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 /* Read as much as possible into the currently-allocated stdout buffer, and
  64  * possibly realloc it for the next read */
  65 static int process_read_stdout_once(struct process_info *procinfo)
  66 {
  67         struct process *process = &procinfo->process;
  68         int rc, fd, max_len;
  69
  70         assert(process->keep_stdout);
  71
  72         fd = procinfo->stdout_pipe[0];
  73
  74         max_len =  procinfo->stdout_buf_len - process->stdout_len - 1;
  75
  76         rc = read(fd, process->stdout_buf + process->stdout_len, max_len);
  77         if (rc <= 0)
  78                 return rc;
  79
  80         process->stdout_len += rc;
  81         if (process->stdout_len == procinfo->stdout_buf_len - 1) {
  82                 procinfo->stdout_buf_len *= 2;
  83                 process->stdout_buf = talloc_realloc(procinfo,
  84                                 process->stdout_buf, char,
  85                                 procinfo->stdout_buf_len);
  86         }
  87
  88         return rc;
  89 }
  90
  91 static int process_setup_stdout_pipe(struct process_info *procinfo)
  92 {
  93         int rc;
  94
  95         if (!procinfo->process.keep_stdout)
  96                 return 0;
  97
  98         procinfo->stdout_buf_len = 4096;
  99         procinfo->process.stdout_len = 0;
 100         procinfo->process.stdout_buf = talloc_array(procinfo, char,
 101                         procinfo->stdout_buf_len);
 102
 103         rc = pipe(procinfo->stdout_pipe);
 104         if (rc) {
 105                 pb_log("pipe failed");
 106                 return rc;
 107         }
 108         return 0;
 109 }
 110
 111 static void process_setup_stdout_parent(struct process_info *procinfo)
 112 {
 113         if (!procinfo->process.keep_stdout)
 114                 return;
 115
 116         close(procinfo->stdout_pipe[1]);
 117 }
 118
 119 static void process_setup_stdout_child(struct process_info *procinfo)
 120 {
 121         int log = fileno(pb_log_get_stream());
 122
 123         if (procinfo->process.keep_stdout)
 124                 dup2(procinfo->stdout_pipe[1], STDOUT_FILENO);
 125         else
 126                 dup2(log, STDOUT_FILENO);
 127
 128         dup2(log, STDERR_FILENO);
 129 }
 130
 131 static void process_finish_stdout(struct process_info *procinfo)
 132 {
 133         close(procinfo->stdout_pipe[0]);
 134         procinfo->process.stdout_buf[procinfo->process.stdout_len] = '\0';
 135 }
 136
 137 static int process_read_stdout(struct process_info *procinfo)
 138 {
 139         int rc;
 140
 141         if (!procinfo->process.keep_stdout)
 142                 return 0;
 143
 144         do {
 145                 rc = process_read_stdout_once(procinfo);
 146         } while (rc > 0);
 147
 148         process_finish_stdout(procinfo);
 149
 150         return rc < 0 ? rc : 0;
 151 }
 152
 153 static int process_stdout_cb(void *arg)
 154 {
 155         struct process_info *procinfo = arg;
 156         int rc;
 157
 158         rc = process_read_stdout_once(procinfo);
 159
 160         /* if we're going to signal to the waitset that we're done (ie, non-zero
 161          * return value), then the waiters will remove us, so we drop the
 162          * reference */
 163         if (rc < 0) {
 164                 talloc_unlink(procset, procinfo);
 165                 procinfo->stdout_waiter = NULL;
 166                 rc = -1;
 167         } else {
 168                 rc = 0;
 169         }
 170
 171         return rc;
 172 }
 173
 174 static void sigchld_sigaction(int signo, siginfo_t *info,
 175                 void *arg __attribute__((unused)))
 176 {
 177         pid_t pid;
 178         int rc;
 179
 180         if (signo != SIGCHLD)
 181                 return;
 182
 183         pid = info->si_pid;
 184
 185         rc = write(procset->sigchld_pipe[1], &pid, sizeof(pid));
 186         if (rc != sizeof(pid))
 187                 pb_log("%s: write failed: %s\n", __func__, strerror(errno));
 188 }
 189
 190 static int sigchld_pipe_event(void *arg)
 191 {
 192         struct process_info *procinfo;
 193         struct procset *procset = arg;
 194         struct process *process;
 195         int pid, rc;
 196
 197         rc = read(procset->sigchld_pipe[0], &pid, sizeof(pid));
 198         if (rc != sizeof(pid))
 199                 return 0;
 200
 201         process = NULL;
 202         list_for_each_entry(&procset->async_list, procinfo, async_list) {
 203                 if (procinfo->process.pid == pid) {
 204                         process = &procinfo->process;
 205                         break;
 206                 }
 207         }
 208
 209         /* We'll receive SIGCHLD for synchronous processes too; just ignore */
 210         if (!process)
 211                 return 0;
 212
 213         rc = waitpid(process->pid, &process->exit_status, WNOHANG);
 214
 215         /* if the process is still running, ignore the event. We leave
 216          * the process in async_list so we can manage the final signal */
 217         if (rc == 0)
 218                 return 0;
 219
 220         /* ensure we have all of the child's stdout */
 221         process_read_stdout(procinfo);
 222
 223         if (process->exit_cb)
 224                 process->exit_cb(process);
 225
 226         list_remove(&procinfo->async_list);
 227         talloc_unlink(procset, procinfo);
 228
 229         return 0;
 230 }
 231
 232 static int process_fini(void *p)
 233 {
 234         struct procset *procset = p;
 235         struct sigaction sa;
 236
 237         memset(&sa, 0, sizeof(sa));
 238         sa.sa_handler = SIG_DFL;
 239
 240         sigaction(SIGCHLD, &sa, NULL);
 241
 242         waiter_remove(procset->sigchld_waiter);
 243
 244         close(procset->sigchld_pipe[0]);
 245         close(procset->sigchld_pipe[1]);
 246         return 0;
 247 }
 248
 249 struct procset *process_init(void *ctx, struct waitset *set, bool dry_run)
 250 {
 251         struct sigaction sa;
 252         int rc;
 253
 254         procset = talloc(ctx, struct procset);
 255         procset->waitset = set;
 256         procset->dry_run = dry_run;
 257         list_init(&procset->async_list);
 258
 259         rc = pipe(procset->sigchld_pipe);
 260         if (rc) {
 261                 pb_log("%s: pipe() failed: %s\n", __func__, strerror(errno));
 262                 goto err_free;
 263         }
 264
 265         procset->sigchld_waiter = waiter_register_io(set,
 266                                         procset->sigchld_pipe[0], WAIT_IN,
 267                                         sigchld_pipe_event, procset);
 268         if (!procset->sigchld_waiter)
 269                 goto err_close;
 270
 271         memset(&sa, 0, sizeof(sa));
 272         sa.sa_sigaction = sigchld_sigaction;
 273         sa.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
 274
 275         rc = sigaction(SIGCHLD, &sa, NULL);
 276         if (rc) {
 277                 pb_log("%s: sigaction() failed: %s\n", __func__,
 278                                 strerror(errno));
 279                 goto err_remove;
 280         }
 281
 282         talloc_set_destructor(procset, process_fini);
 283
 284         return procset;
 285
 286 err_remove:
 287         waiter_remove(procset->sigchld_waiter);
 288 err_close:
 289         close(procset->sigchld_pipe[0]);
 290         close(procset->sigchld_pipe[1]);
 291 err_free:
 292         talloc_free(procset);
 293         return NULL;
 294 }
 295
 296 struct process *process_create(void *ctx)
 297 {
 298         struct process_info *info = talloc_zero(ctx, struct process_info);
 299         info->orig_ctx = ctx;
 300         return &info->process;
 301 }
 302
 303 void process_release(struct process *process)
 304 {
 305         struct process_info *info = get_info(process);
 306         talloc_unlink(info->orig_ctx, info);
 307 }
 308
 309 static int process_run_common(struct process_info *procinfo)
 310 {
 311         struct process *process = &procinfo->process;
 312         const char *arg;
 313         char *logmsg;
 314         pid_t pid;
 315         int rc, i;
 316
 317         logmsg = talloc_asprintf(procinfo, " exe:  %s\n argv:", process->path);
 318         for (i = 0, arg = process->argv[i]; arg; i++, arg = process->argv[i])
 319                 logmsg = talloc_asprintf_append(logmsg, " '%s'", arg);
 320
 321         pb_log("Running command:\n%s\n", logmsg);
 322
 323         rc = process_setup_stdout_pipe(procinfo);
 324         if (rc)
 325                 return rc;
 326
 327         pid = fork();
 328         if (pid < 0) {
 329                 pb_log("%s: fork failed: %s\n", __func__, strerror(errno));
 330                 return pid;
 331         }
 332
 333         if (pid == 0) {
 334                 process_setup_stdout_child(procinfo);
 335                 if (procset->dry_run)
 336                         exit(EXIT_SUCCESS);
 337                 execvp(process->path, (char * const *)process->argv);
 338                 exit(EXIT_FAILURE);
 339         }
 340
 341         process_setup_stdout_parent(procinfo);
 342         process->pid = pid;
 343
 344         return 0;
 345 }
 346
 347 int process_run_sync(struct process *process)
 348 {
 349         struct process_info *procinfo = get_info(process);
 350         int rc;
 351
 352         rc = process_run_common(procinfo);
 353         if (rc)
 354                 return rc;
 355
 356         process_read_stdout(procinfo);
 357
 358         for (;;) {
 359                 rc = waitpid(process->pid, &process->exit_status, 0);
 360                 if (rc >= 0)
 361                         break;
 362                 if (errno == EINTR)
 363                         continue;
 364
 365                 pb_log("%s: waitpid failed: %s\n", __func__, strerror(errno));
 366                 return rc;
 367         }
 368
 369         return 0;
 370 }
 371
 372 int process_run_async(struct process *process)
 373 {
 374         struct process_info *procinfo = get_info(process);
 375         int rc;
 376
 377         rc = process_run_common(procinfo);
 378         if (rc)
 379                 return rc;
 380
 381         if (process->keep_stdout) {
 382                 procinfo->stdout_waiter = waiter_register_io(procset->waitset,
 383                                                 procinfo->stdout_pipe[0],
 384                                                 WAIT_IN, process_stdout_cb,
 385                                                 procinfo);
 386                 talloc_reference(procset, procinfo);
 387         }
 388
 389         list_add(&procset->async_list, &procinfo->async_list);
 390         talloc_reference(procset, procinfo);
 391
 392         return 0;
 393 }
 394
 395 void process_stop_async(struct process *process)
 396 {
 397         kill(process->pid, SIGTERM);
 398 }
 399
 400 int process_run_simple_argv(void *ctx, const char *argv[])
 401 {
 402         struct process *process;
 403         int rc;
 404
 405         process = process_create(ctx);
 406
 407         process->path = argv[0];
 408         process->argv = argv;
 409
 410         rc = process_run_sync(process);
 411
 412         if (!rc)
 413                 rc = process->exit_status;
 414
 415         process_release(process);
 416
 417         return rc;
 418 }
 419
 420 int process_run_simple(void *ctx, const char *name, ...)
 421 {
 422         int rc, i, n_argv = 1;
 423         const char **argv;
 424         va_list ap;
 425
 426         va_start(ap, name);
 427         while (va_arg(ap, char *))
 428                 n_argv++;
 429         va_end(ap);
 430
 431         argv = talloc_array(ctx, const char *, n_argv + 1);
 432         argv[0] = name;
 433
 434         va_start(ap, name);
 435         for (i = 1; i < n_argv; i++)
 436                 argv[i] = va_arg(ap, const char *);
 437         va_end(ap);
 438
 439         argv[i] = NULL;
 440
 441         rc = process_run_simple_argv(ctx, argv);
 442
 443         talloc_free(argv);
 444
 445         return rc;
 446 }