src/basic/process-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   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 License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <assert.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <signal.h>
  24 #include <stdbool.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <sys/types.h>
  28 #include <sys/wait.h>
  29 #include <unistd.h>
  30
  31 #include "escape.h"
  32 #include "fd-util.h"
  33 #include "fileio.h"
  34 #include "log.h"
  35 #include "process-util.h"
  36 #include "signal-util.h"
  37 #include "string-util.h"
  38 #include "user-util.h"
  39 #include "util.h"
  40
  41 int get_process_state(pid_t pid) {
  42         const char *p;
  43         char state;
  44         int r;
  45         _cleanup_free_ char *line = NULL;
  46
  47         assert(pid >= 0);
  48
  49         p = procfs_file_alloca(pid, "stat");
  50
  51         r = read_one_line_file(p, &line);
  52         if (r == -ENOENT)
  53                 return -ESRCH;
  54         if (r < 0)
  55                 return r;
  56
  57         p = strrchr(line, ')');
  58         if (!p)
  59                 return -EIO;
  60
  61         p++;
  62
  63         if (sscanf(p, " %c", &state) != 1)
  64                 return -EIO;
  65
  66         return (unsigned char) state;
  67 }
  68
  69 int get_process_comm(pid_t pid, char **name) {
  70         const char *p;
  71         int r;
  72
  73         assert(name);
  74         assert(pid >= 0);
  75
  76         p = procfs_file_alloca(pid, "comm");
  77
  78         r = read_one_line_file(p, name);
  79         if (r == -ENOENT)
  80                 return -ESRCH;
  81
  82         return r;
  83 }
  84
  85 int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line) {
  86         _cleanup_fclose_ FILE *f = NULL;
  87         char *r = NULL, *k;
  88         const char *p;
  89         int c;
  90
  91         assert(line);
  92         assert(pid >= 0);
  93
  94         p = procfs_file_alloca(pid, "cmdline");
  95
  96         f = fopen(p, "re");
  97         if (!f) {
  98                 if (errno == ENOENT)
  99                         return -ESRCH;
 100                 return -errno;
 101         }
 102
 103         if (max_length == 0) {
 104                 size_t len = 0, allocated = 0;
 105
 106                 while ((c = getc(f)) != EOF) {
 107
 108                         if (!GREEDY_REALLOC(r, allocated, len+2)) {
 109                                 free(r);
 110                                 return -ENOMEM;
 111                         }
 112
 113                         r[len++] = isprint(c) ? c : ' ';
 114                 }
 115
 116                 if (len > 0)
 117                         r[len-1] = 0;
 118
 119         } else {
 120                 bool space = false;
 121                 size_t left;
 122
 123                 r = new(char, max_length);
 124                 if (!r)
 125                         return -ENOMEM;
 126
 127                 k = r;
 128                 left = max_length;
 129                 while ((c = getc(f)) != EOF) {
 130
 131                         if (isprint(c)) {
 132                                 if (space) {
 133                                         if (left <= 4)
 134                                                 break;
 135
 136                                         *(k++) = ' ';
 137                                         left--;
 138                                         space = false;
 139                                 }
 140
 141                                 if (left <= 4)
 142                                         break;
 143
 144                                 *(k++) = (char) c;
 145                                 left--;
 146                         }  else
 147                                 space = true;
 148                 }
 149
 150                 if (left <= 4) {
 151                         size_t n = MIN(left-1, 3U);
 152                         memcpy(k, "...", n);
 153                         k[n] = 0;
 154                 } else
 155                         *k = 0;
 156         }
 157
 158         /* Kernel threads have no argv[] */
 159         if (isempty(r)) {
 160                 _cleanup_free_ char *t = NULL;
 161                 int h;
 162
 163                 free(r);
 164
 165                 if (!comm_fallback)
 166                         return -ENOENT;
 167
 168                 h = get_process_comm(pid, &t);
 169                 if (h < 0)
 170                         return h;
 171
 172                 r = strjoin("[", t, "]", NULL);
 173                 if (!r)
 174                         return -ENOMEM;
 175         }
 176
 177         *line = r;
 178         return 0;
 179 }
 180
 181 int is_kernel_thread(pid_t pid) {
 182         const char *p;
 183         size_t count;
 184         char c;
 185         bool eof;
 186         FILE *f;
 187
 188         if (pid == 0 || pid == 1) /* pid 1, and we ourselves certainly aren't a kernel thread */
 189                 return 0;
 190
 191         assert(pid > 1);
 192
 193         p = procfs_file_alloca(pid, "cmdline");
 194         f = fopen(p, "re");
 195         if (!f) {
 196                 if (errno == ENOENT)
 197                         return -ESRCH;
 198                 return -errno;
 199         }
 200
 201         count = fread(&c, 1, 1, f);
 202         eof = feof(f);
 203         fclose(f);
 204
 205         /* Kernel threads have an empty cmdline */
 206
 207         if (count <= 0)
 208                 return eof ? 1 : -errno;
 209
 210         return 0;
 211 }
 212
 213 int get_process_capeff(pid_t pid, char **capeff) {
 214         const char *p;
 215         int r;
 216
 217         assert(capeff);
 218         assert(pid >= 0);
 219
 220         p = procfs_file_alloca(pid, "status");
 221
 222         r = get_proc_field(p, "CapEff", WHITESPACE, capeff);
 223         if (r == -ENOENT)
 224                 return -ESRCH;
 225
 226         return r;
 227 }
 228
 229 static int get_process_link_contents(const char *proc_file, char **name) {
 230         int r;
 231
 232         assert(proc_file);
 233         assert(name);
 234
 235         r = readlink_malloc(proc_file, name);
 236         if (r == -ENOENT)
 237                 return -ESRCH;
 238         if (r < 0)
 239                 return r;
 240
 241         return 0;
 242 }
 243
 244 int get_process_exe(pid_t pid, char **name) {
 245         const char *p;
 246         char *d;
 247         int r;
 248
 249         assert(pid >= 0);
 250
 251         p = procfs_file_alloca(pid, "exe");
 252         r = get_process_link_contents(p, name);
 253         if (r < 0)
 254                 return r;
 255
 256         d = endswith(*name, " (deleted)");
 257         if (d)
 258                 *d = '\0';
 259
 260         return 0;
 261 }
 262
 263 static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
 264         _cleanup_fclose_ FILE *f = NULL;
 265         char line[LINE_MAX];
 266         const char *p;
 267
 268         assert(field);
 269         assert(uid);
 270
 271         if (pid == 0)
 272                 return getuid();
 273
 274         p = procfs_file_alloca(pid, "status");
 275         f = fopen(p, "re");
 276         if (!f) {
 277                 if (errno == ENOENT)
 278                         return -ESRCH;
 279                 return -errno;
 280         }
 281
 282         FOREACH_LINE(line, f, return -errno) {
 283                 char *l;
 284
 285                 l = strstrip(line);
 286
 287                 if (startswith(l, field)) {
 288                         l += strlen(field);
 289                         l += strspn(l, WHITESPACE);
 290
 291                         l[strcspn(l, WHITESPACE)] = 0;
 292
 293                         return parse_uid(l, uid);
 294                 }
 295         }
 296
 297         return -EIO;
 298 }
 299
 300 int get_process_uid(pid_t pid, uid_t *uid) {
 301         return get_process_id(pid, "Uid:", uid);
 302 }
 303
 304 int get_process_gid(pid_t pid, gid_t *gid) {
 305         assert_cc(sizeof(uid_t) == sizeof(gid_t));
 306         return get_process_id(pid, "Gid:", gid);
 307 }
 308
 309 int get_process_cwd(pid_t pid, char **cwd) {
 310         const char *p;
 311
 312         assert(pid >= 0);
 313
 314         p = procfs_file_alloca(pid, "cwd");
 315
 316         return get_process_link_contents(p, cwd);
 317 }
 318
 319 int get_process_root(pid_t pid, char **root) {
 320         const char *p;
 321
 322         assert(pid >= 0);
 323
 324         p = procfs_file_alloca(pid, "root");
 325
 326         return get_process_link_contents(p, root);
 327 }
 328
 329 int get_process_environ(pid_t pid, char **env) {
 330         _cleanup_fclose_ FILE *f = NULL;
 331         _cleanup_free_ char *outcome = NULL;
 332         int c;
 333         const char *p;
 334         size_t allocated = 0, sz = 0;
 335
 336         assert(pid >= 0);
 337         assert(env);
 338
 339         p = procfs_file_alloca(pid, "environ");
 340
 341         f = fopen(p, "re");
 342         if (!f) {
 343                 if (errno == ENOENT)
 344                         return -ESRCH;
 345                 return -errno;
 346         }
 347
 348         while ((c = fgetc(f)) != EOF) {
 349                 if (!GREEDY_REALLOC(outcome, allocated, sz + 5))
 350                         return -ENOMEM;
 351
 352                 if (c == '\0')
 353                         outcome[sz++] = '\n';
 354                 else
 355                         sz += cescape_char(c, outcome + sz);
 356         }
 357
 358         if (!outcome) {
 359                 outcome = strdup("");
 360                 if (!outcome)
 361                         return -ENOMEM;
 362         } else
 363                 outcome[sz] = '\0';
 364
 365         *env = outcome;
 366         outcome = NULL;
 367
 368         return 0;
 369 }
 370
 371 int get_parent_of_pid(pid_t pid, pid_t *_ppid) {
 372         int r;
 373         _cleanup_free_ char *line = NULL;
 374         long unsigned ppid;
 375         const char *p;
 376
 377         assert(pid >= 0);
 378         assert(_ppid);
 379
 380         if (pid == 0) {
 381                 *_ppid = getppid();
 382                 return 0;
 383         }
 384
 385         p = procfs_file_alloca(pid, "stat");
 386         r = read_one_line_file(p, &line);
 387         if (r == -ENOENT)
 388                 return -ESRCH;
 389         if (r < 0)
 390                 return r;
 391
 392         /* Let's skip the pid and comm fields. The latter is enclosed
 393          * in () but does not escape any () in its value, so let's
 394          * skip over it manually */
 395
 396         p = strrchr(line, ')');
 397         if (!p)
 398                 return -EIO;
 399
 400         p++;
 401
 402         if (sscanf(p, " "
 403                    "%*c "  /* state */
 404                    "%lu ", /* ppid */
 405                    &ppid) != 1)
 406                 return -EIO;
 407
 408         if ((long unsigned) (pid_t) ppid != ppid)
 409                 return -ERANGE;
 410
 411         *_ppid = (pid_t) ppid;
 412
 413         return 0;
 414 }
 415
 416 int wait_for_terminate(pid_t pid, siginfo_t *status) {
 417         siginfo_t dummy;
 418
 419         assert(pid >= 1);
 420
 421         if (!status)
 422                 status = &dummy;
 423
 424         for (;;) {
 425                 zero(*status);
 426
 427                 if (waitid(P_PID, pid, status, WEXITED) < 0) {
 428
 429                         if (errno == EINTR)
 430                                 continue;
 431
 432                         return -errno;
 433                 }
 434
 435                 return 0;
 436         }
 437 }
 438
 439 /*
 440  * Return values:
 441  * < 0 : wait_for_terminate() failed to get the state of the
 442  *       process, the process was terminated by a signal, or
 443  *       failed for an unknown reason.
 444  * >=0 : The process terminated normally, and its exit code is
 445  *       returned.
 446  *
 447  * That is, success is indicated by a return value of zero, and an
 448  * error is indicated by a non-zero value.
 449  *
 450  * A warning is emitted if the process terminates abnormally,
 451  * and also if it returns non-zero unless check_exit_code is true.
 452  */
 453 int wait_for_terminate_and_warn(const char *name, pid_t pid, bool check_exit_code) {
 454         int r;
 455         siginfo_t status;
 456
 457         assert(name);
 458         assert(pid > 1);
 459
 460         r = wait_for_terminate(pid, &status);
 461         if (r < 0)
 462                 return log_warning_errno(r, "Failed to wait for %s: %m", name);
 463
 464         if (status.si_code == CLD_EXITED) {
 465                 if (status.si_status != 0)
 466                         log_full(check_exit_code ? LOG_WARNING : LOG_DEBUG,
 467                                  "%s failed with error code %i.", name, status.si_status);
 468                 else
 469                         log_debug("%s succeeded.", name);
 470
 471                 return status.si_status;
 472         } else if (status.si_code == CLD_KILLED ||
 473                    status.si_code == CLD_DUMPED) {
 474
 475                 log_warning("%s terminated by signal %s.", name, signal_to_string(status.si_status));
 476                 return -EPROTO;
 477         }
 478
 479         log_warning("%s failed due to unknown reason.", name);
 480         return -EPROTO;
 481 }
 482
 483 void sigkill_wait(pid_t *pid) {
 484         if (!pid)
 485                 return;
 486         if (*pid <= 1)
 487                 return;
 488
 489         if (kill(*pid, SIGKILL) > 0)
 490                 (void) wait_for_terminate(*pid, NULL);
 491 }
 492
 493 int kill_and_sigcont(pid_t pid, int sig) {
 494         int r;
 495
 496         r = kill(pid, sig) < 0 ? -errno : 0;
 497
 498         if (r >= 0)
 499                 kill(pid, SIGCONT);
 500
 501         return r;
 502 }
 503
 504 int getenv_for_pid(pid_t pid, const char *field, char **_value) {
 505         _cleanup_fclose_ FILE *f = NULL;
 506         char *value = NULL;
 507         int r;
 508         bool done = false;
 509         size_t l;
 510         const char *path;
 511
 512         assert(pid >= 0);
 513         assert(field);
 514         assert(_value);
 515
 516         path = procfs_file_alloca(pid, "environ");
 517
 518         f = fopen(path, "re");
 519         if (!f) {
 520                 if (errno == ENOENT)
 521                         return -ESRCH;
 522                 return -errno;
 523         }
 524
 525         l = strlen(field);
 526         r = 0;
 527
 528         do {
 529                 char line[LINE_MAX];
 530                 unsigned i;
 531
 532                 for (i = 0; i < sizeof(line)-1; i++) {
 533                         int c;
 534
 535                         c = getc(f);
 536                         if (_unlikely_(c == EOF)) {
 537                                 done = true;
 538                                 break;
 539                         } else if (c == 0)
 540                                 break;
 541
 542                         line[i] = c;
 543                 }
 544                 line[i] = 0;
 545
 546                 if (memcmp(line, field, l) == 0 && line[l] == '=') {
 547                         value = strdup(line + l + 1);
 548                         if (!value)
 549                                 return -ENOMEM;
 550
 551                         r = 1;
 552                         break;
 553                 }
 554
 555         } while (!done);
 556
 557         *_value = value;
 558         return r;
 559 }
 560
 561 bool pid_is_unwaited(pid_t pid) {
 562         /* Checks whether a PID is still valid at all, including a zombie */
 563
 564         if (pid <= 0)
 565                 return false;
 566
 567         if (kill(pid, 0) >= 0)
 568                 return true;
 569
 570         return errno != ESRCH;
 571 }
 572
 573 bool pid_is_alive(pid_t pid) {
 574         int r;
 575
 576         /* Checks whether a PID is still valid and not a zombie */
 577
 578         if (pid <= 0)
 579                 return false;
 580
 581         r = get_process_state(pid);
 582         if (r == -ESRCH || r == 'Z')
 583                 return false;
 584
 585         return true;
 586 }