| 1 | /* unlinkdir.c - determine (and maybe change) whether we can unlink directories
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| 2 |
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| 3 | Copyright (C) 2005, 2006 Free Software Foundation, Inc.
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| 4 |
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| 5 | This program is free software; you can redistribute it and/or modify
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| 6 | it under the terms of the GNU General Public License as published by
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| 7 | the Free Software Foundation; either version 2, or (at your option)
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| 8 | any later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program; if not, write to the Free Software Foundation,
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| 17 | Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
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| 18 |
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| 19 | /* Written by Paul Eggert and Jim Meyering. */
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| 20 |
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| 21 | #include <config.h>
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| 22 |
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| 23 | #include "unlinkdir.h"
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| 24 |
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| 25 | #if HAVE_PRIV_H
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| 26 | # include <priv.h>
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| 27 | #endif
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| 28 | #include <unistd.h>
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| 29 |
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| 30 | #if ! UNLINK_CANNOT_UNLINK_DIR
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| 31 |
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| 32 | /* Return true if we cannot unlink directories, false if we might be
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| 33 | able to unlink directories. If possible, tell the kernel we don't
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| 34 | want to be able to unlink directories, so that we can return true. */
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| 35 |
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| 36 | bool
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| 37 | cannot_unlink_dir (void)
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| 38 | {
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| 39 | static bool initialized;
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| 40 | static bool cannot;
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| 41 |
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| 42 | if (! initialized)
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| 43 | {
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| 44 | # if defined PRIV_EFFECTIVE && defined PRIV_SYS_LINKDIR
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| 45 | /* We might be able to unlink directories if we cannot
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| 46 | determine our privileges, or if we have the
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| 47 | PRIV_SYS_LINKDIR privilege and cannot delete it. */
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| 48 | priv_set_t *pset = priv_allocset ();
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| 49 | if (pset)
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| 50 | {
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| 51 | cannot =
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| 52 | (getppriv (PRIV_EFFECTIVE, pset) == 0
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| 53 | && (! priv_ismember (pset, PRIV_SYS_LINKDIR)
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| 54 | || (priv_delset (pset, PRIV_SYS_LINKDIR) == 0
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| 55 | && setppriv (PRIV_SET, PRIV_EFFECTIVE, pset) == 0)));
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| 56 | priv_freeset (pset);
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| 57 | }
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| 58 | # else
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| 59 | /* In traditional Unix, only root can unlink directories. */
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| 60 | cannot = (geteuid () != 0);
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| 61 | # endif
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| 62 | initialized = true;
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| 63 | }
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| 64 |
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| 65 | return cannot;
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| 66 | }
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| 67 |
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| 68 | #endif
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