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
39struct env_var *environ = NULL;
40
41/*
42 * Look up (name) and return it's env_var structure.
43 */
44struct env_var	*
45env_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 */
63int
64env_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
136char *
137getenv(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
150int
151setenv(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
159int
160putenv(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
173int
174unsetenv(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
192void
193env_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
207int
208env_noset(struct env_var *ev __unused, int flags __unused,
209    const void *value __unused)
210{
211	return (EPERM);
212}
213
214int
215env_nounset(struct env_var *ev __unused)
216{
217	return (EPERM);
218}
219