1 /* getusershell.c -- Return names of valid user shells.
3 Copyright (C) 1991, 1997, 2000, 2001, 2003, 2004, 2005, 2006 Free
4 Software Foundation, Inc.
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> */
26 /* File containing a list of nonrestricted shells, one per line. */
27 # define SHELLS_FILE "/etc/shells"
29 /* This is a horrible kludge. Isn't there a better way? */
30 # define SHELLS_FILE "/dev/env/DJDIR/etc/shells"
41 # include "unlocked-io.h"
44 static size_t readname (char **, size_t *, FILE *);
46 #if ! defined ADDITIONAL_DEFAULT_SHELLS && defined __MSDOS__
47 # define ADDITIONAL_DEFAULT_SHELLS \
48 "c:/dos/command.com", "c:/windows/command.com", "c:/command.com",
50 # define ADDITIONAL_DEFAULT_SHELLS /* empty */
53 /* List of shells to use if the shells file is missing. */
54 static char const* const default_shells[] =
56 ADDITIONAL_DEFAULT_SHELLS
57 "/bin/sh", "/bin/csh", "/usr/bin/sh", "/usr/bin/csh", NULL
60 /* Index of the next shell in `default_shells' to return.
61 0 means we are not using `default_shells'. */
62 static size_t default_index = 0;
64 /* Input stream from the shells file. */
65 static FILE *shellstream = NULL;
67 /* Line of input from the shells file. */
68 static char *line = NULL;
70 /* Number of bytes allocated for `line'. */
71 static size_t line_size = 0;
73 /* Return an entry from the shells file, ignoring comment lines.
74 If the file doesn't exist, use the list in DEFAULT_SHELLS (above).
75 In any case, the returned string is in memory allocated through malloc.
76 Return NULL if there are no more entries. */
81 if (default_index > 0)
83 if (default_shells[default_index])
84 /* Not at the end of the list yet. */
85 return xstrdup (default_shells[default_index++]);
89 if (shellstream == NULL)
91 shellstream = fopen (SHELLS_FILE, "r");
92 if (shellstream == NULL)
94 /* No shells file. Use the default list. */
96 return xstrdup (default_shells[0]);
100 while (readname (&line, &line_size, shellstream))
105 return NULL; /* End of file. */
108 /* Rewind the shells file. */
115 rewind (shellstream);
118 /* Close the shells file. */
125 fclose (shellstream);
130 /* Read a line from STREAM, removing any newline at the end.
131 Place the result in *NAME, which is malloc'd
132 and/or realloc'd as necessary and can start out NULL,
133 and whose size is passed and returned in *SIZE.
135 Return the number of bytes placed in *NAME
136 if some nonempty sequence was found, otherwise 0. */
139 readname (char **name, size_t *size, FILE *stream)
142 size_t name_index = 0;
144 /* Skip blank space. */
145 while ((c = getc (stream)) != EOF && isspace (c))
150 if (*size <= name_index)
151 *name = x2nrealloc (*name, size, sizeof **name);
152 if (c == EOF || isspace (c))
154 (*name)[name_index++] = c;
157 (*name)[name_index] = '\0';
167 while (s = getusershell ())