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
37struct env_var	*environ = NULL;
38
39/*
40 * Look up (name) and return it's env_var structure.
41 */
42struct env_var	*
43env_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 */
61int
62env_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 there's a set hook, let it do the work
70		 * (unless we are working for one already).
71		 */
72		if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK))
73			return (ev->ev_sethook(ev, flags, value));
74
75		/* If there is data in the variable, discard it. */
76		if (ev->ev_value != NULL && (ev->ev_flags & EV_DYNAMIC) != 0)
77			free(ev->ev_value);
78		ev->ev_value = NULL;
79		ev->ev_flags &= ~EV_DYNAMIC;
80
81	} else {
82
83		/*
84		 * New variable; create and sort into list
85		 */
86		ev = malloc(sizeof(struct env_var));
87		ev->ev_name = strdup(name);
88		ev->ev_value = NULL;
89		ev->ev_flags = 0;
90		/* hooks can only be set when the variable is instantiated */
91		ev->ev_sethook = sethook;
92		ev->ev_unsethook = unsethook;
93
94		/* Sort into list */
95		ev->ev_prev = NULL;
96		ev->ev_next = NULL;
97		/* Search for the record to insert before */
98		for (last = NULL, curr = environ; curr != NULL;
99		    last = curr, curr = curr->ev_next) {
100
101			if (strcmp(ev->ev_name, curr->ev_name) < 0) {
102				if (curr->ev_prev) {
103					curr->ev_prev->ev_next = ev;
104				} else {
105					environ = ev;
106				}
107				ev->ev_next = curr;
108				ev->ev_prev = curr->ev_prev;
109				curr->ev_prev = ev;
110				break;
111			}
112		}
113		if (curr == NULL) {
114			if (last == NULL) {
115				environ = ev;
116			} else {
117				last->ev_next = ev;
118				ev->ev_prev = last;
119			}
120		}
121	}
122
123	/* If we have a new value, use it */
124	if (flags & EV_VOLATILE) {
125		ev->ev_value = strdup(value);
126		ev->ev_flags |= EV_DYNAMIC;
127	} else {
128		ev->ev_value = (char *)value;
129		ev->ev_flags |= flags & EV_DYNAMIC;
130	}
131
132	return (0);
133}
134
135/* coverity[ -tainted_string_return_content ] */
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(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