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 /* 30 * Manage an environment-like space in which string variables may be stored. 31 * Provide support for some method-like operations for setting/retrieving 32 * variables in order to allow some type strength. 33 */ 34 35 #include "stand.h" 36 37 #include <string.h> 38 39 struct env_var *environ = NULL; 40 41 /* 42 * Look up (name) and return it's env_var structure. 43 */ 44 struct env_var * 45 env_getenv(const char *name) 46 { 47 struct env_var *ev; 48 49 for (ev = environ; ev != NULL; ev = ev->ev_next) 50 if (strcmp(ev->ev_name, name) == 0) 51 break; 52 return (ev); 53 } 54 55 /* 56 * Some notes: 57 * 58 * If the EV_VOLATILE flag is set, a copy of the variable is made. 59 * If EV_DYNAMIC is set, the variable has been allocated with 60 * malloc and ownership transferred to the environment. 61 * If (value) is NULL, the variable is set but has no value. 62 */ 63 int 64 env_setenv(const char *name, int flags, const void *value, 65 ev_sethook_t sethook, ev_unsethook_t unsethook) 66 { 67 struct env_var *ev, *curr, *last; 68 69 if ((ev = env_getenv(name)) != NULL) { 70 /* 71 * If there's a set hook, let it do the work 72 * (unless we are working for one already). 73 */ 74 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 75 return (ev->ev_sethook(ev, flags, value)); 76 77 /* If there is data in the variable, discard it. */ 78 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 79 free(ev->ev_value); 80 ev->ev_value = NULL; 81 ev->ev_flags &= ~EV_DYNAMIC; 82 83 } else { 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 char * 137 getenv(const char *name) 138 { 139 struct env_var *ev; 140 141 /* Set but no value gives empty string */ 142 if ((ev = env_getenv(name)) != NULL) { 143 if (ev->ev_value != NULL) 144 return (ev->ev_value); 145 return (""); 146 } 147 return (NULL); 148 } 149 150 int 151 setenv(const char *name, const char *value, int overwrite) 152 { 153 /* No guarantees about state, always assume volatile */ 154 if (overwrite || (env_getenv(name) == NULL)) 155 return (env_setenv(name, EV_VOLATILE, value, NULL, NULL)); 156 return (0); 157 } 158 159 int 160 putenv(const char *string) 161 { 162 char *value, *copy; 163 int result; 164 165 copy = strdup(string); 166 if ((value = strchr(copy, '=')) != NULL) 167 *(value++) = 0; 168 result = setenv(copy, value, 1); 169 free(copy); 170 return (result); 171 } 172 173 int 174 unsetenv(const char *name) 175 { 176 struct env_var *ev; 177 int err; 178 179 err = 0; 180 if ((ev = env_getenv(name)) == NULL) { 181 err = ENOENT; 182 } else { 183 if (ev->ev_unsethook != NULL) 184 err = ev->ev_unsethook(ev); 185 if (err == 0) { 186 env_discard(ev); 187 } 188 } 189 return (err); 190 } 191 192 void 193 env_discard(struct env_var *ev) 194 { 195 if (ev->ev_prev) 196 ev->ev_prev->ev_next = ev->ev_next; 197 if (ev->ev_next) 198 ev->ev_next->ev_prev = ev->ev_prev; 199 if (environ == ev) 200 environ = ev->ev_next; 201 free(ev->ev_name); 202 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 203 free(ev->ev_value); 204 free(ev); 205 } 206 207 int 208 env_noset(struct env_var *ev __unused, int flags __unused, 209 const void *value __unused) 210 { 211 return (EPERM); 212 } 213 214 int 215 env_nounset(struct env_var *ev __unused) 216 { 217 return (EPERM); 218 } 219