1 /* $NetBSD: environment.c,v 1.1 2006/04/07 14:21:29 cherry Exp $ */ 2 3 4 /* 5 * Copyright (c) 1998 Michael Smith. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 32 /* 33 * Manage an environment-like space in which string variables may be stored. 34 * Provide support for some method-like operations for setting/retrieving 35 * variables in order to allow some type strength. 36 */ 37 38 #include <lib/libsa/stand.h> 39 #include <lib/libkern/libkern.h> 40 41 #include <bootstrap.h> 42 43 static void env_discard(struct env_var *ev); 44 45 struct env_var *environ = NULL; 46 47 /* 48 * Look up (name) and return it's env_var structure. 49 */ 50 struct env_var * 51 env_getenv(const char *name) 52 { 53 struct env_var *ev; 54 55 for (ev = environ; ev != NULL; ev = ev->ev_next) 56 if (!strcmp(ev->ev_name, name)) 57 break; 58 return(ev); 59 } 60 61 /* 62 * Some notes: 63 * 64 * If the EV_VOLATILE flag is set, a copy of the variable is made. 65 * If EV_DYNAMIC is set, the the variable has been allocated with 66 * malloc and ownership transferred to the environment. 67 * If (value) is NULL, the variable is set but has no value. 68 */ 69 int 70 env_setenv(const char *name, int flags, const void *value, 71 ev_sethook_t sethook, ev_unsethook_t unsethook) 72 { 73 struct env_var *ev, *curr, *last; 74 75 if ((ev = env_getenv(name)) != NULL) { 76 /* 77 * If there's a set hook, let it do the work (unless we are working 78 * for one already. 79 */ 80 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 81 return(ev->ev_sethook(ev, flags, value)); 82 } else { 83 84 /* 85 * New variable; create and sort into list 86 */ 87 ev = alloc(sizeof(struct env_var)); 88 ev->ev_name = strdup(name); 89 ev->ev_value = NULL; 90 /* hooks can only be set when the variable is instantiated */ 91 ev->ev_sethook = sethook; 92 ev->ev_unsethook = unsethook; 93 94 /* Sort into list */ 95 ev->ev_prev = NULL; 96 ev->ev_next = NULL; 97 /* Search for the record to insert before */ 98 for (last = NULL, curr = environ; 99 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 there is data in the variable, discard it */ 125 if (ev->ev_value != NULL) 126 free(ev->ev_value); 127 128 /* If we have a new value, use it */ 129 if (flags & EV_VOLATILE) { 130 ev->ev_value = strdup(value); 131 } else { 132 ev->ev_value = (void *) value; 133 } 134 135 /* Keep the flag components that are relevant */ 136 ev->ev_flags = flags & (EV_DYNAMIC); 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_flags & EV_DYNAMIC) 208 free(ev->ev_value); 209 free(ev); 210 } 211 212 int 213 env_noset(struct env_var *ev, int flags, const void *value) 214 { 215 return(EPERM); 216 } 217 218 int 219 env_nounset(struct env_var *ev) 220 { 221 return(EPERM); 222 } 223