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 "io/channel-command.h"
  22 #include "io/channel-watch.h"
  23 #include "qemu/sockets.h"
  24 #include "trace.h"
  25
  26
  27 QIOChannelCommand *
  28 qio_channel_command_new_pid(int writefd,
  29                             int readfd,
  30                             pid_t pid)
  31 {
  32     QIOChannelCommand *ioc;
  33
  34     ioc = QIO_CHANNEL_COMMAND(object_new(TYPE_QIO_CHANNEL_COMMAND));
  35
  36     ioc->readfd = readfd;
  37     ioc->writefd = writefd;
  38     ioc->pid = pid;
  39
  40     trace_qio_channel_command_new_pid(ioc, writefd, readfd, pid);
  41     return ioc;
  42 }
  43
  44
  45 #ifndef WIN32
  46 QIOChannelCommand *
  47 qio_channel_command_new_spawn(const char *const argv[],
  48                               int flags,
  49                               Error **errp)
  50 {
  51     pid_t pid = -1;
  52     int stdinfd[2] = { -1, -1 };
  53     int stdoutfd[2] = { -1, -1 };
  54     int devnull = -1;
  55     bool stdinnull = false, stdoutnull = false;
  56     QIOChannelCommand *ioc;
  57
  58     flags = flags & O_ACCMODE;
  59
  60     if (flags == O_RDONLY) {
  61         stdinnull = true;
  62     }
  63     if (flags == O_WRONLY) {
  64         stdoutnull = true;
  65     }
  66
  67     if (stdinnull || stdoutnull) {
  68         devnull = open("/dev/null", O_RDWR);
  69         if (devnull < 0) {
  70             error_setg_errno(errp, errno,
  71                              "Unable to open /dev/null");
  72             goto error;
  73         }
  74     }
  75
  76     if ((!stdinnull && pipe(stdinfd) < 0) ||
  77         (!stdoutnull && pipe(stdoutfd) < 0)) {
  78         error_setg_errno(errp, errno,
  79                          "Unable to open pipe");
  80         goto error;
  81     }
  82
  83     pid = qemu_fork(errp);
  84     if (pid < 0) {
  85         goto error;
  86     }
  87
  88     if (pid == 0) { /* child */
  89         dup2(stdinnull ? devnull : stdinfd[0], STDIN_FILENO);
  90         dup2(stdoutnull ? devnull : stdoutfd[1], STDOUT_FILENO);
  91         /* Leave stderr connected to qemu's stderr */
  92
  93         if (!stdinnull) {
  94             close(stdinfd[0]);
  95             close(stdinfd[1]);
  96         }
  97         if (!stdoutnull) {
  98             close(stdoutfd[0]);
  99             close(stdoutfd[1]);
 100         }
 101         if (devnull != -1) {
 102             close(devnull);
 103         }
 104
 105         execv(argv[0], (char * const *)argv);
 106         _exit(1);
 107     }
 108
 109     if (!stdinnull) {
 110         close(stdinfd[0]);
 111     }
 112     if (!stdoutnull) {
 113         close(stdoutfd[1]);
 114     }
 115
 116     ioc = qio_channel_command_new_pid(stdinnull ? devnull : stdinfd[1],
 117                                       stdoutnull ? devnull : stdoutfd[0],
 118                                       pid);
 119     trace_qio_channel_command_new_spawn(ioc, argv[0], flags);
 120     return ioc;
 121
 122  error:
 123     if (devnull != -1) {
 124         close(devnull);
 125     }
 126     if (stdinfd[0] != -1) {
 127         close(stdinfd[0]);
 128     }
 129     if (stdinfd[1] != -1) {
 130         close(stdinfd[1]);
 131     }
 132     if (stdoutfd[0] != -1) {
 133         close(stdoutfd[0]);
 134     }
 135     if (stdoutfd[1] != -1) {
 136         close(stdoutfd[1]);
 137     }
 138     return NULL;
 139 }
 140
 141 #else /* WIN32 */
 142 QIOChannelCommand *
 143 qio_channel_command_new_spawn(const char *const argv[],
 144                               int flags,
 145                               Error **errp)
 146 {
 147     error_setg_errno(errp, ENOSYS,
 148                      "Command spawn not supported on this platform");
 149     return NULL;
 150 }
 151 #endif /* WIN32 */
 152
 153 #ifndef WIN32
 154 static int qio_channel_command_abort(QIOChannelCommand *ioc,
 155                                      Error **errp)
 156 {
 157     pid_t ret;
 158     int status;
 159     int step = 0;
 160
 161     /* See if intermediate process has exited; if not, try a nice
 162      * SIGTERM followed by a more severe SIGKILL.
 163      */
 164  rewait:
 165     trace_qio_channel_command_abort(ioc, ioc->pid);
 166     ret = waitpid(ioc->pid, &status, WNOHANG);
 167     trace_qio_channel_command_wait(ioc, ioc->pid, ret, status);
 168     if (ret == (pid_t)-1) {
 169         if (errno == EINTR) {
 170             goto rewait;
 171         } else {
 172             error_setg_errno(errp, errno,
 173                              "Cannot wait on pid %llu",
 174                              (unsigned long long)ioc->pid);
 175             return -1;
 176         }
 177     } else if (ret == 0) {
 178         if (step == 0) {
 179             kill(ioc->pid, SIGTERM);
 180         } else if (step == 1) {
 181             kill(ioc->pid, SIGKILL);
 182         } else {
 183             error_setg(errp,
 184                        "Process %llu refused to die",
 185                        (unsigned long long)ioc->pid);
 186             return -1;
 187         }
 188         step++;
 189         usleep(10 * 1000);
 190         goto rewait;
 191     }
 192
 193     return 0;
 194 }
 195 #endif /* ! WIN32 */
 196
 197
 198 static void qio_channel_command_init(Object *obj)
 199 {
 200     QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
 201     ioc->readfd = -1;
 202     ioc->writefd = -1;
 203     ioc->pid = -1;
 204 }
 205
 206 static void qio_channel_command_finalize(Object *obj)
 207 {
 208     QIOChannelCommand *ioc = QIO_CHANNEL_COMMAND(obj);
 209     if (ioc->readfd != -1) {
 210         close(ioc->readfd);
 211     }
 212     if (ioc->writefd != -1 &&
 213         ioc->writefd != ioc->readfd) {
 214         close(ioc->writefd);
 215     }
 216     ioc->writefd = ioc->readfd = -1;
 217     if (ioc->pid > 0) {
 218 #ifndef WIN32
 219         qio_channel_command_abort(ioc, NULL);
 220 #endif
 221     }
 222 }
 223
 224
 225 static ssize_t qio_channel_command_readv(QIOChannel *ioc,
 226                                          const struct iovec *iov,
 227                                          size_t niov,
 228                                          int **fds,
 229                                          size_t *nfds,
 230                                          Error **errp)
 231 {
 232     QIOChannelCommand *cioc = QIO_CHANNEL_COMMAND(ioc);
 233     ssize_t ret;
 234
 235  retry:
 236     ret = readv(cioc->readfd, iov, niov);
 237     if (ret < 0) {
 238         if (errno == EAGAIN ||
 239             errno == EWOULDBLOCK) {
 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             errno == EWOULDBLOCK) {
 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);