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