src/basic/env-util.c

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