git.ozlabs.org Git - petitboot/blob - lib/process/process.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; version 2 of the License.
   5  *
   6  * This program is distributed in the hope that it will be useful,
   7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9  * GNU General Public License for more details.
  10  *
  11  * You should have received a copy of the GNU General Public License
  12  * along with this program; if not, write to the Free Software
  13  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  14  */
  15
  16 #include <assert.h>
  17 #include <errno.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <sys/wait.h>
  21
  22 #include <process/process.h>
  23 #include <talloc/talloc.h>
  24 #include <waiter/waiter.h>
  25 #include <log/log.h>
  26
  27 struct procset {
  28         struct waitset          *waitset;
  29         struct list             async_list;
  30         int                     sigchld_pipe[2];
  31         struct waiter           *sigchld_waiter;
  32         bool                    dry_run;
  33 };
  34
  35 /* Internal data type for process handling
  36  *
  37  * Allocation: these structures may have multiple references:
  38  *  - from the original ctx pointer
  39  *  - due to inclusion in async_list
  40  *  - due to a currently-registered waiter
  41  *
  42  */
  43 struct process_info {
  44 #ifdef DEBUG
  45         /* prevent talloc_free(process) from working */
  46         int                     __pad;
  47 #endif
  48         struct process          process;
  49         struct list_item        async_list;
  50         int                     stdout_buf_len;
  51         struct waiter           *stdout_waiter;
  52         int                     stdout_pipe[2];
  53         void                    *orig_ctx;
  54 };
  55
  56 static struct procset *procset;
  57
  58 static struct process_info *get_info(struct process *process)
  59 {
  60         return container_of(process, struct process_info, process);
  61 }
  62
  63 struct process *procinfo_get_process(struct process_info *procinfo)
  64 {
  65         return &procinfo->process;
  66 }
  67
  68 /* Read as much as possible into the currently-allocated stdout buffer, and
  69  * possibly realloc it for the next read
  70  * If the line pointer is not NULL, it is set to the start of the latest
  71  * output.
  72  *
  73  * Returns:
  74  *  > 0 on success (even though no bytes may have been read)
  75  *    0 on EOF (no error, but no more reads can be performed)
  76  *  < 0 on error
  77  **/
  78 static int process_read_stdout_once(struct process_info *procinfo, char **line)
  79 {
  80         struct process *process = &procinfo->process;
  81         int rc, fd, max_len;
  82
  83         assert(process->keep_stdout);
  84
  85         fd = procinfo->stdout_pipe[0];
  86
  87         max_len =  procinfo->stdout_buf_len - process->stdout_len - 1;
  88
  89         rc = read(fd, process->stdout_buf + process->stdout_len, max_len);
  90         if (rc == 0)
  91                 return 0;
  92         if (rc < 0) {
  93                 if (errno == EINTR)
  94                         return 1;
  95                 pb_log("%s: read failed: %s\n", __func__, strerror(errno));
  96                 return rc;
  97         }
  98
  99         if (line)
 100                 *line = process->stdout_buf + process->stdout_len;
 101
 102         process->stdout_len += rc;
 103         if (process->stdout_len == procinfo->stdout_buf_len - 1) {
 104                 procinfo->stdout_buf_len *= 2;
 105                 process->stdout_buf = talloc_realloc(procinfo,
 106                                 process->stdout_buf, char,
 107                                 procinfo->stdout_buf_len);
 108         }
 109
 110         return 1;
 111 }
 112
 113 static int process_setup_stdout_pipe(struct process_info *procinfo)
 114 {
 115         int rc;
 116
 117         if (!procinfo->process.keep_stdout)
 118                 return 0;
 119
 120         procinfo->stdout_buf_len = 4096;
 121         procinfo->process.stdout_len = 0;
 122         procinfo->process.stdout_buf = talloc_array(procinfo, char,
 123                         procinfo->stdout_buf_len);
 124
 125         rc = pipe(procinfo->stdout_pipe);
 126         if (rc) {
 127                 pb_log("pipe failed");
 128                 return rc;
 129         }
 130         return 0;
 131 }
 132
 133 static void process_setup_stdout_parent(struct process_info *procinfo)
 134 {
 135         if (!procinfo->process.keep_stdout)
 136                 return;
 137
 138         close(procinfo->stdout_pipe[1]);
 139 }
 140
 141 static void process_setup_stdout_child(struct process_info *procinfo)
 142 {
 143         int log = fileno(pb_log_get_stream());
 144
 145         if (procinfo->process.keep_stdout)
 146                 dup2(procinfo->stdout_pipe[1], STDOUT_FILENO);
 147         else
 148                 dup2(log, STDOUT_FILENO);
 149
 150         if (procinfo->process.keep_stdout && procinfo->process.add_stderr)
 151                 dup2(procinfo->stdout_pipe[1], STDERR_FILENO);
 152         else
 153                 dup2(log, STDERR_FILENO);
 154 }
 155
 156 static void process_finish_stdout(struct process_info *procinfo)
 157 {
 158         close(procinfo->stdout_pipe[0]);
 159         procinfo->process.stdout_buf[procinfo->process.stdout_len] = '\0';
 160 }
 161
 162 static int process_read_stdout(struct process_info *procinfo)
 163 {
 164         int rc;
 165
 166         if (!procinfo->process.keep_stdout)
 167                 return 0;
 168
 169         do {
 170                 rc = process_read_stdout_once(procinfo, NULL);
 171         } while (rc > 0);
 172
 173         process_finish_stdout(procinfo);
 174
 175         return rc < 0 ? rc : 0;
 176 }
 177
 178 static int process_stdout_cb(void *arg)
 179 {
 180         struct process_info *procinfo = arg;
 181         int rc;
 182
 183         rc = process_read_stdout_once(procinfo, NULL);
 184
 185         /* if we're going to signal to the waitset that we're done (ie, non-zero
 186          * return value), then the waiters will remove us, so we drop the
 187          * reference */
 188         if (rc < 0) {
 189                 talloc_unlink(procset, procinfo);
 190                 procinfo->stdout_waiter = NULL;
 191                 rc = -1;
 192         } else {
 193                 rc = 0;
 194         }
 195
 196         return rc;
 197 }
 198
 199 int process_stdout_custom(struct process_info *procinfo, char **line)
 200 {
 201         int rc;
 202
 203         rc = process_read_stdout_once(procinfo, line);
 204
 205         /* if we're going to signal to the waitset that we're done (ie, non-zero
 206          * return value), then the waiters will remove us, so we drop the
 207          * reference */
 208         if (rc < 0) {
 209                 talloc_unlink(procset, procinfo);
 210                 procinfo->stdout_waiter = NULL;
 211                 rc = -1;
 212         } else {
 213                 rc = 0;
 214         }
 215
 216         return rc;
 217 }
 218
 219 static void sigchld_sigaction(int signo, siginfo_t *info,
 220                 void *arg __attribute__((unused)))
 221 {
 222         pid_t pid;
 223         int rc;
 224
 225         if (signo != SIGCHLD)
 226                 return;
 227
 228         pid = info->si_pid;
 229
 230         rc = write(procset->sigchld_pipe[1], &pid, sizeof(pid));
 231         if (rc != sizeof(pid))
 232                 pb_log("%s: write failed: %s\n", __func__, strerror(errno));
 233 }
 234
 235 static int sigchld_pipe_event(void *arg)
 236 {
 237         struct process_info *procinfo;
 238         struct procset *procset = arg;
 239         struct process *process;
 240         int pid, rc;
 241
 242         rc = read(procset->sigchld_pipe[0], &pid, sizeof(pid));
 243         if (rc != sizeof(pid))
 244                 return 0;
 245
 246         process = NULL;
 247         list_for_each_entry(&procset->async_list, procinfo, async_list) {
 248                 if (procinfo->process.pid == pid) {
 249                         process = &procinfo->process;
 250                         break;
 251                 }
 252         }
 253
 254         /* We'll receive SIGCHLD for synchronous processes too; just ignore */
 255         if (!process)
 256                 return 0;
 257
 258         rc = waitpid(process->pid, &process->exit_status, WNOHANG);
 259
 260         /* if the process is still running, ignore the event. We leave
 261          * the process in async_list so we can manage the final signal */
 262         if (rc == 0)
 263                 return 0;
 264
 265         /* ensure we have all of the child's stdout */
 266         process_read_stdout(procinfo);
 267
 268         if (process->exit_cb)
 269                 process->exit_cb(process);
 270
 271         list_remove(&procinfo->async_list);
 272         talloc_unlink(procset, procinfo);
 273
 274         return 0;
 275 }
 276
 277 static int process_fini(void *p)
 278 {
 279         struct procset *procset = p;
 280         struct sigaction sa;
 281
 282         memset(&sa, 0, sizeof(sa));
 283         sa.sa_handler = SIG_DFL;
 284
 285         sigaction(SIGCHLD, &sa, NULL);
 286
 287         waiter_remove(procset->sigchld_waiter);
 288
 289         close(procset->sigchld_pipe[0]);
 290         close(procset->sigchld_pipe[1]);
 291         return 0;
 292 }
 293
 294 struct procset *process_init(void *ctx, struct waitset *set, bool dry_run)
 295 {
 296         struct sigaction sa;
 297         int rc;
 298
 299         procset = talloc(ctx, struct procset);
 300         procset->waitset = set;
 301         procset->dry_run = dry_run;
 302         list_init(&procset->async_list);
 303
 304         rc = pipe(procset->sigchld_pipe);
 305         if (rc) {
 306                 pb_log("%s: pipe() failed: %s\n", __func__, strerror(errno));
 307                 goto err_free;
 308         }
 309
 310         procset->sigchld_waiter = waiter_register_io(set,
 311                                         procset->sigchld_pipe[0], WAIT_IN,
 312                                         sigchld_pipe_event, procset);
 313         if (!procset->sigchld_waiter)
 314                 goto err_close;
 315
 316         memset(&sa, 0, sizeof(sa));
 317         sa.sa_sigaction = sigchld_sigaction;
 318         sa.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
 319
 320         rc = sigaction(SIGCHLD, &sa, NULL);
 321         if (rc) {
 322                 pb_log("%s: sigaction() failed: %s\n", __func__,
 323                                 strerror(errno));
 324                 goto err_remove;
 325         }
 326
 327         talloc_set_destructor(procset, process_fini);
 328
 329         return procset;
 330
 331 err_remove:
 332         waiter_remove(procset->sigchld_waiter);
 333 err_close:
 334         close(procset->sigchld_pipe[0]);
 335         close(procset->sigchld_pipe[1]);
 336 err_free:
 337         talloc_free(procset);
 338         return NULL;
 339 }
 340
 341 struct process *process_create(void *ctx)
 342 {
 343         struct process_info *info = talloc_zero(ctx, struct process_info);
 344         info->orig_ctx = ctx;
 345         return &info->process;
 346 }
 347
 348 void process_release(struct process *process)
 349 {
 350         struct process_info *info = get_info(process);
 351         talloc_unlink(info->orig_ctx, info);
 352 }
 353
 354 static int process_run_common(struct process_info *procinfo)
 355 {
 356         struct process *process = &procinfo->process;
 357         const char *arg;
 358         char *logmsg;
 359         pid_t pid;
 360         int rc, i;
 361
 362         logmsg = talloc_asprintf(procinfo, " exe:  %s\n argv:", process->path);
 363         for (i = 0, arg = process->argv[i]; arg; i++, arg = process->argv[i])
 364                 logmsg = talloc_asprintf_append(logmsg, " '%s'", arg);
 365
 366         pb_log("Running command:\n%s\n", logmsg);
 367
 368         rc = process_setup_stdout_pipe(procinfo);
 369         if (rc)
 370                 return rc;
 371
 372         pid = fork();
 373         if (pid < 0) {
 374                 pb_log("%s: fork failed: %s\n", __func__, strerror(errno));
 375                 return pid;
 376         }
 377
 378         if (pid == 0) {
 379                 process_setup_stdout_child(procinfo);
 380                 if (procset->dry_run)
 381                         exit(EXIT_SUCCESS);
 382                 execvp(process->path, (char * const *)process->argv);
 383                 exit(EXIT_FAILURE);
 384         }
 385
 386         process_setup_stdout_parent(procinfo);
 387         process->pid = pid;
 388
 389         return 0;
 390 }
 391
 392 int process_run_sync(struct process *process)
 393 {
 394         struct process_info *procinfo = get_info(process);
 395         int rc;
 396
 397         rc = process_run_common(procinfo);
 398         if (rc)
 399                 return rc;
 400
 401         process_read_stdout(procinfo);
 402
 403         for (;;) {
 404                 rc = waitpid(process->pid, &process->exit_status, 0);
 405                 if (rc >= 0)
 406                         break;
 407                 if (errno == EINTR)
 408                         continue;
 409
 410                 pb_log("%s: waitpid failed: %s\n", __func__, strerror(errno));
 411                 return rc;
 412         }
 413
 414         return 0;
 415 }
 416
 417 int process_run_async(struct process *process)
 418 {
 419         struct process_info *procinfo = get_info(process);
 420         waiter_cb stdout_cb;
 421         int rc;
 422
 423         rc = process_run_common(procinfo);
 424         if (rc)
 425                 return rc;
 426
 427         if (process->keep_stdout) {
 428                 stdout_cb = process->stdout_cb ?: process_stdout_cb;
 429                 procinfo->stdout_waiter = waiter_register_io(procset->waitset,
 430                                                 procinfo->stdout_pipe[0],
 431                                                 WAIT_IN, stdout_cb, procinfo);
 432                 talloc_reference(procset, procinfo);
 433         }
 434
 435         list_add(&procset->async_list, &procinfo->async_list);
 436         talloc_reference(procset, procinfo);
 437
 438         return 0;
 439 }
 440
 441 void process_stop_async(struct process *process)
 442 {
 443         /* Avoid signalling an old pid */
 444         if (process->cancelled)
 445                 return;
 446
 447         pb_debug("process: sending SIGTERM to pid %d\n", process->pid);
 448         kill(process->pid, SIGTERM);
 449         process->cancelled = true;
 450 }
 451
 452 void process_stop_async_all(void)
 453 {
 454         struct process_info *procinfo;
 455         struct process *process = NULL;
 456
 457         pb_debug("process: cancelling all async jobs\n");
 458
 459         list_for_each_entry(&procset->async_list, procinfo, async_list) {
 460                 process = &procinfo->process;
 461                 /* Ignore the process completion - callbacks may use stale data */
 462                 process->exit_cb = NULL;
 463                 process->stdout_cb = NULL;
 464                 process_stop_async(process);
 465         }
 466 }
 467
 468 int process_run_simple_argv(void *ctx, const char *argv[])
 469 {
 470         struct process *process;
 471         int rc;
 472
 473         process = process_create(ctx);
 474
 475         process->path = argv[0];
 476         process->argv = argv;
 477
 478         rc = process_run_sync(process);
 479
 480         if (!rc)
 481                 rc = process->exit_status;
 482
 483         process_release(process);
 484
 485         return rc;
 486 }
 487
 488 int process_run_simple(void *ctx, const char *name, ...)
 489 {
 490         int rc, i, n_argv = 1;
 491         const char **argv;
 492         va_list ap;
 493
 494         va_start(ap, name);
 495         while (va_arg(ap, char *))
 496                 n_argv++;
 497         va_end(ap);
 498
 499         argv = talloc_array(ctx, const char *, n_argv + 1);
 500         argv[0] = name;
 501
 502         va_start(ap, name);
 503         for (i = 1; i < n_argv; i++)
 504                 argv[i] = va_arg(ap, const char *);
 505         va_end(ap);
 506
 507         argv[i] = NULL;
 508
 509         rc = process_run_simple_argv(ctx, argv);
 510
 511         talloc_free(argv);
 512
 513         return rc;
 514 }
 515
 516 bool process_exit_ok(struct process *process)
 517 {
 518         return WIFEXITED(process->exit_status) &&
 519                 WEXITSTATUS(process->exit_status) == 0;
 520 }