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[/] [openrisc/] [trunk/] [gnu-src/] [gdb-7.1/] [gdb/] [gdbserver/] [event-loop.c] - Rev 310
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/* Event loop machinery for the remote server for GDB. Copyright (C) 1999, 2000, 2001, 2002, 2005, 2006, 2007, 2008, 2010 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/>. */ /* Based on src/gdb/event-loop.c. */ #include "server.h" #include <sys/types.h> #include <string.h> #include <sys/time.h> #ifdef USE_WIN32API #include <windows.h> #include <io.h> #endif #ifdef HAVE_ERRNO_H #include <errno.h> #endif #ifdef HAVE_UNISTD_H #include <unistd.h> #endif typedef struct gdb_event gdb_event; typedef void (event_handler_func) (int); /* Tell create_file_handler what events we are interested in. */ #define GDB_READABLE (1<<1) #define GDB_WRITABLE (1<<2) #define GDB_EXCEPTION (1<<3) /* Events are queued by calling async_queue_event and serviced later on by do_one_event. An event can be, for instance, a file descriptor becoming ready to be read. Servicing an event simply means that the procedure PROC will be called. We have 2 queues, one for file handlers that we listen to in the event loop, and one for the file handlers+events that are ready. The procedure PROC associated with each event is always the same (handle_file_event). Its duty is to invoke the handler associated with the file descriptor whose state change generated the event, plus doing other cleanups and such. */ struct gdb_event { /* Procedure to call to service this event. */ event_handler_func *proc; /* File descriptor that is ready. */ int fd; /* Next in list of events or NULL. */ struct gdb_event *next_event; }; /* Information about each file descriptor we register with the event loop. */ typedef struct file_handler { /* File descriptor. */ int fd; /* Events we want to monitor. */ int mask; /* Events that have been seen since the last time. */ int ready_mask; /* Procedure to call when fd is ready. */ handler_func *proc; /* Argument to pass to proc. */ gdb_client_data client_data; /* Was an error detected on this fd? */ int error; /* Next registered file descriptor. */ struct file_handler *next_file; } file_handler; /* Event 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 fashion, 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 { /* The first pending event. */ gdb_event *first_event; /* The last pending event. */ gdb_event *last_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. 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. */ 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_set check_masks[3]; /* What file descriptors were found ready by select. */ fd_set ready_masks[3]; /* Number of valid bits (highest fd value + 1). (for select) */ int num_fds; } gdb_notifier; /* Insert an event object into the gdb event queue. 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 will be processed first in first out. */ static void async_queue_event (gdb_event *event_ptr) { /* 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; } /* Process one event. If an event was processed, 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 (void) { gdb_event *event_ptr, *prev_ptr; event_handler_func *proc; int fd; /* 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, since the proc function could end up jumping out to the caller of this function. In that case, we would have on the event queue an event which 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 (event_ptr); /* Now call the procedure associated with the event. */ (*proc) (fd); return 1; } /* This is the case if there are no event on the event queue. */ return 0; } /* 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. 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. */ static void create_file_handler (int fd, int mask, handler_func *proc, gdb_client_data client_data) { file_handler *file_ptr; /* 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. Add it to the list. Otherwise, just change the data associated with it. */ if (file_ptr == NULL) { file_ptr = xmalloc (sizeof (*file_ptr)); 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; if (mask & GDB_READABLE) FD_SET (fd, &gdb_notifier.check_masks[0]); else FD_CLR (fd, &gdb_notifier.check_masks[0]); if (mask & GDB_WRITABLE) FD_SET (fd, &gdb_notifier.check_masks[1]); else FD_CLR (fd, &gdb_notifier.check_masks[1]); if (mask & GDB_EXCEPTION) FD_SET (fd, &gdb_notifier.check_masks[2]); else FD_CLR (fd, &gdb_notifier.check_masks[2]); if (gdb_notifier.num_fds <= fd) gdb_notifier.num_fds = fd + 1; } file_ptr->proc = proc; file_ptr->client_data = client_data; file_ptr->mask = mask; } /* Wrapper function for create_file_handler. */ void add_file_handler (int fd, handler_func *proc, gdb_client_data client_data) { create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION, proc, client_data); } /* 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 (int fd) { file_handler *file_ptr, *prev_ptr = NULL; int i; /* 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; if (file_ptr->mask & GDB_READABLE) FD_CLR (fd, &gdb_notifier.check_masks[0]); if (file_ptr->mask & GDB_WRITABLE) FD_CLR (fd, &gdb_notifier.check_masks[1]); if (file_ptr->mask & GDB_EXCEPTION) FD_CLR (fd, &gdb_notifier.check_masks[2]); /* Find current max fd. */ if ((fd + 1) == gdb_notifier.num_fds) { gdb_notifier.num_fds--; for (i = gdb_notifier.num_fds; i; i--) { if (FD_ISSET (i - 1, &gdb_notifier.check_masks[0]) || FD_ISSET (i - 1, &gdb_notifier.check_masks[1]) || FD_ISSET (i - 1, &gdb_notifier.check_masks[2])) break; } gdb_notifier.num_fds = i; } /* Deactivate the file descriptor, by clearing its mask, so that it will not fire again. */ file_ptr->mask = 0; /* 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 (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 (int event_file_desc) { file_handler *file_ptr; int 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) { /* See if the desired events (mask) match the received events (ready_mask). */ if (file_ptr->ready_mask & GDB_EXCEPTION) { fprintf (stderr, "Exception condition detected on fd %d\n", file_ptr->fd); file_ptr->error = 1; } else file_ptr->error = 0; mask = file_ptr->ready_mask & file_ptr->mask; /* 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->error, file_ptr->client_data); break; } } } /* Create a file event, to be enqueued in the event queue for processing. The procedure associated to this event is always handle_file_event, which will in turn invoke the one that was associated to FD when it was registered with the event loop. */ static gdb_event * create_file_event (int fd) { gdb_event *file_event_ptr; file_event_ptr = xmalloc (sizeof (gdb_event)); file_event_ptr->proc = handle_file_event; file_event_ptr->fd = fd; return file_event_ptr; } /* Called by 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 select. Return -1 if there are no files descriptors to monitor, otherwise return 0. */ static int wait_for_event (void) { file_handler *file_ptr; gdb_event *file_event_ptr; int num_found = 0; /* Make sure all output is done before getting another event. */ fflush (stdout); fflush (stderr); if (gdb_notifier.num_fds == 0) return -1; gdb_notifier.ready_masks[0] = gdb_notifier.check_masks[0]; gdb_notifier.ready_masks[1] = gdb_notifier.check_masks[1]; gdb_notifier.ready_masks[2] = gdb_notifier.check_masks[2]; num_found = select (gdb_notifier.num_fds, &gdb_notifier.ready_masks[0], &gdb_notifier.ready_masks[1], &gdb_notifier.ready_masks[2], NULL); /* Clear the masks after an error from select. */ if (num_found == -1) { FD_ZERO (&gdb_notifier.ready_masks[0]); FD_ZERO (&gdb_notifier.ready_masks[1]); FD_ZERO (&gdb_notifier.ready_masks[2]); #ifdef EINTR /* Dont print anything if we got a signal, let gdb handle it. */ if (errno != EINTR) perror_with_name ("select"); #endif } /* 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. */ }
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