1/*	$OpenBSD: setenv.c,v 1.14 2012/09/23 16:08:04 jeremy Exp $ */
2/*
3 * Copyright (c) 1987 Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <errno.h>
32#include <stdlib.h>
33#include <string.h>
34
35char *__findenv(const char *name, int len, int *offset);
36
37extern char **environ;
38static char **lastenv;				/* last value of environ */
39
40/*
41 * putenv --
42 *	Add a name=value string directly to the environmental, replacing
43 *	any current value.
44 */
45int
46putenv(char *str)
47{
48	char **P, *cp;
49	size_t cnt;
50	int offset = 0;
51
52	for (cp = str; *cp && *cp != '='; ++cp)
53		;
54	if (*cp != '=') {
55		errno = EINVAL;
56		return (-1);			/* missing `=' in string */
57	}
58
59	if (__findenv(str, (int)(cp - str), &offset) != NULL) {
60		environ[offset++] = str;
61		/* could be set multiple times */
62		while (__findenv(str, (int)(cp - str), &offset)) {
63			for (P = &environ[offset];; ++P)
64				if (!(*P = *(P + 1)))
65					break;
66		}
67		return (0);
68	}
69
70	/* create new slot for string */
71	for (P = environ; *P != NULL; P++)
72		;
73	cnt = P - environ;
74	P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
75	if (!P)
76		return (-1);
77	if (lastenv != environ)
78		memcpy(P, environ, cnt * sizeof(char *));
79	lastenv = environ = P;
80	environ[cnt] = str;
81	environ[cnt + 1] = NULL;
82	return (0);
83}
84
85/*
86 * setenv --
87 *	Set the value of the environmental variable "name" to be
88 *	"value".  If rewrite is set, replace any current value.
89 */
90int
91setenv(const char *name, const char *value, int rewrite)
92{
93	char *C, **P;
94	const char *np;
95	int l_value, offset = 0;
96
97	if (!name || !*name) {
98		errno = EINVAL;
99		return (-1);
100	}
101	for (np = name; *np && *np != '='; ++np)
102		;
103	if (*np) {
104		errno = EINVAL;
105		return (-1);			/* has `=' in name */
106	}
107
108	l_value = strlen(value);
109	if ((C = __findenv(name, (int)(np - name), &offset)) != NULL) {
110		int tmpoff = offset + 1;
111		if (!rewrite)
112			return (0);
113#if 0 /* XXX - existing entry may not be writable */
114		if (strlen(C) >= l_value) {	/* old larger; copy over */
115			while ((*C++ = *value++))
116				;
117			return (0);
118		}
119#endif
120		/* could be set multiple times */
121		while (__findenv(name, (int)(np - name), &tmpoff)) {
122			for (P = &environ[tmpoff];; ++P)
123				if (!(*P = *(P + 1)))
124					break;
125		}
126	} else {					/* create new slot */
127		size_t cnt;
128
129		for (P = environ; *P != NULL; P++)
130			;
131		cnt = P - environ;
132		P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
133		if (!P)
134			return (-1);
135		if (lastenv != environ)
136			memcpy(P, environ, cnt * sizeof(char *));
137		lastenv = environ = P;
138		offset = cnt;
139		environ[cnt + 1] = NULL;
140	}
141	if (!(environ[offset] =			/* name + `=' + value */
142	    malloc((size_t)((int)(np - name) + l_value + 2))))
143		return (-1);
144	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
145		;
146	for (*C++ = '='; (*C++ = *value++); )
147		;
148	return (0);
149}
150
151/*
152 * unsetenv(name) --
153 *	Delete environmental variable "name".
154 */
155int
156unsetenv(const char *name)
157{
158	char **P;
159	const char *np;
160	int offset = 0;
161
162	if (!name || !*name) {
163		errno = EINVAL;
164		return (-1);
165	}
166	for (np = name; *np && *np != '='; ++np)
167		;
168	if (*np) {
169		errno = EINVAL;
170		return (-1);			/* has `=' in name */
171	}
172
173	/* could be set multiple times */
174	while (__findenv(name, (int)(np - name), &offset)) {
175		for (P = &environ[offset];; ++P)
176			if (!(*P = *(P + 1)))
177				break;
178	}
179	return (0);
180}
181