aboutsummaryrefslogtreecommitdiff
path: root/io/channel-command.c
blob: 6d5f64e146d45c7ed330063711b5295816591a38 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
/*
 * QEMU I/O channels external command driver
 *
 * Copyright (c) 2015 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "qemu/osdep.h"
#include "io/channel-command.h"
#include "io/channel-util.h"
#include "io/channel-watch.h"
#include "qapi/error.h"
#include "qemu/module.h"
#include "qemu/sockets.h"
#include "trace.h"

/**
 * qio_channel_command_new_pid:
 * @writefd: the FD connected to the command's stdin
 * @readfd: the FD connected to the command's stdout
 * @pid: the PID/HANDLE of the running child command
 * @errp: pointer to a NULL-initialized error object
 *
 * Create a channel for performing I/O with the
 * previously spawned command identified by @pid.
 * The two file descriptors provide the connection
 * to command's stdio streams, either one or which
 * may be -1 to indicate that stream is not open.
 *
 * The channel will take ownership of the process
 * @pid and will kill it when closing the channel.
 * Similarly it will take responsibility for
 * closing the file descriptors @writefd and @readfd.
 *
 * Returns: the command channel object, or NULL on error
 */
static QIOChannelCommand *
qio_channel_command_new_pid(int writefd,
                            int readfd,
                            GPid pid)
{
    QIOChannelCommand *ioc;

    ioc = QIO_CHANNEL_COMMAND(object_new(TYPE_QIO_CHANNEL_COMMAND));

    ioc->readfd = readfd;
    ioc->writefd = writefd;
    ioc->pid = pid;

    trace_qio_channel_command_new_pid(ioc, writefd, readfd,
#ifdef WIN32
                                      GetProcessId(pid)
#else
                                      pid
#endif
        );
    return ioc;
}

QIOChannelCommand *
qio_channel_command_new_spawn(const char *const argv[],
                              int flags,
                              Error **errp)
{
    g_autoptr(GError) err = NULL;
    GPid pid = 0;
    GSpawnFlags gflags = G_SPAWN_CLOEXEC_PIPES | G_SPAWN_DO_NOT_REAP_CHILD;
    int stdinfd = -1, stdoutfd = -1;

    flags = flags & O_ACCMODE;
    gflags |= flags == O_WRONLY ? G_SPAWN_STDOUT_TO_DEV_NULL : 0;

    if (!g_spawn_async_with_pipes(NULL, (char **)argv, NULL, gflags, NULL, NULL,
                                  &pid,
                                  flags == O_RDONLY ? NULL : &stdinfd,
                                  flags == O_WRONLY ? NULL : &stdoutfd,
                                  NULL, &err)) {
        error_setg(errp, "%s", err->message);
        return NULL;
    }

    return qio_channel_command_new_pid(stdinfd, stdoutfd, pid);
}

#ifndef WIN32
static int qio_channel_command_abort(QIOChannelCommand *ioc,
                                     Error **errp)
{
    pid_t ret;
    int status;
    int step = 0;

    /* See if intermediate process has exited; if not, try a nice
     * SIGTERM followed by a more severe SIGKILL.
     */
 rewait:
    trace_qio_channel_command_abort(ioc, ioc->pid);
    ret = waitpid(ioc->pid, &status, WNOHANG);
    trace_qio_channel_command_wait(ioc, ioc->pid, ret, status);
    if (ret == (pid_t)-1) {
        if (errno == EINTR) {
            goto rewait;
        } else {
            error_setg_errno(errp, errno,
                             "Cannot wait on pid %llu",
                             (unsigned long long)ioc->pid);
            return -1;
        }
    } else if (ret == 0) {
        if (step == 0) {
            kill(ioc->pid, SIGTERM);
        } else if (step == 1) {
            kill(ioc->pid, SIGKILL);
        } else {
            error_setg(errp,
                       "Process %llu refused to die",
                       (unsigned long long)ioc->pid);
            return -1;
        }
        step++;
        usleep(10 * 1000);
        goto rewait;
    }

    return 0;
}
#else
static int qio_channel_command_abort(QIOChannelCommand *ioc,
                                     Error **errp)
{
    DWORD ret;

    TerminateProcess(ioc->pid, 0);
    ret = WaitForSingleObject(ioc->pid, 1000);
    if (ret != WAIT_OBJECT_0) {
        error_setg(errp,
                   "Process %llu refused to die",
                   (unsigned long long)GetProcessId(ioc->pid));
        return -1;
    }

    return 0;
}
#endif /* ! WIN32 */


static void qio_channel_command_init(Object *obj)
{
    QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
    ioc->readfd = -1;
    ioc->writefd = -1;
    ioc->pid = 0;
}

static void qio_channel_command_finalize(Object *obj)
{
    QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
    if (ioc->readfd != -1) {
        close(ioc->readfd);
    }
    if (ioc->writefd != -1 &&
        ioc->writefd != ioc->readfd) {
        close(ioc->writefd);
    }
    ioc->writefd = ioc->readfd = -1;
    if (ioc->pid > 0) {
        qio_channel_command_abort(ioc, NULL);
        g_spawn_close_pid(ioc->pid);
    }
}

#ifdef WIN32
static bool win32_fd_poll(int fd, gushort events)
{
    GPollFD pfd = { .fd = _get_osfhandle(fd), .events = events };
    int res;

    do {
        res = g_poll(&pfd, 1, 0);
    } while (res < 0 && errno == EINTR);
    if (res == 0) {
        return false;
    }

    return true;
}
#endif

static ssize_t qio_channel_command_readv(QIOChannel *ioc,
                                         const struct iovec *iov,
                                         size_t niov,
                                         int **fds,
                                         size_t *nfds,
                                         int flags,
                                         Error **errp)
{
    QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
    ssize_t ret;

#ifdef WIN32
    if (!cioc->blocking && !win32_fd_poll(cioc->readfd, G_IO_IN)) {
        return QIO_CHANNEL_ERR_BLOCK;
    }
#endif

 retry:
    ret = readv(cioc->readfd, iov, niov);
    if (ret < 0) {
        if (errno == EAGAIN) {
            return QIO_CHANNEL_ERR_BLOCK;
        }
        if (errno == EINTR) {
            goto retry;
        }

        error_setg_errno(errp, errno,
                         "Unable to read from command");
        return -1;
    }

    return ret;
}

static ssize_t qio_channel_command_writev(QIOChannel *ioc,
                                          const struct iovec *iov,
                                          size_t niov,
                                          int *fds,
                                          size_t nfds,
                                          int flags,
                                          Error **errp)
{
    QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
    ssize_t ret;

#ifdef WIN32
    if (!cioc->blocking && !win32_fd_poll(cioc->writefd, G_IO_OUT)) {
        return QIO_CHANNEL_ERR_BLOCK;
    }
#endif

 retry:
    ret = writev(cioc->writefd, iov, niov);
    if (ret <= 0) {
        if (errno == EAGAIN) {
            return QIO_CHANNEL_ERR_BLOCK;
        }
        if (errno == EINTR) {
            goto retry;
        }
        error_setg_errno(errp, errno, "%s",
                         "Unable to write to command");
        return -1;
    }
    return ret;
}

static int qio_channel_command_set_blocking(QIOChannel *ioc,
                                            bool enabled,
                                            Error **errp)
{
    QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);

#ifdef WIN32
    cioc->blocking = enabled;
#else

    if ((cioc->writefd >= 0 && !g_unix_set_fd_nonblocking(cioc->writefd, !enabled, NULL)) ||
        (cioc->readfd >= 0 && !g_unix_set_fd_nonblocking(cioc->readfd, !enabled, NULL))) {
        error_setg_errno(errp, errno, "Failed to set FD nonblocking");
        return -1;
    }
#endif
    return 0;
}


static int qio_channel_command_close(QIOChannel *ioc,
                                     Error **errp)
{
    QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
    int rv = 0;
#ifndef WIN32
    pid_t wp;
#endif

    /* We close FDs before killing, because that
     * gives a better chance of clean shutdown
     */
    if (cioc->readfd != -1 &&
        close(cioc->readfd) < 0) {
        rv = -1;
    }
    if (cioc->writefd != -1 &&
        cioc->writefd != cioc->readfd &&
        close(cioc->writefd) < 0) {
        rv = -1;
    }
    cioc->writefd = cioc->readfd = -1;

#ifndef WIN32
    do {
        wp = waitpid(cioc->pid, NULL, 0);
    } while (wp == (pid_t)-1 && errno == EINTR);
    if (wp == (pid_t)-1) {
        error_setg_errno(errp, errno, "Failed to wait for pid %llu",
                         (unsigned long long)cioc->pid);
        return -1;
    }
#else
    WaitForSingleObject(cioc->pid, INFINITE);
#endif

    if (rv < 0) {
        error_setg_errno(errp, errno, "%s",
                         "Unable to close command");
    }
    return rv;
}


static void qio_channel_command_set_aio_fd_handler(QIOChannel *ioc,
                                                   AioContext *read_ctx,
                                                   IOHandler *io_read,
                                                   AioContext *write_ctx,
                                                   IOHandler *io_write,
                                                   void *opaque)
{
    QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);

    qio_channel_util_set_aio_fd_handler(cioc->readfd, read_ctx, io_read,
                                        cioc->writefd, write_ctx, io_write,
                                        opaque);
}


static GSource *qio_channel_command_create_watch(QIOChannel *ioc,
                                                 GIOCondition condition)
{
    QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
    return qio_channel_create_fd_pair_watch(ioc,
                                            cioc->readfd,
                                            cioc->writefd,
                                            condition);
}


static void qio_channel_command_class_init(ObjectClass *klass,
                                           void *class_data G_GNUC_UNUSED)
{
    QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);

    ioc_klass->io_writev = qio_channel_command_writev;
    ioc_klass->io_readv = qio_channel_command_readv;
    ioc_klass->io_set_blocking = qio_channel_command_set_blocking;
    ioc_klass->io_close = qio_channel_command_close;
    ioc_klass->io_create_watch = qio_channel_command_create_watch;
    ioc_klass->io_set_aio_fd_handler = qio_channel_command_set_aio_fd_handler;
}

static const TypeInfo qio_channel_command_info = {
    .parent = TYPE_QIO_CHANNEL,
    .name = TYPE_QIO_CHANNEL_COMMAND,
    .instance_size = sizeof(QIOChannelCommand),
    .instance_init = qio_channel_command_init,
    .instance_finalize = qio_channel_command_finalize,
    .class_init = qio_channel_command_class_init,
};

static void qio_channel_command_register_types(void)
{
    type_register_static(&qio_channel_command_info);
}

type_init(qio_channel_command_register_types);