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 * $FreeBSD: src/lib/libstand/environment.c,v 1.3.2.1 2000/09/10 01:24:16 ps Exp $ 27 * $DragonFly: src/lib/libstand/environment.c,v 1.2 2003/06/17 04:26:51 dillon Exp $ 28 * 29 */ 30 31 /* 32 * Manage an environment-like space in which string variables may be stored. 33 * Provide support for some method-like operations for setting/retrieving 34 * variables in order to allow some type strength. 35 */ 36 37 #include "stand.h" 38 39 #include <string.h> 40 41 static void env_discard(struct env_var *ev); 42 43 struct env_var *environ = NULL; 44 45 /* 46 * Look up (name) and return it's env_var structure. 47 */ 48 struct env_var * 49 env_getenv(const char *name) 50 { 51 struct env_var *ev; 52 53 for (ev = environ; ev != NULL; ev = ev->ev_next) 54 if (!strcmp(ev->ev_name, name)) 55 break; 56 return(ev); 57 } 58 59 /* 60 * Some notes: 61 * 62 * If the EV_VOLATILE flag is set, a copy of the variable is made. 63 * If EV_DYNAMIC is set, the the variable has been allocated with 64 * malloc and ownership transferred to the environment. 65 * If (value) is NULL, the variable is set but has no value. 66 */ 67 int 68 env_setenv(const char *name, int flags, const void *value, 69 ev_sethook_t sethook, ev_unsethook_t unsethook) 70 { 71 struct env_var *ev, *curr, *last; 72 73 if ((ev = env_getenv(name)) != NULL) { 74 /* 75 * If there's a set hook, let it do the work (unless we are working 76 * for one already. 77 */ 78 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 79 return(ev->ev_sethook(ev, flags, value)); 80 } else { 81 82 /* 83 * New variable; create and sort into list 84 */ 85 ev = malloc(sizeof(struct env_var)); 86 ev->ev_name = strdup(name); 87 ev->ev_value = NULL; 88 /* hooks can only be set when the variable is instantiated */ 89 ev->ev_sethook = sethook; 90 ev->ev_unsethook = unsethook; 91 92 /* Sort into list */ 93 ev->ev_prev = NULL; 94 ev->ev_next = NULL; 95 /* Search for the record to insert before */ 96 for (last = NULL, curr = environ; 97 curr != NULL; 98 last = curr, curr = curr->ev_next) { 99 100 if (strcmp(ev->ev_name, curr->ev_name) < 0) { 101 if (curr->ev_prev) { 102 curr->ev_prev->ev_next = ev; 103 } else { 104 environ = ev; 105 } 106 ev->ev_next = curr; 107 ev->ev_prev = curr->ev_prev; 108 curr->ev_prev = ev; 109 break; 110 } 111 } 112 if (curr == NULL) { 113 if (last == NULL) { 114 environ = ev; 115 } else { 116 last->ev_next = ev; 117 ev->ev_prev = last; 118 } 119 } 120 } 121 122 /* If there is data in the variable, discard it */ 123 if (ev->ev_value != NULL) 124 free(ev->ev_value); 125 126 /* If we have a new value, use it */ 127 if (flags & EV_VOLATILE) { 128 ev->ev_value = strdup(value); 129 } else { 130 ev->ev_value = (char *)value; 131 } 132 133 /* Keep the flag components that are relevant */ 134 ev->ev_flags = flags & (EV_DYNAMIC); 135 136 return(0); 137 } 138 139 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(const 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 static 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_flags & EV_DYNAMIC) 206 free(ev->ev_value); 207 free(ev); 208 } 209 210 int 211 env_noset(struct env_var *ev, int flags, const void *value) 212 { 213 return(EPERM); 214 } 215 216 int 217 env_nounset(struct env_var *ev) 218 { 219 return(EPERM); 220 } 221