src/basic/env-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <limits.h>
   5 #include <stdarg.h>
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8
   9 #include "alloc-util.h"
  10 #include "env-util.h"
  11 #include "escape.h"
  12 #include "extract-word.h"
  13 #include "macro.h"
  14 #include "parse-util.h"
  15 #include "path-util.h"
  16 #include "process-util.h"
  17 #include "stdio-util.h"
  18 #include "string-util.h"
  19 #include "strv.h"
  20 #include "utf8.h"
  21
  22 /* We follow bash for the character set. Different shells have different rules. */
  23 #define VALID_BASH_ENV_NAME_CHARS               \
  24         DIGITS LETTERS                          \
  25         "_"
  26
  27 static bool env_name_is_valid_n(const char *e, size_t n) {
  28         if (!e)
  29                 return false;
  30
  31         if (n <= 0)
  32                 return false;
  33
  34         if (e[0] >= '0' && e[0] <= '9')
  35                 return false;
  36
  37         /* POSIX says the overall size of the environment block cannot
  38          * be > ARG_MAX, an individual assignment hence cannot be
  39          * either. Discounting the equal sign and trailing NUL this
  40          * hence leaves ARG_MAX-2 as longest possible variable
  41          * name. */
  42         if (n > (size_t) sysconf(_SC_ARG_MAX) - 2)
  43                 return false;
  44
  45         for (const char *p = e; p < e + n; p++)
  46                 if (!strchr(VALID_BASH_ENV_NAME_CHARS, *p))
  47                         return false;
  48
  49         return true;
  50 }
  51
  52 bool env_name_is_valid(const char *e) {
  53         return env_name_is_valid_n(e, strlen_ptr(e));
  54 }
  55
  56 bool env_value_is_valid(const char *e) {
  57         if (!e)
  58                 return false;
  59
  60         if (!utf8_is_valid(e))
  61                 return false;
  62
  63         /* Note that variable *values* may contain control characters, in particular NL, TAB, BS, DEL, ESC…
  64          * When printing those variables with show-environment, we'll escape them. Make sure to print
  65          * environment variables carefully! */
  66
  67         /* POSIX says the overall size of the environment block cannot be > ARG_MAX, an individual assignment
  68          * hence cannot be either. Discounting the shortest possible variable name of length 1, the equal
  69          * sign and trailing NUL this hence leaves ARG_MAX-3 as longest possible variable value. */
  70         if (strlen(e) > sc_arg_max() - 3)
  71                 return false;
  72
  73         return true;
  74 }
  75
  76 bool env_assignment_is_valid(const char *e) {
  77         const char *eq;
  78
  79         eq = strchr(e, '=');
  80         if (!eq)
  81                 return false;
  82
  83         if (!env_name_is_valid_n(e, eq - e))
  84                 return false;
  85
  86         if (!env_value_is_valid(eq + 1))
  87                 return false;
  88
  89         /* POSIX says the overall size of the environment block cannot be > ARG_MAX, hence the individual
  90          * variable assignments cannot be either, but let's leave room for one trailing NUL byte. */
  91         if (strlen(e) > sc_arg_max() - 1)
  92                 return false;
  93
  94         return true;
  95 }
  96
  97 bool strv_env_is_valid(char **e) {
  98         char **p, **q;
  99
 100         STRV_FOREACH(p, e) {
 101                 size_t k;
 102
 103                 if (!env_assignment_is_valid(*p))
 104                         return false;
 105
 106                 /* Check if there are duplicate assignments */
 107                 k = strcspn(*p, "=");
 108                 STRV_FOREACH(q, p + 1)
 109                         if (strneq(*p, *q, k) && (*q)[k] == '=')
 110                                 return false;
 111         }
 112
 113         return true;
 114 }
 115
 116 bool strv_env_name_is_valid(char **l) {
 117         char **p;
 118
 119         STRV_FOREACH(p, l) {
 120                 if (!env_name_is_valid(*p))
 121                         return false;
 122
 123                 if (strv_contains(p + 1, *p))
 124                         return false;
 125         }
 126
 127         return true;
 128 }
 129
 130 bool strv_env_name_or_assignment_is_valid(char **l) {
 131         char **p;
 132
 133         STRV_FOREACH(p, l) {
 134                 if (!env_assignment_is_valid(*p) && !env_name_is_valid(*p))
 135                         return false;
 136
 137                 if (strv_contains(p + 1, *p))
 138                         return false;
 139         }
 140
 141         return true;
 142 }
 143
 144 static int env_append(char **r, char ***k, char **a) {
 145         assert(r);
 146         assert(k);
 147         assert(*k >= r);
 148
 149         if (!a)
 150                 return 0;
 151
 152         /* Expects the following arguments: 'r' shall point to the beginning of an strv we are going to append to, 'k'
 153          * to a pointer pointing to the NULL entry at the end of the same array. 'a' shall point to another strv.
 154          *
 155          * This call adds every entry of 'a' to 'r', either overriding an existing matching entry, or appending to it.
 156          *
 157          * This call assumes 'r' has enough pre-allocated space to grow by all of 'a''s items. */
 158
 159         for (; *a; a++) {
 160                 char **j, *c;
 161                 size_t n;
 162
 163                 n = strcspn(*a, "=");
 164                 if ((*a)[n] == '=')
 165                         n++;
 166
 167                 for (j = r; j < *k; j++)
 168                         if (strneq(*j, *a, n))
 169                                 break;
 170
 171                 c = strdup(*a);
 172                 if (!c)
 173                         return -ENOMEM;
 174
 175                 if (j >= *k) { /* Append to the end? */
 176                         (*k)[0] = c;
 177                         (*k)[1] = NULL;
 178                         (*k)++;
 179                 } else
 180                         free_and_replace(*j, c); /* Override existing item */
 181         }
 182
 183         return 0;
 184 }
 185
 186 char **strv_env_merge(size_t n_lists, ...) {
 187         _cleanup_strv_free_ char **ret = NULL;
 188         size_t n = 0;
 189         char **l, **k;
 190         va_list ap;
 191
 192         /* Merges an arbitrary number of environment sets */
 193
 194         va_start(ap, n_lists);
 195         for (size_t i = 0; i < n_lists; i++) {
 196                 l = va_arg(ap, char**);
 197                 n += strv_length(l);
 198         }
 199         va_end(ap);
 200
 201         ret = new(char*, n+1);
 202         if (!ret)
 203                 return NULL;
 204
 205         *ret = NULL;
 206         k = ret;
 207
 208         va_start(ap, n_lists);
 209         for (size_t i = 0; i < n_lists; i++) {
 210                 l = va_arg(ap, char**);
 211                 if (env_append(ret, &k, l) < 0) {
 212                         va_end(ap);
 213                         return NULL;
 214                 }
 215         }
 216         va_end(ap);
 217
 218         return TAKE_PTR(ret);
 219 }
 220
 221 static bool env_match(const char *t, const char *pattern) {
 222         assert(t);
 223         assert(pattern);
 224
 225         /* pattern a matches string a
 226          *         a matches a=
 227          *         a matches a=b
 228          *         a= matches a=
 229          *         a=b matches a=b
 230          *         a= does not match a
 231          *         a=b does not match a=
 232          *         a=b does not match a
 233          *         a=b does not match a=c */
 234
 235         if (streq(t, pattern))
 236                 return true;
 237
 238         if (!strchr(pattern, '=')) {
 239                 size_t l = strlen(pattern);
 240
 241                 return strneq(t, pattern, l) && t[l] == '=';
 242         }
 243
 244         return false;
 245 }
 246
 247 static bool env_entry_has_name(const char *entry, const char *name) {
 248         const char *t;
 249
 250         assert(entry);
 251         assert(name);
 252
 253         t = startswith(entry, name);
 254         if (!t)
 255                 return false;
 256
 257         return *t == '=';
 258 }
 259
 260 char **strv_env_delete(char **x, size_t n_lists, ...) {
 261         size_t n, i = 0;
 262         char **k, **r;
 263         va_list ap;
 264
 265         /* Deletes every entry from x that is mentioned in the other
 266          * string lists */
 267
 268         n = strv_length(x);
 269
 270         r = new(char*, n+1);
 271         if (!r)
 272                 return NULL;
 273
 274         STRV_FOREACH(k, x) {
 275                 va_start(ap, n_lists);
 276                 for (size_t v = 0; v < n_lists; v++) {
 277                         char **l, **j;
 278
 279                         l = va_arg(ap, char**);
 280                         STRV_FOREACH(j, l)
 281                                 if (env_match(*k, *j))
 282                                         goto skip;
 283                 }
 284                 va_end(ap);
 285
 286                 r[i] = strdup(*k);
 287                 if (!r[i]) {
 288                         strv_free(r);
 289                         return NULL;
 290                 }
 291
 292                 i++;
 293                 continue;
 294
 295         skip:
 296                 va_end(ap);
 297         }
 298
 299         r[i] = NULL;
 300
 301         assert(i <= n);
 302
 303         return r;
 304 }
 305
 306 char **strv_env_unset(char **l, const char *p) {
 307         char **f, **t;
 308
 309         if (!l)
 310                 return NULL;
 311
 312         assert(p);
 313
 314         /* Drops every occurrence of the env var setting p in the
 315          * string list. Edits in-place. */
 316
 317         for (f = t = l; *f; f++) {
 318
 319                 if (env_match(*f, p)) {
 320                         free(*f);
 321                         continue;
 322                 }
 323
 324                 *(t++) = *f;
 325         }
 326
 327         *t = NULL;
 328         return l;
 329 }
 330
 331 char **strv_env_unset_many(char **l, ...) {
 332         char **f, **t;
 333
 334         if (!l)
 335                 return NULL;
 336
 337         /* Like strv_env_unset() but applies many at once. Edits in-place. */
 338
 339         for (f = t = l; *f; f++) {
 340                 bool found = false;
 341                 const char *p;
 342                 va_list ap;
 343
 344                 va_start(ap, l);
 345
 346                 while ((p = va_arg(ap, const char*))) {
 347                         if (env_match(*f, p)) {
 348                                 found = true;
 349                                 break;
 350                         }
 351                 }
 352
 353                 va_end(ap);
 354
 355                 if (found) {
 356                         free(*f);
 357                         continue;
 358                 }
 359
 360                 *(t++) = *f;
 361         }
 362
 363         *t = NULL;
 364         return l;
 365 }
 366
 367 int strv_env_replace_consume(char ***l, char *p) {
 368         const char *t, *name;
 369         char **f;
 370         int r;
 371
 372         assert(p);
 373
 374         /* Replace first occurrence of the env var or add a new one in the string list. Drop other
 375          * occurrences. Edits in-place. Does not copy p and CONSUMES p EVEN ON FAILURE.
 376          *
 377          * p must be a valid key=value assignment. */
 378
 379         t = strchr(p, '=');
 380         if (!t) {
 381                 free(p);
 382                 return -EINVAL;
 383         }
 384
 385         name = strndupa(p, t - p);
 386
 387         STRV_FOREACH(f, *l)
 388                 if (env_entry_has_name(*f, name)) {
 389                         free_and_replace(*f, p);
 390                         strv_env_unset(f + 1, *f);
 391                         return 0;
 392                 }
 393
 394         /* We didn't find a match, we need to append p or create a new strv */
 395         r = strv_consume(l, p);
 396         if (r < 0)
 397                 return r;
 398
 399         return 1;
 400 }
 401
 402 int strv_env_replace_strdup(char ***l, const char *assignment) {
 403         /* Like strv_env_replace_consume(), but copies the argument. */
 404
 405         char *p = strdup(assignment);
 406         if (!p)
 407                 return -ENOMEM;
 408
 409         return strv_env_replace_consume(l, p);
 410 }
 411
 412 int strv_env_assign(char ***l, const char *key, const char *value) {
 413         if (!env_name_is_valid(key))
 414                 return -EINVAL;
 415
 416         /* NULL removes assignment, "" creates an empty assignment. */
 417
 418         if (!value) {
 419                 strv_env_unset(*l, key);
 420                 return 0;
 421         }
 422
 423         char *p = strjoin(key, "=", value);
 424         if (!p)
 425                 return -ENOMEM;
 426
 427         return strv_env_replace_consume(l, p);
 428 }
 429
 430 char *strv_env_get_n(char **l, const char *name, size_t k, unsigned flags) {
 431         char **i;
 432
 433         assert(name);
 434
 435         if (k <= 0)
 436                 return NULL;
 437
 438         STRV_FOREACH_BACKWARDS(i, l)
 439                 if (strneq(*i, name, k) &&
 440                     (*i)[k] == '=')
 441                         return *i + k + 1;
 442
 443         if (flags & REPLACE_ENV_USE_ENVIRONMENT) {
 444                 const char *t;
 445
 446                 t = strndupa(name, k);
 447                 return getenv(t);
 448         };
 449
 450         return NULL;
 451 }
 452
 453 char *strv_env_get(char **l, const char *name) {
 454         assert(name);
 455
 456         return strv_env_get_n(l, name, strlen(name), 0);
 457 }
 458
 459 char *strv_env_pairs_get(char **l, const char *name) {
 460         char **key, **value, *result = NULL;
 461
 462         assert(name);
 463
 464         STRV_FOREACH_PAIR(key, value, l)
 465                 if (streq(*key, name))
 466                         result = *value;
 467
 468         return result;
 469 }
 470
 471 char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const char *p, void *userdata), void *userdata) {
 472         char **p, **q;
 473         int k = 0;
 474
 475         STRV_FOREACH(p, e) {
 476                 size_t n;
 477                 bool duplicate = false;
 478
 479                 if (!env_assignment_is_valid(*p)) {
 480                         if (invalid_callback)
 481                                 invalid_callback(*p, userdata);
 482                         free(*p);
 483                         continue;
 484                 }
 485
 486                 n = strcspn(*p, "=");
 487                 STRV_FOREACH(q, p + 1)
 488                         if (strneq(*p, *q, n) && (*q)[n] == '=') {
 489                                 duplicate = true;
 490                                 break;
 491                         }
 492
 493                 if (duplicate) {
 494                         free(*p);
 495                         continue;
 496                 }
 497
 498                 e[k++] = *p;
 499         }
 500
 501         if (e)
 502                 e[k] = NULL;
 503
 504         return e;
 505 }
 506
 507 char *replace_env_n(const char *format, size_t n, char **env, unsigned flags) {
 508         enum {
 509                 WORD,
 510                 CURLY,
 511                 VARIABLE,
 512                 VARIABLE_RAW,
 513                 TEST,
 514                 DEFAULT_VALUE,
 515                 ALTERNATE_VALUE,
 516         } state = WORD;
 517
 518         const char *e, *word = format, *test_value = NULL; /* test_value is initialized to appease gcc */
 519         char *k;
 520         _cleanup_free_ char *r = NULL;
 521         size_t i, len = 0; /* len is initialized to appease gcc */
 522         int nest = 0;
 523
 524         assert(format);
 525
 526         for (e = format, i = 0; *e && i < n; e ++, i ++)
 527                 switch (state) {
 528
 529                 case WORD:
 530                         if (*e == '$')
 531                                 state = CURLY;
 532                         break;
 533
 534                 case CURLY:
 535                         if (*e == '{') {
 536                                 k = strnappend(r, word, e-word-1);
 537                                 if (!k)
 538                                         return NULL;
 539
 540                                 free_and_replace(r, k);
 541
 542                                 word = e-1;
 543                                 state = VARIABLE;
 544                                 nest++;
 545                         } else if (*e == '$') {
 546                                 k = strnappend(r, word, e-word);
 547                                 if (!k)
 548                                         return NULL;
 549
 550                                 free_and_replace(r, k);
 551
 552                                 word = e+1;
 553                                 state = WORD;
 554
 555                         } else if (flags & REPLACE_ENV_ALLOW_BRACELESS && strchr(VALID_BASH_ENV_NAME_CHARS, *e)) {
 556                                 k = strnappend(r, word, e-word-1);
 557                                 if (!k)
 558                                         return NULL;
 559
 560                                 free_and_replace(r, k);
 561
 562                                 word = e-1;
 563                                 state = VARIABLE_RAW;
 564
 565                         } else
 566                                 state = WORD;
 567                         break;
 568
 569                 case VARIABLE:
 570                         if (*e == '}') {
 571                                 const char *t;
 572
 573                                 t = strv_env_get_n(env, word+2, e-word-2, flags);
 574
 575                                 if (!strextend(&r, t))
 576                                         return NULL;
 577
 578                                 word = e+1;
 579                                 state = WORD;
 580                         } else if (*e == ':') {
 581                                 if (flags & REPLACE_ENV_ALLOW_EXTENDED) {
 582                                         len = e - word - 2;
 583                                         state = TEST;
 584                                 } else
 585                                         /* Treat this as unsupported syntax, i.e. do no replacement */
 586                                         state = WORD;
 587                         }
 588                         break;
 589
 590                 case TEST:
 591                         if (*e == '-')
 592                                 state = DEFAULT_VALUE;
 593                         else if (*e == '+')
 594                                 state = ALTERNATE_VALUE;
 595                         else {
 596                                 state = WORD;
 597                                 break;
 598                         }
 599
 600                         test_value = e+1;
 601                         break;
 602
 603                 case DEFAULT_VALUE: /* fall through */
 604                 case ALTERNATE_VALUE:
 605                         assert(flags & REPLACE_ENV_ALLOW_EXTENDED);
 606
 607                         if (*e == '{') {
 608                                 nest++;
 609                                 break;
 610                         }
 611
 612                         if (*e != '}')
 613                                 break;
 614
 615                         nest--;
 616                         if (nest == 0) {
 617                                 const char *t;
 618                                 _cleanup_free_ char *v = NULL;
 619
 620                                 t = strv_env_get_n(env, word+2, len, flags);
 621
 622                                 if (t && state == ALTERNATE_VALUE)
 623                                         t = v = replace_env_n(test_value, e-test_value, env, flags);
 624                                 else if (!t && state == DEFAULT_VALUE)
 625                                         t = v = replace_env_n(test_value, e-test_value, env, flags);
 626
 627                                 if (!strextend(&r, t))
 628                                         return NULL;
 629
 630                                 word = e+1;
 631                                 state = WORD;
 632                         }
 633                         break;
 634
 635                 case VARIABLE_RAW:
 636                         assert(flags & REPLACE_ENV_ALLOW_BRACELESS);
 637
 638                         if (!strchr(VALID_BASH_ENV_NAME_CHARS, *e)) {
 639                                 const char *t;
 640
 641                                 t = strv_env_get_n(env, word+1, e-word-1, flags);
 642
 643                                 if (!strextend(&r, t))
 644                                         return NULL;
 645
 646                                 word = e--;
 647                                 i--;
 648                                 state = WORD;
 649                         }
 650                         break;
 651                 }
 652
 653         if (state == VARIABLE_RAW) {
 654                 const char *t;
 655
 656                 assert(flags & REPLACE_ENV_ALLOW_BRACELESS);
 657
 658                 t = strv_env_get_n(env, word+1, e-word-1, flags);
 659                 return strjoin(r, t);
 660         } else
 661                 return strnappend(r, word, e-word);
 662 }
 663
 664 char **replace_env_argv(char **argv, char **env) {
 665         char **ret, **i;
 666         size_t k = 0, l = 0;
 667
 668         l = strv_length(argv);
 669
 670         ret = new(char*, l+1);
 671         if (!ret)
 672                 return NULL;
 673
 674         STRV_FOREACH(i, argv) {
 675
 676                 /* If $FOO appears as single word, replace it by the split up variable */
 677                 if ((*i)[0] == '$' && !IN_SET((*i)[1], '{', '$')) {
 678                         char *e;
 679                         char **w, **m = NULL;
 680                         size_t q;
 681
 682                         e = strv_env_get(env, *i+1);
 683                         if (e) {
 684                                 int r;
 685
 686                                 r = strv_split_full(&m, e, WHITESPACE, EXTRACT_RELAX|EXTRACT_UNQUOTE);
 687                                 if (r < 0) {
 688                                         ret[k] = NULL;
 689                                         strv_free(ret);
 690                                         return NULL;
 691                                 }
 692                         } else
 693                                 m = NULL;
 694
 695                         q = strv_length(m);
 696                         l = l + q - 1;
 697
 698                         w = reallocarray(ret, l + 1, sizeof(char *));
 699                         if (!w) {
 700                                 ret[k] = NULL;
 701                                 strv_free(ret);
 702                                 strv_free(m);
 703                                 return NULL;
 704                         }
 705
 706                         ret = w;
 707                         if (m) {
 708                                 memcpy(ret + k, m, q * sizeof(char*));
 709                                 free(m);
 710                         }
 711
 712                         k += q;
 713                         continue;
 714                 }
 715
 716                 /* If ${FOO} appears as part of a word, replace it by the variable as-is */
 717                 ret[k] = replace_env(*i, env, 0);
 718                 if (!ret[k]) {
 719                         strv_free(ret);
 720                         return NULL;
 721                 }
 722                 k++;
 723         }
 724
 725         ret[k] = NULL;
 726         return ret;
 727 }
 728
 729 int getenv_bool(const char *p) {
 730         const char *e;
 731
 732         e = getenv(p);
 733         if (!e)
 734                 return -ENXIO;
 735
 736         return parse_boolean(e);
 737 }
 738
 739 int getenv_bool_secure(const char *p) {
 740         const char *e;
 741
 742         e = secure_getenv(p);
 743         if (!e)
 744                 return -ENXIO;
 745
 746         return parse_boolean(e);
 747 }
 748
 749 int set_unset_env(const char *name, const char *value, bool overwrite) {
 750         int r;
 751
 752         if (value)
 753                 r = setenv(name, value, overwrite);
 754         else
 755                 r = unsetenv(name);
 756         if (r < 0)
 757                 return -errno;
 758         return 0;
 759 }
 760
 761 int putenv_dup(const char *assignment, bool override) {
 762         const char *e, *n;
 763
 764         e = strchr(assignment, '=');
 765         if (!e)
 766                 return -EINVAL;
 767
 768         n = strndupa(assignment, e - assignment);
 769
 770         /* This is like putenv(), but uses setenv() so that our memory doesn't become part of environ[]. */
 771         if (setenv(n, e + 1, override) < 0)
 772                 return -errno;
 773         return 0;
 774 }
 775
 776 int setenv_systemd_exec_pid(bool update_only) {
 777         char str[DECIMAL_STR_MAX(pid_t)];
 778         const char *e;
 779
 780         /* Update $SYSTEMD_EXEC_PID=pid except when '*' is set for the variable. */
 781
 782         e = secure_getenv("SYSTEMD_EXEC_PID");
 783         if (!e && update_only)
 784                 return 0;
 785
 786         if (streq_ptr(e, "*"))
 787                 return 0;
 788
 789         xsprintf(str, PID_FMT, getpid_cached());
 790
 791         if (setenv("SYSTEMD_EXEC_PID", str, 1) < 0)
 792                 return -errno;
 793
 794         return 1;
 795 }
 796
 797 int getenv_path_list(const char *name, char ***ret_paths) {
 798         _cleanup_strv_free_ char **l = NULL;
 799         const char *e;
 800         char **p;
 801         int r;
 802
 803         assert(name);
 804         assert(ret_paths);
 805
 806         e = secure_getenv(name);
 807         if (!e)
 808                 return -ENXIO;
 809
 810         r = strv_split_full(&l, e, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
 811         if (r < 0)
 812                 return log_debug_errno(r, "Failed to parse $%s: %m", name);
 813
 814         STRV_FOREACH(p, l) {
 815                 if (!path_is_absolute(*p))
 816                         return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 817                                                "Path '%s' is not absolute, refusing.", *p);
 818
 819                 if (!path_is_normalized(*p))
 820                         return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 821                                                "Path '%s' is not normalized, refusing.", *p);
 822
 823                 if (path_equal(*p, "/"))
 824                         return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 825                                                "Path '%s' is the root fs, refusing.", *p);
 826         }
 827
 828         if (strv_isempty(l))
 829                 return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
 830                                        "No paths specified, refusing.");
 831
 832         *ret_paths = TAKE_PTR(l);
 833         return 1;
 834 }