1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
/* getusershell.c -- Return names of valid user shells.
Copyright (C) 1991, 1997, 2000, 2001, 2003, 2004, 2005 Free Software
Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by David MacKenzie <djm@gnu.ai.mit.edu> */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#ifndef SHELLS_FILE
# ifndef __DJGPP__
/* File containing a list of nonrestricted shells, one per line. */
# define SHELLS_FILE "/etc/shells"
# else
/* This is a horrible kludge. Isn't there a better way? */
# define SHELLS_FILE "/dev/env/DJDIR/etc/shells"
# endif
#endif
#include <stdlib.h>
#include <ctype.h>
#include "stdio--.h"
#include "xalloc.h"
#if USE_UNLOCKED_IO
# include "unlocked-io.h"
#endif
#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
# define IN_CTYPE_DOMAIN(c) 1
#else
# define IN_CTYPE_DOMAIN(c) isascii(c)
#endif
#define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c))
static size_t readname (char **, size_t *, FILE *);
#if ! defined ADDITIONAL_DEFAULT_SHELLS && defined __MSDOS__
# define ADDITIONAL_DEFAULT_SHELLS \
"c:/dos/command.com", "c:/windows/command.com", "c:/command.com",
#else
# define ADDITIONAL_DEFAULT_SHELLS /* empty */
#endif
/* List of shells to use if the shells file is missing. */
static char const* const default_shells[] =
{
ADDITIONAL_DEFAULT_SHELLS
"/bin/sh", "/bin/csh", "/usr/bin/sh", "/usr/bin/csh", NULL
};
/* Index of the next shell in `default_shells' to return.
0 means we are not using `default_shells'. */
static size_t default_index = 0;
/* Input stream from the shells file. */
static FILE *shellstream = NULL;
/* Line of input from the shells file. */
static char *line = NULL;
/* Number of bytes allocated for `line'. */
static size_t line_size = 0;
/* Return an entry from the shells file, ignoring comment lines.
If the file doesn't exist, use the list in DEFAULT_SHELLS (above).
In any case, the returned string is in memory allocated through malloc.
Return NULL if there are no more entries. */
char *
getusershell (void)
{
if (default_index > 0)
{
if (default_shells[default_index])
/* Not at the end of the list yet. */
return xstrdup (default_shells[default_index++]);
return NULL;
}
if (shellstream == NULL)
{
shellstream = fopen (SHELLS_FILE, "r");
if (shellstream == NULL)
{
/* No shells file. Use the default list. */
default_index = 1;
return xstrdup (default_shells[0]);
}
}
while (readname (&line, &line_size, shellstream))
{
if (*line != '#')
return line;
}
return NULL; /* End of file. */
}
/* Rewind the shells file. */
void
setusershell (void)
{
default_index = 0;
if (shellstream)
rewind (shellstream);
}
/* Close the shells file. */
void
endusershell (void)
{
if (shellstream)
{
fclose (shellstream);
shellstream = NULL;
}
}
/* Read a line from STREAM, removing any newline at the end.
Place the result in *NAME, which is malloc'd
and/or realloc'd as necessary and can start out NULL,
and whose size is passed and returned in *SIZE.
Return the number of bytes placed in *NAME
if some nonempty sequence was found, otherwise 0. */
static size_t
readname (char **name, size_t *size, FILE *stream)
{
int c;
size_t name_index = 0;
/* Skip blank space. */
while ((c = getc (stream)) != EOF && ISSPACE (c))
/* Do nothing. */ ;
for (;;)
{
if (*size <= name_index)
*name = x2nrealloc (*name, size, sizeof **name);
if (c == EOF || ISSPACE (c))
break;
(*name)[name_index++] = c;
c = getc (stream);
}
(*name)[name_index] = '\0';
return name_index;
}
#ifdef TEST
int
main (void)
{
char *s;
while (s = getusershell ())
puts (s);
exit (0);
}
#endif
|
