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