1 /* $OpenBSD: getusershell.c,v 1.18 2019/12/10 02:35:16 millert Exp $ */
2 /*
3 * Copyright (c) 1985, 1993
4 * The Regents of the University of California. 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 <paths.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36
37 /*
38 * Local shells should NOT be added here. They should be added in
39 * /etc/shells.
40 */
41
42 static char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, _PATH_KSHELL, NULL };
43 static char **curshell, **shells;
44 static char **initshells(void);
45
46 /*
47 * Get a list of shells from _PATH_SHELLS, if it exists.
48 */
49 char *
getusershell(void)50 getusershell(void)
51 {
52 char *ret;
53
54 if (curshell == NULL)
55 curshell = initshells();
56 ret = *curshell;
57 if (ret != NULL)
58 curshell++;
59 return (ret);
60 }
61
62 void
endusershell(void)63 endusershell(void)
64 {
65 char **s;
66
67 if ((s = shells))
68 while (*s)
69 free(*s++);
70 free(shells);
71 shells = NULL;
72
73 curshell = NULL;
74 }
75
76 void
setusershell(void)77 setusershell(void)
78 {
79
80 curshell = initshells();
81 }
82
83 static char **
initshells(void)84 initshells(void)
85 {
86 size_t nshells, nalloc, linesize;
87 char *line;
88 FILE *fp;
89
90 free(shells);
91 shells = NULL;
92
93 if ((fp = fopen(_PATH_SHELLS, "re")) == NULL)
94 return (okshells);
95
96 line = NULL;
97 nalloc = 10; // just an initial guess
98 nshells = 0;
99 shells = reallocarray(NULL, nalloc, sizeof (char *));
100 if (shells == NULL)
101 goto fail;
102 linesize = 0;
103 while (getline(&line, &linesize, fp) != -1) {
104 if (*line != '/')
105 continue;
106 line[strcspn(line, "#\n")] = '\0';
107 if (!(shells[nshells] = strdup(line)))
108 goto fail;
109
110 if (nshells + 1 == nalloc) {
111 char **new = reallocarray(shells, nalloc * 2, sizeof(char *));
112 if (!new)
113 goto fail;
114 shells = new;
115 nalloc *= 2;
116 }
117 nshells++;
118 }
119 free(line);
120 shells[nshells] = NULL;
121 (void)fclose(fp);
122 return (shells);
123
124 fail:
125 free(line);
126 while (nshells)
127 free(shells[nshells--]);
128 free(shells);
129 shells = NULL;
130 (void)fclose(fp);
131 return (okshells);
132 }
133