1 /* euidaccess-stat -- check if effective user id can access lstat'd file
2 This function is probably useful only for choosing whether to issue
3 a prompt in an implementation of POSIX-specified rm.
5 Copyright (C) 2005, 2006 Free Software Foundation, Inc.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License along
18 with this program; if not, write to the Free Software Foundation,
19 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
21 /* Adapted for use in GNU remove.c by Jim Meyering. */
25 #include "euidaccess-stat.h"
36 #include "group-member.h"
37 #include "stat-macros.h"
39 /* Return true if the current user has permission of type MODE
40 on the file from which stat buffer *ST was obtained, ignoring
41 ACLs, attributes, `read-only'ness, etc...
42 Otherwise, return false.
44 Like the reentrant version of euidaccess, but starting with
45 a stat buffer rather than a file name. Hence, this function
46 never calls access or accessx, and doesn't take into account
47 whether the file has ACLs or other attributes, or resides on
48 a read-only file system. */
51 euidaccess_stat (struct stat const *st, int mode)
56 /* Convert the mode to traditional form, clearing any bogus bits. */
57 if (R_OK == 4 && W_OK == 2 && X_OK == 1 && F_OK == 0)
60 mode = ((mode & R_OK ? 4 : 0)
61 + (mode & W_OK ? 2 : 0)
62 + (mode & X_OK ? 1 : 0));
65 return true; /* The file exists. */
69 /* The super-user can read and write any file, and execute any file
70 that anyone can execute. */
71 if (euid == 0 && ((mode & X_OK) == 0
72 || (st->st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
75 /* Convert the file's permission bits to traditional form. */
76 if ( S_IRUSR == (4 << 6)
77 && S_IWUSR == (2 << 6)
78 && S_IXUSR == (1 << 6)
79 && S_IRGRP == (4 << 3)
80 && S_IWGRP == (2 << 3)
81 && S_IXGRP == (1 << 3)
82 && S_IROTH == (4 << 0)
83 && S_IWOTH == (2 << 0)
84 && S_IXOTH == (1 << 0))
85 granted = st->st_mode;
87 granted = ( (st->st_mode & S_IRUSR ? 4 << 6 : 0)
88 + (st->st_mode & S_IWUSR ? 2 << 6 : 0)
89 + (st->st_mode & S_IXUSR ? 1 << 6 : 0)
90 + (st->st_mode & S_IRGRP ? 4 << 3 : 0)
91 + (st->st_mode & S_IWGRP ? 2 << 3 : 0)
92 + (st->st_mode & S_IXGRP ? 1 << 3 : 0)
93 + (st->st_mode & S_IROTH ? 4 << 0 : 0)
94 + (st->st_mode & S_IWOTH ? 2 << 0 : 0)
95 + (st->st_mode & S_IXOTH ? 1 << 0 : 0));
97 if (euid == st->st_uid)
101 gid_t egid = getegid ();
102 if (egid == st->st_gid || group_member (st->st_gid))
106 if ((mode & ~granted) == 0)
124 main (int argc, char **argv)
131 program_name = argv[0];
135 mode = atoi (argv[2]);
136 if (lstat (file, &st) != 0)
137 error (EXIT_FAILURE, errno, _("cannot stat %s"), file);
139 ok = euidaccess_stat (&st, mode);
140 printf ("%s: %s\n", file, ok ? "y" : "n");