1/*- 2 * Copyright (c) 2007-2009 Sean C. Farley <scf@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer, 10 * without modification, immediately at the beginning of the file. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD$"); 29 30 31#include "namespace.h" 32#include <sys/types.h> 33#include <errno.h> 34#include <stdbool.h> 35#include <stddef.h> 36#include <stdlib.h> 37#include <string.h> 38#include <unistd.h> 39#include "un-namespace.h" 40 41 42static const char CorruptEnvFindMsg[] = "environment corrupt; unable to find "; 43static const char CorruptEnvValueMsg[] = 44 "environment corrupt; missing value for "; 45 46 47/* 48 * Standard environ. environ variable is exposed to entire process. 49 * 50 * origEnviron: Upon cleanup on unloading of library or failure, this 51 * allows environ to return to as it was before. 52 * environSize: Number of variables environ can hold. Can only 53 * increase. 54 * intEnviron: Internally-built environ. Exposed via environ during 55 * (re)builds of the environment. 56 */ 57extern char **environ; 58static char **origEnviron; 59static char **intEnviron = NULL; 60static int environSize = 0; 61 62/* 63 * Array of environment variables built from environ. Each element records: 64 * name: Pointer to name=value string 65 * name length: Length of name not counting '=' character 66 * value: Pointer to value within same string as name 67 * value size: Size (not length) of space for value not counting the 68 * nul character 69 * active state: true/false value to signify whether variable is active. 70 * Useful since multiple variables with the same name can 71 * co-exist. At most, one variable can be active at any 72 * one time. 73 * putenv: Created from putenv() call. This memory must not be 74 * reused. 75 */ 76static struct envVars { 77 size_t nameLen; 78 size_t valueSize; 79 char *name; 80 char *value; 81 bool active; 82 bool putenv; 83} *envVars = NULL; 84 85/* 86 * Environment array information. 87 * 88 * envActive: Number of active variables in array. 89 * envVarsSize: Size of array. 90 * envVarsTotal: Number of total variables in array (active or not). 91 */ 92static int envActive = 0; 93static int envVarsSize = 0; 94static int envVarsTotal = 0; 95 96 97/* Deinitialization of new environment. */ 98static void __attribute__ ((destructor)) __clean_env_destructor(void); 99 100 101/* 102 * A simple version of warnx() to avoid the bloat of including stdio in static 103 * binaries. 104 */ 105static void 106__env_warnx(const char *msg, const char *name, size_t nameLen) 107{ 108 static const char nl[] = "\n"; 109 static const char progSep[] = ": "; 110 111debug_printf("%s:\n", __func__); 112 // _write(STDERR_FILENO, _getprogname(), strlen(_getprogname())); 113 // _write(STDERR_FILENO, progSep, sizeof(progSep) - 1); 114 // _write(STDERR_FILENO, msg, strlen(msg)); 115 // _write(STDERR_FILENO, name, nameLen); 116 // _write(STDERR_FILENO, nl, sizeof(nl) - 1); 117 118 return; 119} 120 121 122/* 123 * Inline strlen() for performance. Also, perform check for an equals sign. 124 * Cheaper here than peforming a strchr() later. 125 */ 126static inline size_t 127__strleneq(const char *str) 128{ 129 const char *s; 130 131 for (s = str; *s != '\0'; ++s) 132 if (*s == '=') 133 return (0); 134 135 return (s - str); 136} 137 138 139/* 140 * Comparison of an environment name=value to a name. 141 */ 142static inline bool 143strncmpeq(const char *nameValue, const char *name, size_t nameLen) 144{ 145 if (strncmp(nameValue, name, nameLen) == 0 && nameValue[nameLen] == '=') 146 return (true); 147 148 return (false); 149} 150 151 152/* 153 * Using environment, returns pointer to value associated with name, if any, 154 * else NULL. If the onlyActive flag is set to true, only variables that are 155 * active are returned else all are. 156 */ 157static inline char * 158__findenv(const char *name, size_t nameLen, int *envNdx, bool onlyActive) 159{ 160 int ndx; 161 162 /* 163 * Find environment variable from end of array (more likely to be 164 * active). A variable created by putenv is always active, or it is not 165 * tracked in the array. 166 */ 167 for (ndx = *envNdx; ndx >= 0; ndx--) 168 if (envVars[ndx].putenv) { 169 if (strncmpeq(envVars[ndx].name, name, nameLen)) { 170 *envNdx = ndx; 171 return (envVars[ndx].name + nameLen + 172 sizeof ("=") - 1); 173 } 174 } else if ((!onlyActive || envVars[ndx].active) && 175 (envVars[ndx].nameLen == nameLen && 176 strncmpeq(envVars[ndx].name, name, nameLen))) { 177 *envNdx = ndx; 178 return (envVars[ndx].value); 179 } 180 181 return (NULL); 182} 183 184 185/* 186 * Using environ, returns pointer to value associated with name, if any, else 187 * NULL. Used on the original environ passed into the program. 188 */ 189static char * 190__findenv_environ(const char *name, size_t nameLen) 191{ 192 int envNdx; 193 194 /* Find variable within environ. */ 195 for (envNdx = 0; environ[envNdx] != NULL; envNdx++) 196 if (strncmpeq(environ[envNdx], name, nameLen)) 197 return (&(environ[envNdx][nameLen + sizeof("=") - 1])); 198 199 return (NULL); 200} 201 202 203/* 204 * Remove variable added by putenv() from variable tracking array. 205 */ 206static void 207__remove_putenv(int envNdx) 208{ 209 envVarsTotal--; 210 if (envVarsTotal > envNdx) 211 memmove(&(envVars[envNdx]), &(envVars[envNdx + 1]), 212 (envVarsTotal - envNdx) * sizeof (*envVars)); 213 memset(&(envVars[envVarsTotal]), 0, sizeof (*envVars)); 214 215 return; 216} 217 218 219/* 220 * Deallocate the environment built from environ as well as environ then set 221 * both to NULL. Eases debugging of memory leaks. 222 */ 223static void 224__clean_env(bool freeVars) 225{ 226 int envNdx; 227 228 /* Deallocate environment and environ if created by *env(). */ 229 if (envVars != NULL) { 230 for (envNdx = envVarsTotal - 1; envNdx >= 0; envNdx--) 231 /* Free variables or deactivate them. */ 232 if (envVars[envNdx].putenv) { 233 if (!freeVars) 234 __remove_putenv(envNdx); 235 } else { 236 if (freeVars) 237 free(envVars[envNdx].name); 238 else 239 envVars[envNdx].active = false; 240 } 241 if (freeVars) { 242 free(envVars); 243 envVars = NULL; 244 } else 245 envActive = 0; 246 247 /* Restore original environ if it has not updated by program. */ 248 if (origEnviron != NULL) { 249 if (environ == intEnviron) 250 environ = origEnviron; 251 free(intEnviron); 252 intEnviron = NULL; 253 environSize = 0; 254 } 255 } 256 257 return; 258} 259 260 261/* 262 * Using the environment, rebuild the environ array for use by other C library 263 * calls that depend upon it. 264 */ 265static int 266__rebuild_environ(int newEnvironSize) 267{ 268 char **tmpEnviron; 269 int envNdx; 270 int environNdx; 271 int tmpEnvironSize; 272 273 /* Resize environ. */ 274 if (newEnvironSize > environSize) { 275 tmpEnvironSize = newEnvironSize * 2; 276 tmpEnviron = realloc(intEnviron, sizeof (*intEnviron) * 277 (tmpEnvironSize + 1)); 278 if (tmpEnviron == NULL) 279 return (-1); 280 environSize = tmpEnvironSize; 281 intEnviron = tmpEnviron; 282 } 283 envActive = newEnvironSize; 284 285 /* Assign active variables to environ. */ 286 for (envNdx = envVarsTotal - 1, environNdx = 0; envNdx >= 0; envNdx--) 287 if (envVars[envNdx].active) 288 intEnviron[environNdx++] = envVars[envNdx].name; 289 intEnviron[environNdx] = NULL; 290 291 /* Always set environ which may have been replaced by program. */ 292 environ = intEnviron; 293 294 return (0); 295} 296 297 298/* 299 * Enlarge new environment. 300 */ 301static inline bool 302__enlarge_env(void) 303{ 304 int newEnvVarsSize; 305 struct envVars *tmpEnvVars; 306 307 envVarsTotal++; 308 if (envVarsTotal > envVarsSize) { 309 newEnvVarsSize = envVarsTotal * 2; 310 tmpEnvVars = realloc(envVars, sizeof (*envVars) * 311 newEnvVarsSize); 312 if (tmpEnvVars == NULL) { 313 envVarsTotal--; 314 return (false); 315 } 316 envVarsSize = newEnvVarsSize; 317 envVars = tmpEnvVars; 318 } 319 320 return (true); 321} 322 323 324/* 325 * Using environ, build an environment for use by standard C library calls. 326 */ 327static int 328__build_env(void) 329{ 330 char **env; 331 int activeNdx; 332 int envNdx; 333 int savedErrno; 334 size_t nameLen; 335 336 /* Check for non-existant environment. */ 337 if (environ == NULL || environ[0] == NULL) 338 return (0); 339 340 /* Count environment variables. */ 341 for (env = environ, envVarsTotal = 0; *env != NULL; env++) 342 envVarsTotal++; 343 envVarsSize = envVarsTotal * 2; 344 345 /* Create new environment. */ 346 envVars = calloc(1, sizeof (*envVars) * envVarsSize); 347 if (envVars == NULL) 348 goto Failure; 349 350 /* Copy environ values and keep track of them. */ 351 for (envNdx = envVarsTotal - 1; envNdx >= 0; envNdx--) { 352 envVars[envNdx].putenv = false; 353 envVars[envNdx].name = 354 strdup(environ[envVarsTotal - envNdx - 1]); 355 if (envVars[envNdx].name == NULL) 356 goto Failure; 357 envVars[envNdx].value = strchr(envVars[envNdx].name, '='); 358 if (envVars[envNdx].value != NULL) { 359 envVars[envNdx].value++; 360 envVars[envNdx].valueSize = 361 strlen(envVars[envNdx].value); 362 } else { 363 __env_warnx(CorruptEnvValueMsg, envVars[envNdx].name, 364 strlen(envVars[envNdx].name)); 365 errno = EFAULT; 366 goto Failure; 367 } 368 369 /* 370 * Find most current version of variable to make active. This 371 * will prevent multiple active variables from being created 372 * during this initialization phase. 373 */ 374 nameLen = envVars[envNdx].value - envVars[envNdx].name - 1; 375 envVars[envNdx].nameLen = nameLen; 376 activeNdx = envVarsTotal - 1; 377 if (__findenv(envVars[envNdx].name, nameLen, &activeNdx, 378 false) == NULL) { 379 __env_warnx(CorruptEnvFindMsg, envVars[envNdx].name, 380 nameLen); 381 errno = EFAULT; 382 goto Failure; 383 } 384 envVars[activeNdx].active = true; 385 } 386 387 /* Create a new environ. */ 388 origEnviron = environ; 389 environ = NULL; 390 if (__rebuild_environ(envVarsTotal) == 0) 391 return (0); 392 393Failure: 394 savedErrno = errno; 395 __clean_env(true); 396 errno = savedErrno; 397 398 return (-1); 399} 400 401 402/* 403 * Destructor function with default argument to __clean_env(). 404 */ 405static void 406__clean_env_destructor(void) 407{ 408 __clean_env(true); 409 410 return; 411} 412 413 414/* 415 * Returns the value of a variable or NULL if none are found. 416 */ 417char * 418getenv(const char *name) 419{ 420 int envNdx; 421 size_t nameLen; 422 423 /* Check for malformed name. */ 424 if (name == NULL || (nameLen = __strleneq(name)) == 0) { 425 errno = EINVAL; 426 return (NULL); 427 } 428 429 /* 430 * Variable search order: 431 * 1. Check for an empty environ. This allows an application to clear 432 * the environment. 433 * 2. Search the external environ array. 434 * 3. Search the internal environment. 435 * 436 * Since malloc() depends upon getenv(), getenv() must never cause the 437 * internal environment storage to be generated. 438 */ 439 if (environ == NULL || environ[0] == NULL) 440 return (NULL); 441 else if (envVars == NULL || environ != intEnviron) 442 return (__findenv_environ(name, nameLen)); 443 else { 444 envNdx = envVarsTotal - 1; 445 return (__findenv(name, nameLen, &envNdx, true)); 446 } 447} 448 449 450/* 451 * Set the value of a variable. Older settings are labeled as inactive. If an 452 * older setting has enough room to store the new value, it will be reused. No 453 * previous variables are ever freed here to avoid causing a segmentation fault 454 * in a user's code. 455 * 456 * The variables nameLen and valueLen are passed into here to allow the caller 457 * to calculate the length by means besides just strlen(). 458 */ 459static int 460__setenv(const char *name, size_t nameLen, const char *value, int overwrite) 461{ 462 bool reuse; 463 char *env; 464 int envNdx; 465 int newEnvActive; 466 size_t valueLen; 467 468 /* Find existing environment variable large enough to use. */ 469 envNdx = envVarsTotal - 1; 470 newEnvActive = envActive; 471 valueLen = strlen(value); 472 reuse = false; 473 if (__findenv(name, nameLen, &envNdx, false) != NULL) { 474 /* Deactivate entry if overwrite is allowed. */ 475 if (envVars[envNdx].active) { 476 if (overwrite == 0) 477 return (0); 478 envVars[envNdx].active = false; 479 newEnvActive--; 480 } 481 482 /* putenv() created variable cannot be reused. */ 483 if (envVars[envNdx].putenv) 484 __remove_putenv(envNdx); 485 486 /* Entry is large enough to reuse. */ 487 else if (envVars[envNdx].valueSize >= valueLen) 488 reuse = true; 489 } 490 491 /* Create new variable if none was found of sufficient size. */ 492 if (! reuse) { 493 /* Enlarge environment. */ 494 envNdx = envVarsTotal; 495 if (!__enlarge_env()) 496 return (-1); 497 498 /* Create environment entry. */ 499 envVars[envNdx].name = malloc(nameLen + sizeof ("=") + 500 valueLen); 501 if (envVars[envNdx].name == NULL) { 502 envVarsTotal--; 503 return (-1); 504 } 505 envVars[envNdx].nameLen = nameLen; 506 envVars[envNdx].valueSize = valueLen; 507 508 /* Save name of name/value pair. */ 509 env = stpncpy(envVars[envNdx].name, name, nameLen); 510 *env++ = '='; 511 } 512 else 513 env = envVars[envNdx].value; 514 515 /* Save value of name/value pair. */ 516 strcpy(env, value); 517 envVars[envNdx].value = env; 518 envVars[envNdx].active = true; 519 newEnvActive++; 520 521 /* No need to rebuild environ if an active variable was reused. */ 522 if (reuse && newEnvActive == envActive) 523 return (0); 524 else 525 return (__rebuild_environ(newEnvActive)); 526} 527 528 529/* 530 * If the program attempts to replace the array of environment variables 531 * (environ) environ or sets the first varible to NULL, then deactivate all 532 * variables and merge in the new list from environ. 533 */ 534static int 535__merge_environ(void) 536{ 537 char **env; 538 char *equals; 539 540 /* 541 * Internally-built environ has been replaced or cleared (detected by 542 * using the count of active variables against a NULL as the first value 543 * in environ). Clean up everything. 544 */ 545 if (intEnviron != NULL && (environ != intEnviron || (envActive > 0 && 546 environ[0] == NULL))) { 547 /* Deactivate all environment variables. */ 548 if (envActive > 0) { 549 origEnviron = NULL; 550 __clean_env(false); 551 } 552 553 /* 554 * Insert new environ into existing, yet deactivated, 555 * environment array. 556 */ 557 origEnviron = environ; 558 if (origEnviron != NULL) 559 for (env = origEnviron; *env != NULL; env++) { 560 if ((equals = strchr(*env, '=')) == NULL) { 561 __env_warnx(CorruptEnvValueMsg, *env, 562 strlen(*env)); 563 errno = EFAULT; 564 return (-1); 565 } 566 if (__setenv(*env, equals - *env, equals + 1, 567 1) == -1) 568 return (-1); 569 } 570 } 571 572 return (0); 573} 574 575 576/* 577 * The exposed setenv() that peforms a few tests before calling the function 578 * (__setenv()) that does the actual work of inserting a variable into the 579 * environment. 580 */ 581int 582setenv(const char *name, const char *value, int overwrite) 583{ 584 size_t nameLen; 585 586 /* Check for malformed name. */ 587 if (name == NULL || (nameLen = __strleneq(name)) == 0) { 588 errno = EINVAL; 589 return (-1); 590 } 591 592 /* Initialize environment. */ 593 if (__merge_environ() == -1 || (envVars == NULL && __build_env() == -1)) 594 return (-1); 595 596 return (__setenv(name, nameLen, value, overwrite)); 597} 598 599 600/* 601 * Insert a "name=value" string into the environment. Special settings must be 602 * made to keep setenv() from reusing this memory block and unsetenv() from 603 * allowing it to be tracked. 604 */ 605int 606putenv(char *string) 607{ 608 char *equals; 609 int envNdx; 610 int newEnvActive; 611 size_t nameLen; 612 613 /* Check for malformed argument. */ 614 if (string == NULL || (equals = strchr(string, '=')) == NULL || 615 (nameLen = equals - string) == 0) { 616 errno = EINVAL; 617 return (-1); 618 } 619 620 /* Initialize environment. */ 621 if (__merge_environ() == -1 || (envVars == NULL && __build_env() == -1)) 622 return (-1); 623 624 /* Deactivate previous environment variable. */ 625 envNdx = envVarsTotal - 1; 626 newEnvActive = envActive; 627 if (__findenv(string, nameLen, &envNdx, true) != NULL) { 628 /* Reuse previous putenv slot. */ 629 if (envVars[envNdx].putenv) { 630 envVars[envNdx].name = string; 631 return (__rebuild_environ(envActive)); 632 } else { 633 newEnvActive--; 634 envVars[envNdx].active = false; 635 } 636 } 637 638 /* Enlarge environment. */ 639 envNdx = envVarsTotal; 640 if (!__enlarge_env()) 641 return (-1); 642 643 /* Create environment entry. */ 644 envVars[envNdx].name = string; 645 envVars[envNdx].nameLen = -1; 646 envVars[envNdx].value = NULL; 647 envVars[envNdx].valueSize = -1; 648 envVars[envNdx].putenv = true; 649 envVars[envNdx].active = true; 650 newEnvActive++; 651 652 return (__rebuild_environ(newEnvActive)); 653} 654 655 656/* 657 * Unset variable with the same name by flagging it as inactive. No variable is 658 * ever freed. 659 */ 660int 661unsetenv(const char *name) 662{ 663 int envNdx; 664 size_t nameLen; 665 int newEnvActive; 666 667 /* Check for malformed name. */ 668 if (name == NULL || (nameLen = __strleneq(name)) == 0) { 669 errno = EINVAL; 670 return (-1); 671 } 672 673 /* Initialize environment. */ 674 if (__merge_environ() == -1 || (envVars == NULL && __build_env() == -1)) 675 return (-1); 676 677 /* Deactivate specified variable. */ 678 /* Remove all occurrences. */ 679 envNdx = envVarsTotal - 1; 680 newEnvActive = envActive; 681 while (__findenv(name, nameLen, &envNdx, true) != NULL) { 682 envVars[envNdx].active = false; 683 if (envVars[envNdx].putenv) 684 __remove_putenv(envNdx); 685 envNdx--; 686 newEnvActive--; 687 } 688 if (newEnvActive != envActive) 689 __rebuild_environ(newEnvActive); 690 691 return (0); 692} 693