| 1 | /* Serial interface for a selectable event. |
| 2 | Copyright (C) 2016-2019 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 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. |
| 10 | |
| 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. |
| 15 | |
| 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/>. */ |
| 18 | |
| 19 | #include "defs.h" |
| 20 | #include "ser-event.h" |
| 21 | #include "serial.h" |
| 22 | #include "gdbsupport/filestuff.h" |
| 23 | |
| 24 | /* On POSIX hosts, a serial_event is basically an abstraction for the |
| 25 | classical self-pipe trick. |
| 26 | |
| 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. */ |
| 36 | |
| 37 | struct serial_event_state |
| 38 | { |
| 39 | #ifdef USE_WIN32API |
| 40 | /* The Windows event object, created with CreateEvent. */ |
| 41 | HANDLE event; |
| 42 | #else |
| 43 | /* The write side of the pipe. The read side is in |
| 44 | serial->fd. */ |
| 45 | int write_fd; |
| 46 | #endif |
| 47 | }; |
| 48 | |
| 49 | /* Open a new serial event. */ |
| 50 | |
| 51 | static int |
| 52 | serial_event_open (struct serial *scb, const char *name) |
| 53 | { |
| 54 | struct serial_event_state *state; |
| 55 | |
| 56 | state = XNEW (struct serial_event_state); |
| 57 | scb->state = state; |
| 58 | |
| 59 | #ifndef USE_WIN32API |
| 60 | { |
| 61 | int fds[2]; |
| 62 | |
| 63 | if (gdb_pipe_cloexec (fds) == -1) |
| 64 | internal_error (__FILE__, __LINE__, |
| 65 | "creating serial event pipe failed."); |
| 66 | |
| 67 | fcntl (fds[0], F_SETFL, O_NONBLOCK); |
| 68 | fcntl (fds[1], F_SETFL, O_NONBLOCK); |
| 69 | |
| 70 | scb->fd = fds[0]; |
| 71 | state->write_fd = fds[1]; |
| 72 | } |
| 73 | #else |
| 74 | { |
| 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. */ |
| 78 | HANDLE dummy_file; |
| 79 | |
| 80 | /* A manual-reset event. */ |
| 81 | state->event = CreateEvent (0, TRUE, FALSE, 0); |
| 82 | |
| 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); |
| 87 | } |
| 88 | #endif |
| 89 | |
| 90 | return 0; |
| 91 | } |
| 92 | |
| 93 | static void |
| 94 | serial_event_close (struct serial *scb) |
| 95 | { |
| 96 | struct serial_event_state *state = (struct serial_event_state *) scb->state; |
| 97 | |
| 98 | close (scb->fd); |
| 99 | #ifndef USE_WIN32API |
| 100 | close (state->write_fd); |
| 101 | #else |
| 102 | CloseHandle (state->event); |
| 103 | #endif |
| 104 | |
| 105 | scb->fd = -1; |
| 106 | |
| 107 | xfree (state); |
| 108 | scb->state = NULL; |
| 109 | } |
| 110 | |
| 111 | #ifdef USE_WIN32API |
| 112 | |
| 113 | /* Implementation of the wait_handle method. Returns the native |
| 114 | Windows event object handle. */ |
| 115 | |
| 116 | static void |
| 117 | serial_event_wait_handle (struct serial *scb, HANDLE *read, HANDLE *except) |
| 118 | { |
| 119 | struct serial_event_state *state = (struct serial_event_state *) scb->state; |
| 120 | |
| 121 | *read = state->event; |
| 122 | } |
| 123 | |
| 124 | #endif |
| 125 | |
| 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. */ |
| 130 | |
| 131 | static const struct serial_ops serial_event_ops = |
| 132 | { |
| 133 | "event", |
| 134 | serial_event_open, |
| 135 | serial_event_close, |
| 136 | NULL, /* fdopen */ |
| 137 | NULL, /* readchar */ |
| 138 | NULL, /* write */ |
| 139 | NULL, /* flush_output */ |
| 140 | NULL, /* flush_input */ |
| 141 | NULL, /* send_break */ |
| 142 | NULL, /* go_raw */ |
| 143 | NULL, /* get_tty_state */ |
| 144 | NULL, /* copy_tty_state */ |
| 145 | NULL, /* set_tty_state */ |
| 146 | NULL, /* print_tty_state */ |
| 147 | NULL, /* setbaudrate */ |
| 148 | NULL, /* setstopbits */ |
| 149 | NULL, /* setparity */ |
| 150 | NULL, /* drain_output */ |
| 151 | NULL, /* async */ |
| 152 | NULL, /* read_prim */ |
| 153 | NULL, /* write_prim */ |
| 154 | NULL, /* avail */ |
| 155 | #ifdef USE_WIN32API |
| 156 | serial_event_wait_handle, |
| 157 | #endif |
| 158 | }; |
| 159 | |
| 160 | /* See ser-event.h. */ |
| 161 | |
| 162 | struct serial_event * |
| 163 | make_serial_event (void) |
| 164 | { |
| 165 | return (struct serial_event *) serial_open_ops (&serial_event_ops); |
| 166 | } |
| 167 | |
| 168 | /* See ser-event.h. */ |
| 169 | |
| 170 | int |
| 171 | serial_event_fd (struct serial_event *event) |
| 172 | { |
| 173 | struct serial *ser = (struct serial *) event; |
| 174 | |
| 175 | return ser->fd; |
| 176 | } |
| 177 | |
| 178 | /* See ser-event.h. */ |
| 179 | |
| 180 | void |
| 181 | serial_event_set (struct serial_event *event) |
| 182 | { |
| 183 | struct serial *ser = (struct serial *) event; |
| 184 | struct serial_event_state *state = (struct serial_event_state *) ser->state; |
| 185 | #ifndef USE_WIN32API |
| 186 | int r; |
| 187 | char c = '+'; /* Anything. */ |
| 188 | |
| 189 | do |
| 190 | { |
| 191 | r = write (state->write_fd, &c, 1); |
| 192 | } |
| 193 | while (r < 0 && errno == EINTR); |
| 194 | #else |
| 195 | SetEvent (state->event); |
| 196 | #endif |
| 197 | } |
| 198 | |
| 199 | /* See ser-event.h. */ |
| 200 | |
| 201 | void |
| 202 | serial_event_clear (struct serial_event *event) |
| 203 | { |
| 204 | struct serial *ser = (struct serial *) event; |
| 205 | #ifndef USE_WIN32API |
| 206 | int r; |
| 207 | |
| 208 | do |
| 209 | { |
| 210 | char c; |
| 211 | |
| 212 | r = read (ser->fd, &c, 1); |
| 213 | } |
| 214 | while (r > 0 || (r < 0 && errno == EINTR)); |
| 215 | #else |
| 216 | struct serial_event_state *state = (struct serial_event_state *) ser->state; |
| 217 | ResetEvent (state->event); |
| 218 | #endif |
| 219 | } |