diff options
| -rw-r--r-- | lib/unlinkdir.c | 70 | ||||
| -rw-r--r-- | lib/unlinkdir.h | 27 | ||||
| -rw-r--r-- | m4/unlinkdir.m4 | 31 |
3 files changed, 128 insertions, 0 deletions
diff --git a/lib/unlinkdir.c b/lib/unlinkdir.c new file mode 100644 index 000000000..c30aa1020 --- /dev/null +++ b/lib/unlinkdir.c @@ -0,0 +1,70 @@ +/* unlinkdir.c - determine (and maybe change) whether we can unlink directories + + Copyright (C) 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 St, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Written by Paul Eggert and Jim Meyering. */ + +#include <config.h> + +#include "unlinkdir.h" + +#if HAVE_PRIV_H +# include <priv.h> +#endif +#if HAVE_UNISTD_H +# include <unistd.h> +#endif + +#if ! UNLINK_CANNOT_UNLINK_DIR + +/* Return true if we cannot unlink directories, false if we might be + able to unlink directories. If possible, tell the kernel we don't + want to be able to unlink directories, so that we can return true. */ + +bool +cannot_unlink_dir (void) +{ + static bool initialized; + static bool cannot; + + if (! initialized) + { +# if defined PRIV_EFFECTIVE && defined PRIV_SYS_LINKDIR + /* We might be able to unlink directories if we cannot + determine our privileges, or if we have the + PRIV_SYS_LINKDIR privilege and cannot delete it. */ + priv_set_t *pset = priv_allocset (); + if (pset) + { + cannot = + (getppriv (PRIV_EFFECTIVE, pset) == 0 + && (! priv_ismember (pset, PRIV_SYS_LINKDIR) + || (priv_delset (pset, PRIV_SYS_LINKDIR) == 0 + && setppriv (PRIV_SET, PRIV_EFFECTIVE, pset) == 0))); + priv_freeset (pset); + } +# else + /* In traditional Unix, only root can unlink directories. */ + cannot = (getuid () != 0); +# endif + } + + initialized = true; + return cannot; +} + +#endif diff --git a/lib/unlinkdir.h b/lib/unlinkdir.h new file mode 100644 index 000000000..f705f1233 --- /dev/null +++ b/lib/unlinkdir.h @@ -0,0 +1,27 @@ +/* unlinkdir.h - determine (and maybe change) whether we can unlink directories + + Copyright (C) 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 St, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Written by Paul Eggert and Jim Meyering. */ + +#include <stdbool.h> + +#if UNLINK_CANNOT_UNLINK_DIR +static bool cannot_unlink_dir (void) { return true; } +#else +bool cannot_unlink_dir (void); +#endif diff --git a/m4/unlinkdir.m4 b/m4/unlinkdir.m4 new file mode 100644 index 000000000..c3f9c018b --- /dev/null +++ b/m4/unlinkdir.m4 @@ -0,0 +1,31 @@ +#serial 1 + +# Copyright (C) 2005 Free Software Foundation, Inc. +# +# This file is free software; the Free Software Foundation +# gives unlimited permission to copy and/or distribute it, +# with or without modifications, as long as this notice is preserved. + +# Written by Paul Eggert. + +AC_DEFUN([gl_UNLINKDIR], +[ + AC_REQUIRE([AC_CANONICAL_HOST]) + AC_CHECK_HEADERS_ONCE(priv.h unistd.h) + + # The Hurd, the Linux kernel, the FreeBSD kernel version 2.2 and later, + # and Cygwin never let anyone (even root) unlink directories. + # If anyone knows of another system for which unlink can never + # remove a directory, please report it to <bug-coreutils@gnu.org>. + # Unfortunately this is difficult to test for, since it requires root access + # and might create garbage in the file system, + # so the code below simply relies on the kernel name and version number. + case $host in + *-*-gnu[0-9]* | \ + *-*-linux-* | *-*-linux | \ + *-*-freebsd2.2* | *-*-freebsd[3-9]* | *-*-freebsd[1-9][0-9]* | \ + *-cygwin) + AC_DEFINE([UNLINK_CANNOT_UNLINK_DIR], 1, + [Define to 1 if unlink (dir) cannot possibly succeed.]);; + esac +]) |