src/basic/path-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <limits.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <sys/stat.h>
   9 #include <unistd.h>
  10
  11 /* When we include libgen.h because we need dirname() we immediately
  12  * undefine basename() since libgen.h defines it as a macro to the
  13  * POSIX version which is really broken. We prefer GNU basename(). */
  14 #include <libgen.h>
  15 #undef basename
  16
  17 #include "alloc-util.h"
  18 #include "extract-word.h"
  19 #include "fs-util.h"
  20 #include "glob-util.h"
  21 #include "log.h"
  22 #include "macro.h"
  23 #include "missing.h"
  24 #include "parse-util.h"
  25 #include "path-util.h"
  26 #include "stat-util.h"
  27 #include "string-util.h"
  28 #include "strv.h"
  29 #include "time-util.h"
  30 #include "utf8.h"
  31
  32 bool path_is_absolute(const char *p) {
  33         return p[0] == '/';
  34 }
  35
  36 bool is_path(const char *p) {
  37         return !!strchr(p, '/');
  38 }
  39
  40 int path_split_and_make_absolute(const char *p, char ***ret) {
  41         char **l;
  42         int r;
  43
  44         assert(p);
  45         assert(ret);
  46
  47         l = strv_split(p, ":");
  48         if (!l)
  49                 return -ENOMEM;
  50
  51         r = path_strv_make_absolute_cwd(l);
  52         if (r < 0) {
  53                 strv_free(l);
  54                 return r;
  55         }
  56
  57         *ret = l;
  58         return r;
  59 }
  60
  61 char *path_make_absolute(const char *p, const char *prefix) {
  62         assert(p);
  63
  64         /* Makes every item in the list an absolute path by prepending
  65          * the prefix, if specified and necessary */
  66
  67         if (path_is_absolute(p) || isempty(prefix))
  68                 return strdup(p);
  69
  70         if (endswith(prefix, "/"))
  71                 return strjoin(prefix, p);
  72         else
  73                 return strjoin(prefix, "/", p);
  74 }
  75
  76 int safe_getcwd(char **ret) {
  77         char *cwd;
  78
  79         cwd = get_current_dir_name();
  80         if (!cwd)
  81                 return negative_errno();
  82
  83         /* Let's make sure the directory is really absolute, to protect us from the logic behind
  84          * CVE-2018-1000001 */
  85         if (cwd[0] != '/') {
  86                 free(cwd);
  87                 return -ENOMEDIUM;
  88         }
  89
  90         *ret = cwd;
  91         return 0;
  92 }
  93
  94 int path_make_absolute_cwd(const char *p, char **ret) {
  95         char *c;
  96         int r;
  97
  98         assert(p);
  99         assert(ret);
 100
 101         /* Similar to path_make_absolute(), but prefixes with the
 102          * current working directory. */
 103
 104         if (path_is_absolute(p))
 105                 c = strdup(p);
 106         else {
 107                 _cleanup_free_ char *cwd = NULL;
 108
 109                 r = safe_getcwd(&cwd);
 110                 if (r < 0)
 111                         return r;
 112
 113                 c = path_join(NULL, cwd, p);
 114         }
 115         if (!c)
 116                 return -ENOMEM;
 117
 118         *ret = c;
 119         return 0;
 120 }
 121
 122 int path_make_relative(const char *from_dir, const char *to_path, char **_r) {
 123         char *f, *t, *r, *p;
 124         unsigned n_parents = 0;
 125
 126         assert(from_dir);
 127         assert(to_path);
 128         assert(_r);
 129
 130         /* Strips the common part, and adds ".." elements as necessary. */
 131
 132         if (!path_is_absolute(from_dir) || !path_is_absolute(to_path))
 133                 return -EINVAL;
 134
 135         f = strdupa(from_dir);
 136         t = strdupa(to_path);
 137
 138         path_simplify(f, true);
 139         path_simplify(t, true);
 140
 141         /* Skip the common part. */
 142         for (;;) {
 143                 size_t a, b;
 144
 145                 f += *f == '/';
 146                 t += *t == '/';
 147
 148                 if (!*f) {
 149                         if (!*t)
 150                                 /* from_dir equals to_path. */
 151                                 r = strdup(".");
 152                         else
 153                                 /* from_dir is a parent directory of to_path. */
 154                                 r = strdup(t);
 155                         if (!r)
 156                                 return -ENOMEM;
 157
 158                         *_r = r;
 159                         return 0;
 160                 }
 161
 162                 if (!*t)
 163                         break;
 164
 165                 a = strcspn(f, "/");
 166                 b = strcspn(t, "/");
 167
 168                 if (a != b || memcmp(f, t, a) != 0)
 169                         break;
 170
 171                 f += a;
 172                 t += b;
 173         }
 174
 175         /* If we're here, then "from_dir" has one or more elements that need to
 176          * be replaced with "..". */
 177
 178         /* Count the number of necessary ".." elements. */
 179         for (; *f;) {
 180                 size_t w;
 181
 182                 w = strcspn(f, "/");
 183
 184                 /* If this includes ".." we can't do a simple series of "..", refuse */
 185                 if (w == 2 && f[0] == '.' && f[1] == '.')
 186                         return -EINVAL;
 187
 188                 /* Count number of elements */
 189                 n_parents++;
 190
 191                 f += w;
 192                 f += *f == '/';
 193         }
 194
 195         r = new(char, n_parents * 3 + strlen(t) + 1);
 196         if (!r)
 197                 return -ENOMEM;
 198
 199         for (p = r; n_parents > 0; n_parents--)
 200                 p = mempcpy(p, "../", 3);
 201
 202         if (*t)
 203                 strcpy(p, t);
 204         else
 205                 /* Remove trailing slash */
 206                 *(--p) = 0;
 207
 208         *_r = r;
 209         return 0;
 210 }
 211
 212 int path_strv_make_absolute_cwd(char **l) {
 213         char **s;
 214         int r;
 215
 216         /* Goes through every item in the string list and makes it
 217          * absolute. This works in place and won't rollback any
 218          * changes on failure. */
 219
 220         STRV_FOREACH(s, l) {
 221                 char *t;
 222
 223                 r = path_make_absolute_cwd(*s, &t);
 224                 if (r < 0)
 225                         return r;
 226
 227                 path_simplify(t, false);
 228                 free_and_replace(*s, t);
 229         }
 230
 231         return 0;
 232 }
 233
 234 char **path_strv_resolve(char **l, const char *root) {
 235         char **s;
 236         unsigned k = 0;
 237         bool enomem = false;
 238         int r;
 239
 240         if (strv_isempty(l))
 241                 return l;
 242
 243         /* Goes through every item in the string list and canonicalize
 244          * the path. This works in place and won't rollback any
 245          * changes on failure. */
 246
 247         STRV_FOREACH(s, l) {
 248                 _cleanup_free_ char *orig = NULL;
 249                 char *t, *u;
 250
 251                 if (!path_is_absolute(*s)) {
 252                         free(*s);
 253                         continue;
 254                 }
 255
 256                 if (root) {
 257                         orig = *s;
 258                         t = prefix_root(root, orig);
 259                         if (!t) {
 260                                 enomem = true;
 261                                 continue;
 262                         }
 263                 } else
 264                         t = *s;
 265
 266                 r = chase_symlinks(t, root, 0, &u);
 267                 if (r == -ENOENT) {
 268                         if (root) {
 269                                 u = TAKE_PTR(orig);
 270                                 free(t);
 271                         } else
 272                                 u = t;
 273                 } else if (r < 0) {
 274                         free(t);
 275
 276                         if (r == -ENOMEM)
 277                                 enomem = true;
 278
 279                         continue;
 280                 } else if (root) {
 281                         char *x;
 282
 283                         free(t);
 284                         x = path_startswith(u, root);
 285                         if (x) {
 286                                 /* restore the slash if it was lost */
 287                                 if (!startswith(x, "/"))
 288                                         *(--x) = '/';
 289
 290                                 t = strdup(x);
 291                                 free(u);
 292                                 if (!t) {
 293                                         enomem = true;
 294                                         continue;
 295                                 }
 296                                 u = t;
 297                         } else {
 298                                 /* canonicalized path goes outside of
 299                                  * prefix, keep the original path instead */
 300                                 free_and_replace(u, orig);
 301                         }
 302                 } else
 303                         free(t);
 304
 305                 l[k++] = u;
 306         }
 307
 308         l[k] = NULL;
 309
 310         if (enomem)
 311                 return NULL;
 312
 313         return l;
 314 }
 315
 316 char **path_strv_resolve_uniq(char **l, const char *root) {
 317
 318         if (strv_isempty(l))
 319                 return l;
 320
 321         if (!path_strv_resolve(l, root))
 322                 return NULL;
 323
 324         return strv_uniq(l);
 325 }
 326
 327 char *path_simplify(char *path, bool kill_dots) {
 328         char *f, *t;
 329         bool slash = false, ignore_slash = false, absolute;
 330
 331         assert(path);
 332
 333         /* Removes redundant inner and trailing slashes. Also removes unnecessary dots
 334          * if kill_dots is true. Modifies the passed string in-place.
 335          *
 336          * ///foo//./bar/.   becomes /foo/./bar/.  (if kill_dots is false)
 337          * ///foo//./bar/.   becomes /foo/bar      (if kill_dots is true)
 338          * .//./foo//./bar/. becomes ./foo/bar     (if kill_dots is false)
 339          * .//./foo//./bar/. becomes foo/bar       (if kill_dots is true)
 340          */
 341
 342         absolute = path_is_absolute(path);
 343
 344         f = path;
 345         if (kill_dots && *f == '.' && IN_SET(f[1], 0, '/')) {
 346                 ignore_slash = true;
 347                 f++;
 348         }
 349
 350         for (t = path; *f; f++) {
 351
 352                 if (*f == '/') {
 353                         slash = true;
 354                         continue;
 355                 }
 356
 357                 if (slash) {
 358                         if (kill_dots && *f == '.' && IN_SET(f[1], 0, '/'))
 359                                 continue;
 360
 361                         slash = false;
 362                         if (ignore_slash)
 363                                 ignore_slash = false;
 364                         else
 365                                 *(t++) = '/';
 366                 }
 367
 368                 *(t++) = *f;
 369         }
 370
 371         /* Special rule, if we are talking of the root directory, a trailing slash is good */
 372         if (absolute && t == path)
 373                 *(t++) = '/';
 374
 375         *t = 0;
 376         return path;
 377 }
 378
 379 char* path_startswith(const char *path, const char *prefix) {
 380         assert(path);
 381         assert(prefix);
 382
 383         /* Returns a pointer to the start of the first component after the parts matched by
 384          * the prefix, iff
 385          * - both paths are absolute or both paths are relative,
 386          * and
 387          * - each component in prefix in turn matches a component in path at the same position.
 388          * An empty string will be returned when the prefix and path are equivalent.
 389          *
 390          * Returns NULL otherwise.
 391          */
 392
 393         if ((path[0] == '/') != (prefix[0] == '/'))
 394                 return NULL;
 395
 396         for (;;) {
 397                 size_t a, b;
 398
 399                 path += strspn(path, "/");
 400                 prefix += strspn(prefix, "/");
 401
 402                 if (*prefix == 0)
 403                         return (char*) path;
 404
 405                 if (*path == 0)
 406                         return NULL;
 407
 408                 a = strcspn(path, "/");
 409                 b = strcspn(prefix, "/");
 410
 411                 if (a != b)
 412                         return NULL;
 413
 414                 if (memcmp(path, prefix, a) != 0)
 415                         return NULL;
 416
 417                 path += a;
 418                 prefix += b;
 419         }
 420 }
 421
 422 int path_compare(const char *a, const char *b) {
 423         int d;
 424
 425         assert(a);
 426         assert(b);
 427
 428         /* A relative path and an abolute path must not compare as equal.
 429          * Which one is sorted before the other does not really matter.
 430          * Here a relative path is ordered before an absolute path. */
 431         d = (a[0] == '/') - (b[0] == '/');
 432         if (d != 0)
 433                 return d;
 434
 435         for (;;) {
 436                 size_t j, k;
 437
 438                 a += strspn(a, "/");
 439                 b += strspn(b, "/");
 440
 441                 if (*a == 0 && *b == 0)
 442                         return 0;
 443
 444                 /* Order prefixes first: "/foo" before "/foo/bar" */
 445                 if (*a == 0)
 446                         return -1;
 447                 if (*b == 0)
 448                         return 1;
 449
 450                 j = strcspn(a, "/");
 451                 k = strcspn(b, "/");
 452
 453                 /* Alphabetical sort: "/foo/aaa" before "/foo/b" */
 454                 d = memcmp(a, b, MIN(j, k));
 455                 if (d != 0)
 456                         return (d > 0) - (d < 0); /* sign of d */
 457
 458                 /* Sort "/foo/a" before "/foo/aaa" */
 459                 d = (j > k) - (j < k);  /* sign of (j - k) */
 460                 if (d != 0)
 461                         return d;
 462
 463                 a += j;
 464                 b += k;
 465         }
 466 }
 467
 468 bool path_equal(const char *a, const char *b) {
 469         return path_compare(a, b) == 0;
 470 }
 471
 472 bool path_equal_or_files_same(const char *a, const char *b, int flags) {
 473         return path_equal(a, b) || files_same(a, b, flags) > 0;
 474 }
 475
 476 char* path_join(const char *root, const char *path, const char *rest) {
 477         assert(path);
 478
 479         if (!isempty(root))
 480                 return strjoin(root, endswith(root, "/") ? "" : "/",
 481                                path[0] == '/' ? path+1 : path,
 482                                rest ? (endswith(path, "/") ? "" : "/") : NULL,
 483                                rest && rest[0] == '/' ? rest+1 : rest);
 484         else
 485                 return strjoin(path,
 486                                rest ? (endswith(path, "/") ? "" : "/") : NULL,
 487                                rest && rest[0] == '/' ? rest+1 : rest);
 488 }
 489
 490 int find_binary(const char *name, char **ret) {
 491         int last_error, r;
 492         const char *p;
 493
 494         assert(name);
 495
 496         if (is_path(name)) {
 497                 if (access(name, X_OK) < 0)
 498                         return -errno;
 499
 500                 if (ret) {
 501                         r = path_make_absolute_cwd(name, ret);
 502                         if (r < 0)
 503                                 return r;
 504                 }
 505
 506                 return 0;
 507         }
 508
 509         /**
 510          * Plain getenv, not secure_getenv, because we want
 511          * to actually allow the user to pick the binary.
 512          */
 513         p = getenv("PATH");
 514         if (!p)
 515                 p = DEFAULT_PATH;
 516
 517         last_error = -ENOENT;
 518
 519         for (;;) {
 520                 _cleanup_free_ char *j = NULL, *element = NULL;
 521
 522                 r = extract_first_word(&p, &element, ":", EXTRACT_RELAX|EXTRACT_DONT_COALESCE_SEPARATORS);
 523                 if (r < 0)
 524                         return r;
 525                 if (r == 0)
 526                         break;
 527
 528                 if (!path_is_absolute(element))
 529                         continue;
 530
 531                 j = strjoin(element, "/", name);
 532                 if (!j)
 533                         return -ENOMEM;
 534
 535                 if (access(j, X_OK) >= 0) {
 536                         /* Found it! */
 537
 538                         if (ret) {
 539                                 *ret = path_simplify(j, false);
 540                                 j = NULL;
 541                         }
 542
 543                         return 0;
 544                 }
 545
 546                 last_error = -errno;
 547         }
 548
 549         return last_error;
 550 }
 551
 552 bool paths_check_timestamp(const char* const* paths, usec_t *timestamp, bool update) {
 553         bool changed = false;
 554         const char* const* i;
 555
 556         assert(timestamp);
 557
 558         if (!paths)
 559                 return false;
 560
 561         STRV_FOREACH(i, paths) {
 562                 struct stat stats;
 563                 usec_t u;
 564
 565                 if (stat(*i, &stats) < 0)
 566                         continue;
 567
 568                 u = timespec_load(&stats.st_mtim);
 569
 570                 /* first check */
 571                 if (*timestamp >= u)
 572                         continue;
 573
 574                 log_debug("timestamp of '%s' changed", *i);
 575
 576                 /* update timestamp */
 577                 if (update) {
 578                         *timestamp = u;
 579                         changed = true;
 580                 } else
 581                         return true;
 582         }
 583
 584         return changed;
 585 }
 586
 587 static int binary_is_good(const char *binary) {
 588         _cleanup_free_ char *p = NULL, *d = NULL;
 589         int r;
 590
 591         r = find_binary(binary, &p);
 592         if (r == -ENOENT)
 593                 return 0;
 594         if (r < 0)
 595                 return r;
 596
 597         /* An fsck that is linked to /bin/true is a non-existent
 598          * fsck */
 599
 600         r = readlink_malloc(p, &d);
 601         if (r == -EINVAL) /* not a symlink */
 602                 return 1;
 603         if (r < 0)
 604                 return r;
 605
 606         return !PATH_IN_SET(d, "true"
 607                                "/bin/true",
 608                                "/usr/bin/true",
 609                                "/dev/null");
 610 }
 611
 612 int fsck_exists(const char *fstype) {
 613         const char *checker;
 614
 615         assert(fstype);
 616
 617         if (streq(fstype, "auto"))
 618                 return -EINVAL;
 619
 620         checker = strjoina("fsck.", fstype);
 621         return binary_is_good(checker);
 622 }
 623
 624 int mkfs_exists(const char *fstype) {
 625         const char *mkfs;
 626
 627         assert(fstype);
 628
 629         if (streq(fstype, "auto"))
 630                 return -EINVAL;
 631
 632         mkfs = strjoina("mkfs.", fstype);
 633         return binary_is_good(mkfs);
 634 }
 635
 636 char *prefix_root(const char *root, const char *path) {
 637         char *n, *p;
 638         size_t l;
 639
 640         /* If root is passed, prefixes path with it. Otherwise returns
 641          * it as is. */
 642
 643         assert(path);
 644
 645         /* First, drop duplicate prefixing slashes from the path */
 646         while (path[0] == '/' && path[1] == '/')
 647                 path++;
 648
 649         if (empty_or_root(root))
 650                 return strdup(path);
 651
 652         l = strlen(root) + 1 + strlen(path) + 1;
 653
 654         n = new(char, l);
 655         if (!n)
 656                 return NULL;
 657
 658         p = stpcpy(n, root);
 659
 660         while (p > n && p[-1] == '/')
 661                 p--;
 662
 663         if (path[0] != '/')
 664                 *(p++) = '/';
 665
 666         strcpy(p, path);
 667         return n;
 668 }
 669
 670 int parse_path_argument_and_warn(const char *path, bool suppress_root, char **arg) {
 671         char *p;
 672         int r;
 673
 674         /*
 675          * This function is intended to be used in command line
 676          * parsers, to handle paths that are passed in. It makes the
 677          * path absolute, and reduces it to NULL if omitted or
 678          * root (the latter optionally).
 679          *
 680          * NOTE THAT THIS WILL FREE THE PREVIOUS ARGUMENT POINTER ON
 681          * SUCCESS! Hence, do not pass in uninitialized pointers.
 682          */
 683
 684         if (isempty(path)) {
 685                 *arg = mfree(*arg);
 686                 return 0;
 687         }
 688
 689         r = path_make_absolute_cwd(path, &p);
 690         if (r < 0)
 691                 return log_error_errno(r, "Failed to parse path \"%s\" and make it absolute: %m", path);
 692
 693         path_simplify(p, false);
 694         if (suppress_root && empty_or_root(p))
 695                 p = mfree(p);
 696
 697         free_and_replace(*arg, p);
 698
 699         return 0;
 700 }
 701
 702 char* dirname_malloc(const char *path) {
 703         char *d, *dir, *dir2;
 704
 705         assert(path);
 706
 707         d = strdup(path);
 708         if (!d)
 709                 return NULL;
 710
 711         dir = dirname(d);
 712         assert(dir);
 713
 714         if (dir == d)
 715                 return d;
 716
 717         dir2 = strdup(dir);
 718         free(d);
 719
 720         return dir2;
 721 }
 722
 723 const char *last_path_component(const char *path) {
 724
 725         /* Finds the last component of the path, preserving the optional trailing slash that signifies a directory.
 726          *
 727          *    a/b/c → c
 728          *    a/b/c/ → c/
 729          *    x → x
 730          *    x/ → x/
 731          *    /y → y
 732          *    /y/ → y/
 733          *    / → /
 734          *    // → /
 735          *    /foo/a → a
 736          *    /foo/a/ → a/
 737          *
 738          *    Also, the empty string is mapped to itself.
 739          *
 740          * This is different than basename(), which returns "" when a trailing slash is present.
 741          */
 742
 743         unsigned l, k;
 744
 745         l = k = strlen(path);
 746         if (l == 0) /* special case — an empty string */
 747                 return path;
 748
 749         while (k > 0 && path[k-1] == '/')
 750                 k--;
 751
 752         if (k == 0) /* the root directory */
 753                 return path + l - 1;
 754
 755         while (k > 0 && path[k-1] != '/')
 756                 k--;
 757
 758         return path + k;
 759 }
 760
 761 bool filename_is_valid(const char *p) {
 762         const char *e;
 763
 764         if (isempty(p))
 765                 return false;
 766
 767         if (dot_or_dot_dot(p))
 768                 return false;
 769
 770         e = strchrnul(p, '/');
 771         if (*e != 0)
 772                 return false;
 773
 774         if (e - p > FILENAME_MAX)
 775                 return false;
 776
 777         return true;
 778 }
 779
 780 bool path_is_normalized(const char *p) {
 781
 782         if (isempty(p))
 783                 return false;
 784
 785         if (dot_or_dot_dot(p))
 786                 return false;
 787
 788         if (startswith(p, "../") || endswith(p, "/..") || strstr(p, "/../"))
 789                 return false;
 790
 791         if (strlen(p)+1 > PATH_MAX)
 792                 return false;
 793
 794         if (startswith(p, "./") || endswith(p, "/.") || strstr(p, "/./"))
 795                 return false;
 796
 797         if (strstr(p, "//"))
 798                 return false;
 799
 800         return true;
 801 }
 802
 803 char *file_in_same_dir(const char *path, const char *filename) {
 804         char *e, *ret;
 805         size_t k;
 806
 807         assert(path);
 808         assert(filename);
 809
 810         /* This removes the last component of path and appends
 811          * filename, unless the latter is absolute anyway or the
 812          * former isn't */
 813
 814         if (path_is_absolute(filename))
 815                 return strdup(filename);
 816
 817         e = strrchr(path, '/');
 818         if (!e)
 819                 return strdup(filename);
 820
 821         k = strlen(filename);
 822         ret = new(char, (e + 1 - path) + k + 1);
 823         if (!ret)
 824                 return NULL;
 825
 826         memcpy(mempcpy(ret, path, e + 1 - path), filename, k + 1);
 827         return ret;
 828 }
 829
 830 bool hidden_or_backup_file(const char *filename) {
 831         const char *p;
 832
 833         assert(filename);
 834
 835         if (filename[0] == '.' ||
 836             streq(filename, "lost+found") ||
 837             streq(filename, "aquota.user") ||
 838             streq(filename, "aquota.group") ||
 839             endswith(filename, "~"))
 840                 return true;
 841
 842         p = strrchr(filename, '.');
 843         if (!p)
 844                 return false;
 845
 846         /* Please, let's not add more entries to the list below. If external projects think it's a good idea to come up
 847          * with always new suffixes and that everybody else should just adjust to that, then it really should be on
 848          * them. Hence, in future, let's not add any more entries. Instead, let's ask those packages to instead adopt
 849          * one of the generic suffixes/prefixes for hidden files or backups, possibly augmented with an additional
 850          * string. Specifically: there's now:
 851          *
 852          *    The generic suffixes "~" and ".bak" for backup files
 853          *    The generic prefix "." for hidden files
 854          *
 855          * Thus, if a new package manager "foopkg" wants its own set of ".foopkg-new", ".foopkg-old", ".foopkg-dist"
 856          * or so registered, let's refuse that and ask them to use ".foopkg.new", ".foopkg.old" or ".foopkg~" instead.
 857          */
 858
 859         return STR_IN_SET(p + 1,
 860                           "rpmnew",
 861                           "rpmsave",
 862                           "rpmorig",
 863                           "dpkg-old",
 864                           "dpkg-new",
 865                           "dpkg-tmp",
 866                           "dpkg-dist",
 867                           "dpkg-bak",
 868                           "dpkg-backup",
 869                           "dpkg-remove",
 870                           "ucf-new",
 871                           "ucf-old",
 872                           "ucf-dist",
 873                           "swp",
 874                           "bak",
 875                           "old",
 876                           "new");
 877 }
 878
 879 bool is_device_path(const char *path) {
 880
 881         /* Returns true on paths that likely refer to a device, either by path in sysfs or to something in /dev */
 882
 883         return PATH_STARTSWITH_SET(path, "/dev/", "/sys/");
 884 }
 885
 886 bool valid_device_node_path(const char *path) {
 887
 888         /* Some superficial checks whether the specified path is a valid device node path, all without looking at the
 889          * actual device node. */
 890
 891         if (!PATH_STARTSWITH_SET(path, "/dev/", "/run/systemd/inaccessible/"))
 892                 return false;
 893
 894         if (endswith(path, "/")) /* can't be a device node if it ends in a slash */
 895                 return false;
 896
 897         return path_is_normalized(path);
 898 }
 899
 900 bool valid_device_allow_pattern(const char *path) {
 901         assert(path);
 902
 903         /* Like valid_device_node_path(), but also allows full-subsystem expressions, like DeviceAllow= and DeviceDeny=
 904          * accept it */
 905
 906         if (startswith(path, "block-") ||
 907             startswith(path, "char-"))
 908                 return true;
 909
 910         return valid_device_node_path(path);
 911 }
 912
 913 int systemd_installation_has_version(const char *root, unsigned minimal_version) {
 914         const char *pattern;
 915         int r;
 916
 917         /* Try to guess if systemd installation is later than the specified version. This
 918          * is hacky and likely to yield false negatives, particularly if the installation
 919          * is non-standard. False positives should be relatively rare.
 920          */
 921
 922         NULSTR_FOREACH(pattern,
 923                        /* /lib works for systems without usr-merge, and for systems with a sane
 924                         * usr-merge, where /lib is a symlink to /usr/lib. /usr/lib is necessary
 925                         * for Gentoo which does a merge without making /lib a symlink.
 926                         */
 927                        "lib/systemd/libsystemd-shared-*.so\0"
 928                        "lib64/systemd/libsystemd-shared-*.so\0"
 929                        "usr/lib/systemd/libsystemd-shared-*.so\0"
 930                        "usr/lib64/systemd/libsystemd-shared-*.so\0") {
 931
 932                 _cleanup_strv_free_ char **names = NULL;
 933                 _cleanup_free_ char *path = NULL;
 934                 char *c, **name;
 935
 936                 path = prefix_root(root, pattern);
 937                 if (!path)
 938                         return -ENOMEM;
 939
 940                 r = glob_extend(&names, path);
 941                 if (r == -ENOENT)
 942                         continue;
 943                 if (r < 0)
 944                         return r;
 945
 946                 assert_se(c = endswith(path, "*.so"));
 947                 *c = '\0'; /* truncate the glob part */
 948
 949                 STRV_FOREACH(name, names) {
 950                         /* This is most likely to run only once, hence let's not optimize anything. */
 951                         char *t, *t2;
 952                         unsigned version;
 953
 954                         t = startswith(*name, path);
 955                         if (!t)
 956                                 continue;
 957
 958                         t2 = endswith(t, ".so");
 959                         if (!t2)
 960                                 continue;
 961
 962                         t2[0] = '\0'; /* truncate the suffix */
 963
 964                         r = safe_atou(t, &version);
 965                         if (r < 0) {
 966                                 log_debug_errno(r, "Found libsystemd shared at \"%s.so\", but failed to parse version: %m", *name);
 967                                 continue;
 968                         }
 969
 970                         log_debug("Found libsystemd shared at \"%s.so\", version %u (%s).",
 971                                   *name, version,
 972                                   version >= minimal_version ? "OK" : "too old");
 973                         if (version >= minimal_version)
 974                                 return true;
 975                 }
 976         }
 977
 978         return false;
 979 }
 980
 981 bool dot_or_dot_dot(const char *path) {
 982         if (!path)
 983                 return false;
 984         if (path[0] != '.')
 985                 return false;
 986         if (path[1] == 0)
 987                 return true;
 988         if (path[1] != '.')
 989                 return false;
 990
 991         return path[2] == 0;
 992 }
 993
 994 bool empty_or_root(const char *root) {
 995
 996         /* For operations relative to some root directory, returns true if the specified root directory is redundant,
 997          * i.e. either / or NULL or the empty string or any equivalent. */
 998
 999         if (!root)
1000                 return true;
1001
1002         return root[strspn(root, "/")] == 0;
1003 }
1004
1005 int path_simplify_and_warn(
1006                 char *path,
1007                 unsigned flag,
1008                 const char *unit,
1009                 const char *filename,
1010                 unsigned line,
1011                 const char *lvalue) {
1012
1013         bool absolute, fatal = flag & PATH_CHECK_FATAL;
1014
1015         assert(!FLAGS_SET(flag, PATH_CHECK_ABSOLUTE | PATH_CHECK_RELATIVE));
1016
1017         if (!utf8_is_valid(path)) {
1018                 log_syntax_invalid_utf8(unit, LOG_ERR, filename, line, path);
1019                 return -EINVAL;
1020         }
1021
1022         if (flag & (PATH_CHECK_ABSOLUTE | PATH_CHECK_RELATIVE)) {
1023                 absolute = path_is_absolute(path);
1024
1025                 if (!absolute && (flag & PATH_CHECK_ABSOLUTE)) {
1026                         log_syntax(unit, LOG_ERR, filename, line, 0,
1027                                    "%s= path is not absolute%s: %s",
1028                                    lvalue, fatal ? "" : ", ignoring", path);
1029                         return -EINVAL;
1030                 }
1031
1032                 if (absolute && (flag & PATH_CHECK_RELATIVE)) {
1033                         log_syntax(unit, LOG_ERR, filename, line, 0,
1034                                    "%s= path is absolute%s: %s",
1035                                    lvalue, fatal ? "" : ", ignoring", path);
1036                         return -EINVAL;
1037                 }
1038         }
1039
1040         path_simplify(path, true);
1041
1042         if (!path_is_normalized(path)) {
1043                 log_syntax(unit, LOG_ERR, filename, line, 0,
1044                            "%s= path is not normalized%s: %s",
1045                            lvalue, fatal ? "" : ", ignoring", path);
1046                 return -EINVAL;
1047         }
1048
1049         return 0;
1050 }