io/channel-command.c

   1 /*
   2  * QEMU I/O channels external command driver
   3  *
   4  * Copyright (c) 2015 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library 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 GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "io/channel-command.h"
  23 #include "io/channel-watch.h"
  24 #include "qapi/error.h"
  25 #include "qemu/module.h"
  26 #include "qemu/sockets.h"
  27 #include "trace.h"
  28
  29
  30 QIOChannelCommand *
  31 qio_channel_command_new_pid(int writefd,
  32                             int readfd,
  33                             pid_t pid)
  34 {
  35     QIOChannelCommand *ioc;
  36
  37     ioc = QIO_CHANNEL_COMMAND(object_new(TYPE_QIO_CHANNEL_COMMAND));
  38
  39     ioc->readfd = readfd;
  40     ioc->writefd = writefd;
  41     ioc->pid = pid;
  42
  43     trace_qio_channel_command_new_pid(ioc, writefd, readfd, pid);
  44     return ioc;
  45 }
  46
  47
  48 #ifndef WIN32
  49 QIOChannelCommand *
  50 qio_channel_command_new_spawn(const char *const argv[],
  51                               int flags,
  52                               Error **errp)
  53 {
  54     pid_t pid = -1;
  55     int stdinfd[2] = { -1, -1 };
  56     int stdoutfd[2] = { -1, -1 };
  57     int devnull = -1;
  58     bool stdinnull = false, stdoutnull = false;
  59     QIOChannelCommand *ioc;
  60
  61     flags = flags & O_ACCMODE;
  62
  63     if (flags == O_RDONLY) {
  64         stdinnull = true;
  65     }
  66     if (flags == O_WRONLY) {
  67         stdoutnull = true;
  68     }
  69
  70     if (stdinnull || stdoutnull) {
  71         devnull = open("/dev/null", O_RDWR);
  72         if (devnull < 0) {
  73             error_setg_errno(errp, errno,
  74                              "Unable to open /dev/null");
  75             goto error;
  76         }
  77     }
  78
  79     if ((!stdinnull && pipe(stdinfd) < 0) ||
  80         (!stdoutnull && pipe(stdoutfd) < 0)) {
  81         error_setg_errno(errp, errno,
  82                          "Unable to open pipe");
  83         goto error;
  84     }
  85
  86     pid = qemu_fork(errp);
  87     if (pid < 0) {
  88         goto error;
  89     }
  90
  91     if (pid == 0) { /* child */
  92         dup2(stdinnull ? devnull : stdinfd[0], STDIN_FILENO);
  93         dup2(stdoutnull ? devnull : stdoutfd[1], STDOUT_FILENO);
  94         /* Leave stderr connected to qemu's stderr */
  95
  96         if (!stdinnull) {
  97             close(stdinfd[0]);
  98             close(stdinfd[1]);
  99         }
 100         if (!stdoutnull) {
 101             close(stdoutfd[0]);
 102             close(stdoutfd[1]);
 103         }
 104         if (devnull != -1) {
 105             close(devnull);
 106         }
 107
 108         execv(argv[0], (char * const *)argv);
 109         _exit(1);
 110     }
 111
 112     if (!stdinnull) {
 113         close(stdinfd[0]);
 114     }
 115     if (!stdoutnull) {
 116         close(stdoutfd[1]);
 117     }
 118
 119     ioc = qio_channel_command_new_pid(stdinnull ? devnull : stdinfd[1],
 120                                       stdoutnull ? devnull : stdoutfd[0],
 121                                       pid);
 122     trace_qio_channel_command_new_spawn(ioc, argv[0], flags);
 123     return ioc;
 124
 125  error:
 126     if (devnull != -1) {
 127         close(devnull);
 128     }
 129     if (stdinfd[0] != -1) {
 130         close(stdinfd[0]);
 131     }
 132     if (stdinfd[1] != -1) {
 133         close(stdinfd[1]);
 134     }
 135     if (stdoutfd[0] != -1) {
 136         close(stdoutfd[0]);
 137     }
 138     if (stdoutfd[1] != -1) {
 139         close(stdoutfd[1]);
 140     }
 141     return NULL;
 142 }
 143
 144 #else /* WIN32 */
 145 QIOChannelCommand *
 146 qio_channel_command_new_spawn(const char *const argv[],
 147                               int flags,
 148                               Error **errp)
 149 {
 150     error_setg_errno(errp, ENOSYS,
 151                      "Command spawn not supported on this platform");
 152     return NULL;
 153 }
 154 #endif /* WIN32 */
 155
 156 #ifndef WIN32
 157 static int qio_channel_command_abort(QIOChannelCommand *ioc,
 158                                      Error **errp)
 159 {
 160     pid_t ret;
 161     int status;
 162     int step = 0;
 163
 164     /* See if intermediate process has exited; if not, try a nice
 165      * SIGTERM followed by a more severe SIGKILL.
 166      */
 167  rewait:
 168     trace_qio_channel_command_abort(ioc, ioc->pid);
 169     ret = waitpid(ioc->pid, &status, WNOHANG);
 170     trace_qio_channel_command_wait(ioc, ioc->pid, ret, status);
 171     if (ret == (pid_t)-1) {
 172         if (errno == EINTR) {
 173             goto rewait;
 174         } else {
 175             error_setg_errno(errp, errno,
 176                              "Cannot wait on pid %llu",
 177                              (unsigned long long)ioc->pid);
 178             return -1;
 179         }
 180     } else if (ret == 0) {
 181         if (step == 0) {
 182             kill(ioc->pid, SIGTERM);
 183         } else if (step == 1) {
 184             kill(ioc->pid, SIGKILL);
 185         } else {
 186             error_setg(errp,
 187                        "Process %llu refused to die",
 188                        (unsigned long long)ioc->pid);
 189             return -1;
 190         }
 191         step++;
 192         usleep(10 * 1000);
 193         goto rewait;
 194     }
 195
 196     return 0;
 197 }
 198 #endif /* ! WIN32 */
 199
 200
 201 static void qio_channel_command_init(Object *obj)
 202 {
 203     QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
 204     ioc->readfd = -1;
 205     ioc->writefd = -1;
 206     ioc->pid = -1;
 207 }
 208
 209 static void qio_channel_command_finalize(Object *obj)
 210 {
 211     QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
 212     if (ioc->readfd != -1) {
 213         close(ioc->readfd);
 214     }
 215     if (ioc->writefd != -1 &&
 216         ioc->writefd != ioc->readfd) {
 217         close(ioc->writefd);
 218     }
 219     ioc->writefd = ioc->readfd = -1;
 220     if (ioc->pid > 0) {
 221 #ifndef WIN32
 222         qio_channel_command_abort(ioc, NULL);
 223 #endif
 224     }
 225 }
 226
 227
 228 static ssize_t qio_channel_command_readv(QIOChannel *ioc,
 229                                          const struct iovec *iov,
 230                                          size_t niov,
 231                                          int **fds,
 232                                          size_t *nfds,
 233                                          Error **errp)
 234 {
 235     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 236     ssize_t ret;
 237
 238  retry:
 239     ret = readv(cioc->readfd, iov, niov);
 240     if (ret < 0) {
 241         if (errno == EAGAIN) {
 242             return QIO_CHANNEL_ERR_BLOCK;
 243         }
 244         if (errno == EINTR) {
 245             goto retry;
 246         }
 247
 248         error_setg_errno(errp, errno,
 249                          "Unable to read from command");
 250         return -1;
 251     }
 252
 253     return ret;
 254 }
 255
 256 static ssize_t qio_channel_command_writev(QIOChannel *ioc,
 257                                           const struct iovec *iov,
 258                                           size_t niov,
 259                                           int *fds,
 260                                           size_t nfds,
 261                                           Error **errp)
 262 {
 263     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 264     ssize_t ret;
 265
 266  retry:
 267     ret = writev(cioc->writefd, iov, niov);
 268     if (ret <= 0) {
 269         if (errno == EAGAIN) {
 270             return QIO_CHANNEL_ERR_BLOCK;
 271         }
 272         if (errno == EINTR) {
 273             goto retry;
 274         }
 275         error_setg_errno(errp, errno, "%s",
 276                          "Unable to write to command");
 277         return -1;
 278     }
 279     return ret;
 280 }
 281
 282 static int qio_channel_command_set_blocking(QIOChannel *ioc,
 283                                             bool enabled,
 284                                             Error **errp)
 285 {
 286     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 287
 288     if (enabled) {
 289         qemu_set_block(cioc->writefd);
 290         qemu_set_block(cioc->readfd);
 291     } else {
 292         qemu_set_nonblock(cioc->writefd);
 293         qemu_set_nonblock(cioc->readfd);
 294     }
 295
 296     return 0;
 297 }
 298
 299
 300 static int qio_channel_command_close(QIOChannel *ioc,
 301                                      Error **errp)
 302 {
 303     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 304     int rv = 0;
 305 #ifndef WIN32
 306     pid_t wp;
 307 #endif
 308
 309     /* We close FDs before killing, because that
 310      * gives a better chance of clean shutdown
 311      */
 312     if (cioc->readfd != -1 &&
 313         close(cioc->readfd) < 0) {
 314         rv = -1;
 315     }
 316     if (cioc->writefd != -1 &&
 317         cioc->writefd != cioc->readfd &&
 318         close(cioc->writefd) < 0) {
 319         rv = -1;
 320     }
 321     cioc->writefd = cioc->readfd = -1;
 322
 323 #ifndef WIN32
 324     do {
 325         wp = waitpid(cioc->pid, NULL, 0);
 326     } while (wp == (pid_t)-1 && errno == EINTR);
 327     if (wp == (pid_t)-1) {
 328         error_setg_errno(errp, errno, "Failed to wait for pid %llu",
 329                          (unsigned long long)cioc->pid);
 330         return -1;
 331     }
 332 #endif
 333
 334     if (rv < 0) {
 335         error_setg_errno(errp, errno, "%s",
 336                          "Unable to close command");
 337     }
 338     return rv;
 339 }
 340
 341
 342 static void qio_channel_command_set_aio_fd_handler(QIOChannel *ioc,
 343                                                    AioContext *ctx,
 344                                                    IOHandler *io_read,
 345                                                    IOHandler *io_write,
 346                                                    void *opaque)
 347 {
 348     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 349     aio_set_fd_handler(ctx, cioc->readfd, false, io_read, NULL, NULL, opaque);
 350     aio_set_fd_handler(ctx, cioc->writefd, false, NULL, io_write, NULL, opaque);
 351 }
 352
 353
 354 static GSource *qio_channel_command_create_watch(QIOChannel *ioc,
 355                                                  GIOCondition condition)
 356 {
 357     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 358     return qio_channel_create_fd_pair_watch(ioc,
 359                                             cioc->readfd,
 360                                             cioc->writefd,
 361                                             condition);
 362 }
 363
 364
 365 static void qio_channel_command_class_init(ObjectClass *klass,
 366                                            void *class_data G_GNUC_UNUSED)
 367 {
 368     QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
 369
 370     ioc_klass->io_writev = qio_channel_command_writev;
 371     ioc_klass->io_readv = qio_channel_command_readv;
 372     ioc_klass->io_set_blocking = qio_channel_command_set_blocking;
 373     ioc_klass->io_close = qio_channel_command_close;
 374     ioc_klass->io_create_watch = qio_channel_command_create_watch;
 375     ioc_klass->io_set_aio_fd_handler = qio_channel_command_set_aio_fd_handler;
 376 }
 377
 378 static const TypeInfo qio_channel_command_info = {
 379     .parent = TYPE_QIO_CHANNEL,
 380     .name = TYPE_QIO_CHANNEL_COMMAND,
 381     .instance_size = sizeof(QIOChannelCommand),
 382     .instance_init = qio_channel_command_init,
 383     .instance_finalize = qio_channel_command_finalize,
 384     .class_init = qio_channel_command_class_init,
 385 };
 386
 387 static void qio_channel_command_register_types(void)
 388 {
 389     type_register_static(&qio_channel_command_info);
 390 }
 391
 392 type_init(qio_channel_command_register_types);