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 #ifndef ARG_MAX
  25 #define ARG_MAX ((size_t) sysconf(_SC_ARG_MAX))
  26 #endif
  27
  28 static bool env_name_is_valid_n(const char *e, size_t n) {
  29         const char *p;
  30
  31         if (!e)
  32                 return false;
  33
  34         if (n <= 0)
  35                 return false;
  36
  37         if (e[0] >= '0' && e[0] <= '9')
  38                 return false;
  39
  40         /* POSIX says the overall size of the environment block cannot
  41          * be > ARG_MAX, an individual assignment hence cannot be
  42          * either. Discounting the equal sign and trailing NUL this
  43          * hence leaves ARG_MAX-2 as longest possible variable
  44          * name. */
  45         if (n > ARG_MAX - 2)
  46                 return false;
  47
  48         for (p = e; p < e + n; p++)
  49                 if (!strchr(VALID_CHARS_ENV_NAME, *p))
  50                         return false;
  51
  52         return true;
  53 }
  54
  55 bool env_name_is_valid(const char *e) {
  56         if (!e)
  57                 return false;
  58
  59         return env_name_is_valid_n(e, strlen(e));
  60 }
  61
  62 bool env_value_is_valid(const char *e) {
  63         if (!e)
  64                 return false;
  65
  66         if (!utf8_is_valid(e))
  67                 return false;
  68
  69         /* bash allows tabs and newlines in environment variables, and so
  70          * should we */
  71         if (string_has_cc(e, "\t\n"))
  72                 return false;
  73
  74         /* POSIX says the overall size of the environment block cannot
  75          * be > ARG_MAX, an individual assignment hence cannot be
  76          * either. Discounting the shortest possible variable name of
  77          * length 1, the equal sign and trailing NUL this hence leaves
  78          * ARG_MAX-3 as longest possible variable value. */
  79         if (strlen(e) > ARG_MAX - 3)
  80                 return false;
  81
  82         return true;
  83 }
  84
  85 bool env_assignment_is_valid(const char *e) {
  86         const char *eq;
  87
  88         eq = strchr(e, '=');
  89         if (!eq)
  90                 return false;
  91
  92         if (!env_name_is_valid_n(e, eq - e))
  93                 return false;
  94
  95         if (!env_value_is_valid(eq + 1))
  96                 return false;
  97
  98         /* POSIX says the overall size of the environment block cannot
  99          * be > ARG_MAX, hence the individual variable assignments
 100          * cannot be either, but let's leave room for one trailing NUL
 101          * byte. */
 102         if (strlen(e) > ARG_MAX - 1)
 103                 return false;
 104
 105         return true;
 106 }
 107
 108 bool strv_env_is_valid(char **e) {
 109         char **p, **q;
 110
 111         STRV_FOREACH(p, e) {
 112                 size_t k;
 113
 114                 if (!env_assignment_is_valid(*p))
 115                         return false;
 116
 117                 /* Check if there are duplicate assginments */
 118                 k = strcspn(*p, "=");
 119                 STRV_FOREACH(q, p + 1)
 120                         if (strneq(*p, *q, k) && (*q)[k] == '=')
 121                                 return false;
 122         }
 123
 124         return true;
 125 }
 126
 127 bool strv_env_name_is_valid(char **l) {
 128         char **p, **q;
 129
 130         STRV_FOREACH(p, l) {
 131                 if (!env_name_is_valid(*p))
 132                         return false;
 133
 134                 STRV_FOREACH(q, p + 1)
 135                         if (streq(*p, *q))
 136                                 return false;
 137         }
 138
 139         return true;
 140 }
 141
 142 bool strv_env_name_or_assignment_is_valid(char **l) {
 143         char **p, **q;
 144
 145         STRV_FOREACH(p, l) {
 146                 if (!env_assignment_is_valid(*p) && !env_name_is_valid(*p))
 147                         return false;
 148
 149                 STRV_FOREACH(q, p + 1)
 150                         if (streq(*p, *q))
 151                                 return false;
 152         }
 153
 154         return true;
 155 }
 156
 157 static int env_append(char **r, char ***k, char **a) {
 158         assert(r);
 159         assert(k);
 160
 161         if (!a)
 162                 return 0;
 163
 164         /* Add the entries of a to *k unless they already exist in *r
 165          * in which case they are overridden instead. This assumes
 166          * there is enough space in the r array. */
 167
 168         for (; *a; a++) {
 169                 char **j;
 170                 size_t n;
 171
 172                 n = strcspn(*a, "=");
 173
 174                 if ((*a)[n] == '=')
 175                         n++;
 176
 177                 for (j = r; j < *k; j++)
 178                         if (strneq(*j, *a, n))
 179                                 break;
 180
 181                 if (j >= *k)
 182                         (*k)++;
 183                 else
 184                         free(*j);
 185
 186                 *j = strdup(*a);
 187                 if (!*j)
 188                         return -ENOMEM;
 189         }
 190
 191         return 0;
 192 }
 193
 194 char **strv_env_merge(size_t n_lists, ...) {
 195         size_t n = 0;
 196         char **l, **k, **r;
 197         va_list ap;
 198         size_t i;
 199
 200         /* Merges an arbitrary number of environment sets */
 201
 202         va_start(ap, n_lists);
 203         for (i = 0; i < n_lists; i++) {
 204                 l = va_arg(ap, char**);
 205                 n += strv_length(l);
 206         }
 207         va_end(ap);
 208
 209         r = new(char*, n+1);
 210         if (!r)
 211                 return NULL;
 212
 213         k = r;
 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(r, &k, l) < 0)
 219                         goto fail;
 220         }
 221         va_end(ap);
 222
 223         *k = NULL;
 224
 225         return r;
 226
 227 fail:
 228         va_end(ap);
 229         strv_free(r);
 230
 231         return NULL;
 232 }
 233
 234 static bool env_match(const char *t, const char *pattern) {
 235         assert(t);
 236         assert(pattern);
 237
 238         /* pattern a matches string a
 239          *         a matches a=
 240          *         a matches a=b
 241          *         a= matches a=
 242          *         a=b matches a=b
 243          *         a= does not match a
 244          *         a=b does not match a=
 245          *         a=b does not match a
 246          *         a=b does not match a=c */
 247
 248         if (streq(t, pattern))
 249                 return true;
 250
 251         if (!strchr(pattern, '=')) {
 252                 size_t l = strlen(pattern);
 253
 254                 return strneq(t, pattern, l) && t[l] == '=';
 255         }
 256
 257         return false;
 258 }
 259
 260 static bool env_entry_has_name(const char *entry, const char *name) {
 261         const char *t;
 262
 263         assert(entry);
 264         assert(name);
 265
 266         t = startswith(entry, name);
 267         if (!t)
 268                 return false;
 269
 270         return *t == '=';
 271 }
 272
 273 char **strv_env_delete(char **x, size_t n_lists, ...) {
 274         size_t n, i = 0;
 275         char **k, **r;
 276         va_list ap;
 277
 278         /* Deletes every entry from x that is mentioned in the other
 279          * string lists */
 280
 281         n = strv_length(x);
 282
 283         r = new(char*, n+1);
 284         if (!r)
 285                 return NULL;
 286
 287         STRV_FOREACH(k, x) {
 288                 size_t v;
 289
 290                 va_start(ap, n_lists);
 291                 for (v = 0; v < n_lists; v++) {
 292                         char **l, **j;
 293
 294                         l = va_arg(ap, char**);
 295                         STRV_FOREACH(j, l)
 296                                 if (env_match(*k, *j))
 297                                         goto skip;
 298                 }
 299                 va_end(ap);
 300
 301                 r[i] = strdup(*k);
 302                 if (!r[i]) {
 303                         strv_free(r);
 304                         return NULL;
 305                 }
 306
 307                 i++;
 308                 continue;
 309
 310         skip:
 311                 va_end(ap);
 312         }
 313
 314         r[i] = NULL;
 315
 316         assert(i <= n);
 317
 318         return r;
 319 }
 320
 321 char **strv_env_unset(char **l, const char *p) {
 322
 323         char **f, **t;
 324
 325         if (!l)
 326                 return NULL;
 327
 328         assert(p);
 329
 330         /* Drops every occurrence of the env var setting p in the
 331          * string list. Edits in-place. */
 332
 333         for (f = t = l; *f; f++) {
 334
 335                 if (env_match(*f, p)) {
 336                         free(*f);
 337                         continue;
 338                 }
 339
 340                 *(t++) = *f;
 341         }
 342
 343         *t = NULL;
 344         return l;
 345 }
 346
 347 char **strv_env_unset_many(char **l, ...) {
 348
 349         char **f, **t;
 350
 351         if (!l)
 352                 return NULL;
 353
 354         /* Like strv_env_unset() but applies many at once. Edits in-place. */
 355
 356         for (f = t = l; *f; f++) {
 357                 bool found = false;
 358                 const char *p;
 359                 va_list ap;
 360
 361                 va_start(ap, l);
 362
 363                 while ((p = va_arg(ap, const char*))) {
 364                         if (env_match(*f, p)) {
 365                                 found = true;
 366                                 break;
 367                         }
 368                 }
 369
 370                 va_end(ap);
 371
 372                 if (found) {
 373                         free(*f);
 374                         continue;
 375                 }
 376
 377                 *(t++) = *f;
 378         }
 379
 380         *t = NULL;
 381         return l;
 382 }
 383
 384 int strv_env_replace(char ***l, char *p) {
 385         char **f;
 386         const char *t, *name;
 387
 388         assert(p);
 389
 390         /* Replace first occurrence of the env var or add a new one in the
 391          * string list. Drop other occurences. Edits in-place. Does not copy p.
 392          * p must be a valid key=value assignment.
 393          */
 394
 395         t = strchr(p, '=');
 396         assert(t);
 397
 398         name = strndupa(p, t - p);
 399
 400         for (f = *l; f && *f; f++)
 401                 if (env_entry_has_name(*f, name)) {
 402                         free_and_replace(*f, p);
 403                         strv_env_unset(f + 1, *f);
 404                         return 0;
 405                 }
 406
 407         /* We didn't find a match, we need to append p or create a new strv */
 408         if (strv_push(l, p) < 0)
 409                 return -ENOMEM;
 410         return 1;
 411 }
 412
 413 char **strv_env_set(char **x, const char *p) {
 414
 415         char **k;
 416         _cleanup_strv_free_ char **r = NULL;
 417         char* m[2] = { (char*) p, NULL };
 418
 419         /* Overrides the env var setting of p, returns a new copy */
 420
 421         r = new(char*, strv_length(x)+2);
 422         if (!r)
 423                 return NULL;
 424
 425         k = r;
 426         if (env_append(r, &k, x) < 0)
 427                 return NULL;
 428
 429         if (env_append(r, &k, m) < 0)
 430                 return NULL;
 431
 432         *k = NULL;
 433
 434         return TAKE_PTR(r);
 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 }
 753
 754 int serialize_environment(FILE *f, char **environment) {
 755         char **e;
 756
 757         STRV_FOREACH(e, environment) {
 758                 _cleanup_free_ char *ce;
 759
 760                 ce = cescape(*e);
 761                 if (!ce)
 762                         return -ENOMEM;
 763
 764                 fprintf(f, "env=%s\n", ce);
 765         }
 766
 767         /* caller should call ferror() */
 768
 769         return 0;
 770 }
 771
 772 int deserialize_environment(char ***environment, const char *line) {
 773         char *uce;
 774         int r;
 775
 776         assert(line);
 777         assert(environment);
 778
 779         assert(startswith(line, "env="));
 780         r = cunescape(line + 4, 0, &uce);
 781         if (r < 0)
 782                 return r;
 783
 784         return strv_env_replace(environment, uce);
 785 }