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
|
/* group-member.c -- determine whether group id is in calling user's group list
Copyright (C) 1994, 1997-1998, 2003, 2005-2006, 2009-2011 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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include "group-member.h"
#include <stdbool.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include "xalloc.h"
struct group_info
{
int n_groups;
gid_t *group;
};
static void
free_group_info (struct group_info const *g)
{
free (g->group);
}
static bool
get_group_info (struct group_info *gi)
{
int n_groups;
int n_group_slots = getgroups (0, NULL);
gid_t *group;
if (n_group_slots < 0)
return false;
/* Avoid xnmalloc, as it goes awry when SIZE_MAX < n_group_slots. */
if (xalloc_oversized (n_group_slots, sizeof *group))
xalloc_die ();
group = xmalloc (n_group_slots * sizeof *group);
n_groups = getgroups (n_group_slots, group);
/* In case of error, the user loses. */
if (n_groups < 0)
{
free (group);
return false;
}
gi->n_groups = n_groups;
gi->group = group;
return true;
}
/* Return non-zero if GID is one that we have in our groups list.
Note that the groups list is not guaranteed to contain the current
or effective group ID, so they should generally be checked
separately. */
int
group_member (gid_t gid)
{
int i;
int found;
struct group_info gi;
if (! get_group_info (&gi))
return 0;
/* Search through the list looking for GID. */
found = 0;
for (i = 0; i < gi.n_groups; i++)
{
if (gid == gi.group[i])
{
found = 1;
break;
}
}
free_group_info (&gi);
return found;
}
#ifdef TEST
char *program_name;
int
main (int argc, char **argv)
{
int i;
program_name = argv[0];
for (i = 1; i < argc; i++)
{
gid_t gid;
gid = atoi (argv[i]);
printf ("%d: %s\n", gid, group_member (gid) ? "yes" : "no");
}
exit (0);
}
#endif /* TEST */
|
