xref: /freebsd/lib/libc/gen/getusershell.c (revision 1130b656e5fe4c2d1ba299e024d1b40eaeebd380)
1 /*
2  * Copyright (c) 1985, 1993
3  *	The Regents of the University of California.  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  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)getusershell.c	8.1 (Berkeley) 6/4/93";
36 #endif /* LIBC_SCCS and not lint */
37 
38 #include <sys/param.h>
39 #include <sys/file.h>
40 #include <sys/stat.h>
41 #include <stdio.h>
42 #include <ctype.h>
43 #include <stdlib.h>
44 #include <unistd.h>
45 #include <paths.h>
46 
47 /*
48  * Local shells should NOT be added here.  They should be added in
49  * /etc/shells.
50  */
51 
52 static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
53 static char **curshell, **shells, *strings;
54 static char **initshells __P((void));
55 
56 /*
57  * Get a list of shells from _PATH_SHELLS, if it exists.
58  */
59 char *
60 getusershell()
61 {
62 	char *ret;
63 
64 	if (curshell == NULL)
65 		curshell = initshells();
66 	ret = *curshell;
67 	if (ret != NULL)
68 		curshell++;
69 	return (ret);
70 }
71 
72 void
73 endusershell()
74 {
75 
76 	if (shells != NULL)
77 		free(shells);
78 	shells = NULL;
79 	if (strings != NULL)
80 		free(strings);
81 	strings = NULL;
82 	curshell = NULL;
83 }
84 
85 void
86 setusershell()
87 {
88 
89 	curshell = initshells();
90 }
91 
92 static char **
93 initshells()
94 {
95 	register char **sp, *cp;
96 	register FILE *fp;
97 	struct stat statb;
98 
99 	if (shells != NULL)
100 		free(shells);
101 	shells = NULL;
102 	if (strings != NULL)
103 		free(strings);
104 	strings = NULL;
105 	if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
106 		return (okshells);
107 	if (fstat(fileno(fp), &statb) == -1) {
108 		(void)fclose(fp);
109 		return (okshells);
110 	}
111 	if ((strings = malloc((u_int)statb.st_size)) == NULL) {
112 		(void)fclose(fp);
113 		return (okshells);
114 	}
115 	shells = calloc((unsigned)statb.st_size / 3, sizeof (char *));
116 	if (shells == NULL) {
117 		(void)fclose(fp);
118 		free(strings);
119 		strings = NULL;
120 		return (okshells);
121 	}
122 	sp = shells;
123 	cp = strings;
124 	while (fgets(cp, MAXPATHLEN + 1, fp) != NULL) {
125 		while (*cp != '#' && *cp != '/' && *cp != '\0')
126 			cp++;
127 		if (*cp == '#' || *cp == '\0')
128 			continue;
129 		*sp++ = cp;
130 		while (!isspace(*cp) && *cp != '#' && *cp != '\0')
131 			cp++;
132 		*cp++ = '\0';
133 	}
134 	*sp = NULL;
135 	(void)fclose(fp);
136 	return (shells);
137 }
138