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_fn("read failed: %s\n", 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 || procinfo->process.raw_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 || procinfo->process.raw_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.raw_stdout)
 146                 return;
 147
 148         if (procinfo->process.keep_stdout)
 149                 dup2(procinfo->stdout_pipe[1], STDOUT_FILENO);
 150         else
 151                 dup2(log, STDOUT_FILENO);
 152
 153         if (procinfo->process.keep_stdout && procinfo->process.add_stderr)
 154                 dup2(procinfo->stdout_pipe[1], STDERR_FILENO);
 155         else
 156                 dup2(log, STDERR_FILENO);
 157 }
 158
 159 static void process_finish_stdout(struct process_info *procinfo)
 160 {
 161         close(procinfo->stdout_pipe[0]);
 162         procinfo->process.stdout_buf[procinfo->process.stdout_len] = '\0';
 163 }
 164
 165 static int process_read_stdout(struct process_info *procinfo)
 166 {
 167         int rc;
 168
 169         if (!procinfo->process.keep_stdout)
 170                 return 0;
 171
 172         do {
 173                 rc = process_read_stdout_once(procinfo, NULL);
 174         } while (rc > 0);
 175
 176         process_finish_stdout(procinfo);
 177
 178         return rc < 0 ? rc : 0;
 179 }
 180
 181 static int process_stdout_cb(void *arg)
 182 {
 183         struct process_info *procinfo = arg;
 184         int rc;
 185
 186         rc = process_read_stdout_once(procinfo, NULL);
 187
 188         /* if we're going to signal to the waitset that we're done (ie, non-zero
 189          * return value), then the waiters will remove us, so we drop the
 190          * reference */
 191         if (rc < 0) {
 192                 talloc_unlink(procset, procinfo);
 193                 procinfo->stdout_waiter = NULL;
 194                 rc = -1;
 195         } else {
 196                 rc = 0;
 197         }
 198
 199         return rc;
 200 }
 201
 202 int process_stdout_custom(struct process_info *procinfo, char **line)
 203 {
 204         int rc;
 205
 206         rc = process_read_stdout_once(procinfo, line);
 207
 208         /* if we're going to signal to the waitset that we're done (ie, non-zero
 209          * return value), then the waiters will remove us, so we drop the
 210          * reference */
 211         if (rc < 0) {
 212                 talloc_unlink(procset, procinfo);
 213                 procinfo->stdout_waiter = NULL;
 214                 rc = -1;
 215         } else {
 216                 rc = 0;
 217         }
 218
 219         return rc;
 220 }
 221
 222 static void sigchld_sigaction(int signo, siginfo_t *info,
 223                 void *arg __attribute__((unused)))
 224 {
 225         pid_t pid;
 226         int rc;
 227
 228         if (signo != SIGCHLD)
 229                 return;
 230
 231         pid = info->si_pid;
 232
 233         rc = write(procset->sigchld_pipe[1], &pid, sizeof(pid));
 234         if (rc != sizeof(pid))
 235                 pb_log_fn("write failed: %s\n", strerror(errno));
 236 }
 237
 238 static int sigchld_pipe_event(void *arg)
 239 {
 240         struct process_info *procinfo;
 241         struct procset *procset = arg;
 242         struct process *process;
 243         int pid, rc;
 244
 245         rc = read(procset->sigchld_pipe[0], &pid, sizeof(pid));
 246         if (rc != sizeof(pid))
 247                 return 0;
 248
 249         process = NULL;
 250         list_for_each_entry(&procset->async_list, procinfo, async_list) {
 251                 if (procinfo->process.pid == pid) {
 252                         process = &procinfo->process;
 253                         break;
 254                 }
 255         }
 256
 257         /* We'll receive SIGCHLD for synchronous processes too; just ignore */
 258         if (!process)
 259                 return 0;
 260
 261         rc = waitpid(process->pid, &process->exit_status, WNOHANG);
 262
 263         /* if the process is still running, ignore the event. We leave
 264          * the process in async_list so we can manage the final signal */
 265         if (rc == 0)
 266                 return 0;
 267
 268         /* ensure we have all of the child's stdout */
 269         process_read_stdout(procinfo);
 270
 271         if (process->exit_cb)
 272                 process->exit_cb(process);
 273
 274         list_remove(&procinfo->async_list);
 275         talloc_unlink(procset, procinfo);
 276
 277         return 0;
 278 }
 279
 280 static int process_fini(void *p)
 281 {
 282         struct procset *procset = p;
 283         struct sigaction sa;
 284
 285         memset(&sa, 0, sizeof(sa));
 286         sa.sa_handler = SIG_DFL;
 287
 288         sigaction(SIGCHLD, &sa, NULL);
 289
 290         waiter_remove(procset->sigchld_waiter);
 291
 292         close(procset->sigchld_pipe[0]);
 293         close(procset->sigchld_pipe[1]);
 294         return 0;
 295 }
 296
 297 struct procset *process_init(void *ctx, struct waitset *set, bool dry_run)
 298 {
 299         struct sigaction sa;
 300         int rc;
 301
 302         procset = talloc(ctx, struct procset);
 303         procset->waitset = set;
 304         procset->dry_run = dry_run;
 305         list_init(&procset->async_list);
 306
 307         rc = pipe(procset->sigchld_pipe);
 308         if (rc) {
 309                 pb_log_fn("pipe() failed: %s\n", strerror(errno));
 310                 goto err_free;
 311         }
 312
 313         procset->sigchld_waiter = waiter_register_io(set,
 314                                         procset->sigchld_pipe[0], WAIT_IN,
 315                                         sigchld_pipe_event, procset);
 316         if (!procset->sigchld_waiter)
 317                 goto err_close;
 318
 319         memset(&sa, 0, sizeof(sa));
 320         sa.sa_sigaction = sigchld_sigaction;
 321         sa.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
 322
 323         rc = sigaction(SIGCHLD, &sa, NULL);
 324         if (rc) {
 325                 pb_log_fn("sigaction() failed: %s\n",
 326                                 strerror(errno));
 327                 goto err_remove;
 328         }
 329
 330         talloc_set_destructor(procset, process_fini);
 331
 332         return procset;
 333
 334 err_remove:
 335         waiter_remove(procset->sigchld_waiter);
 336 err_close:
 337         close(procset->sigchld_pipe[0]);
 338         close(procset->sigchld_pipe[1]);
 339 err_free:
 340         talloc_free(procset);
 341         return NULL;
 342 }
 343
 344 struct process *process_create(void *ctx)
 345 {
 346         struct process_info *info = talloc_zero(ctx, struct process_info);
 347         info->orig_ctx = ctx;
 348         return &info->process;
 349 }
 350
 351 void process_release(struct process *process)
 352 {
 353         struct process_info *info = get_info(process);
 354         talloc_unlink(info->orig_ctx, info);
 355 }
 356
 357 static int process_run_common(struct process_info *procinfo)
 358 {
 359         struct process *process = &procinfo->process;
 360         const char *arg;
 361         char *logmsg;
 362         pid_t pid;
 363         int rc, i;
 364
 365         logmsg = talloc_asprintf(procinfo, " exe:  %s\n argv:", process->path);
 366         for (i = 0, arg = process->argv[i]; arg; i++, arg = process->argv[i])
 367                 logmsg = talloc_asprintf_append(logmsg, " '%s'", arg);
 368
 369         pb_log("Running command:\n%s\n", logmsg);
 370
 371         rc = process_setup_stdout_pipe(procinfo);
 372         if (rc)
 373                 return rc;
 374
 375         pid = fork();
 376         if (pid < 0) {
 377                 pb_log_fn("fork failed: %s\n", strerror(errno));
 378                 return pid;
 379         }
 380
 381         if (pid == 0) {
 382                 process_setup_stdout_child(procinfo);
 383                 if (procset->dry_run)
 384                         exit(EXIT_SUCCESS);
 385                 execvp(process->path, (char * const *)process->argv);
 386                 exit(EXIT_FAILURE);
 387         }
 388
 389         process_setup_stdout_parent(procinfo);
 390         process->pid = pid;
 391
 392         return 0;
 393 }
 394
 395 int process_run_sync(struct process *process)
 396 {
 397         struct process_info *procinfo = get_info(process);
 398         int rc;
 399
 400         rc = process_run_common(procinfo);
 401         if (rc)
 402                 return rc;
 403
 404         process_read_stdout(procinfo);
 405
 406         for (;;) {
 407                 rc = waitpid(process->pid, &process->exit_status, 0);
 408                 if (rc >= 0)
 409                         break;
 410                 if (errno == EINTR)
 411                         continue;
 412
 413                 pb_log_fn("waitpid failed: %s\n", strerror(errno));
 414                 return rc;
 415         }
 416
 417         return 0;
 418 }
 419
 420 int process_run_async(struct process *process)
 421 {
 422         struct process_info *procinfo = get_info(process);
 423         waiter_cb stdout_cb;
 424         int rc;
 425
 426         rc = process_run_common(procinfo);
 427         if (rc)
 428                 return rc;
 429
 430         if (process->keep_stdout) {
 431                 stdout_cb = process->stdout_cb ?: process_stdout_cb;
 432                 procinfo->stdout_waiter = waiter_register_io(procset->waitset,
 433                                                 procinfo->stdout_pipe[0],
 434                                                 WAIT_IN, stdout_cb, procinfo);
 435                 talloc_reference(procset, procinfo);
 436         }
 437
 438         list_add(&procset->async_list, &procinfo->async_list);
 439         talloc_reference(procset, procinfo);
 440
 441         return 0;
 442 }
 443
 444 void process_stop_async(struct process *process)
 445 {
 446         /* Avoid signalling an old pid */
 447         if (process->cancelled)
 448                 return;
 449
 450         pb_debug("process: sending SIGTERM to pid %d\n", process->pid);
 451         kill(process->pid, SIGTERM);
 452         process->cancelled = true;
 453 }
 454
 455 void process_stop_async_all(void)
 456 {
 457         struct process_info *procinfo;
 458         struct process *process = NULL;
 459
 460         pb_debug("process: cancelling all async jobs\n");
 461
 462         list_for_each_entry(&procset->async_list, procinfo, async_list) {
 463                 process = &procinfo->process;
 464                 /* Ignore the process completion - callbacks may use stale data */
 465                 process->exit_cb = NULL;
 466                 process->stdout_cb = NULL;
 467                 process_stop_async(process);
 468         }
 469 }
 470
 471 int process_run_simple_argv(void *ctx, const char *argv[])
 472 {
 473         struct process *process;
 474         int rc;
 475
 476         process = process_create(ctx);
 477
 478         process->path = argv[0];
 479         process->argv = argv;
 480
 481         rc = process_run_sync(process);
 482
 483         if (!rc)
 484                 rc = process->exit_status;
 485
 486         process_release(process);
 487
 488         return rc;
 489 }
 490
 491 int process_run_simple(void *ctx, const char *name, ...)
 492 {
 493         int rc, i, n_argv = 1;
 494         const char **argv;
 495         va_list ap;
 496
 497         va_start(ap, name);
 498         while (va_arg(ap, char *))
 499                 n_argv++;
 500         va_end(ap);
 501
 502         argv = talloc_array(ctx, const char *, n_argv + 1);
 503         argv[0] = name;
 504
 505         va_start(ap, name);
 506         for (i = 1; i < n_argv; i++)
 507                 argv[i] = va_arg(ap, const char *);
 508         va_end(ap);
 509
 510         argv[i] = NULL;
 511
 512         rc = process_run_simple_argv(ctx, argv);
 513
 514         talloc_free(argv);
 515
 516         return rc;
 517 }
 518
 519 bool process_exit_ok(struct process *process)
 520 {
 521         return WIFEXITED(process->exit_status) &&
 522                 WEXITSTATUS(process->exit_status) == 0;
 523 }