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 *
env_getenv(const char * name)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
env_setenv(const char * name,int flags,const void * value,ev_sethook_t sethook,ev_unsethook_t unsethook)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 } else {
80
81 /*
82 * New variable; create and sort into list
83 */
84 ev = malloc(sizeof(struct env_var));
85 ev->ev_name = strdup(name);
86 ev->ev_value = NULL;
87 /* hooks can only be set when the variable is instantiated */
88 ev->ev_sethook = sethook;
89 ev->ev_unsethook = unsethook;
90
91 /* Sort into list */
92 ev->ev_prev = NULL;
93 ev->ev_next = NULL;
94 /* Search for the record to insert before */
95 for (last = NULL, curr = environ;
96 curr != NULL;
97 last = curr, curr = curr->ev_next) {
98
99 if (strcmp(ev->ev_name, curr->ev_name) < 0) {
100 if (curr->ev_prev) {
101 curr->ev_prev->ev_next = ev;
102 } else {
103 environ = ev;
104 }
105 ev->ev_next = curr;
106 ev->ev_prev = curr->ev_prev;
107 curr->ev_prev = ev;
108 break;
109 }
110 }
111 if (curr == NULL) {
112 if (last == NULL) {
113 environ = ev;
114 } else {
115 last->ev_next = ev;
116 ev->ev_prev = last;
117 }
118 }
119 }
120
121 /* If there is data in the variable, discard it */
122 if (ev->ev_value != NULL)
123 free(ev->ev_value);
124
125 /* If we have a new value, use it */
126 if (flags & EV_VOLATILE) {
127 ev->ev_value = strdup(value);
128 } else {
129 ev->ev_value = (char *)value;
130 }
131
132 /* Keep the flag components that are relevant */
133 ev->ev_flags = flags & (EV_DYNAMIC);
134
135 return(0);
136 }
137
138 char *
getenv(const char * name)139 getenv(const char *name)
140 {
141 struct env_var *ev;
142
143 /* Set but no value gives empty string */
144 if ((ev = env_getenv(name)) != NULL) {
145 if (ev->ev_value != NULL)
146 return(ev->ev_value);
147 return("");
148 }
149 return(NULL);
150 }
151
152 int
setenv(const char * name,const char * value,int overwrite)153 setenv(const char *name, const char *value, int overwrite)
154 {
155 /* No guarantees about state, always assume volatile */
156 if (overwrite || (env_getenv(name) == NULL))
157 return(env_setenv(name, EV_VOLATILE, value, NULL, NULL));
158 return(0);
159 }
160
161 int
putenv(const char * string)162 putenv(const char *string)
163 {
164 char *value, *copy;
165 int result;
166
167 copy = strdup(string);
168 if ((value = strchr(copy, '=')) != NULL)
169 *(value++) = 0;
170 result = setenv(copy, value, 1);
171 free(copy);
172 return(result);
173 }
174
175 int
unsetenv(const char * name)176 unsetenv(const char *name)
177 {
178 struct env_var *ev;
179 int err;
180
181 err = 0;
182 if ((ev = env_getenv(name)) == NULL) {
183 err = ENOENT;
184 } else {
185 if (ev->ev_unsethook != NULL)
186 err = ev->ev_unsethook(ev);
187 if (err == 0) {
188 env_discard(ev);
189 }
190 }
191 return(err);
192 }
193
194 static void
env_discard(struct env_var * ev)195 env_discard(struct env_var *ev)
196 {
197 if (ev->ev_prev)
198 ev->ev_prev->ev_next = ev->ev_next;
199 if (ev->ev_next)
200 ev->ev_next->ev_prev = ev->ev_prev;
201 if (environ == ev)
202 environ = ev->ev_next;
203 free(ev->ev_name);
204 if (ev->ev_flags & EV_DYNAMIC)
205 free(ev->ev_value);
206 free(ev);
207 }
208
209 int
env_noset(struct env_var * ev __unused,int flags __unused,const void * value __unused)210 env_noset(struct env_var *ev __unused, int flags __unused,
211 const void *value __unused)
212 {
213 return(EPERM);
214 }
215
216 int
env_nounset(struct env_var * ev __unused)217 env_nounset(struct env_var *ev __unused)
218 {
219 return(EPERM);
220 }
221