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 static void env_discard(struct env_var *ev); 41 42 struct env_var *environ = NULL; 43 44 /* 45 * Look up (name) and return it's env_var structure. 46 */ 47 struct env_var * 48 env_getenv(const char *name) 49 { 50 struct env_var *ev; 51 52 for (ev = environ; ev != NULL; ev = ev->ev_next) 53 if (!strcmp(ev->ev_name, name)) 54 break; 55 return(ev); 56 } 57 58 /* 59 * Some notes: 60 * 61 * If the EV_VOLATILE flag is set, a copy of the variable is made. 62 * If EV_DYNAMIC is set, the variable has been allocated with 63 * malloc and ownership transferred to the environment. 64 * If (value) is NULL, the variable is set but has no value. 65 */ 66 int 67 env_setenv(const char *name, int flags, const void *value, 68 ev_sethook_t sethook, ev_unsethook_t unsethook) 69 { 70 struct env_var *ev, *curr, *last; 71 72 if ((ev = env_getenv(name)) != NULL) { 73 /* 74 * If there's a set hook, let it do the work (unless we are working 75 * for one already. 76 */ 77 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 78 return (ev->ev_sethook(ev, flags, value)); 79 80 /* If there is data in the variable, discard it. */ 81 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 82 free(ev->ev_value); 83 ev->ev_value = NULL; 84 ev->ev_flags &= ~EV_DYNAMIC; 85 86 } else { 87 88 /* 89 * New variable; create and sort into list 90 */ 91 ev = malloc(sizeof(struct env_var)); 92 ev->ev_name = strdup(name); 93 ev->ev_value = NULL; 94 ev->ev_flags = 0; 95 /* hooks can only be set when the variable is instantiated */ 96 ev->ev_sethook = sethook; 97 ev->ev_unsethook = unsethook; 98 99 /* Sort into list */ 100 ev->ev_prev = NULL; 101 ev->ev_next = NULL; 102 /* Search for the record to insert before */ 103 for (last = NULL, curr = environ; 104 curr != NULL; 105 last = curr, curr = curr->ev_next) { 106 107 if (strcmp(ev->ev_name, curr->ev_name) < 0) { 108 if (curr->ev_prev) { 109 curr->ev_prev->ev_next = ev; 110 } else { 111 environ = ev; 112 } 113 ev->ev_next = curr; 114 ev->ev_prev = curr->ev_prev; 115 curr->ev_prev = ev; 116 break; 117 } 118 } 119 if (curr == NULL) { 120 if (last == NULL) { 121 environ = ev; 122 } else { 123 last->ev_next = ev; 124 ev->ev_prev = last; 125 } 126 } 127 } 128 129 /* If we have a new value, use it */ 130 if (flags & EV_VOLATILE) { 131 ev->ev_value = strdup(value); 132 ev->ev_flags |= EV_DYNAMIC; 133 } else { 134 ev->ev_value = (char *)value; 135 ev->ev_flags |= flags & EV_DYNAMIC; 136 } 137 138 return(0); 139 } 140 141 char * 142 getenv(const char *name) 143 { 144 struct env_var *ev; 145 146 /* Set but no value gives empty string */ 147 if ((ev = env_getenv(name)) != NULL) { 148 if (ev->ev_value != NULL) 149 return(ev->ev_value); 150 return(""); 151 } 152 return(NULL); 153 } 154 155 int 156 setenv(const char *name, const char *value, int overwrite) 157 { 158 /* No guarantees about state, always assume volatile */ 159 if (overwrite || (env_getenv(name) == NULL)) 160 return(env_setenv(name, EV_VOLATILE, value, NULL, NULL)); 161 return(0); 162 } 163 164 int 165 putenv(const char *string) 166 { 167 char *value, *copy; 168 int result; 169 170 copy = strdup(string); 171 if ((value = strchr(copy, '=')) != NULL) 172 *(value++) = 0; 173 result = setenv(copy, value, 1); 174 free(copy); 175 return(result); 176 } 177 178 int 179 unsetenv(const char *name) 180 { 181 struct env_var *ev; 182 int err; 183 184 err = 0; 185 if ((ev = env_getenv(name)) == NULL) { 186 err = ENOENT; 187 } else { 188 if (ev->ev_unsethook != NULL) 189 err = ev->ev_unsethook(ev); 190 if (err == 0) { 191 env_discard(ev); 192 } 193 } 194 return(err); 195 } 196 197 static void 198 env_discard(struct env_var *ev) 199 { 200 if (ev->ev_prev) 201 ev->ev_prev->ev_next = ev->ev_next; 202 if (ev->ev_next) 203 ev->ev_next->ev_prev = ev->ev_prev; 204 if (environ == ev) 205 environ = ev->ev_next; 206 free(ev->ev_name); 207 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 208 free(ev->ev_value); 209 free(ev); 210 } 211 212 int 213 env_noset(struct env_var *ev __unused, int flags __unused, 214 const void *value __unused) 215 { 216 return(EPERM); 217 } 218 219 int 220 env_nounset(struct env_var *ev __unused) 221 { 222 return(EPERM); 223 } 224