The function write_extended_header() only ever returns 0. Simplify it and its caller by dropping its return value, like we did with write_global_extended_header() earlier. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
We never do any error checks, and so never return anything but "0". Let's just drop this to simplify the code. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
The ustar format represents timestamps as seconds since the epoch, but only has room to store 11 octal digits. To express anything larger, we need to use an extended header. This is exactly the same case we fixed for the size field in the previous commit, and the solution here follows the same pattern. This is even mentioned as an issue in f2f0267 (archive-tar: use xsnprintf for trivial formatting, 2015-09-24), but since it only affected things far in the future, it wasn't deemed worth dealing with. But note that my calculations claiming thousands of years were off there; because our xsnprintf produces a NUL byte, we only have until the year 2242 to fix this. Given that this is just around the corner (geologically speaking, anyway), and because it's easy to fix, let's just make it work. Unlike the previous fix for "size", where we had to write an individual extended header for each file, we can write one global header (since we have only one mtime for the whole archive). There's a slight bit of trickiness there. We may already be writing a global header with a "comment" field for the commit sha1. So we need to write our new field into the same header. To do this, we push the decision of whether to write such a header down into write_global_extended_header(), which will now assemble the header as it sees fit, and will return early if we have nothing to write (in practice, we'll only have a large mtime if it comes from a commit, but this makes it also work if you set your system clock ahead such that time() returns a huge value). Note that we don't (and never did) handle negative timestamps (i.e., before 1970). This would probably not be too hard to support in the same way, but since git does not support negative timestamps at all, I didn't bother here. After writing the extended header, we munge the timestamp in the ustar headers to the maximum-allowable size. This is wrong, but it's the least-wrong thing we can provide to a tar implementation that doesn't understand pax headers (it's also what GNU tar does). Helped-by: René Scharfe <l.s.r@web.de> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
The ustar format has a fixed-length field for the size of
each file entry which is supposed to contain up to 11 bytes
of octal-formatted data plus a NUL or space terminator.
These means that the largest size we can represent is
077777777777, or 1 byte short of 8GB. The correct solution
for a larger file, according to POSIX.1-2001, is to add an
extended pax header, similar to how we handle long
filenames. This patch does that, and writes zero for the
size field in the ustar header (the last bit is not
mentioned by POSIX, but it matches how GNU tar behaves with
--format=pax).
This should be a strict improvement over the current
behavior, which is to die in xsnprintf with a "BUG".
However, there's some interesting history here.
Prior to f2f0267 (archive-tar: use xsnprintf for trivial
formatting, 2015-09-24), we silently overflowed the "size"
field. The extra bytes ended up in the "mtime" field of the
header, which was then immediately written itself,
overwriting our extra bytes. What that means depends on how
many bytes we wrote.
If the size was 64GB or greater, then we actually overflowed
digits into the mtime field, meaning our value was
effectively right-shifted by those lost octal digits. And
this patch is again a strict improvement over that.
But if the size was between 8GB and 64GB, then our 12-byte
field held all of the actual digits, and only our NUL
terminator overflowed. According to POSIX, there should be a
NUL or space at the end of the field. However, GNU tar seems
to be lenient here, and will correctly parse a size up 64GB
(minus one) from the field. So sizes in this range might
have just worked, depending on the implementation reading
the tarfile.
This patch is mostly still an improvement there, as the 8GB
limit is specifically mentioned in POSIX as the correct
limit. But it's possible that it could be a regression
(versus the pre-f2f0267 state) if all of the following are
true:
1. You have a file between 8GB and 64GB.
2. Your tar implementation _doesn't_ know about pax
extended headers.
3. Your tar implementation _does_ parse 12-byte sizes from
the ustar header without a delimiter.
It's probably not worth worrying about such an obscure set
of conditions, but I'm documenting it here just in case.
Helped-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The ustar format only has room for 11 (or 12, depending on
some implementations) octal digits for the size and mtime of
each file. For values larger than this, we have to add pax
extended headers to specify the real data, and git does not
yet know how to do so.
Before fixing that, let's start off with some test
infrastructure, as designing portable and efficient tests
for this is non-trivial.
We want to use the system tar to check our output (because
what we really care about is interoperability), but we can't
rely on it:
1. being able to read pax headers
2. being able to handle huge sizes or mtimes
3. supporting a "t" format we can parse
So as a prerequisite, we can feed the system tar a reference
tarball to make sure it can handle these features. The
reference tar here was created with:
dd if=/dev/zero seek=64G bs=1 count=1 of=huge
touch -d @68719476737 huge
tar cf - --format=pax |
head -c 2048
using GNU tar. Note that this is not a complete tarfile, but
it's enough to contain the headers we want to examine.
Likewise, we need to convince git that it has a 64GB blob to
output. Running "git add" on that 64GB file takes many
minutes of CPU, and even compressed, the result is 64MB. So
again, I pre-generated that loose object, and then took only
the first 2k of it. That should be enough to generate 2MB of
data before hitting an inflate error, which is plenty for us
to generate the tar header (and then die of SIGPIPE while
streaming the rest out).
The tests are split so that we test as much as we can even
with an uncooperative system tar. This actually catches the
current breakage (which is that we die("BUG") trying to
write the ustar header) on every system, and then on systems
where we can, we go farther and actually verify the result.
Helped-by: Robin H. Johnson <robbat2@gentoo.org>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is sometimes useful to be able to read exactly N bytes from a
pipe. Doing this portably turns out to be surprisingly difficult
in shell scripts.
We want a solution that:
- is portable
- never reads more than N bytes due to buffering (which
would mean those bytes are not available to the next
program to read from the same pipe)
- handles partial reads by looping until N bytes are read
(or we see EOF)
- is resilient to stray signals giving us EINTR while
trying to read (even though we don't send them, things
like SIGWINCH could cause apparently-random failures)
Some possible solutions are:
- "head -c" is not portable, and implementations may
buffer (though GNU head does not)
- "read -N" is a bash-ism, and thus not portable
- "dd bs=$n count=1" does not handle partial reads. GNU dd
has iflags=fullblock, but that is not portable
- "dd bs=1 count=$n" fixes the partial read problem (all
reads are 1-byte, so there can be no partial response).
It does make a lot of write() calls, but for our tests
that's unlikely to matter. It's fairly portable. We
already use it in our tests, and it's unlikely that
implementations would screw up any of our criteria. The
most unknown one would be signal handling.
- perl can do a sysread() loop pretty easily. On my Linux
system, at least, it seems to restart the read() call
automatically. If that turns out not to be portable,
though, it would be easy for us to handle it.
That makes the perl solution the least bad (because we
conveniently omitted "length of code" as a criterion).
It's also what t9300 is currently using, so we can just pull
the implementation from there.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
l10n-2.9.0-rc0 * tag 'l10n-2.9.0-rc0' of git://github.com/git-l10n/git-po: l10n: ko.po: Update Korean translation l10n: ru.po: update Russian translation l10n: de.po: translate 104 new messages l10n: zh_CN: review for git v2.9.0 l10n round 1 l10n: zh_CN: for git v2.9.0 l10n round 1 l10n: pt_PT: update Portuguese translation l10n: pt_PT: update according to git-gui glossary l10n: pt_PT: merge git.pot file l10n: Updated Bulgarian translation of git (2597t,0f,0u) l10n: sv.po: Update Swedish translation (2597t0f0u) l10n: fr.po v2.9.0rnd1 l10n: Updated Vietnamese translation (2597t) l10n: git.pot: v2.9.0 round 1 (104 new, 37 removed) l10n: fr.po Fixed grammar mistake
* 'russian-l10n' of https://github.com/DJm00n/git-po-ru: l10n: ru.po: update Russian translation