1 /* Environment handling for dynamic loader. 2 Copyright (C) 1995-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #include <string.h> 20 #include <stdlib.h> 21 #include <unistd.h> 22 #include <ldsodefs.h> 23 24 /* Walk through the environment of the process and return all entries 25 starting with `LD_'. */ 26 char * _dl_next_ld_env_entry(char *** position)27_dl_next_ld_env_entry (char ***position) 28 { 29 char **current = *position; 30 char *result = NULL; 31 32 while (*current != NULL) 33 { 34 if (__builtin_expect ((*current)[0] == 'L', 0) 35 && (*current)[1] == 'D' && (*current)[2] == '_') 36 { 37 result = &(*current)[3]; 38 39 /* Save current position for next visit. */ 40 *position = ++current; 41 42 break; 43 } 44 45 ++current; 46 } 47 48 return result; 49 } 50 51 52 /* In ld.so __environ is not exported. */ 53 extern char **__environ attribute_hidden; 54 55 int unsetenv(const char * name)56unsetenv (const char *name) 57 { 58 char **ep; 59 60 ep = __environ; 61 while (*ep != NULL) 62 { 63 size_t cnt = 0; 64 65 while ((*ep)[cnt] == name[cnt] && name[cnt] != '\0') 66 ++cnt; 67 68 if (name[cnt] == '\0' && (*ep)[cnt] == '=') 69 { 70 /* Found it. Remove this pointer by moving later ones to 71 the front. */ 72 char **dp = ep; 73 74 do 75 dp[0] = dp[1]; 76 while (*dp++); 77 /* Continue the loop in case NAME appears again. */ 78 } 79 else 80 ++ep; 81 } 82 83 return 0; 84 } 85