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
29 /*
30 * Manage an environment-like space in which string variables may be stored.
31 * Provide support for some method-like operations for setting/retrieving
32 * variables in order to allow some type strength.
33 */
34
35 #include "stand.h"
36
37 #include <string.h>
38
39 struct env_var *environ = NULL;
40
41 /*
42 * Look up (name) and return it's env_var structure.
43 */
44 struct env_var *
env_getenv(const char * name)45 env_getenv(const char *name)
46 {
47 struct env_var *ev;
48
49 for (ev = environ; ev != NULL; ev = ev->ev_next)
50 if (strcmp(ev->ev_name, name) == 0)
51 break;
52 return (ev);
53 }
54
55 /*
56 * Some notes:
57 *
58 * If the EV_VOLATILE flag is set, a copy of the variable is made.
59 * If EV_DYNAMIC is set, the variable has been allocated with
60 * malloc and ownership transferred to the environment.
61 * If (value) is NULL, the variable is set but has no value.
62 */
63 int
env_setenv(const char * name,int flags,const void * value,ev_sethook_t sethook,ev_unsethook_t unsethook)64 env_setenv(const char *name, int flags, const void *value,
65 ev_sethook_t sethook, ev_unsethook_t unsethook)
66 {
67 struct env_var *ev, *curr, *last;
68
69 if ((ev = env_getenv(name)) != NULL) {
70 /*
71 * If there's a set hook, let it do the work
72 * (unless we are working for one already).
73 */
74 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK))
75 return (ev->ev_sethook(ev, flags, value));
76
77 /* If there is data in the variable, discard it. */
78 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0)
79 free(ev->ev_value);
80 ev->ev_value = NULL;
81 ev->ev_flags &= ~EV_DYNAMIC;
82
83 } else {
84 /*
85 * New variable; create and sort into list
86 */
87 ev = malloc(sizeof (struct env_var));
88 ev->ev_name = strdup(name);
89 ev->ev_value = NULL;
90 ev->ev_flags = 0;
91 /* hooks can only be set when the variable is instantiated */
92 ev->ev_sethook = sethook;
93 ev->ev_unsethook = unsethook;
94
95 /* Sort into list */
96 ev->ev_prev = NULL;
97 ev->ev_next = NULL;
98 /* Search for the record to insert before */
99 for (last = NULL, curr = environ; 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 we have a new value, use it */
125 if (flags & EV_VOLATILE) {
126 ev->ev_value = strdup(value);
127 ev->ev_flags |= EV_DYNAMIC;
128 } else {
129 ev->ev_value = (char *)value;
130 ev->ev_flags |= flags & EV_DYNAMIC;
131 }
132
133 return (0);
134 }
135
136 char *
getenv(const char * name)137 getenv(const char *name)
138 {
139 struct env_var *ev;
140
141 /* Set but no value gives empty string */
142 if ((ev = env_getenv(name)) != NULL) {
143 if (ev->ev_value != NULL)
144 return (ev->ev_value);
145 return ("");
146 }
147 return (NULL);
148 }
149
150 int
setenv(const char * name,const char * value,int overwrite)151 setenv(const char *name, const char *value, int overwrite)
152 {
153 /* No guarantees about state, always assume volatile */
154 if (overwrite || (env_getenv(name) == NULL))
155 return (env_setenv(name, EV_VOLATILE, value, NULL, NULL));
156 return (0);
157 }
158
159 int
putenv(const char * string)160 putenv(const char *string)
161 {
162 char *value, *copy;
163 int result;
164
165 copy = strdup(string);
166 if ((value = strchr(copy, '=')) != NULL)
167 *(value++) = 0;
168 result = setenv(copy, value, 1);
169 free(copy);
170 return (result);
171 }
172
173 int
unsetenv(const char * name)174 unsetenv(const char *name)
175 {
176 struct env_var *ev;
177 int err;
178
179 err = 0;
180 if ((ev = env_getenv(name)) == NULL) {
181 err = ENOENT;
182 } else {
183 if (ev->ev_unsethook != NULL)
184 err = ev->ev_unsethook(ev);
185 if (err == 0) {
186 env_discard(ev);
187 }
188 }
189 return (err);
190 }
191
192 void
env_discard(struct env_var * ev)193 env_discard(struct env_var *ev)
194 {
195 if (ev->ev_prev)
196 ev->ev_prev->ev_next = ev->ev_next;
197 if (ev->ev_next)
198 ev->ev_next->ev_prev = ev->ev_prev;
199 if (environ == ev)
200 environ = ev->ev_next;
201 free(ev->ev_name);
202 if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0)
203 free(ev->ev_value);
204 free(ev);
205 }
206
207 int
env_noset(struct env_var * ev __unused,int flags __unused,const void * value __unused)208 env_noset(struct env_var *ev __unused, int flags __unused,
209 const void *value __unused)
210 {
211 return (EPERM);
212 }
213
214 int
env_nounset(struct env_var * ev __unused)215 env_nounset(struct env_var *ev __unused)
216 {
217 return (EPERM);
218 }
219