1 /* 2 * Copyright (c) 1998 Michael Smith. 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 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 /* 31 * Manage an environment-like space in which string variables may be stored. 32 * Provide support for some method-like operations for setting/retrieving 33 * variables in order to allow some type strength. 34 */ 35 36 #include "stand.h" 37 38 #include <string.h> 39 40 struct env_var *environ = NULL; 41 42 /* 43 * Look up (name) and return it's env_var structure. 44 */ 45 struct env_var * 46 env_getenv(const char *name) 47 { 48 struct env_var *ev; 49 50 for (ev = environ; ev != NULL; ev = ev->ev_next) 51 if (!strcmp(ev->ev_name, name)) 52 break; 53 return (ev); 54 } 55 56 /* 57 * Some notes: 58 * 59 * If the EV_VOLATILE flag is set, a copy of the variable is made. 60 * If EV_DYNAMIC is set, the variable has been allocated with 61 * malloc and ownership transferred to the environment. 62 * If (value) is NULL, the variable is set but has no value. 63 */ 64 int 65 env_setenv(const char *name, int flags, const void *value, 66 ev_sethook_t sethook, ev_unsethook_t unsethook) 67 { 68 struct env_var *ev, *curr, *last; 69 70 if ((ev = env_getenv(name)) != NULL) { 71 /* 72 * If there's a set hook, let it do the work 73 * (unless we are working for one already). 74 */ 75 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 76 return (ev->ev_sethook(ev, flags, value)); 77 78 /* If there is data in the variable, discard it. */ 79 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 80 free(ev->ev_value); 81 ev->ev_value = NULL; 82 ev->ev_flags &= ~EV_DYNAMIC; 83 84 } else { 85 86 /* 87 * New variable; create and sort into list 88 */ 89 ev = malloc(sizeof(struct env_var)); 90 ev->ev_name = strdup(name); 91 ev->ev_value = NULL; 92 ev->ev_flags = 0; 93 /* hooks can only be set when the variable is instantiated */ 94 ev->ev_sethook = sethook; 95 ev->ev_unsethook = unsethook; 96 97 /* Sort into list */ 98 ev->ev_prev = NULL; 99 ev->ev_next = NULL; 100 /* Search for the record to insert before */ 101 for (last = NULL, curr = environ; curr != NULL; 102 last = curr, curr = curr->ev_next) { 103 104 if (strcmp(ev->ev_name, curr->ev_name) < 0) { 105 if (curr->ev_prev) { 106 curr->ev_prev->ev_next = ev; 107 } else { 108 environ = ev; 109 } 110 ev->ev_next = curr; 111 ev->ev_prev = curr->ev_prev; 112 curr->ev_prev = ev; 113 break; 114 } 115 } 116 if (curr == NULL) { 117 if (last == NULL) { 118 environ = ev; 119 } else { 120 last->ev_next = ev; 121 ev->ev_prev = last; 122 } 123 } 124 } 125 126 /* If we have a new value, use it */ 127 if (flags & EV_VOLATILE) { 128 ev->ev_value = strdup(value); 129 ev->ev_flags |= EV_DYNAMIC; 130 } else { 131 ev->ev_value = (char *)value; 132 ev->ev_flags |= flags & EV_DYNAMIC; 133 } 134 135 return (0); 136 } 137 138 /* coverity[ -tainted_string_return_content ] */ 139 char * 140 getenv(const char *name) 141 { 142 struct env_var *ev; 143 144 /* Set but no value gives empty string */ 145 if ((ev = env_getenv(name)) != NULL) { 146 if (ev->ev_value != NULL) 147 return (ev->ev_value); 148 return (""); 149 } 150 return (NULL); 151 } 152 153 int 154 setenv(const char *name, const char *value, int overwrite) 155 { 156 /* No guarantees about state, always assume volatile */ 157 if (overwrite || (env_getenv(name) == NULL)) 158 return (env_setenv(name, EV_VOLATILE, value, NULL, NULL)); 159 return (0); 160 } 161 162 int 163 putenv(char *string) 164 { 165 char *value, *copy; 166 int result; 167 168 copy = strdup(string); 169 if ((value = strchr(copy, '=')) != NULL) 170 *(value++) = 0; 171 result = setenv(copy, value, 1); 172 free(copy); 173 return (result); 174 } 175 176 int 177 unsetenv(const char *name) 178 { 179 struct env_var *ev; 180 int err; 181 182 err = 0; 183 if ((ev = env_getenv(name)) == NULL) { 184 err = ENOENT; 185 } else { 186 if (ev->ev_unsethook != NULL) 187 err = ev->ev_unsethook(ev); 188 if (err == 0) { 189 env_discard(ev); 190 } 191 } 192 return (err); 193 } 194 195 void 196 env_discard(struct env_var *ev) 197 { 198 if (ev->ev_prev) 199 ev->ev_prev->ev_next = ev->ev_next; 200 if (ev->ev_next) 201 ev->ev_next->ev_prev = ev->ev_prev; 202 if (environ == ev) 203 environ = ev->ev_next; 204 free(ev->ev_name); 205 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 206 free(ev->ev_value); 207 free(ev); 208 } 209 210 int 211 env_noset(struct env_var *ev __unused, int flags __unused, 212 const void *value __unused) 213 { 214 return (EPERM); 215 } 216 217 int 218 env_nounset(struct env_var *ev __unused) 219 { 220 return (EPERM); 221 } 222