Although this might help (or hurt) performance, the main
motivation is to make it easier in future commits
to prevent tarballs from escaping the extraction directory.
* src/common.h: (BADFD): New constant.
(struct fdbase): New type.
* src/create.c (dump_file0): Use parent->fd instead of caching
it into a local, as the latter approach is now awkward.
* src/extract.c (extract_link): Don’t save errno unless needed.
* src/misc.c (safer_rmdir): New arg F. All callers changed.
(maybe_backup_file): Construct full after_backup_name, now
that find_backup_file_name no longer does that for us.
(chdir_fd): Now static not extern, as other modules now use fdbase.
(fdbase_cache): New static var.
(fdbase_clear): New function. Call it whenever removing
or renaming directories or symlinks to directories.
(fdbase_opendir): New static function.
(fdbase, fdbase1): New functions. Call them whenever the
code formerly passed chdir_fd to a syscall.
* gnulib.modules: Add issymlinkat, already an indirect dependency.
* src/extract.c: Include issymlink.h.
(is_directory_link, open_output_file):
Prefer issymlinkat to doing it by hand.
* src/exclist.c (excluded_name):
* src/misc.c (normalize_filename_x, must_be_dot_or_slash)
(chdir_arg):
Use dotslash or dotslashlen instead of doing things by hand.
* src/misc.c (slashlen, dotslashlen): New functions.
(safer_rmdir): Do not worry about unlinkat with AT_REMOVEDIR
succeeding on ".", as POSIX prohibits it, and it does not succeed
on any known platform. This simplifies the file name test.
Continue to worry about "/" though, as POSIX does allow
it to be removed.
This prepares for future changes that need directory IDs.
* src/common.h (struct chdir_id): New struct.
* src/extract.c (extract_dir): Use chdir_id to avoid duplicate stats.
* src/misc.c (struct wd): New member ID.
(grow_wd): New function, extracted from chdir_arg and that
also initializes id.err.
(chdir_arg): Use it. Initialize id.err.
(chdir_id): New function.
I ported our fix into Gnulib so there’s no longer a need
for a separate copy.
* doc/Makefile.am (GENDOCS): Now in ../build-aux, not here.
* doc/gendocs.sh, doc/gendocs_template: Remove.
* gnulib.modules: Add gendocs.
Caught by gcc -fsanitize=address.
Inspired by Matthias Andree’s bug report in:
https://lists.gnu.org/r/bug-tar/2025-08/msg00019.html
though I found this bug via a simple "make check"
with sanitization enabled.
* src/common.h (TIMESPEC_STRSIZE_BOUND):
Make room for leading '-', needed in addition to the '-' room
supplied by SYSINT_BUFSIZE due to the way code_timespec works.
This is more portable to non-POSIX systems.
However, don’t bother trying to port to systems
where st_ino is not a scalar of type dev_t,
as these systems no longer seem to be active targets
and it’s not worth the maintenance hassle.
* gnulib.modules: Add same-inode, now that we use it
explicitly rather than indirectly.
* src/compare.c (diff_link):
* src/create.c (compare_links, restore_parent_fd):
* src/incremen.c (compare_directory_meta, procdir):
* src/extract.c (dl_compare, repair_delayed_set_stat)
(apply_nonancestor_delayed_set_stat, extract_link)
(apply_delayed_link):
* src/names.c (add_file_id):
* src/system.c (sys_file_is_archive, sys_detect_dev_null_output):
Include same-inode.h, and prefer its macros and functions
to doing things by hand.
* src/create.c (struct link):
* src/extract.c (struct delayed_set_stat, struct delayed_link):
* src/incremen.c (struct directory):
* src/names.c (struct file_id_list):
Rename members to st_dev and st_ino so that SAME_INODE and
PSAME_INODE can be used on the type. All uses changed.
* src/system.c (sys_compare_links): Remove.
All uses replaced by psame_inode.
Texinfo 7.2 began warning about the '.info' suffix in the manual names
passed to @xref and similar commands. They eventually plan to stop
stripping the '.info' suffix internally which will lead to broken links
in the manuals without this change.
* doc/tar.texi (files): Remove '.info' suffix from manual name.
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.
* src/incremen.c: Include flexmember.h.
(struct dumpdir): contents is now a flexible member, not a pointer.
This is more idiomatic and slightly more efficient.
(dumpdir_create0): Adjust to the new struct dumpdir layout.
* src/buffer.c (check_compressed_archive):
* src/list.c (read_header, decode_header):
Use memcmp, not strcmp, when looking for magic strings in
headers, since input headers are not guaranteed to be
strings and strcmp has undefined behavior otherwise.
Problem with extract_file reported by Kirill Furman in:
https://lists.gnu.org/r/bug-tar/2025-07/msg00003.html
Since the UBSan thing seems to be a recurring issue,
I fixed other instances of the problem that I found.
Also, I noticed that the same line of code had another failure to
conform to C23’s rules for pointers (an alignment issue not caught
by UBSan), so I fixed that too. None of these issues matter on
practical production hosts.
* src/common.h (charptr): New function.
* src/buffer.c (available_space_after, short_read, flush_archive)
(backspace_output, try_new_volume, simple_flush_read)
(_gnu_flush_read, _gnu_flush_write):
* src/compare.c (read_and_process):
* src/create.c (write_eot, write_gnu_long_link)
(dump_regular_file, dump_dir0):
* src/extract.c (extract_file):
* src/incremen.c (get_gnu_dumpdir):
* src/list.c (read_header):
* src/sparse.c (sparse_dump_region, sparse_extract_region):
* src/system.c (sys_write_archive_buffer)
(sys_child_open_for_compress, sys_child_open_for_uncompress):
* src/update.c (append_file, update_archive):
Use it.
* src/buffer.c (set_next_block_after): Arg is now void *,
not union block *, since it need not be a valid union block * pointer
and this can matter on unusual or debugging implementations.
Turn a loop into an if so that the code is O(1) not O(N).
Problem reported by Kirill Furman in:
https://lists.gnu.org/r/bug-tar/2025-06/msg00002.html
* src/buffer.c (short_read): Use (char *) record_start,
instead of record_start->buffer, to avoid undefined behavior
accessing past end of buffer. In practice the undefined
behavior is harmless unless running with -fsanitize=undefined
or a similarly-picky implementation.
* src/names.c (namelist_match_from): New function.
(namelist_match): Rewrite as a wrapper over it.
(register_match): New function.
(name_match)" Update all possible matches in the name list.
* tests/extrac29.at: New test.
* tests/Makefile.am: Add new test.
* tests/testsuite.at: Likewise.
* src/list.c (skim_member): Recognize directory members using
the same rules as during extraction.
* tests/skipdir.at: New testcase.
* tests/testsuite.at: Add new test.
* tests/Makefile.am: Likewise.
Per POSIX, the type of the file to be created should be OR'ed to the
`mode` argument of mknodat().
However, set_xattr() creates an empty file using mknodat() and does not
do that.
E.g. Linux kernel considers zero type as S_IFREG, so the code works on
most systems.
However, e.g. fakeroot, at least up to the current v1.36, does not
consider 0 as S_IFREG, instead creating an invalid file, causing tar to
enter an infinite retry loop when trying to create a file with xattrs
under fakeroot.
Since set_xattr is used only when extracting regular files, fix that
by ORing its mode argument with S_IFREG.
Copyright-paperwork-exempt: Yes
Detailed bug report: https://savannah.gnu.org/bugs/index.php?66774
* src/extract.c (update_interdir_set_stat): New function.
(extract_dir): If the directory already exists, check if it
has been created as intermediate directory earlier. If so,
update its delayed_set_stat data from archive.
* tests/Makefile.am: Add new testcase.
* tests/testsuite.at: Add new testcase.
* tests/extrac28.at: New file.
