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 *
env_getenv(const char * name)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
env_setenv(const char * name,int flags,const void * value,ev_sethook_t sethook,ev_unsethook_t unsethook)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 *
getenv(const char * name)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
setenv(const char * name,const char * value,int overwrite)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
putenv(const char * string)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
unsetenv(const char * name)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
env_discard(struct env_var * ev)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
env_noset(struct env_var * ev,int flags,const void * value)211 env_noset(struct env_var *ev, int flags, const void *value)
212 {
213 return(EPERM);
214 }
215
216 int
env_nounset(struct env_var * ev)217 env_nounset(struct env_var *ev)
218 {
219 return(EPERM);
220 }
221