src/basic/env-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2012 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <limits.h>
   8 #include <stdarg.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <unistd.h>
  12
  13 #include "alloc-util.h"
  14 #include "env-util.h"
  15 #include "escape.h"
  16 #include "extract-word.h"
  17 #include "macro.h"
  18 #include "parse-util.h"
  19 #include "string-util.h"
  20 #include "strv.h"
  21 #include "utf8.h"
  22
  23 #define VALID_CHARS_ENV_NAME                    \
  24         DIGITS LETTERS                          \
  25         "_"
  26
  27 #ifndef ARG_MAX
  28 #define ARG_MAX ((size_t) sysconf(_SC_ARG_MAX))
  29 #endif
  30
  31 static bool env_name_is_valid_n(const char *e, size_t n) {
  32         const char *p;
  33
  34         if (!e)
  35                 return false;
  36
  37         if (n <= 0)
  38                 return false;
  39
  40         if (e[0] >= '0' && e[0] <= '9')
  41                 return false;
  42
  43         /* POSIX says the overall size of the environment block cannot
  44          * be > ARG_MAX, an individual assignment hence cannot be
  45          * either. Discounting the equal sign and trailing NUL this
  46          * hence leaves ARG_MAX-2 as longest possible variable
  47          * name. */
  48         if (n > ARG_MAX - 2)
  49                 return false;
  50
  51         for (p = e; p < e + n; p++)
  52                 if (!strchr(VALID_CHARS_ENV_NAME, *p))
  53                         return false;
  54
  55         return true;
  56 }
  57
  58 bool env_name_is_valid(const char *e) {
  59         if (!e)
  60                 return false;
  61
  62         return env_name_is_valid_n(e, strlen(e));
  63 }
  64
  65 bool env_value_is_valid(const char *e) {
  66         if (!e)
  67                 return false;
  68
  69         if (!utf8_is_valid(e))
  70                 return false;
  71
  72         /* bash allows tabs and newlines in environment variables, and so
  73          * should we */
  74         if (string_has_cc(e, "\t\n"))
  75                 return false;
  76
  77         /* POSIX says the overall size of the environment block cannot
  78          * be > ARG_MAX, an individual assignment hence cannot be
  79          * either. Discounting the shortest possible variable name of
  80          * length 1, the equal sign and trailing NUL this hence leaves
  81          * ARG_MAX-3 as longest possible variable value. */
  82         if (strlen(e) > ARG_MAX - 3)
  83                 return false;
  84
  85         return true;
  86 }
  87
  88 bool env_assignment_is_valid(const char *e) {
  89         const char *eq;
  90
  91         eq = strchr(e, '=');
  92         if (!eq)
  93                 return false;
  94
  95         if (!env_name_is_valid_n(e, eq - e))
  96                 return false;
  97
  98         if (!env_value_is_valid(eq + 1))
  99                 return false;
 100
 101         /* POSIX says the overall size of the environment block cannot
 102          * be > ARG_MAX, hence the individual variable assignments
 103          * cannot be either, but let's leave room for one trailing NUL
 104          * byte. */
 105         if (strlen(e) > ARG_MAX - 1)
 106                 return false;
 107
 108         return true;
 109 }
 110
 111 bool strv_env_is_valid(char **e) {
 112         char **p, **q;
 113
 114         STRV_FOREACH(p, e) {
 115                 size_t k;
 116
 117                 if (!env_assignment_is_valid(*p))
 118                         return false;
 119
 120                 /* Check if there are duplicate assginments */
 121                 k = strcspn(*p, "=");
 122                 STRV_FOREACH(q, p + 1)
 123                         if (strneq(*p, *q, k) && (*q)[k] == '=')
 124                                 return false;
 125         }
 126
 127         return true;
 128 }
 129
 130 bool strv_env_name_is_valid(char **l) {
 131         char **p, **q;
 132
 133         STRV_FOREACH(p, l) {
 134                 if (!env_name_is_valid(*p))
 135                         return false;
 136
 137                 STRV_FOREACH(q, p + 1)
 138                         if (streq(*p, *q))
 139                                 return false;
 140         }
 141
 142         return true;
 143 }
 144
 145 bool strv_env_name_or_assignment_is_valid(char **l) {
 146         char **p, **q;
 147
 148         STRV_FOREACH(p, l) {
 149                 if (!env_assignment_is_valid(*p) && !env_name_is_valid(*p))
 150                         return false;
 151
 152                 STRV_FOREACH(q, p + 1)
 153                         if (streq(*p, *q))
 154                                 return false;
 155         }
 156
 157         return true;
 158 }
 159
 160 static int env_append(char **r, char ***k, char **a) {
 161         assert(r);
 162         assert(k);
 163
 164         if (!a)
 165                 return 0;
 166
 167         /* Add the entries of a to *k unless they already exist in *r
 168          * in which case they are overridden instead. This assumes
 169          * there is enough space in the r array. */
 170
 171         for (; *a; a++) {
 172                 char **j;
 173                 size_t n;
 174
 175                 n = strcspn(*a, "=");
 176
 177                 if ((*a)[n] == '=')
 178                         n++;
 179
 180                 for (j = r; j < *k; j++)
 181                         if (strneq(*j, *a, n))
 182                                 break;
 183
 184                 if (j >= *k)
 185                         (*k)++;
 186                 else
 187                         free(*j);
 188
 189                 *j = strdup(*a);
 190                 if (!*j)
 191                         return -ENOMEM;
 192         }
 193
 194         return 0;
 195 }
 196
 197 char **strv_env_merge(size_t n_lists, ...) {
 198         size_t n = 0;
 199         char **l, **k, **r;
 200         va_list ap;
 201         size_t i;
 202
 203         /* Merges an arbitrary number of environment sets */
 204
 205         va_start(ap, n_lists);
 206         for (i = 0; i < n_lists; i++) {
 207                 l = va_arg(ap, char**);
 208                 n += strv_length(l);
 209         }
 210         va_end(ap);
 211
 212         r = new(char*, n+1);
 213         if (!r)
 214                 return NULL;
 215
 216         k = r;
 217
 218         va_start(ap, n_lists);
 219         for (i = 0; i < n_lists; i++) {
 220                 l = va_arg(ap, char**);
 221                 if (env_append(r, &k, l) < 0)
 222                         goto fail;
 223         }
 224         va_end(ap);
 225
 226         *k = NULL;
 227
 228         return r;
 229
 230 fail:
 231         va_end(ap);
 232         strv_free(r);
 233
 234         return NULL;
 235 }
 236
 237 static bool env_match(const char *t, const char *pattern) {
 238         assert(t);
 239         assert(pattern);
 240
 241         /* pattern a matches string a
 242          *         a matches a=
 243          *         a matches a=b
 244          *         a= matches a=
 245          *         a=b matches a=b
 246          *         a= does not match a
 247          *         a=b does not match a=
 248          *         a=b does not match a
 249          *         a=b does not match a=c */
 250
 251         if (streq(t, pattern))
 252                 return true;
 253
 254         if (!strchr(pattern, '=')) {
 255                 size_t l = strlen(pattern);
 256
 257                 return strneq(t, pattern, l) && t[l] == '=';
 258         }
 259
 260         return false;
 261 }
 262
 263 static bool env_entry_has_name(const char *entry, const char *name) {
 264         const char *t;
 265
 266         assert(entry);
 267         assert(name);
 268
 269         t = startswith(entry, name);
 270         if (!t)
 271                 return false;
 272
 273         return *t == '=';
 274 }
 275
 276 char **strv_env_delete(char **x, size_t n_lists, ...) {
 277         size_t n, i = 0;
 278         char **k, **r;
 279         va_list ap;
 280
 281         /* Deletes every entry from x that is mentioned in the other
 282          * string lists */
 283
 284         n = strv_length(x);
 285
 286         r = new(char*, n+1);
 287         if (!r)
 288                 return NULL;
 289
 290         STRV_FOREACH(k, x) {
 291                 size_t v;
 292
 293                 va_start(ap, n_lists);
 294                 for (v = 0; v < n_lists; v++) {
 295                         char **l, **j;
 296
 297                         l = va_arg(ap, char**);
 298                         STRV_FOREACH(j, l)
 299                                 if (env_match(*k, *j))
 300                                         goto skip;
 301                 }
 302                 va_end(ap);
 303
 304                 r[i] = strdup(*k);
 305                 if (!r[i]) {
 306                         strv_free(r);
 307                         return NULL;
 308                 }
 309
 310                 i++;
 311                 continue;
 312
 313         skip:
 314                 va_end(ap);
 315         }
 316
 317         r[i] = NULL;
 318
 319         assert(i <= n);
 320
 321         return r;
 322 }
 323
 324 char **strv_env_unset(char **l, const char *p) {
 325
 326         char **f, **t;
 327
 328         if (!l)
 329                 return NULL;
 330
 331         assert(p);
 332
 333         /* Drops every occurrence of the env var setting p in the
 334          * string list. Edits in-place. */
 335
 336         for (f = t = l; *f; f++) {
 337
 338                 if (env_match(*f, p)) {
 339                         free(*f);
 340                         continue;
 341                 }
 342
 343                 *(t++) = *f;
 344         }
 345
 346         *t = NULL;
 347         return l;
 348 }
 349
 350 char **strv_env_unset_many(char **l, ...) {
 351
 352         char **f, **t;
 353
 354         if (!l)
 355                 return NULL;
 356
 357         /* Like strv_env_unset() but applies many at once. Edits in-place. */
 358
 359         for (f = t = l; *f; f++) {
 360                 bool found = false;
 361                 const char *p;
 362                 va_list ap;
 363
 364                 va_start(ap, l);
 365
 366                 while ((p = va_arg(ap, const char*))) {
 367                         if (env_match(*f, p)) {
 368                                 found = true;
 369                                 break;
 370                         }
 371                 }
 372
 373                 va_end(ap);
 374
 375                 if (found) {
 376                         free(*f);
 377                         continue;
 378                 }
 379
 380                 *(t++) = *f;
 381         }
 382
 383         *t = NULL;
 384         return l;
 385 }
 386
 387 int strv_env_replace(char ***l, char *p) {
 388         char **f;
 389         const char *t, *name;
 390
 391         assert(p);
 392
 393         /* Replace first occurrence of the env var or add a new one in the
 394          * string list. Drop other occurences. Edits in-place. Does not copy p.
 395          * p must be a valid key=value assignment.
 396          */
 397
 398         t = strchr(p, '=');
 399         assert(t);
 400
 401         name = strndupa(p, t - p);
 402
 403         for (f = *l; f && *f; f++)
 404                 if (env_entry_has_name(*f, name)) {
 405                         free_and_replace(*f, p);
 406                         strv_env_unset(f + 1, *f);
 407                         return 0;
 408                 }
 409
 410         /* We didn't find a match, we need to append p or create a new strv */
 411         if (strv_push(l, p) < 0)
 412                 return -ENOMEM;
 413         return 1;
 414 }
 415
 416 char **strv_env_set(char **x, const char *p) {
 417
 418         char **k;
 419         _cleanup_strv_free_ char **r = NULL;
 420         char* m[2] = { (char*) p, NULL };
 421
 422         /* Overrides the env var setting of p, returns a new copy */
 423
 424         r = new(char*, strv_length(x)+2);
 425         if (!r)
 426                 return NULL;
 427
 428         k = r;
 429         if (env_append(r, &k, x) < 0)
 430                 return NULL;
 431
 432         if (env_append(r, &k, m) < 0)
 433                 return NULL;
 434
 435         *k = NULL;
 436
 437         return TAKE_PTR(r);
 438 }
 439
 440 char *strv_env_get_n(char **l, const char *name, size_t k, unsigned flags) {
 441         char **i;
 442
 443         assert(name);
 444
 445         if (k <= 0)
 446                 return NULL;
 447
 448         STRV_FOREACH_BACKWARDS(i, l)
 449                 if (strneq(*i, name, k) &&
 450                     (*i)[k] == '=')
 451                         return *i + k + 1;
 452
 453         if (flags & REPLACE_ENV_USE_ENVIRONMENT) {
 454                 const char *t;
 455
 456                 t = strndupa(name, k);
 457                 return getenv(t);
 458         };
 459
 460         return NULL;
 461 }
 462
 463 char *strv_env_get(char **l, const char *name) {
 464         assert(name);
 465
 466         return strv_env_get_n(l, name, strlen(name), 0);
 467 }
 468
 469 char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const char *p, void *userdata), void *userdata) {
 470         char **p, **q;
 471         int k = 0;
 472
 473         STRV_FOREACH(p, e) {
 474                 size_t n;
 475                 bool duplicate = false;
 476
 477                 if (!env_assignment_is_valid(*p)) {
 478                         if (invalid_callback)
 479                                 invalid_callback(*p, userdata);
 480                         free(*p);
 481                         continue;
 482                 }
 483
 484                 n = strcspn(*p, "=");
 485                 STRV_FOREACH(q, p + 1)
 486                         if (strneq(*p, *q, n) && (*q)[n] == '=') {
 487                                 duplicate = true;
 488                                 break;
 489                         }
 490
 491                 if (duplicate) {
 492                         free(*p);
 493                         continue;
 494                 }
 495
 496                 e[k++] = *p;
 497         }
 498
 499         if (e)
 500                 e[k] = NULL;
 501
 502         return e;
 503 }
 504
 505 char *replace_env_n(const char *format, size_t n, char **env, unsigned flags) {
 506         enum {
 507                 WORD,
 508                 CURLY,
 509                 VARIABLE,
 510                 VARIABLE_RAW,
 511                 TEST,
 512                 DEFAULT_VALUE,
 513                 ALTERNATE_VALUE,
 514         } state = WORD;
 515
 516         const char *e, *word = format, *test_value;
 517         char *k;
 518         _cleanup_free_ char *r = NULL;
 519         size_t i, len;
 520         int nest = 0;
 521
 522         assert(format);
 523
 524         for (e = format, i = 0; *e && i < n; e ++, i ++)
 525                 switch (state) {
 526
 527                 case WORD:
 528                         if (*e == '$')
 529                                 state = CURLY;
 530                         break;
 531
 532                 case CURLY:
 533                         if (*e == '{') {
 534                                 k = strnappend(r, word, e-word-1);
 535                                 if (!k)
 536                                         return NULL;
 537
 538                                 free_and_replace(r, k);
 539
 540                                 word = e-1;
 541                                 state = VARIABLE;
 542                                 nest++;
 543                         } else if (*e == '$') {
 544                                 k = strnappend(r, word, e-word);
 545                                 if (!k)
 546                                         return NULL;
 547
 548                                 free_and_replace(r, k);
 549
 550                                 word = e+1;
 551                                 state = WORD;
 552
 553                         } else if (flags & REPLACE_ENV_ALLOW_BRACELESS && strchr(VALID_CHARS_ENV_NAME, *e)) {
 554                                 k = strnappend(r, word, e-word-1);
 555                                 if (!k)
 556                                         return NULL;
 557
 558                                 free_and_replace(r, k);
 559
 560                                 word = e-1;
 561                                 state = VARIABLE_RAW;
 562
 563                         } else
 564                                 state = WORD;
 565                         break;
 566
 567                 case VARIABLE:
 568                         if (*e == '}') {
 569                                 const char *t;
 570
 571                                 t = strv_env_get_n(env, word+2, e-word-2, flags);
 572
 573                                 k = strappend(r, t);
 574                                 if (!k)
 575                                         return NULL;
 576
 577                                 free_and_replace(r, k);
 578
 579                                 word = e+1;
 580                                 state = WORD;
 581                         } else if (*e == ':') {
 582                                 if (!(flags & REPLACE_ENV_ALLOW_EXTENDED))
 583                                         /* Treat this as unsupported syntax, i.e. do no replacement */
 584                                         state = WORD;
 585                                 else {
 586                                         len = e-word-2;
 587                                         state = TEST;
 588                                 }
 589                         }
 590                         break;
 591
 592                 case TEST:
 593                         if (*e == '-')
 594                                 state = DEFAULT_VALUE;
 595                         else if (*e == '+')
 596                                 state = ALTERNATE_VALUE;
 597                         else {
 598                                 state = WORD;
 599                                 break;
 600                         }
 601
 602                         test_value = e+1;
 603                         break;
 604
 605                 case DEFAULT_VALUE: /* fall through */
 606                 case ALTERNATE_VALUE:
 607                         assert(flags & REPLACE_ENV_ALLOW_EXTENDED);
 608
 609                         if (*e == '{') {
 610                                 nest++;
 611                                 break;
 612                         }
 613
 614                         if (*e != '}')
 615                                 break;
 616
 617                         nest--;
 618                         if (nest == 0) {
 619                                 const char *t;
 620                                 _cleanup_free_ char *v = NULL;
 621
 622                                 t = strv_env_get_n(env, word+2, len, flags);
 623
 624                                 if (t && state == ALTERNATE_VALUE)
 625                                         t = v = replace_env_n(test_value, e-test_value, env, flags);
 626                                 else if (!t && state == DEFAULT_VALUE)
 627                                         t = v = replace_env_n(test_value, e-test_value, env, flags);
 628
 629                                 k = strappend(r, t);
 630                                 if (!k)
 631                                         return NULL;
 632
 633                                 free_and_replace(r, k);
 634
 635                                 word = e+1;
 636                                 state = WORD;
 637                         }
 638                         break;
 639
 640                 case VARIABLE_RAW:
 641                         assert(flags & REPLACE_ENV_ALLOW_BRACELESS);
 642
 643                         if (!strchr(VALID_CHARS_ENV_NAME, *e)) {
 644                                 const char *t;
 645
 646                                 t = strv_env_get_n(env, word+1, e-word-1, flags);
 647
 648                                 k = strappend(r, t);
 649                                 if (!k)
 650                                         return NULL;
 651
 652                                 free_and_replace(r, k);
 653
 654                                 word = e--;
 655                                 i--;
 656                                 state = WORD;
 657                         }
 658                         break;
 659                 }
 660
 661         if (state == VARIABLE_RAW) {
 662                 const char *t;
 663
 664                 assert(flags & REPLACE_ENV_ALLOW_BRACELESS);
 665
 666                 t = strv_env_get_n(env, word+1, e-word-1, flags);
 667                 return strappend(r, t);
 668         } else
 669                 return strnappend(r, word, e-word);
 670 }
 671
 672 char **replace_env_argv(char **argv, char **env) {
 673         char **ret, **i;
 674         size_t k = 0, l = 0;
 675
 676         l = strv_length(argv);
 677
 678         ret = new(char*, l+1);
 679         if (!ret)
 680                 return NULL;
 681
 682         STRV_FOREACH(i, argv) {
 683
 684                 /* If $FOO appears as single word, replace it by the split up variable */
 685                 if ((*i)[0] == '$' && !IN_SET((*i)[1], '{', '$')) {
 686                         char *e;
 687                         char **w, **m = NULL;
 688                         size_t q;
 689
 690                         e = strv_env_get(env, *i+1);
 691                         if (e) {
 692                                 int r;
 693
 694                                 r = strv_split_extract(&m, e, WHITESPACE, EXTRACT_RELAX|EXTRACT_QUOTES);
 695                                 if (r < 0) {
 696                                         ret[k] = NULL;
 697                                         strv_free(ret);
 698                                         return NULL;
 699                                 }
 700                         } else
 701                                 m = NULL;
 702
 703                         q = strv_length(m);
 704                         l = l + q - 1;
 705
 706                         w = reallocarray(ret, l + 1, sizeof(char *));
 707                         if (!w) {
 708                                 ret[k] = NULL;
 709                                 strv_free(ret);
 710                                 strv_free(m);
 711                                 return NULL;
 712                         }
 713
 714                         ret = w;
 715                         if (m) {
 716                                 memcpy(ret + k, m, q * sizeof(char*));
 717                                 free(m);
 718                         }
 719
 720                         k += q;
 721                         continue;
 722                 }
 723
 724                 /* If ${FOO} appears as part of a word, replace it by the variable as-is */
 725                 ret[k] = replace_env(*i, env, 0);
 726                 if (!ret[k]) {
 727                         strv_free(ret);
 728                         return NULL;
 729                 }
 730                 k++;
 731         }
 732
 733         ret[k] = NULL;
 734         return ret;
 735 }
 736
 737 int getenv_bool(const char *p) {
 738         const char *e;
 739
 740         e = getenv(p);
 741         if (!e)
 742                 return -ENXIO;
 743
 744         return parse_boolean(e);
 745 }
 746
 747 int getenv_bool_secure(const char *p) {
 748         const char *e;
 749
 750         e = secure_getenv(p);
 751         if (!e)
 752                 return -ENXIO;
 753
 754         return parse_boolean(e);
 755 }
 756
 757 int serialize_environment(FILE *f, char **environment) {
 758         char **e;
 759
 760         STRV_FOREACH(e, environment) {
 761                 _cleanup_free_ char *ce;
 762
 763                 ce = cescape(*e);
 764                 if (!ce)
 765                         return -ENOMEM;
 766
 767                 fprintf(f, "env=%s\n", ce);
 768         }
 769
 770         /* caller should call ferror() */
 771
 772         return 0;
 773 }
 774
 775 int deserialize_environment(char ***environment, const char *line) {
 776         char *uce;
 777         int r;
 778
 779         assert(line);
 780         assert(environment);
 781
 782         assert(startswith(line, "env="));
 783         r = cunescape(line + 4, 0, &uce);
 784         if (r < 0)
 785                 return r;
 786
 787         return strv_env_replace(environment, uce);
 788 }