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- /* Serial interface for a selectable event.
- Copyright (C) 2016-2022 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 "ser-event.h"
- #include "serial.h"
- #include "gdbsupport/filestuff.h"
- /* On POSIX hosts, a serial_event is basically an abstraction for the
- classical self-pipe trick.
- On Windows, a serial_event is a wrapper around a native Windows
- event object. Because we want to interface with gdb_select, which
- takes file descriptors, we need to wrap that Windows event object
- in a file descriptor. As _open_osfhandle can not be used with
- event objects, we instead create a dummy file wrap that in a file
- descriptor with _open_osfhandle, and pass that as selectable
- descriptor to callers. As Windows' gdb_select converts file
- descriptors back to Windows handles by calling serial->wait_handle,
- nothing ever actually waits on that file descriptor. */
- struct serial_event_state
- {
- #ifdef USE_WIN32API
- /* The Windows event object, created with CreateEvent. */
- HANDLE event;
- #else
- /* The write side of the pipe. The read side is in
- serial->fd. */
- int write_fd;
- #endif
- };
- /* Open a new serial event. */
- static int
- serial_event_open (struct serial *scb, const char *name)
- {
- struct serial_event_state *state;
- state = XNEW (struct serial_event_state);
- scb->state = state;
- #ifndef USE_WIN32API
- {
- int fds[2];
- if (gdb_pipe_cloexec (fds) == -1)
- internal_error (__FILE__, __LINE__,
- "creating serial event pipe failed.");
- fcntl (fds[0], F_SETFL, O_NONBLOCK);
- fcntl (fds[1], F_SETFL, O_NONBLOCK);
- scb->fd = fds[0];
- state->write_fd = fds[1];
- }
- #else
- {
- /* A dummy file object that can be wrapped in a file descriptor.
- We don't need to store this handle because closing the file
- descriptor automatically closes this. */
- HANDLE dummy_file;
- /* A manual-reset event. */
- state->event = CreateEvent (0, TRUE, FALSE, 0);
- /* The dummy file handle. Created just so we have something
- wrappable in a file descriptor. */
- dummy_file = CreateFile ("nul", 0, 0, NULL, OPEN_EXISTING, 0, NULL);
- scb->fd = _open_osfhandle ((intptr_t) dummy_file, 0);
- }
- #endif
- return 0;
- }
- static void
- serial_event_close (struct serial *scb)
- {
- struct serial_event_state *state = (struct serial_event_state *) scb->state;
- close (scb->fd);
- #ifndef USE_WIN32API
- close (state->write_fd);
- #else
- CloseHandle (state->event);
- #endif
- scb->fd = -1;
- xfree (state);
- scb->state = NULL;
- }
- #ifdef USE_WIN32API
- /* Implementation of the wait_handle method. Returns the native
- Windows event object handle. */
- static void
- serial_event_wait_handle (struct serial *scb, HANDLE *read, HANDLE *except)
- {
- struct serial_event_state *state = (struct serial_event_state *) scb->state;
- *read = state->event;
- }
- #endif
- /* The serial_ops for struct serial_event objects. Note we never
- register this serial type with serial_add_interface, because this
- is internal implementation detail never to be used by remote
- targets for protocol transport. */
- static const struct serial_ops serial_event_ops =
- {
- "event",
- serial_event_open,
- serial_event_close,
- NULL, /* fdopen */
- NULL, /* readchar */
- NULL, /* write */
- NULL, /* flush_output */
- NULL, /* flush_input */
- NULL, /* send_break */
- NULL, /* go_raw */
- NULL, /* get_tty_state */
- NULL, /* copy_tty_state */
- NULL, /* set_tty_state */
- NULL, /* print_tty_state */
- NULL, /* setbaudrate */
- NULL, /* setstopbits */
- NULL, /* setparity */
- NULL, /* drain_output */
- NULL, /* async */
- NULL, /* read_prim */
- NULL, /* write_prim */
- NULL, /* avail */
- #ifdef USE_WIN32API
- serial_event_wait_handle,
- #endif
- };
- /* See ser-event.h. */
- struct serial_event *
- make_serial_event (void)
- {
- return (struct serial_event *) serial_open_ops (&serial_event_ops);
- }
- /* See ser-event.h. */
- int
- serial_event_fd (struct serial_event *event)
- {
- struct serial *ser = (struct serial *) event;
- return ser->fd;
- }
- /* See ser-event.h. */
- void
- serial_event_set (struct serial_event *event)
- {
- struct serial *ser = (struct serial *) event;
- struct serial_event_state *state = (struct serial_event_state *) ser->state;
- #ifndef USE_WIN32API
- int r;
- char c = '+'; /* Anything. */
- do
- {
- r = write (state->write_fd, &c, 1);
- }
- while (r < 0 && errno == EINTR);
- #else
- SetEvent (state->event);
- #endif
- }
- /* See ser-event.h. */
- void
- serial_event_clear (struct serial_event *event)
- {
- struct serial *ser = (struct serial *) event;
- #ifndef USE_WIN32API
- int r;
- do
- {
- char c;
- r = read (ser->fd, &c, 1);
- }
- while (r > 0 || (r < 0 && errno == EINTR));
- #else
- struct serial_event_state *state = (struct serial_event_state *) ser->state;
- ResetEvent (state->event);
- #endif
- }
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