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 /* 29 * Manage an environment-like space in which string variables may be stored. 30 * Provide support for some method-like operations for setting/retrieving 31 * variables in order to allow some type strength. 32 */ 33 34 #include "stand.h" 35 36 #include <string.h> 37 38 struct env_var *environ = NULL; 39 40 /* 41 * Look up (name) and return it's env_var structure. 42 */ 43 struct env_var * 44 env_getenv(const char *name) 45 { 46 struct env_var *ev; 47 48 for (ev = environ; ev != NULL; ev = ev->ev_next) 49 if (!strcmp(ev->ev_name, name)) 50 break; 51 return (ev); 52 } 53 54 /* 55 * Some notes: 56 * 57 * If the EV_VOLATILE flag is set, a copy of the variable is made. 58 * If EV_DYNAMIC is set, the variable has been allocated with 59 * malloc and ownership transferred to the environment. 60 * If (value) is NULL, the variable is set but has no value. 61 */ 62 int 63 env_setenv(const char *name, int flags, const void *value, 64 ev_sethook_t sethook, ev_unsethook_t unsethook) 65 { 66 struct env_var *ev, *curr, *last; 67 68 if ((ev = env_getenv(name)) != NULL) { 69 /* 70 * If there's a set hook, let it do the work 71 * (unless we are working for one already). 72 */ 73 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 74 return (ev->ev_sethook(ev, flags, value)); 75 76 /* If there is data in the variable, discard it. */ 77 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 78 free(ev->ev_value); 79 ev->ev_value = NULL; 80 ev->ev_flags &= ~EV_DYNAMIC; 81 82 } else { 83 84 /* 85 * New variable; create and sort into list 86 */ 87 ev = malloc(sizeof(struct env_var)); 88 ev->ev_name = strdup(name); 89 ev->ev_value = NULL; 90 ev->ev_flags = 0; 91 /* hooks can only be set when the variable is instantiated */ 92 ev->ev_sethook = sethook; 93 ev->ev_unsethook = unsethook; 94 95 /* Sort into list */ 96 ev->ev_prev = NULL; 97 ev->ev_next = NULL; 98 /* Search for the record to insert before */ 99 for (last = NULL, curr = environ; curr != NULL; 100 last = curr, curr = curr->ev_next) { 101 102 if (strcmp(ev->ev_name, curr->ev_name) < 0) { 103 if (curr->ev_prev) { 104 curr->ev_prev->ev_next = ev; 105 } else { 106 environ = ev; 107 } 108 ev->ev_next = curr; 109 ev->ev_prev = curr->ev_prev; 110 curr->ev_prev = ev; 111 break; 112 } 113 } 114 if (curr == NULL) { 115 if (last == NULL) { 116 environ = ev; 117 } else { 118 last->ev_next = ev; 119 ev->ev_prev = last; 120 } 121 } 122 } 123 124 /* If we have a new value, use it */ 125 if (flags & EV_VOLATILE) { 126 ev->ev_value = strdup(value); 127 ev->ev_flags |= EV_DYNAMIC; 128 } else { 129 ev->ev_value = (char *)value; 130 ev->ev_flags |= flags & EV_DYNAMIC; 131 } 132 133 return (0); 134 } 135 136 /* coverity[ -tainted_string_return_content ] */ 137 char * 138 getenv(const char *name) 139 { 140 struct env_var *ev; 141 142 /* Set but no value gives empty string */ 143 if ((ev = env_getenv(name)) != NULL) { 144 if (ev->ev_value != NULL) 145 return (ev->ev_value); 146 return (""); 147 } 148 return (NULL); 149 } 150 151 int 152 setenv(const char *name, const char *value, int overwrite) 153 { 154 /* No guarantees about state, always assume volatile */ 155 if (overwrite || (env_getenv(name) == NULL)) 156 return (env_setenv(name, EV_VOLATILE, value, NULL, NULL)); 157 return (0); 158 } 159 160 int 161 putenv(char *string) 162 { 163 char *value, *copy; 164 int result; 165 166 copy = strdup(string); 167 if ((value = strchr(copy, '=')) != NULL) 168 *(value++) = 0; 169 result = setenv(copy, value, 1); 170 free(copy); 171 return (result); 172 } 173 174 int 175 unsetenv(const char *name) 176 { 177 struct env_var *ev; 178 int err; 179 180 err = 0; 181 if ((ev = env_getenv(name)) == NULL) { 182 err = ENOENT; 183 } else { 184 if (ev->ev_unsethook != NULL) 185 err = ev->ev_unsethook(ev); 186 if (err == 0) { 187 env_discard(ev); 188 } 189 } 190 return (err); 191 } 192 193 void 194 env_discard(struct env_var *ev) 195 { 196 if (ev->ev_prev) 197 ev->ev_prev->ev_next = ev->ev_next; 198 if (ev->ev_next) 199 ev->ev_next->ev_prev = ev->ev_prev; 200 if (environ == ev) 201 environ = ev->ev_next; 202 free(ev->ev_name); 203 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 204 free(ev->ev_value); 205 free(ev); 206 } 207 208 int 209 env_noset(struct env_var *ev __unused, int flags __unused, 210 const void *value __unused) 211 { 212 return (EPERM); 213 } 214 215 int 216 env_nounset(struct env_var *ev __unused) 217 { 218 return (EPERM); 219 } 220