1 /* getusershell.c -- Return names of valid user shells.
3 Copyright (C) 1991, 1997, 2000, 2001, 2003, 2004, 2005 Free Software
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software Foundation,
18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
20 /* Written by David MacKenzie <djm@gnu.ai.mit.edu> */
28 /* File containing a list of nonrestricted shells, one per line. */
29 # define SHELLS_FILE "/etc/shells"
31 /* This is a horrible kludge. Isn't there a better way? */
32 # define SHELLS_FILE "/dev/env/DJDIR/etc/shells"
40 #include "stdio-safer.h"
44 # include "unlocked-io.h"
47 #if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
48 # define IN_CTYPE_DOMAIN(c) 1
50 # define IN_CTYPE_DOMAIN(c) isascii(c)
53 #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
55 static size_t readname (char **, size_t *, FILE *);
57 #if ! defined ADDITIONAL_DEFAULT_SHELLS && defined __MSDOS__
58 # define ADDITIONAL_DEFAULT_SHELLS \
59 "c:/dos/command.com", "c:/windows/command.com", "c:/command.com",
61 # define ADDITIONAL_DEFAULT_SHELLS /* empty */
64 /* List of shells to use if the shells file is missing. */
65 static char const* const default_shells[] =
67 ADDITIONAL_DEFAULT_SHELLS
68 "/bin/sh", "/bin/csh", "/usr/bin/sh", "/usr/bin/csh", NULL
71 /* Index of the next shell in `default_shells' to return.
72 0 means we are not using `default_shells'. */
73 static size_t default_index = 0;
75 /* Input stream from the shells file. */
76 static FILE *shellstream = NULL;
78 /* Line of input from the shells file. */
79 static char *line = NULL;
81 /* Number of bytes allocated for `line'. */
82 static size_t line_size = 0;
84 /* Return an entry from the shells file, ignoring comment lines.
85 If the file doesn't exist, use the list in DEFAULT_SHELLS (above).
86 In any case, the returned string is in memory allocated through malloc.
87 Return NULL if there are no more entries. */
92 if (default_index > 0)
94 if (default_shells[default_index])
95 /* Not at the end of the list yet. */
96 return xstrdup (default_shells[default_index++]);
100 if (shellstream == NULL)
102 shellstream = fopen_safer (SHELLS_FILE, "r");
103 if (shellstream == NULL)
105 /* No shells file. Use the default list. */
107 return xstrdup (default_shells[0]);
111 while (readname (&line, &line_size, shellstream))
116 return NULL; /* End of file. */
119 /* Rewind the shells file. */
126 rewind (shellstream);
129 /* Close the shells file. */
136 fclose (shellstream);
141 /* Read a line from STREAM, removing any newline at the end.
142 Place the result in *NAME, which is malloc'd
143 and/or realloc'd as necessary and can start out NULL,
144 and whose size is passed and returned in *SIZE.
146 Return the number of bytes placed in *NAME
147 if some nonempty sequence was found, otherwise 0. */
150 readname (char **name, size_t *size, FILE *stream)
153 size_t name_index = 0;
155 /* Skip blank space. */
156 while ((c = getc (stream)) != EOF && ISSPACE (c))
161 if (*size <= name_index)
162 *name = x2nrealloc (*name, size, sizeof **name);
163 if (c == EOF || ISSPACE (c))
165 (*name)[name_index++] = c;
168 (*name)[name_index] = '\0';
178 while (s = getusershell ())