summaryrefslogtreecommitdiffstats
path: root/lib/libstand/environment.c
blob: 1365a1c601d41074af2c96af1d966e2de434d39c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
/* 
 * Copyright (c) 1998 Michael Smith.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * Manage an environment-like space in which string variables may be stored.
 * Provide support for some method-like operations for setting/retrieving
 * variables in order to allow some type strength.
 */

#include "stand.h"

#include <string.h>

static void	env_discard(struct env_var *ev);

struct env_var	*environ = NULL;

/*
 * Look up (name) and return it's env_var structure.
 */
struct env_var	*
env_getenv(const char *name)
{
    struct env_var	*ev;
    
    for (ev = environ; ev != NULL; ev = ev->ev_next)
	if (!strcmp(ev->ev_name, name))
	    break;
    return(ev);
}

/*
 * Some notes:
 *
 * If the EV_VOLATILE flag is set, a copy of the variable is made.
 * If EV_DYNAMIC is set, the the variable has been allocated with
 * malloc and ownership transferred to the environment.
 * If (value) is NULL, the variable is set but has no value.
 */
int
env_setenv(const char *name, int flags, const void *value,
	   ev_sethook_t sethook, ev_unsethook_t unsethook)
{
    struct env_var	*ev, *curr, *last;

    if ((ev = env_getenv(name)) != NULL) {
	/*
	 * If there's a set hook, let it do the work (unless we are working
	 * for one already.
	 */
	if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK))
	    return(ev->ev_sethook(ev, flags, value));
    } else {

	/*
	 * New variable; create and sort into list
	 */
	ev = malloc(sizeof(struct env_var));
	ev->ev_name = strdup(name);
	ev->ev_value = NULL;
	/* hooks can only be set when the variable is instantiated */
	ev->ev_sethook = sethook;
	ev->ev_unsethook = unsethook;

	/* Sort into list */
	ev->ev_prev = NULL;
	ev->ev_next = NULL;
	/* Search for the record to insert before */
	for (last = NULL, curr = environ; 
	     curr != NULL; 
	     last = curr, curr = curr->ev_next) {

	    if (strcmp(ev->ev_name, curr->ev_name) < 0) {
		if (curr->ev_prev) {
		    curr->ev_prev->ev_next = ev;
		} else {
		    environ = ev;
		}
		ev->ev_next = curr;
		ev->ev_prev = curr->ev_prev;
		curr->ev_prev = ev;
		break;
	    }
	}
	if (curr == NULL) {
	    if (last == NULL) {
		environ = ev;
	    } else {
		last->ev_next = ev;
		ev->ev_prev = last;
	    }
	}
    }
    
    /* If there is data in the variable, discard it */
    if (ev->ev_value != NULL)
	free(ev->ev_value);

    /* If we have a new value, use it */
    if (flags & EV_VOLATILE) {
	ev->ev_value = strdup(value);
    } else {
	ev->ev_value = value;
    }

    /* Keep the flag components that are relevant */
    ev->ev_flags = flags & (EV_DYNAMIC);

    return(0);
}

char *
getenv(const char *name)
{
    struct env_var	*ev;

    /* Set but no value gives empty string */
    if ((ev = env_getenv(name)) != NULL) {
	if (ev->ev_value != NULL)
	    return(ev->ev_value);
	return("");
    }
    return(NULL);
}

int
setenv(const char *name, const char *value, int overwrite)
{
    /* No guarantees about state, always assume volatile */
    if (overwrite || (env_getenv(name) == NULL))
	return(env_setenv(name, EV_VOLATILE, value, NULL, NULL));
    return(0);
}

int
putenv(const char *string)
{
    char	*value, *copy;
    int		result;

    copy = strdup(string);
    if ((value = strchr(copy, '=')) != NULL)
	*(value++) = 0;
    result = setenv(copy, value, 1);
    free(copy);
    return(result);
}

int
unsetenv(const char *name)
{
    struct env_var	*ev;
    int			err;

    err = 0;
    if ((ev = env_getenv(name)) == NULL) {
	err = ENOENT;
    } else {
	if (ev->ev_unsethook != NULL)
	    err = ev->ev_unsethook(ev);
	if (err == 0) {
	    env_discard(ev);
	}
    }
    return(err);
}

static void
env_discard(struct env_var *ev)
{
    if (ev->ev_prev)
	ev->ev_prev->ev_next = ev->ev_next;
    if (ev->ev_next)
	ev->ev_next->ev_prev = ev->ev_prev;
    if (environ == ev)
	environ = ev->ev_next;
    free(ev->ev_name);
    if (ev->ev_flags & EV_DYNAMIC)
	free(ev->ev_value);
    free(ev);
}

int
env_noset(struct env_var *ev, int flags, void *value)
{
    return(EPERM);
}

int
env_nounset(struct env_var *ev)
{
    return(EPERM);
}
OpenPOWER on IntegriCloud