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 *
env_getenv(const char * name)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
env_setenv(const char * name,int flags,const void * value,ev_sethook_t sethook,ev_unsethook_t unsethook)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 *
getenv(const char * name)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
setenv(const char * name,const char * value,int overwrite)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
putenv(char * string)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
unsetenv(const char * name)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
env_discard(struct env_var * ev)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
env_noset(struct env_var * ev __unused,int flags __unused,const void * value __unused)219 env_noset(struct env_var *ev __unused, int flags __unused,
220 const void *value __unused)
221 {
222 return (EPERM);
223 }
224
225 int
env_nounset(struct env_var * ev __unused)226 env_nounset(struct env_var *ev __unused)
227 {
228 return (EPERM);
229 }
230