setenv.c 5.3 KB

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  1. /* Copyright (C) 1992,95,96,97,98,99,2000,2001 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA.
  15. modified for uClibc by Erik Andersen <andersen@codepoet.org>
  16. */
  17. #define _GNU_SOURCE
  18. #include <features.h>
  19. #include <errno.h>
  20. #include <stdlib.h>
  21. #include <string.h>
  22. #include <unistd.h>
  23. #ifdef __UCLIBC_HAS_THREADS__
  24. #include <pthread.h>
  25. static pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER;
  26. # define LOCK __pthread_mutex_lock(&mylock)
  27. # define UNLOCK __pthread_mutex_unlock(&mylock);
  28. #else
  29. # define LOCK
  30. # define UNLOCK
  31. #endif
  32. /* If this variable is not a null pointer we allocated the current
  33. environment. */
  34. static char **last_environ;
  35. /* This function is used by `setenv' and `putenv'. The difference between
  36. the two functions is that for the former must create a new string which
  37. is then placed in the environment, while the argument of `putenv'
  38. must be used directly. This is all complicated by the fact that we try
  39. to reuse values once generated for a `setenv' call since we can never
  40. free the strings. */
  41. int __add_to_environ (const char *name, const char *value,
  42. const char *combined, int replace)
  43. {
  44. register char **ep;
  45. register size_t size;
  46. const size_t namelen = strlen (name);
  47. const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
  48. LOCK;
  49. /* We have to get the pointer now that we have the lock and not earlier
  50. since another thread might have created a new environment. */
  51. ep = __environ;
  52. size = 0;
  53. if (ep != NULL) {
  54. for (; *ep != NULL; ++ep) {
  55. if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  56. break;
  57. else
  58. ++size;
  59. }
  60. }
  61. if (ep == NULL || *ep == NULL) {
  62. char **new_environ;
  63. /* We allocated this space; we can extend it. */
  64. new_environ = (char **) realloc (last_environ,
  65. (size + 2) * sizeof (char *));
  66. if (new_environ == NULL) {
  67. UNLOCK;
  68. return -1;
  69. }
  70. /* If the whole entry is given add it. */
  71. if (combined != NULL) {
  72. /* We must not add the string to the search tree since it belongs
  73. to the user. */
  74. new_environ[size] = (char *) combined;
  75. } else {
  76. /* See whether the value is already known. */
  77. new_environ[size] = (char *) malloc (namelen + 1 + vallen);
  78. if (new_environ[size] == NULL) {
  79. __set_errno (ENOMEM);
  80. UNLOCK;
  81. return -1;
  82. }
  83. memcpy (new_environ[size], name, namelen);
  84. new_environ[size][namelen] = '=';
  85. memcpy (&new_environ[size][namelen + 1], value, vallen);
  86. }
  87. if (__environ != last_environ) {
  88. memcpy ((char *) new_environ, (char *) __environ,
  89. size * sizeof (char *));
  90. }
  91. new_environ[size + 1] = NULL;
  92. last_environ = __environ = new_environ;
  93. } else if (replace) {
  94. char *np;
  95. /* Use the user string if given. */
  96. if (combined != NULL) {
  97. np = (char *) combined;
  98. } else {
  99. np = malloc (namelen + 1 + vallen);
  100. if (np == NULL) {
  101. UNLOCK;
  102. return -1;
  103. }
  104. memcpy (np, name, namelen);
  105. np[namelen] = '=';
  106. memcpy (&np[namelen + 1], value, vallen);
  107. }
  108. *ep = np;
  109. }
  110. UNLOCK;
  111. return 0;
  112. }
  113. int setenv (const char *name, const char *value, int replace)
  114. {
  115. return __add_to_environ (name, value, NULL, replace);
  116. }
  117. int unsetenv (const char *name)
  118. {
  119. size_t len;
  120. char **ep;
  121. if (name == NULL || *name == '\0' || strchr (name, '=') != NULL) {
  122. __set_errno (EINVAL);
  123. return -1;
  124. }
  125. len = strlen (name);
  126. LOCK;
  127. ep = __environ;
  128. while (*ep != NULL) {
  129. if (!strncmp (*ep, name, len) && (*ep)[len] == '=') {
  130. /* Found it. Remove this pointer by moving later ones back. */
  131. char **dp = ep;
  132. do {
  133. dp[0] = dp[1];
  134. } while (*dp++);
  135. /* Continue the loop in case NAME appears again. */
  136. } else {
  137. ++ep;
  138. }
  139. }
  140. UNLOCK;
  141. return 0;
  142. }
  143. /* The `clearenv' was planned to be added to POSIX.1 but probably
  144. never made it. Nevertheless the POSIX.9 standard (POSIX bindings
  145. for Fortran 77) requires this function. */
  146. int clearenv (void)
  147. {
  148. LOCK;
  149. if (__environ == last_environ && __environ != NULL) {
  150. /* We allocated this environment so we can free it. */
  151. free (__environ);
  152. last_environ = NULL;
  153. }
  154. /* Clear the environment pointer removes the whole environment. */
  155. __environ = NULL;
  156. UNLOCK;
  157. return 0;
  158. }
  159. /* Put STRING, which is of the form "NAME=VALUE", in the environment. */
  160. int putenv (char *string)
  161. {
  162. int result;
  163. const char *const name_end = strchr (string, '=');
  164. if (name_end != NULL) {
  165. char *name = strndup(string, name_end - string);
  166. result = __add_to_environ (name, NULL, string, 1);
  167. free(name);
  168. return(result);
  169. }
  170. unsetenv (string);
  171. return 0;
  172. }