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 "nulstr-util.h"
  25 #include "parse-util.h"
  26 #include "path-util.h"
  27 #include "stat-util.h"
  28 #include "string-util.h"
  29 #include "strv.h"
  30 #include "time-util.h"
  31 #include "utf8.h"
  32
  33 bool path_is_absolute(const char *p) {
  34         return p[0] == '/';
  35 }
  36
  37 bool is_path(const char *p) {
  38         return !!strchr(p, '/');
  39 }
  40
  41 int path_split_and_make_absolute(const char *p, char ***ret) {
  42         char **l;
  43         int r;
  44
  45         assert(p);
  46         assert(ret);
  47
  48         l = strv_split(p, ":");
  49         if (!l)
  50                 return -ENOMEM;
  51
  52         r = path_strv_make_absolute_cwd(l);
  53         if (r < 0) {
  54                 strv_free(l);
  55                 return r;
  56         }
  57
  58         *ret = l;
  59         return r;
  60 }
  61
  62 char *path_make_absolute(const char *p, const char *prefix) {
  63         assert(p);
  64
  65         /* Makes every item in the list an absolute path by prepending
  66          * the prefix, if specified and necessary */
  67
  68         if (path_is_absolute(p) || isempty(prefix))
  69                 return strdup(p);
  70
  71         return path_join(prefix, p);
  72 }
  73
  74 int safe_getcwd(char **ret) {
  75         char *cwd;
  76
  77         cwd = get_current_dir_name();
  78         if (!cwd)
  79                 return negative_errno();
  80
  81         /* Let's make sure the directory is really absolute, to protect us from the logic behind
  82          * CVE-2018-1000001 */
  83         if (cwd[0] != '/') {
  84                 free(cwd);
  85                 return -ENOMEDIUM;
  86         }
  87
  88         *ret = cwd;
  89         return 0;
  90 }
  91
  92 int path_make_absolute_cwd(const char *p, char **ret) {
  93         char *c;
  94         int r;
  95
  96         assert(p);
  97         assert(ret);
  98
  99         /* Similar to path_make_absolute(), but prefixes with the
 100          * current working directory. */
 101
 102         if (path_is_absolute(p))
 103                 c = strdup(p);
 104         else {
 105                 _cleanup_free_ char *cwd = NULL;
 106
 107                 r = safe_getcwd(&cwd);
 108                 if (r < 0)
 109                         return r;
 110
 111                 c = path_join(cwd, p);
 112         }
 113         if (!c)
 114                 return -ENOMEM;
 115
 116         *ret = c;
 117         return 0;
 118 }
 119
 120 int path_make_relative(const char *from_dir, const char *to_path, char **_r) {
 121         char *f, *t, *r, *p;
 122         unsigned n_parents = 0;
 123
 124         assert(from_dir);
 125         assert(to_path);
 126         assert(_r);
 127
 128         /* Strips the common part, and adds ".." elements as necessary. */
 129
 130         if (!path_is_absolute(from_dir) || !path_is_absolute(to_path))
 131                 return -EINVAL;
 132
 133         f = strdupa(from_dir);
 134         t = strdupa(to_path);
 135
 136         path_simplify(f, true);
 137         path_simplify(t, true);
 138
 139         /* Skip the common part. */
 140         for (;;) {
 141                 size_t a, b;
 142
 143                 f += *f == '/';
 144                 t += *t == '/';
 145
 146                 if (!*f) {
 147                         if (!*t)
 148                                 /* from_dir equals to_path. */
 149                                 r = strdup(".");
 150                         else
 151                                 /* from_dir is a parent directory of to_path. */
 152                                 r = strdup(t);
 153                         if (!r)
 154                                 return -ENOMEM;
 155
 156                         *_r = r;
 157                         return 0;
 158                 }
 159
 160                 if (!*t)
 161                         break;
 162
 163                 a = strcspn(f, "/");
 164                 b = strcspn(t, "/");
 165
 166                 if (a != b || memcmp(f, t, a) != 0)
 167                         break;
 168
 169                 f += a;
 170                 t += b;
 171         }
 172
 173         /* If we're here, then "from_dir" has one or more elements that need to
 174          * be replaced with "..". */
 175
 176         /* Count the number of necessary ".." elements. */
 177         for (; *f;) {
 178                 size_t w;
 179
 180                 w = strcspn(f, "/");
 181
 182                 /* If this includes ".." we can't do a simple series of "..", refuse */
 183                 if (w == 2 && f[0] == '.' && f[1] == '.')
 184                         return -EINVAL;
 185
 186                 /* Count number of elements */
 187                 n_parents++;
 188
 189                 f += w;
 190                 f += *f == '/';
 191         }
 192
 193         r = new(char, n_parents * 3 + strlen(t) + 1);
 194         if (!r)
 195                 return -ENOMEM;
 196
 197         for (p = r; n_parents > 0; n_parents--)
 198                 p = mempcpy(p, "../", 3);
 199
 200         if (*t)
 201                 strcpy(p, t);
 202         else
 203                 /* Remove trailing slash */
 204                 *(--p) = 0;
 205
 206         *_r = r;
 207         return 0;
 208 }
 209
 210 int path_strv_make_absolute_cwd(char **l) {
 211         char **s;
 212         int r;
 213
 214         /* Goes through every item in the string list and makes it
 215          * absolute. This works in place and won't rollback any
 216          * changes on failure. */
 217
 218         STRV_FOREACH(s, l) {
 219                 char *t;
 220
 221                 r = path_make_absolute_cwd(*s, &t);
 222                 if (r < 0)
 223                         return r;
 224
 225                 path_simplify(t, false);
 226                 free_and_replace(*s, t);
 227         }
 228
 229         return 0;
 230 }
 231
 232 char **path_strv_resolve(char **l, const char *root) {
 233         char **s;
 234         unsigned k = 0;
 235         bool enomem = false;
 236         int r;
 237
 238         if (strv_isempty(l))
 239                 return l;
 240
 241         /* Goes through every item in the string list and canonicalize
 242          * the path. This works in place and won't rollback any
 243          * changes on failure. */
 244
 245         STRV_FOREACH(s, l) {
 246                 _cleanup_free_ char *orig = NULL;
 247                 char *t, *u;
 248
 249                 if (!path_is_absolute(*s)) {
 250                         free(*s);
 251                         continue;
 252                 }
 253
 254                 if (root) {
 255                         orig = *s;
 256                         t = prefix_root(root, orig);
 257                         if (!t) {
 258                                 enomem = true;
 259                                 continue;
 260                         }
 261                 } else
 262                         t = *s;
 263
 264                 r = chase_symlinks(t, root, 0, &u);
 265                 if (r == -ENOENT) {
 266                         if (root) {
 267                                 u = TAKE_PTR(orig);
 268                                 free(t);
 269                         } else
 270                                 u = t;
 271                 } else if (r < 0) {
 272                         free(t);
 273
 274                         if (r == -ENOMEM)
 275                                 enomem = true;
 276
 277                         continue;
 278                 } else if (root) {
 279                         char *x;
 280
 281                         free(t);
 282                         x = path_startswith(u, root);
 283                         if (x) {
 284                                 /* restore the slash if it was lost */
 285                                 if (!startswith(x, "/"))
 286                                         *(--x) = '/';
 287
 288                                 t = strdup(x);
 289                                 free(u);
 290                                 if (!t) {
 291                                         enomem = true;
 292                                         continue;
 293                                 }
 294                                 u = t;
 295                         } else {
 296                                 /* canonicalized path goes outside of
 297                                  * prefix, keep the original path instead */
 298                                 free_and_replace(u, orig);
 299                         }
 300                 } else
 301                         free(t);
 302
 303                 l[k++] = u;
 304         }
 305
 306         l[k] = NULL;
 307
 308         if (enomem)
 309                 return NULL;
 310
 311         return l;
 312 }
 313
 314 char **path_strv_resolve_uniq(char **l, const char *root) {
 315
 316         if (strv_isempty(l))
 317                 return l;
 318
 319         if (!path_strv_resolve(l, root))
 320                 return NULL;
 321
 322         return strv_uniq(l);
 323 }
 324
 325 char *path_simplify(char *path, bool kill_dots) {
 326         char *f, *t;
 327         bool slash = false, ignore_slash = false, absolute;
 328
 329         assert(path);
 330
 331         /* Removes redundant inner and trailing slashes. Also removes unnecessary dots
 332          * if kill_dots is true. Modifies the passed string in-place.
 333          *
 334          * ///foo//./bar/.   becomes /foo/./bar/.      (if kill_dots is false)
 335          * ///foo//./bar/.   becomes /foo/bar          (if kill_dots is true)
 336          * .//./foo//./bar/. becomes ././foo/./bar/.   (if kill_dots is false)
 337          * .//./foo//./bar/. becomes foo/bar           (if kill_dots is true)
 338          */
 339
 340         if (isempty(path))
 341                 return path;
 342
 343         absolute = path_is_absolute(path);
 344
 345         f = path;
 346         if (kill_dots && *f == '.' && IN_SET(f[1], 0, '/')) {
 347                 ignore_slash = true;
 348                 f++;
 349         }
 350
 351         for (t = path; *f; f++) {
 352
 353                 if (*f == '/') {
 354                         slash = true;
 355                         continue;
 356                 }
 357
 358                 if (slash) {
 359                         if (kill_dots && *f == '.' && IN_SET(f[1], 0, '/'))
 360                                 continue;
 361
 362                         slash = false;
 363                         if (ignore_slash)
 364                                 ignore_slash = false;
 365                         else
 366                                 *(t++) = '/';
 367                 }
 368
 369                 *(t++) = *f;
 370         }
 371
 372         /* Special rule, if we stripped everything, we either need a "/" (for the root directory)
 373          * or "." for the current directory */
 374         if (t == path) {
 375                 if (absolute)
 376                         *(t++) = '/';
 377                 else
 378                         *(t++) = '.';
 379         }
 380
 381         *t = 0;
 382         return path;
 383 }
 384
 385 char* path_startswith(const char *path, const char *prefix) {
 386         assert(path);
 387         assert(prefix);
 388
 389         /* Returns a pointer to the start of the first component after the parts matched by
 390          * the prefix, iff
 391          * - both paths are absolute or both paths are relative,
 392          * and
 393          * - each component in prefix in turn matches a component in path at the same position.
 394          * An empty string will be returned when the prefix and path are equivalent.
 395          *
 396          * Returns NULL otherwise.
 397          */
 398
 399         if ((path[0] == '/') != (prefix[0] == '/'))
 400                 return NULL;
 401
 402         for (;;) {
 403                 size_t a, b;
 404
 405                 path += strspn(path, "/");
 406                 prefix += strspn(prefix, "/");
 407
 408                 if (*prefix == 0)
 409                         return (char*) path;
 410
 411                 if (*path == 0)
 412                         return NULL;
 413
 414                 a = strcspn(path, "/");
 415                 b = strcspn(prefix, "/");
 416
 417                 if (a != b)
 418                         return NULL;
 419
 420                 if (memcmp(path, prefix, a) != 0)
 421                         return NULL;
 422
 423                 path += a;
 424                 prefix += b;
 425         }
 426 }
 427
 428 int path_compare(const char *a, const char *b) {
 429         int d;
 430
 431         assert(a);
 432         assert(b);
 433
 434         /* A relative path and an absolute path must not compare as equal.
 435          * Which one is sorted before the other does not really matter.
 436          * Here a relative path is ordered before an absolute path. */
 437         d = (a[0] == '/') - (b[0] == '/');
 438         if (d != 0)
 439                 return d;
 440
 441         for (;;) {
 442                 size_t j, k;
 443
 444                 a += strspn(a, "/");
 445                 b += strspn(b, "/");
 446
 447                 if (*a == 0 && *b == 0)
 448                         return 0;
 449
 450                 /* Order prefixes first: "/foo" before "/foo/bar" */
 451                 if (*a == 0)
 452                         return -1;
 453                 if (*b == 0)
 454                         return 1;
 455
 456                 j = strcspn(a, "/");
 457                 k = strcspn(b, "/");
 458
 459                 /* Alphabetical sort: "/foo/aaa" before "/foo/b" */
 460                 d = memcmp(a, b, MIN(j, k));
 461                 if (d != 0)
 462                         return (d > 0) - (d < 0); /* sign of d */
 463
 464                 /* Sort "/foo/a" before "/foo/aaa" */
 465                 d = (j > k) - (j < k);  /* sign of (j - k) */
 466                 if (d != 0)
 467                         return d;
 468
 469                 a += j;
 470                 b += k;
 471         }
 472 }
 473
 474 bool path_equal(const char *a, const char *b) {
 475         return path_compare(a, b) == 0;
 476 }
 477
 478 bool path_equal_or_files_same(const char *a, const char *b, int flags) {
 479         return path_equal(a, b) || files_same(a, b, flags) > 0;
 480 }
 481
 482 char* path_join_internal(const char *first, ...) {
 483         char *joined, *q;
 484         const char *p;
 485         va_list ap;
 486         bool slash;
 487         size_t sz;
 488
 489         /* Joins all listed strings until the sentinel and places a "/" between them unless the strings end/begin
 490          * already with one so that it is unnecessary. Note that slashes which are already duplicate won't be
 491          * removed. The string returned is hence always equal to or longer than the sum of the lengths of each
 492          * individual string.
 493          *
 494          * Note: any listed empty string is simply skipped. This can be useful for concatenating strings of which some
 495          * are optional.
 496          *
 497          * Examples:
 498          *
 499          * path_join("foo", "bar") → "foo/bar"
 500          * path_join("foo/", "bar") → "foo/bar"
 501          * path_join("", "foo", "", "bar", "") → "foo/bar" */
 502
 503         sz = strlen_ptr(first);
 504         va_start(ap, first);
 505         while ((p = va_arg(ap, char*)) != (const char*) -1)
 506                 if (!isempty(p))
 507                         sz += 1 + strlen(p);
 508         va_end(ap);
 509
 510         joined = new(char, sz + 1);
 511         if (!joined)
 512                 return NULL;
 513
 514         if (!isempty(first)) {
 515                 q = stpcpy(joined, first);
 516                 slash = endswith(first, "/");
 517         } else {
 518                 /* Skip empty items */
 519                 joined[0] = 0;
 520                 q = joined;
 521                 slash = true; /* no need to generate a slash anymore */
 522         }
 523
 524         va_start(ap, first);
 525         while ((p = va_arg(ap, char*)) != (const char*) -1) {
 526                 if (isempty(p))
 527                         continue;
 528
 529                 if (!slash && p[0] != '/')
 530                         *(q++) = '/';
 531
 532                 q = stpcpy(q, p);
 533                 slash = endswith(p, "/");
 534         }
 535         va_end(ap);
 536
 537         return joined;
 538 }
 539
 540 int find_binary(const char *name, char **ret) {
 541         int last_error, r;
 542         const char *p;
 543
 544         assert(name);
 545
 546         if (is_path(name)) {
 547                 if (access(name, X_OK) < 0)
 548                         return -errno;
 549
 550                 if (ret) {
 551                         r = path_make_absolute_cwd(name, ret);
 552                         if (r < 0)
 553                                 return r;
 554                 }
 555
 556                 return 0;
 557         }
 558
 559         /**
 560          * Plain getenv, not secure_getenv, because we want
 561          * to actually allow the user to pick the binary.
 562          */
 563         p = getenv("PATH");
 564         if (!p)
 565                 p = DEFAULT_PATH;
 566
 567         last_error = -ENOENT;
 568
 569         for (;;) {
 570                 _cleanup_free_ char *j = NULL, *element = NULL;
 571
 572                 r = extract_first_word(&p, &element, ":", EXTRACT_RELAX|EXTRACT_DONT_COALESCE_SEPARATORS);
 573                 if (r < 0)
 574                         return r;
 575                 if (r == 0)
 576                         break;
 577
 578                 if (!path_is_absolute(element))
 579                         continue;
 580
 581                 j = path_join(element, name);
 582                 if (!j)
 583                         return -ENOMEM;
 584
 585                 if (access(j, X_OK) >= 0) {
 586                         /* Found it! */
 587
 588                         if (ret) {
 589                                 *ret = path_simplify(j, false);
 590                                 j = NULL;
 591                         }
 592
 593                         return 0;
 594                 }
 595
 596                 last_error = -errno;
 597         }
 598
 599         return last_error;
 600 }
 601
 602 bool paths_check_timestamp(const char* const* paths, usec_t *timestamp, bool update) {
 603         bool changed = false;
 604         const char* const* i;
 605
 606         assert(timestamp);
 607
 608         if (!paths)
 609                 return false;
 610
 611         STRV_FOREACH(i, paths) {
 612                 struct stat stats;
 613                 usec_t u;
 614
 615                 if (stat(*i, &stats) < 0)
 616                         continue;
 617
 618                 u = timespec_load(&stats.st_mtim);
 619
 620                 /* first check */
 621                 if (*timestamp >= u)
 622                         continue;
 623
 624                 log_debug("timestamp of '%s' changed", *i);
 625
 626                 /* update timestamp */
 627                 if (update) {
 628                         *timestamp = u;
 629                         changed = true;
 630                 } else
 631                         return true;
 632         }
 633
 634         return changed;
 635 }
 636
 637 static int binary_is_good(const char *binary) {
 638         _cleanup_free_ char *p = NULL, *d = NULL;
 639         int r;
 640
 641         r = find_binary(binary, &p);
 642         if (r == -ENOENT)
 643                 return 0;
 644         if (r < 0)
 645                 return r;
 646
 647         /* An fsck that is linked to /bin/true is a non-existent
 648          * fsck */
 649
 650         r = readlink_malloc(p, &d);
 651         if (r == -EINVAL) /* not a symlink */
 652                 return 1;
 653         if (r < 0)
 654                 return r;
 655
 656         return !PATH_IN_SET(d, "true"
 657                                "/bin/true",
 658                                "/usr/bin/true",
 659                                "/dev/null");
 660 }
 661
 662 int fsck_exists(const char *fstype) {
 663         const char *checker;
 664
 665         assert(fstype);
 666
 667         if (streq(fstype, "auto"))
 668                 return -EINVAL;
 669
 670         checker = strjoina("fsck.", fstype);
 671         return binary_is_good(checker);
 672 }
 673
 674 int mkfs_exists(const char *fstype) {
 675         const char *mkfs;
 676
 677         assert(fstype);
 678
 679         if (streq(fstype, "auto"))
 680                 return -EINVAL;
 681
 682         mkfs = strjoina("mkfs.", fstype);
 683         return binary_is_good(mkfs);
 684 }
 685
 686 char *prefix_root(const char *root, const char *path) {
 687         char *n, *p;
 688         size_t l;
 689
 690         /* If root is passed, prefixes path with it. Otherwise returns
 691          * it as is. */
 692
 693         assert(path);
 694
 695         /* First, drop duplicate prefixing slashes from the path */
 696         while (path[0] == '/' && path[1] == '/')
 697                 path++;
 698
 699         if (empty_or_root(root))
 700                 return strdup(path);
 701
 702         l = strlen(root) + 1 + strlen(path) + 1;
 703
 704         n = new(char, l);
 705         if (!n)
 706                 return NULL;
 707
 708         p = stpcpy(n, root);
 709
 710         while (p > n && p[-1] == '/')
 711                 p--;
 712
 713         if (path[0] != '/')
 714                 *(p++) = '/';
 715
 716         strcpy(p, path);
 717         return n;
 718 }
 719
 720 int parse_path_argument_and_warn(const char *path, bool suppress_root, char **arg) {
 721         char *p;
 722         int r;
 723
 724         /*
 725          * This function is intended to be used in command line
 726          * parsers, to handle paths that are passed in. It makes the
 727          * path absolute, and reduces it to NULL if omitted or
 728          * root (the latter optionally).
 729          *
 730          * NOTE THAT THIS WILL FREE THE PREVIOUS ARGUMENT POINTER ON
 731          * SUCCESS! Hence, do not pass in uninitialized pointers.
 732          */
 733
 734         if (isempty(path)) {
 735                 *arg = mfree(*arg);
 736                 return 0;
 737         }
 738
 739         r = path_make_absolute_cwd(path, &p);
 740         if (r < 0)
 741                 return log_error_errno(r, "Failed to parse path \"%s\" and make it absolute: %m", path);
 742
 743         path_simplify(p, false);
 744         if (suppress_root && empty_or_root(p))
 745                 p = mfree(p);
 746
 747         free_and_replace(*arg, p);
 748
 749         return 0;
 750 }
 751
 752 char* dirname_malloc(const char *path) {
 753         char *d, *dir, *dir2;
 754
 755         assert(path);
 756
 757         d = strdup(path);
 758         if (!d)
 759                 return NULL;
 760
 761         dir = dirname(d);
 762         assert(dir);
 763
 764         if (dir == d)
 765                 return d;
 766
 767         dir2 = strdup(dir);
 768         free(d);
 769
 770         return dir2;
 771 }
 772
 773 const char *last_path_component(const char *path) {
 774
 775         /* Finds the last component of the path, preserving the optional trailing slash that signifies a directory.
 776          *
 777          *    a/b/c → c
 778          *    a/b/c/ → c/
 779          *    x → x
 780          *    x/ → x/
 781          *    /y → y
 782          *    /y/ → y/
 783          *    / → /
 784          *    // → /
 785          *    /foo/a → a
 786          *    /foo/a/ → a/
 787          *
 788          *    Also, the empty string is mapped to itself.
 789          *
 790          * This is different than basename(), which returns "" when a trailing slash is present.
 791          */
 792
 793         unsigned l, k;
 794
 795         if (!path)
 796                 return NULL;
 797
 798         l = k = strlen(path);
 799         if (l == 0) /* special case — an empty string */
 800                 return path;
 801
 802         while (k > 0 && path[k-1] == '/')
 803                 k--;
 804
 805         if (k == 0) /* the root directory */
 806                 return path + l - 1;
 807
 808         while (k > 0 && path[k-1] != '/')
 809                 k--;
 810
 811         return path + k;
 812 }
 813
 814 int path_extract_filename(const char *p, char **ret) {
 815         _cleanup_free_ char *a = NULL;
 816         const char *c, *e = NULL, *q;
 817
 818         /* Extracts the filename part (i.e. right-most component) from a path, i.e. string that passes
 819          * filename_is_valid(). A wrapper around last_path_component(), but eats up trailing slashes. */
 820
 821         if (!p)
 822                 return -EINVAL;
 823
 824         c = last_path_component(p);
 825
 826         for (q = c; *q != 0; q++)
 827                 if (*q != '/')
 828                         e = q + 1;
 829
 830         if (!e) /* no valid character? */
 831                 return -EINVAL;
 832
 833         a = strndup(c, e - c);
 834         if (!a)
 835                 return -ENOMEM;
 836
 837         if (!filename_is_valid(a))
 838                 return -EINVAL;
 839
 840         *ret = TAKE_PTR(a);
 841
 842         return 0;
 843 }
 844
 845 bool filename_is_valid(const char *p) {
 846         const char *e;
 847
 848         if (isempty(p))
 849                 return false;
 850
 851         if (dot_or_dot_dot(p))
 852                 return false;
 853
 854         e = strchrnul(p, '/');
 855         if (*e != 0)
 856                 return false;
 857
 858         if (e - p > FILENAME_MAX) /* FILENAME_MAX is counted *without* the trailing NUL byte */
 859                 return false;
 860
 861         return true;
 862 }
 863
 864 bool path_is_valid(const char *p) {
 865
 866         if (isempty(p))
 867                 return false;
 868
 869         if (strlen(p) >= PATH_MAX) /* PATH_MAX is counted *with* the trailing NUL byte */
 870                 return false;
 871
 872         return true;
 873 }
 874
 875 bool path_is_normalized(const char *p) {
 876
 877         if (!path_is_valid(p))
 878                 return false;
 879
 880         if (dot_or_dot_dot(p))
 881                 return false;
 882
 883         if (startswith(p, "../") || endswith(p, "/..") || strstr(p, "/../"))
 884                 return false;
 885
 886         if (startswith(p, "./") || endswith(p, "/.") || strstr(p, "/./"))
 887                 return false;
 888
 889         if (strstr(p, "//"))
 890                 return false;
 891
 892         return true;
 893 }
 894
 895 char *file_in_same_dir(const char *path, const char *filename) {
 896         char *e, *ret;
 897         size_t k;
 898
 899         assert(path);
 900         assert(filename);
 901
 902         /* This removes the last component of path and appends
 903          * filename, unless the latter is absolute anyway or the
 904          * former isn't */
 905
 906         if (path_is_absolute(filename))
 907                 return strdup(filename);
 908
 909         e = strrchr(path, '/');
 910         if (!e)
 911                 return strdup(filename);
 912
 913         k = strlen(filename);
 914         ret = new(char, (e + 1 - path) + k + 1);
 915         if (!ret)
 916                 return NULL;
 917
 918         memcpy(mempcpy(ret, path, e + 1 - path), filename, k + 1);
 919         return ret;
 920 }
 921
 922 bool hidden_or_backup_file(const char *filename) {
 923         const char *p;
 924
 925         assert(filename);
 926
 927         if (filename[0] == '.' ||
 928             streq(filename, "lost+found") ||
 929             streq(filename, "aquota.user") ||
 930             streq(filename, "aquota.group") ||
 931             endswith(filename, "~"))
 932                 return true;
 933
 934         p = strrchr(filename, '.');
 935         if (!p)
 936                 return false;
 937
 938         /* Please, let's not add more entries to the list below. If external projects think it's a good idea to come up
 939          * with always new suffixes and that everybody else should just adjust to that, then it really should be on
 940          * them. Hence, in future, let's not add any more entries. Instead, let's ask those packages to instead adopt
 941          * one of the generic suffixes/prefixes for hidden files or backups, possibly augmented with an additional
 942          * string. Specifically: there's now:
 943          *
 944          *    The generic suffixes "~" and ".bak" for backup files
 945          *    The generic prefix "." for hidden files
 946          *
 947          * Thus, if a new package manager "foopkg" wants its own set of ".foopkg-new", ".foopkg-old", ".foopkg-dist"
 948          * or so registered, let's refuse that and ask them to use ".foopkg.new", ".foopkg.old" or ".foopkg~" instead.
 949          */
 950
 951         return STR_IN_SET(p + 1,
 952                           "rpmnew",
 953                           "rpmsave",
 954                           "rpmorig",
 955                           "dpkg-old",
 956                           "dpkg-new",
 957                           "dpkg-tmp",
 958                           "dpkg-dist",
 959                           "dpkg-bak",
 960                           "dpkg-backup",
 961                           "dpkg-remove",
 962                           "ucf-new",
 963                           "ucf-old",
 964                           "ucf-dist",
 965                           "swp",
 966                           "bak",
 967                           "old",
 968                           "new");
 969 }
 970
 971 bool is_device_path(const char *path) {
 972
 973         /* Returns true on paths that likely refer to a device, either by path in sysfs or to something in /dev */
 974
 975         return PATH_STARTSWITH_SET(path, "/dev/", "/sys/");
 976 }
 977
 978 bool valid_device_node_path(const char *path) {
 979
 980         /* Some superficial checks whether the specified path is a valid device node path, all without looking at the
 981          * actual device node. */
 982
 983         if (!PATH_STARTSWITH_SET(path, "/dev/", "/run/systemd/inaccessible/"))
 984                 return false;
 985
 986         if (endswith(path, "/")) /* can't be a device node if it ends in a slash */
 987                 return false;
 988
 989         return path_is_normalized(path);
 990 }
 991
 992 bool valid_device_allow_pattern(const char *path) {
 993         assert(path);
 994
 995         /* Like valid_device_node_path(), but also allows full-subsystem expressions, like DeviceAllow= and DeviceDeny=
 996          * accept it */
 997
 998         if (STARTSWITH_SET(path, "block-", "char-"))
 999                 return true;
1000
1001         return valid_device_node_path(path);
1002 }
1003
1004 int systemd_installation_has_version(const char *root, unsigned minimal_version) {
1005         const char *pattern;
1006         int r;
1007
1008         /* Try to guess if systemd installation is later than the specified version. This
1009          * is hacky and likely to yield false negatives, particularly if the installation
1010          * is non-standard. False positives should be relatively rare.
1011          */
1012
1013         NULSTR_FOREACH(pattern,
1014                        /* /lib works for systems without usr-merge, and for systems with a sane
1015                         * usr-merge, where /lib is a symlink to /usr/lib. /usr/lib is necessary
1016                         * for Gentoo which does a merge without making /lib a symlink.
1017                         */
1018                        "lib/systemd/libsystemd-shared-*.so\0"
1019                        "lib64/systemd/libsystemd-shared-*.so\0"
1020                        "usr/lib/systemd/libsystemd-shared-*.so\0"
1021                        "usr/lib64/systemd/libsystemd-shared-*.so\0") {
1022
1023                 _cleanup_strv_free_ char **names = NULL;
1024                 _cleanup_free_ char *path = NULL;
1025                 char *c, **name;
1026
1027                 path = prefix_root(root, pattern);
1028                 if (!path)
1029                         return -ENOMEM;
1030
1031                 r = glob_extend(&names, path);
1032                 if (r == -ENOENT)
1033                         continue;
1034                 if (r < 0)
1035                         return r;
1036
1037                 assert_se(c = endswith(path, "*.so"));
1038                 *c = '\0'; /* truncate the glob part */
1039
1040                 STRV_FOREACH(name, names) {
1041                         /* This is most likely to run only once, hence let's not optimize anything. */
1042                         char *t, *t2;
1043                         unsigned version;
1044
1045                         t = startswith(*name, path);
1046                         if (!t)
1047                                 continue;
1048
1049                         t2 = endswith(t, ".so");
1050                         if (!t2)
1051                                 continue;
1052
1053                         t2[0] = '\0'; /* truncate the suffix */
1054
1055                         r = safe_atou(t, &version);
1056                         if (r < 0) {
1057                                 log_debug_errno(r, "Found libsystemd shared at \"%s.so\", but failed to parse version: %m", *name);
1058                                 continue;
1059                         }
1060
1061                         log_debug("Found libsystemd shared at \"%s.so\", version %u (%s).",
1062                                   *name, version,
1063                                   version >= minimal_version ? "OK" : "too old");
1064                         if (version >= minimal_version)
1065                                 return true;
1066                 }
1067         }
1068
1069         return false;
1070 }
1071
1072 bool dot_or_dot_dot(const char *path) {
1073         if (!path)
1074                 return false;
1075         if (path[0] != '.')
1076                 return false;
1077         if (path[1] == 0)
1078                 return true;
1079         if (path[1] != '.')
1080                 return false;
1081
1082         return path[2] == 0;
1083 }
1084
1085 bool empty_or_root(const char *root) {
1086
1087         /* For operations relative to some root directory, returns true if the specified root directory is redundant,
1088          * i.e. either / or NULL or the empty string or any equivalent. */
1089
1090         if (!root)
1091                 return true;
1092
1093         return root[strspn(root, "/")] == 0;
1094 }
1095
1096 int path_simplify_and_warn(
1097                 char *path,
1098                 unsigned flag,
1099                 const char *unit,
1100                 const char *filename,
1101                 unsigned line,
1102                 const char *lvalue) {
1103
1104         bool fatal = flag & PATH_CHECK_FATAL;
1105
1106         assert(!FLAGS_SET(flag, PATH_CHECK_ABSOLUTE | PATH_CHECK_RELATIVE));
1107
1108         if (!utf8_is_valid(path))
1109                 return log_syntax_invalid_utf8(unit, LOG_ERR, filename, line, path);
1110
1111         if (flag & (PATH_CHECK_ABSOLUTE | PATH_CHECK_RELATIVE)) {
1112                 bool absolute;
1113
1114                 absolute = path_is_absolute(path);
1115
1116                 if (!absolute && (flag & PATH_CHECK_ABSOLUTE))
1117                         return log_syntax(unit, LOG_ERR, filename, line, SYNTHETIC_ERRNO(EINVAL),
1118                                           "%s= path is not absolute%s: %s",
1119                                           lvalue, fatal ? "" : ", ignoring", path);
1120
1121                 if (absolute && (flag & PATH_CHECK_RELATIVE))
1122                         return log_syntax(unit, LOG_ERR, filename, line, SYNTHETIC_ERRNO(EINVAL),
1123                                           "%s= path is absolute%s: %s",
1124                                           lvalue, fatal ? "" : ", ignoring", path);
1125         }
1126
1127         path_simplify(path, true);
1128
1129         if (!path_is_valid(path))
1130                 return log_syntax(unit, LOG_ERR, filename, line, SYNTHETIC_ERRNO(EINVAL),
1131                                   "%s= path has invalid length (%zu bytes)%s.",
1132                                   lvalue, strlen(path), fatal ? "" : ", ignoring");
1133
1134         if (!path_is_normalized(path))
1135                 return log_syntax(unit, LOG_ERR, filename, line, SYNTHETIC_ERRNO(EINVAL),
1136                                   "%s= path is not normalized%s: %s",
1137                                   lvalue, fatal ? "" : ", ignoring", path);
1138
1139         return 0;
1140 }