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--no-overwrite-dir no overwrite even temporarily

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Problem and fix reported by Pavel Cahyna in
https://lists.gnu.org/r/bug-tar/2025-01/msg00000.html
* src/extract.c (extract_dir): With --no-overwrite-dir,
skip the chmod if the directory already exists.
* tests/extrac23.at (--no-overwrite-dir on empty directory):
Move the part of the test that looks at a nonempty directory ...
* tests/extrac30.at: ... to this new file, because the test now
must be run as non-root.  Adjust the test to match the new behavior.
* tests/Makefile.am (TESTSUITE_AT), tests/testsuite.at: Add it.
This commit is contained in:
Paul Eggert
2025-07-26 21:41:23 -07:00
parent 076818f8d9
commit 4e742fc867
6 changed files with 55 additions and 41 deletions
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6
NEWS
View File

@@ -1,4 +1,4 @@
GNU tar NEWS - User visible changes. 2025-07-25
GNU tar NEWS - User visible changes. 2025-07-26
Please send GNU tar bug reports to <bug-tar@gnu.org>
version TBD
@@ -45,6 +45,10 @@ option.
** Transformations that change case (e.g., --transform='s/.*/\L&/')
now work correctly with multi-byte characters.
** --no-overwrite-dir no longer changes permissions of existing directories,
not even temporarily. This matches the documentation better and avoids
some permissions glitches.
** tar now works better in strict debugging environments that do not
allow pointer arithmetic to escape from a sub-element of an array.

25
src/extract.c
View File

@@ -1158,31 +1158,6 @@ extract_dir (char *file_name, char typeflag)
repair_delayed_set_stat (file_name, &st);
return true;
}
else if (old_files_option == NO_OVERWRITE_DIR_OLD_FILES)
{
/* Temporarily change the directory mode to a safe
value, to be able to create files in it, should
the need be.
*/
mode = safe_dir_mode (&st);
status = fd_chmod (-1, file_name, mode,
AT_SYMLINK_NOFOLLOW, DIRTYPE);
if (status == 0)
{
/* Store the actual directory mode, to be restored
later.
*/
current_stat_info.stat = st;
current_mode = mode & ~ current_umask;
current_mode_mask = MODE_RWX;
atflag = AT_SYMLINK_NOFOLLOW;
break;
}
else
{
chmod_error_details (file_name, mode);
}
}
break;
}
}

1
tests/Makefile.am
View File

@@ -139,6 +139,7 @@ TESTSUITE_AT = \
extrac27.at\
extrac28.at\
extrac29.at\
extrac30.at\
filerem01.at\
filerem02.at\
grow.at\

16
tests/extrac23.at
View File

@@ -15,15 +15,12 @@
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
AT_SETUP([--no-overwrite-dir])
AT_SETUP([--no-overwrite-dir on empty directory])
AT_KEYWORDS([extract extrac23 no-overwrite-dir])
# Description: Implementation of the --no-overwrite-dir option was flawed in
# tar versions up to 1.32.90. This option is intended to preserve metadata
# of existing directories. In fact it worked only for non-empty directories.
# Moreover, if the actual directory was owned by the user tar runs as and the
# S_IWUSR bit was not set in its actual permissions, tar failed to create files
# in it.
#
# Reported by: Michael Kaufmann <mail@michael-kaufmann.ch>
# References: <20200207112934.Horde.anXzYhAj2CHiwUrw5CuT0G-@webmail.michael-kaufmann.ch>,
@@ -38,21 +35,10 @@ chmod 777 dir
tar -xf a.tar --no-overwrite-dir
genfile --stat=mode.777 dir
# Test if temporary permissions are set correctly to allow the owner
# to write to the directory.
genfile --file dir/file
tar cf a.tar dir
rm dir/file
chmod 400 dir
tar -xf a.tar --no-overwrite-dir
genfile --stat=mode.777 dir
chmod 700 dir
find dir
],
[0],
[777
400
dir
dir/file
])
AT_CLEANUP

47
tests/extrac30.at Normal file
View File

@@ -0,0 +1,47 @@
# Test suite for GNU tar. -*- Autotest -*-
# Copyright 2020-2025 Free Software Foundation, Inc.
#
# This file is part of GNU tar.
#
# GNU tar 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.
#
# GNU tar 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/>.
AT_SETUP([--no-overwrite-dir on unwritable directory])
AT_KEYWORDS([extract extrac30 no-overwrite-dir])
# Make sure that tar does not change permissions on directories if
# --no-overwrite-dir tells it not to, not even temporarily.
AT_TAR_CHECK([
AT_UNPRIVILEGED_PREREQ
# Test that the user cannot write to a unwritable directory
# if --no-overwrite-dir is used.
mkdir dir
chmod 755 dir
genfile --file dir/file
tar cf a.tar dir
rm dir/file
chmod 555 dir
tar -xf a.tar --no-overwrite-dir
genfile --stat=mode.777 dir
chmod 755 dir
find dir
],
[0],
[555
dir
],
[tar: dir/file: Cannot open: Permission denied
tar: Exiting with failure status due to previous errors
])
AT_CLEANUP

1
tests/testsuite.at
View File

@@ -356,6 +356,7 @@ m4_include([extrac26.at])
m4_include([extrac27.at])
m4_include([extrac28.at])
m4_include([extrac29.at])
m4_include([extrac30.at])
m4_include([backup01.at])