner. All the fields are NULL if the queue is + empty. */ + +static struct + { + gdb_event *first_event; /* First pending event */ + gdb_event *last_event; /* Last pending event */ + } +event_queue; + +/* Gdb_notifier is just a list of file descriptors gdb is interested in. + These are the input file descriptor, and the target file + descriptor. We have two flavors of the notifier, one for platforms + that have the POLL function, the other for those that don't, and + only support SELECT. Each of the elements in the gdb_notifier list is + basically a description of what kind of events gdb is interested + in, for each fd. */ + +/* As of 4/30/99 only the input file descriptor is registered with the + event loop. */ + +#ifdef HAVE_POLL +/* Poll based implementation of the notifier. */ + +static struct + { + /* Ptr to head of file handler list. */ + file_handler *first_file_handler; + + /* Ptr to array of pollfd structures. */ + struct pollfd *poll_fds; + + /* Number of file descriptors to monitor. */ + int num_fds; + + } +gdb_notifier; + +#else /* ! HAVE_POLL */ + +/* Select based implementation of the notifier. */ + +static struct + { + /* Ptr to head of file handler list. */ + file_handler *first_file_handler; + + /* Masks to be used in the next call to select. + Bits are set in response to calls to create_file_handler. */ + fd_mask check_masks[3 * MASK_SIZE]; + + /* What file descriptors were found ready by select. */ + fd_mask ready_masks[3 * MASK_SIZE]; + + /* Number of valid bits (highest fd value + 1). */ + int num_fds; + + } +gdb_notifier; + +#endif /* HAVE_POLL */ + +/* 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; + +/* Is any of the handlers ready? Check this variable using + check_async_ready. This is used by process_event, to determine + whether or not to invoke the invoke_async_signal_handler + function. */ +static int async_handler_ready = 0; + +static void invoke_async_signal_handler PARAMS ((void)); +static int gdb_wait_for_event PARAMS ((void)); +static int check_async_ready PARAMS ((void)); +extern display_gdb_prompt PARAMS ((char *)); + + +/* Insert an event object into the gdb event queue at + the specified position. + POSITION can be head or tail, with values TAIL, HEAD. + EVENT_PTR points to the event to be inserted into the queue. + The caller must allocate memory for the event. It is freed + after the event has ben handled. + Events in the queue will be processed head to tail, therefore, + events inserted at the head of the queue will be processed + as last in first out. Event appended at the tail of the queue + will be processed first in first out. */ +static void +async_queue_event (event_ptr, position) + gdb_event *event_ptr; + queue_position position; +{ + if (position == TAIL) + { + /* The event will become the new last_event. */ + + event_ptr->next_event = NULL; + if (event_queue.first_event == NULL) + event_queue.first_event = event_ptr; + else + event_queue.last_event->next_event = event_ptr; + event_queue.last_event = event_ptr; + } + else if (position == HEAD) + { + /* The event becomes the new first_event. */ + + event_ptr->next_event = event_queue.first_event; + if (event_queue.first_event == NULL) + event_queue.last_event = event_ptr; + event_queue.first_event = event_ptr; + } +} + +/* Process one event. + The event can be the next one to be serviced in the event queue, + or an asynchronous event handler can be invoked in response to + the reception of a signal. + If an event was processed (either way), 1 is returned otherwise + 0 is returned. + Scan the queue from head to tail, processing therefore the high + priority events first, by invoking the associated event handler + procedure. */ +static int +process_event () +{ + gdb_event *event_ptr, *prev_ptr; + event_handler_func *proc; + int fd; + + /* First let's see if there are any asynchronous event handlers that + are ready. These would be the result of invoking any of the + signal handlers. */ + + if (check_async_ready ()) + { + invoke_async_signal_handler (); + return 1; + } + + /* Look in the event queue to find an event that is ready + to be processed. */ + + for (event_ptr = event_queue.first_event; event_ptr != NULL; + event_ptr = event_ptr->next_event) + { + /* Call the handler for the event. */ + + proc = event_ptr->proc; + fd = event_ptr->fd; + + /* Let's get rid of the event from the event queue. We need to + do this now because while processing the event, the proc + function could end up calling 'error' and therefore jump out + to the caller of this function, gdb_do_one_event. In that + case, we would have on the event queue an event wich has been + processed, but not deleted. */ + + if (event_queue.first_event == event_ptr) + { + event_queue.first_event = event_ptr->next_event; + if (event_ptr->next_event == NULL) + event_queue.last_event = NULL; + } + else + { + prev_ptr = event_queue.first_event; + while (prev_ptr->next_event != event_ptr) + prev_ptr = prev_ptr->next_event; + + prev_ptr->next_event = event_ptr->next_event; + if (event_ptr->next_event == NULL) + event_queue.last_event = prev_ptr; + } + free ((char *) event_ptr); + + /* Now call the procedure associted with the event. */ + (*proc) (fd); + return 1; + } + + /* this is the case if there are no event on the event queue. */ + return 0; +} + +/* Process one high level event. If nothing is ready at this time, + wait for something to happen (via gdb_wait_for_event), then process + it. Returns 1 if something was done otherwise returns 0 (this can + happen if there are no event sources to wait for). */ +int +gdb_do_one_event () +{ + int result = 0; + + while (1) + { + if (!SET_TOP_LEVEL ()) + { + /* Any events already waiting in the queue? */ + if (process_event ()) + { + result = 1; + break; + } + + /* Wait for a new event. If gdb_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. */ + + result = gdb_wait_for_event (); + if (result < 0) + { + result = 0; + break; + } + + /* Handle any new events occurred while waiting. */ + if (process_event ()) + { + result = 1; + break; + } + + /* If gdb_wait_for_event has returned 1, it means that one + event has been handled. We break out of the loop. */ + if (result) + break; + } /* end of if !set_top_level */ + else + { + display_gdb_prompt (0); + /* Maybe better to set a flag to be checked somewhere as to + whether display the prompt or not. */ + } + } + return result; +} + + +/* Add a file handler/descriptor to the list of descriptors we are + interested in. + FD is the file descriptor for the file/stream to be listened to. + For the poll case, MASK is a combination (OR) of + POLLIN, POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM, + POLLWRBAND: these are the events we are interested in. If any of them + occurs, proc should be called. + For the select case, MASK is a combination of READABLE, WRITABLE, EXCEPTION. + PROC is the procedure that will be called when an event occurs for + FD. CLIENT_DATA is the argument to pass to PROC. */ +void +create_file_handler (fd, mask, proc, client_data) + int fd; + int mask; + file_handler_func *proc; + gdb_client_data client_data; +{ + file_handler *file_ptr; + +#ifndef HAVE_POLL + int index, bit; +#endif + + /* Do we already have a file handler for this file? (We may be + changing its associated procedure). */ + for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL; + file_ptr = file_ptr->next_file) + { + if (file_ptr->fd == fd) + break; + } + + /* It is a new file descriptor. */ + if (file_ptr == NULL) + { + file_ptr = (file_handler *) xmalloc (sizeof (file_handler)); + file_ptr->fd = fd; + file_ptr->ready_mask = 0; + file_ptr->next_file = gdb_notifier.first_file_handler; + gdb_notifier.first_file_handler = file_ptr; + } + file_ptr->proc = proc; + file_ptr->client_data = client_data; + file_ptr->mask = mask; + +#ifdef HAVE_POLL + + gdb_notifier.num_fds++; + gdb_notifier.poll_fds = + (struct pollfd *) realloc (gdb_notifier.poll_fds, + (gdb_notifier.num_fds) * sizeof (struct pollfd)); + (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->fd = fd; + (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->events = mask; + (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->revents = 0; + +#else /* ! HAVE_POLL */ + + index = fd / (NBBY * sizeof (fd_mask)); + bit = 1 << (fd % (NBBY * sizeof (fd_mask))); + + if (mask & GDB_READABLE) + gdb_notifier.check_masks[index] |= bit; + else + gdb_notifier.check_masks[index] &= ~bit; + + if (mask & GDB_WRITABLE) + (gdb_notifier.check_masks + MASK_SIZE)[index] |= bit; + else + (gdb_notifier.check_masks + MASK_SIZE)[index] &= ~bit; + + if (mask & GDB_EXCEPTION) + (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] |= bit; + else + (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] &= ~bit; + + if (gdb_notifier.num_fds <= fd) + gdb_notifier.num_fds = fd + 1; + +#endif /* HAVE_POLL */ +} + +/* Remove the file descriptor FD from the list of monitored fd's: + i.e. we don't care anymore about events on the FD. */ +void +delete_file_handler (fd) + int fd; +{ + file_handler *file_ptr, *prev_ptr = NULL; + int i, j; + struct pollfd *new_poll_fds; +#ifndef HAVE_POLL + int index, bit; + unsigned long flags; +#endif + + /* Find the entry for the given file. */ + + for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL; + file_ptr = file_ptr->next_file) + { + if (file_ptr->fd == fd) + break; + } + + if (file_ptr == NULL) + return; + + /* Deactivate the file descriptor, by clearing its mask, + so that it will not fire again. */ + + file_ptr->mask = 0; + +#ifdef HAVE_POLL + /* Create a new poll_fds array by copying every fd's information but the + one we want to get rid of. */ + + new_poll_fds = + (struct pollfd *) xmalloc ((gdb_notifier.num_fds - 1) * sizeof (struct pollfd)); + + for (i = 0, j = 0; i < gdb_notifier.num_fds; i++) + { + if ((gdb_notifier.poll_fds + i)->fd != fd) + { + (new_poll_fds + j)->fd = (gdb_notifier.poll_fds + i)->fd; + (new_poll_fds + j)->events = (gdb_notifier.poll_fds + i)->events; + (new_poll_fds + j)->revents = (gdb_notifier.poll_fds + i)->revents; + j++; + } + } + free (gdb_notifier.poll_fds); + gdb_notifier.poll_fds = new_poll_fds; + gdb_notifier.num_fds--; + +#else /* ! HAVE_POLL */ + + index = fd / (NBBY * sizeof (fd_mask)); + bit = 1 << (fd % (NBBY * sizeof (fd_mask))); + + if (file_ptr->mask & GDB_READABLE) + gdb_notifier.check_masks[index] &= ~bit; + if (file_ptr->mask & GDB_WRITABLE) + (gdb_notifier.check_masks + MASK_SIZE)[index] &= ~bit; + if (file_ptr->mask & GDB_EXCEPTION) + (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] &= ~bit; + + /* Find current max fd. */ + + if ((fd + 1) == gdb_notifier.num_fds) + { + for (gdb_notifier.num_fds = 0; index >= 0; index--) + { + flags = gdb_notifier.check_masks[index] + | (gdb_notifier.check_masks + MASK_SIZE)[index] + | (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index]; + if (flags) + { + for (i = (NBBY * sizeof (fd_mask)); i > 0; i--) + { + if (flags & (((unsigned long) 1) << (i - 1))) + break; + } + gdb_notifier.num_fds = index * (NBBY * sizeof (fd_mask)) + i; + break; + } + } + } +#endif /* HAVE_POLL */ + + /* Get rid of the file handler in the file handler list. */ + if (file_ptr == gdb_notifier.first_file_handler) + gdb_notifier.first_file_handler = file_ptr->next_file; + else + { + for (prev_ptr = gdb_notifier.first_file_handler; + prev_ptr->next_file == file_ptr; + prev_ptr = prev_ptr->next_file) + ; + prev_ptr->next_file = file_ptr->next_file; + } + free ((char *) file_ptr); +} + +/* Handle the given event by calling the procedure associated to the + corresponding file handler. Called by process_event indirectly, + through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the + event in the front of the event queue. */ +static void +handle_file_event (event_file_desc) + int event_file_desc; +{ + file_handler *file_ptr; + int mask, error_mask; + + /* Search the file handler list to find one that matches the fd in + the event. */ + for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL; + file_ptr = file_ptr->next_file) + { + if (file_ptr->fd == event_file_desc) + { + /* With poll, the ready_mask could have any of three events + set to 1: POLLHUP, POLLERR, POLLNVAL. These events cannot + be used in the requested event mask (events), but they + can be returned in the return mask (revents). We need to + check for those event too, and add them to the mask which + will be passed to the handler. */ + + /* See if the desired events (mask) match the received + events (ready_mask). */ + +#ifdef HAVE_POLL + error_mask = POLLHUP | POLLERR | POLLNVAL; + mask = (file_ptr->ready_mask & file_ptr->mask) | + (file_ptr->ready_mask & error_mask); + +#else /* ! HAVE_POLL */ + mask = file_ptr->ready_mask & file_ptr->mask; +#endif /* HAVE_POLL */ + + /* Clear the received events for next time around. */ + file_ptr->ready_mask = 0; + + /* 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, 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; +} |