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