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 /* 28 * Manage an environment-like space in which string variables may be stored. 29 * Provide support for some method-like operations for setting/retrieving 30 * variables in order to allow some type strength. 31 */ 32 33 #include "stand.h" 34 35 #include <string.h> 36 37 struct env_var *environ = NULL; 38 39 /* 40 * Look up (name) and return it's env_var structure. 41 */ 42 struct env_var * 43 env_getenv(const char *name) 44 { 45 struct env_var *ev; 46 47 for (ev = environ; ev != NULL; ev = ev->ev_next) 48 if (!strcmp(ev->ev_name, name)) 49 break; 50 return (ev); 51 } 52 53 /* 54 * Some notes: 55 * 56 * If the EV_VOLATILE flag is set, a copy of the variable is made. 57 * If EV_DYNAMIC is set, the variable has been allocated with 58 * malloc and ownership transferred to the environment. 59 * If (value) is NULL, the variable is set but has no value. 60 */ 61 int 62 env_setenv(const char *name, int flags, const void *value, 63 ev_sethook_t sethook, ev_unsethook_t unsethook) 64 { 65 struct env_var *ev, *curr, *last; 66 67 if ((ev = env_getenv(name)) != NULL) { 68 /* 69 * If the new value doesn't have NOKENV set, we'll drop the flag 70 * if it's set on the entry so that the override propagates 71 * correctly. We do this *before* sending it to the hook in 72 * case the hook declines to operate on it (e.g., because the 73 * value matches what was already set) -- we would still want 74 * the explicitly set value to propagate. 75 */ 76 if (!(flags & EV_NOKENV)) 77 ev->ev_flags &= ~EV_NOKENV; 78 79 /* 80 * If there's a set hook, let it do the work 81 * (unless we are working for one already). 82 */ 83 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 84 return (ev->ev_sethook(ev, flags, value)); 85 86 /* If there is data in the variable, discard it. */ 87 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 88 free(ev->ev_value); 89 ev->ev_value = NULL; 90 ev->ev_flags &= ~EV_DYNAMIC; 91 } else { 92 93 /* 94 * New variable; create and sort into list 95 */ 96 ev = malloc(sizeof(struct env_var)); 97 ev->ev_name = strdup(name); 98 ev->ev_value = NULL; 99 ev->ev_flags = 0; 100 /* hooks can only be set when the variable is instantiated */ 101 ev->ev_sethook = sethook; 102 ev->ev_unsethook = unsethook; 103 104 /* Sort into list */ 105 ev->ev_prev = NULL; 106 ev->ev_next = NULL; 107 /* Search for the record to insert before */ 108 for (last = NULL, curr = environ; curr != NULL; 109 last = curr, curr = curr->ev_next) { 110 111 if (strcmp(ev->ev_name, curr->ev_name) < 0) { 112 if (curr->ev_prev) { 113 curr->ev_prev->ev_next = ev; 114 } else { 115 environ = ev; 116 } 117 ev->ev_next = curr; 118 ev->ev_prev = curr->ev_prev; 119 curr->ev_prev = ev; 120 break; 121 } 122 } 123 if (curr == NULL) { 124 if (last == NULL) { 125 environ = ev; 126 } else { 127 last->ev_next = ev; 128 ev->ev_prev = last; 129 } 130 } 131 } 132 133 /* If we have a new value, use it */ 134 if (flags & EV_VOLATILE) { 135 ev->ev_value = strdup(value); 136 flags |= EV_DYNAMIC; 137 } else { 138 ev->ev_value = (char *)value; 139 } 140 141 ev->ev_flags |= flags & (EV_DYNAMIC | EV_NOKENV); 142 143 return (0); 144 } 145 146 /* coverity[ -tainted_string_return_content ] */ 147 char * 148 getenv(const char *name) 149 { 150 struct env_var *ev; 151 152 /* Set but no value gives empty string */ 153 if ((ev = env_getenv(name)) != NULL) { 154 if (ev->ev_value != NULL) 155 return (ev->ev_value); 156 return (""); 157 } 158 return (NULL); 159 } 160 161 int 162 setenv(const char *name, const char *value, int overwrite) 163 { 164 /* No guarantees about state, always assume volatile */ 165 if (overwrite || (env_getenv(name) == NULL)) 166 return (env_setenv(name, EV_VOLATILE, value, NULL, NULL)); 167 return (0); 168 } 169 170 int 171 putenv(char *string) 172 { 173 char *value, *copy; 174 int result; 175 176 copy = strdup(string); 177 if ((value = strchr(copy, '=')) != NULL) 178 *(value++) = 0; 179 result = setenv(copy, value, 1); 180 free(copy); 181 return (result); 182 } 183 184 int 185 unsetenv(const char *name) 186 { 187 struct env_var *ev; 188 int err; 189 190 err = 0; 191 if ((ev = env_getenv(name)) == NULL) { 192 err = ENOENT; 193 } else { 194 if (ev->ev_unsethook != NULL) 195 err = ev->ev_unsethook(ev); 196 if (err == 0) { 197 env_discard(ev); 198 } 199 } 200 return (err); 201 } 202 203 void 204 env_discard(struct env_var *ev) 205 { 206 if (ev->ev_prev) 207 ev->ev_prev->ev_next = ev->ev_next; 208 if (ev->ev_next) 209 ev->ev_next->ev_prev = ev->ev_prev; 210 if (environ == ev) 211 environ = ev->ev_next; 212 free(ev->ev_name); 213 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0) 214 free(ev->ev_value); 215 free(ev); 216 } 217 218 int 219 env_noset(struct env_var *ev __unused, int flags __unused, 220 const void *value __unused) 221 { 222 return (EPERM); 223 } 224 225 int 226 env_nounset(struct env_var *ev __unused) 227 { 228 return (EPERM); 229 } 230