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 "extract-word.h"
  30 #include "macro.h"
  31 #include "parse-util.h"
  32 #include "string-util.h"
  33 #include "strv.h"
  34 #include "utf8.h"
  35
  36 #define VALID_CHARS_ENV_NAME                    \
  37         DIGITS LETTERS                          \
  38         "_"
  39
  40 #ifndef ARG_MAX
  41 #define ARG_MAX ((size_t) sysconf(_SC_ARG_MAX))
  42 #endif
  43
  44 static bool env_name_is_valid_n(const char *e, size_t n) {
  45         const char *p;
  46
  47         if (!e)
  48                 return false;
  49
  50         if (n <= 0)
  51                 return false;
  52
  53         if (e[0] >= '0' && e[0] <= '9')
  54                 return false;
  55
  56         /* POSIX says the overall size of the environment block cannot
  57          * be > ARG_MAX, an individual assignment hence cannot be
  58          * either. Discounting the equal sign and trailing NUL this
  59          * hence leaves ARG_MAX-2 as longest possible variable
  60          * name. */
  61         if (n > ARG_MAX - 2)
  62                 return false;
  63
  64         for (p = e; p < e + n; p++)
  65                 if (!strchr(VALID_CHARS_ENV_NAME, *p))
  66                         return false;
  67
  68         return true;
  69 }
  70
  71 bool env_name_is_valid(const char *e) {
  72         if (!e)
  73                 return false;
  74
  75         return env_name_is_valid_n(e, strlen(e));
  76 }
  77
  78 bool env_value_is_valid(const char *e) {
  79         if (!e)
  80                 return false;
  81
  82         if (!utf8_is_valid(e))
  83                 return false;
  84
  85         /* bash allows tabs in environment variables, and so should
  86          * we */
  87         if (string_has_cc(e, "\t"))
  88                 return false;
  89
  90         /* POSIX says the overall size of the environment block cannot
  91          * be > ARG_MAX, an individual assignment hence cannot be
  92          * either. Discounting the shortest possible variable name of
  93          * length 1, the equal sign and trailing NUL this hence leaves
  94          * ARG_MAX-3 as longest possible variable value. */
  95         if (strlen(e) > ARG_MAX - 3)
  96                 return false;
  97
  98         return true;
  99 }
 100
 101 bool env_assignment_is_valid(const char *e) {
 102         const char *eq;
 103
 104         eq = strchr(e, '=');
 105         if (!eq)
 106                 return false;
 107
 108         if (!env_name_is_valid_n(e, eq - e))
 109                 return false;
 110
 111         if (!env_value_is_valid(eq + 1))
 112                 return false;
 113
 114         /* POSIX says the overall size of the environment block cannot
 115          * be > ARG_MAX, hence the individual variable assignments
 116          * cannot be either, but let's leave room for one trailing NUL
 117          * byte. */
 118         if (strlen(e) > ARG_MAX - 1)
 119                 return false;
 120
 121         return true;
 122 }
 123
 124 bool strv_env_is_valid(char **e) {
 125         char **p, **q;
 126
 127         STRV_FOREACH(p, e) {
 128                 size_t k;
 129
 130                 if (!env_assignment_is_valid(*p))
 131                         return false;
 132
 133                 /* Check if there are duplicate assginments */
 134                 k = strcspn(*p, "=");
 135                 STRV_FOREACH(q, p + 1)
 136                         if (strneq(*p, *q, k) && (*q)[k] == '=')
 137                                 return false;
 138         }
 139
 140         return true;
 141 }
 142
 143 bool strv_env_name_is_valid(char **l) {
 144         char **p, **q;
 145
 146         STRV_FOREACH(p, l) {
 147                 if (!env_name_is_valid(*p))
 148                         return false;
 149
 150                 STRV_FOREACH(q, p + 1)
 151                         if (streq(*p, *q))
 152                                 return false;
 153         }
 154
 155         return true;
 156 }
 157
 158 bool strv_env_name_or_assignment_is_valid(char **l) {
 159         char **p, **q;
 160
 161         STRV_FOREACH(p, l) {
 162                 if (!env_assignment_is_valid(*p) && !env_name_is_valid(*p))
 163                         return false;
 164
 165                 STRV_FOREACH(q, p + 1)
 166                         if (streq(*p, *q))
 167                                 return false;
 168         }
 169
 170         return true;
 171 }
 172
 173 static int env_append(char **r, char ***k, char **a) {
 174         assert(r);
 175         assert(k);
 176
 177         if (!a)
 178                 return 0;
 179
 180         /* Add the entries of a to *k unless they already exist in *r
 181          * in which case they are overridden instead. This assumes
 182          * there is enough space in the r array. */
 183
 184         for (; *a; a++) {
 185                 char **j;
 186                 size_t n;
 187
 188                 n = strcspn(*a, "=");
 189
 190                 if ((*a)[n] == '=')
 191                         n++;
 192
 193                 for (j = r; j < *k; j++)
 194                         if (strneq(*j, *a, n))
 195                                 break;
 196
 197                 if (j >= *k)
 198                         (*k)++;
 199                 else
 200                         free(*j);
 201
 202                 *j = strdup(*a);
 203                 if (!*j)
 204                         return -ENOMEM;
 205         }
 206
 207         return 0;
 208 }
 209
 210 char **strv_env_merge(unsigned n_lists, ...) {
 211         size_t n = 0;
 212         char **l, **k, **r;
 213         va_list ap;
 214         unsigned i;
 215
 216         /* Merges an arbitrary number of environment sets */
 217
 218         va_start(ap, n_lists);
 219         for (i = 0; i < n_lists; i++) {
 220                 l = va_arg(ap, char**);
 221                 n += strv_length(l);
 222         }
 223         va_end(ap);
 224
 225         r = new(char*, n+1);
 226         if (!r)
 227                 return NULL;
 228
 229         k = r;
 230
 231         va_start(ap, n_lists);
 232         for (i = 0; i < n_lists; i++) {
 233                 l = va_arg(ap, char**);
 234                 if (env_append(r, &k, l) < 0)
 235                         goto fail;
 236         }
 237         va_end(ap);
 238
 239         *k = NULL;
 240
 241         return r;
 242
 243 fail:
 244         va_end(ap);
 245         strv_free(r);
 246
 247         return NULL;
 248 }
 249
 250 _pure_ static bool env_match(const char *t, const char *pattern) {
 251         assert(t);
 252         assert(pattern);
 253
 254         /* pattern a matches string a
 255          *         a matches a=
 256          *         a matches a=b
 257          *         a= matches a=
 258          *         a=b matches a=b
 259          *         a= does not match a
 260          *         a=b does not match a=
 261          *         a=b does not match a
 262          *         a=b does not match a=c */
 263
 264         if (streq(t, pattern))
 265                 return true;
 266
 267         if (!strchr(pattern, '=')) {
 268                 size_t l = strlen(pattern);
 269
 270                 return strneq(t, pattern, l) && t[l] == '=';
 271         }
 272
 273         return false;
 274 }
 275
 276 char **strv_env_delete(char **x, unsigned 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                 unsigned 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 char **strv_env_set(char **x, const char *p) {
 388
 389         char **k, **r;
 390         char* m[2] = { (char*) p, NULL };
 391
 392         /* Overrides the env var setting of p, returns a new copy */
 393
 394         r = new(char*, strv_length(x)+2);
 395         if (!r)
 396                 return NULL;
 397
 398         k = r;
 399         if (env_append(r, &k, x) < 0)
 400                 goto fail;
 401
 402         if (env_append(r, &k, m) < 0)
 403                 goto fail;
 404
 405         *k = NULL;
 406
 407         return r;
 408
 409 fail:
 410         strv_free(r);
 411         return NULL;
 412 }
 413
 414 char *strv_env_get_n(char **l, const char *name, size_t k) {
 415         char **i;
 416
 417         assert(name);
 418
 419         if (k <= 0)
 420                 return NULL;
 421
 422         STRV_FOREACH(i, l)
 423                 if (strneq(*i, name, k) &&
 424                     (*i)[k] == '=')
 425                         return *i + k + 1;
 426
 427         return NULL;
 428 }
 429
 430 char *strv_env_get(char **l, const char *name) {
 431         assert(name);
 432
 433         return strv_env_get_n(l, name, strlen(name));
 434 }
 435
 436 char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const char *p, void *userdata), void *userdata) {
 437         char **p, **q;
 438         int k = 0;
 439
 440         STRV_FOREACH(p, e) {
 441                 size_t n;
 442                 bool duplicate = false;
 443
 444                 if (!env_assignment_is_valid(*p)) {
 445                         if (invalid_callback)
 446                                 invalid_callback(*p, userdata);
 447                         free(*p);
 448                         continue;
 449                 }
 450
 451                 n = strcspn(*p, "=");
 452                 STRV_FOREACH(q, p + 1)
 453                         if (strneq(*p, *q, n) && (*q)[n] == '=') {
 454                                 duplicate = true;
 455                                 break;
 456                         }
 457
 458                 if (duplicate) {
 459                         free(*p);
 460                         continue;
 461                 }
 462
 463                 e[k++] = *p;
 464         }
 465
 466         if (e)
 467                 e[k] = NULL;
 468
 469         return e;
 470 }
 471
 472 char *replace_env(const char *format, char **env) {
 473         enum {
 474                 WORD,
 475                 CURLY,
 476                 VARIABLE
 477         } state = WORD;
 478
 479         const char *e, *word = format;
 480         char *r = NULL, *k;
 481
 482         assert(format);
 483
 484         for (e = format; *e; e ++) {
 485
 486                 switch (state) {
 487
 488                 case WORD:
 489                         if (*e == '$')
 490                                 state = CURLY;
 491                         break;
 492
 493                 case CURLY:
 494                         if (*e == '{') {
 495                                 k = strnappend(r, word, e-word-1);
 496                                 if (!k)
 497                                         goto fail;
 498
 499                                 free(r);
 500                                 r = k;
 501
 502                                 word = e-1;
 503                                 state = VARIABLE;
 504
 505                         } else if (*e == '$') {
 506                                 k = strnappend(r, word, e-word);
 507                                 if (!k)
 508                                         goto fail;
 509
 510                                 free(r);
 511                                 r = k;
 512
 513                                 word = e+1;
 514                                 state = WORD;
 515                         } else
 516                                 state = WORD;
 517                         break;
 518
 519                 case VARIABLE:
 520                         if (*e == '}') {
 521                                 const char *t;
 522
 523                                 t = strempty(strv_env_get_n(env, word+2, e-word-2));
 524
 525                                 k = strappend(r, t);
 526                                 if (!k)
 527                                         goto fail;
 528
 529                                 free(r);
 530                                 r = k;
 531
 532                                 word = e+1;
 533                                 state = WORD;
 534                         }
 535                         break;
 536                 }
 537         }
 538
 539         k = strnappend(r, word, e-word);
 540         if (!k)
 541                 goto fail;
 542
 543         free(r);
 544         return k;
 545
 546 fail:
 547         return mfree(r);
 548 }
 549
 550 char **replace_env_argv(char **argv, char **env) {
 551         char **ret, **i;
 552         unsigned k = 0, l = 0;
 553
 554         l = strv_length(argv);
 555
 556         ret = new(char*, l+1);
 557         if (!ret)
 558                 return NULL;
 559
 560         STRV_FOREACH(i, argv) {
 561
 562                 /* If $FOO appears as single word, replace it by the split up variable */
 563                 if ((*i)[0] == '$' && (*i)[1] != '{' && (*i)[1] != '$') {
 564                         char *e;
 565                         char **w, **m = NULL;
 566                         unsigned q;
 567
 568                         e = strv_env_get(env, *i+1);
 569                         if (e) {
 570                                 int r;
 571
 572                                 r = strv_split_extract(&m, e, WHITESPACE, EXTRACT_RELAX|EXTRACT_QUOTES);
 573                                 if (r < 0) {
 574                                         ret[k] = NULL;
 575                                         strv_free(ret);
 576                                         return NULL;
 577                                 }
 578                         } else
 579                                 m = NULL;
 580
 581                         q = strv_length(m);
 582                         l = l + q - 1;
 583
 584                         w = realloc(ret, sizeof(char*) * (l+1));
 585                         if (!w) {
 586                                 ret[k] = NULL;
 587                                 strv_free(ret);
 588                                 strv_free(m);
 589                                 return NULL;
 590                         }
 591
 592                         ret = w;
 593                         if (m) {
 594                                 memcpy(ret + k, m, q * sizeof(char*));
 595                                 free(m);
 596                         }
 597
 598                         k += q;
 599                         continue;
 600                 }
 601
 602                 /* If ${FOO} appears as part of a word, replace it by the variable as-is */
 603                 ret[k] = replace_env(*i, env);
 604                 if (!ret[k]) {
 605                         strv_free(ret);
 606                         return NULL;
 607                 }
 608                 k++;
 609         }
 610
 611         ret[k] = NULL;
 612         return ret;
 613 }
 614
 615 int getenv_bool(const char *p) {
 616         const char *e;
 617
 618         e = getenv(p);
 619         if (!e)
 620                 return -ENXIO;
 621
 622         return parse_boolean(e);
 623 }