src/basic/env-util.c

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