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