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/* euidaccess-stat -- check if effective user id can access lstat'd file
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This function is probably useful only for choosing whether to issue
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a prompt in an implementation of POSIX-specified rm.
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Copyright (C) 2005-2006, 2009-2011 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Adapted for use in GNU remove.c by Jim Meyering. */
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#include "euidaccess-stat.h"
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#include "stat-macros.h"
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/* Return true if the current user has permission of type MODE
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on the file from which stat buffer *ST was obtained, ignoring
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ACLs, attributes, `read-only'ness, etc...
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Otherwise, return false.
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Like the reentrant version of euidaccess, but starting with
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a stat buffer rather than a file name. Hence, this function
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never calls access or accessx, and doesn't take into account
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whether the file has ACLs or other attributes, or resides on
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a read-only file system. */
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euidaccess_stat (struct stat const *st, int mode)
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/* Convert the mode to traditional form, clearing any bogus bits. */
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if (R_OK == 4 && W_OK == 2 && X_OK == 1 && F_OK == 0)
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mode = ((mode & R_OK ? 4 : 0)
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+ (mode & W_OK ? 2 : 0)
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+ (mode & X_OK ? 1 : 0));
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return true; /* The file exists. */
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/* The super-user can read and write any file, and execute any file
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that anyone can execute. */
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if (euid == 0 && ((mode & X_OK) == 0
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|| (st->st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
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/* Convert the file's permission bits to traditional form. */
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if ( S_IRUSR == (4 << 6)
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&& S_IWUSR == (2 << 6)
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&& S_IXUSR == (1 << 6)
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&& S_IRGRP == (4 << 3)
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&& S_IWGRP == (2 << 3)
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&& S_IXGRP == (1 << 3)
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&& S_IROTH == (4 << 0)
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&& S_IWOTH == (2 << 0)
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&& S_IXOTH == (1 << 0))
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granted = st->st_mode;
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granted = ( (st->st_mode & S_IRUSR ? 4 << 6 : 0)
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+ (st->st_mode & S_IWUSR ? 2 << 6 : 0)
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+ (st->st_mode & S_IXUSR ? 1 << 6 : 0)
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+ (st->st_mode & S_IRGRP ? 4 << 3 : 0)
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+ (st->st_mode & S_IWGRP ? 2 << 3 : 0)
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+ (st->st_mode & S_IXGRP ? 1 << 3 : 0)
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+ (st->st_mode & S_IROTH ? 4 << 0 : 0)
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+ (st->st_mode & S_IWOTH ? 2 << 0 : 0)
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+ (st->st_mode & S_IXOTH ? 1 << 0 : 0));
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if (euid == st->st_uid)
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gid_t egid = getegid ();
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if (egid == st->st_gid || group_member (st->st_gid))
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if ((mode & ~granted) == 0)
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main (int argc, char **argv)
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program_name = argv[0];
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mode = atoi (argv[2]);
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if (lstat (file, &st) != 0)
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error (EXIT_FAILURE, errno, _("cannot stat %s"), file);
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ok = euidaccess_stat (&st, mode);
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printf ("%s: %s\n", file, ok ? "y" : "n");