1 /* Serial interface for a selectable event.
2 Copyright (C) 2016-2017 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20 #include "ser-event.h"
22 #include "common/filestuff.h"
24 /* On POSIX hosts, a serial_event is basically an abstraction for the
25 classical self-pipe trick.
27 On Windows, a serial_event is a wrapper around a native Windows
28 event object. Because we want to interface with gdb_select, which
29 takes file descriptors, we need to wrap that Windows event object
30 in a file descriptor. As _open_osfhandle can not be used with
31 event objects, we instead create a dummy file wrap that in a file
32 descriptor with _open_osfhandle, and pass that as selectable
33 descriptor to callers. As Windows' gdb_select converts file
34 descriptors back to Windows handles by calling serial->wait_handle,
35 nothing ever actually waits on that file descriptor. */
37 struct serial_event_state
40 /* The Windows event object, created with CreateEvent. */
43 /* The write side of the pipe. The read side is in
49 /* Open a new serial event. */
52 serial_event_open (struct serial *scb, const char *name)
54 struct serial_event_state *state;
56 state = XNEW (struct serial_event_state);
63 if (gdb_pipe_cloexec (fds) == -1)
64 internal_error (__FILE__, __LINE__,
65 "creating serial event pipe failed.");
67 fcntl (fds[0], F_SETFL, O_NONBLOCK);
68 fcntl (fds[1], F_SETFL, O_NONBLOCK);
71 state->write_fd = fds[1];
75 /* A dummy file object that can be wrapped in a file descriptor.
76 We don't need to store this handle because closing the file
77 descriptor automatically closes this. */
80 /* A manual-reset event. */
81 state->event = CreateEvent (0, TRUE, FALSE, 0);
83 /* The dummy file handle. Created just so we have something
84 wrappable in a file descriptor. */
85 dummy_file = CreateFile ("nul", 0, 0, NULL, OPEN_EXISTING, 0, NULL);
86 scb->fd = _open_osfhandle ((intptr_t) dummy_file, 0);
94 serial_event_close (struct serial *scb)
96 struct serial_event_state *state = (struct serial_event_state *) scb->state;
100 close (state->write_fd);
102 CloseHandle (state->event);
113 /* Implementation of the wait_handle method. Returns the native
114 Windows event object handle. */
117 serial_event_wait_handle (struct serial *scb, HANDLE *read, HANDLE *except)
119 struct serial_event_state *state = (struct serial_event_state *) scb->state;
121 *read = state->event;
126 /* The serial_ops for struct serial_event objects. Note we never
127 register this serial type with serial_add_interface, because this
128 is internal implementation detail never to be used by remote
129 targets for protocol transport. */
131 static const struct serial_ops serial_event_ops =
139 NULL, /* flush_output */
140 NULL, /* flush_input */
141 NULL, /* send_break */
143 NULL, /* get_tty_state */
144 NULL, /* copy_tty_state */
145 NULL, /* set_tty_state */
146 NULL, /* print_tty_state */
147 NULL, /* noflush_set_tty_state */
148 NULL, /* setbaudrate */
149 NULL, /* setstopbits */
150 NULL, /* setparity */
151 NULL, /* drain_output */
153 NULL, /* read_prim */
154 NULL, /* write_prim */
157 serial_event_wait_handle,
161 /* See ser-event.h. */
163 struct serial_event *
164 make_serial_event (void)
166 return (struct serial_event *) serial_open_ops (&serial_event_ops);
169 /* See ser-event.h. */
172 serial_event_fd (struct serial_event *event)
174 struct serial *ser = (struct serial *) event;
179 /* See ser-event.h. */
182 serial_event_set (struct serial_event *event)
184 struct serial *ser = (struct serial *) event;
185 struct serial_event_state *state = (struct serial_event_state *) ser->state;
188 char c = '+'; /* Anything. */
192 r = write (state->write_fd, &c, 1);
194 while (r < 0 && errno == EINTR);
196 SetEvent (state->event);
200 /* See ser-event.h. */
203 serial_event_clear (struct serial_event *event)
205 struct serial *ser = (struct serial *) event;
206 struct serial_event_state *state = (struct serial_event_state *) ser->state;
214 r = read (ser->fd, &c, 1);
216 while (r > 0 || (r < 0 && errno == EINTR));
218 ResetEvent (state->event);