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Автор SHA1 Сообщение Дата
Nicolas Pitre 03aa8ff3be Nicolas Pitre has a new email address
Due to problems at cam.org, my nico@cam.org email address is no longer
valid.  From now on, nico@fluxnic.net should be used instead.

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-09-14 02:23:36 -07:00
Linus Torvalds 48fb7deb5b Fix big left-shifts of unsigned char
Shifting 'unsigned char' or 'unsigned short' left can result in sign
extension errors, since the C integer promotion rules means that the
unsigned char/short will get implicitly promoted to a signed 'int' due to
the shift (or due to other operations).

This normally doesn't matter, but if you shift things up sufficiently, it
will now set the sign bit in 'int', and a subsequent cast to a bigger type
(eg 'long' or 'unsigned long') will now sign-extend the value despite the
original expression being unsigned.

One example of this would be something like

	unsigned long size;
	unsigned char c;

	size += c << 24;

where despite all the variables being unsigned, 'c << 24' ends up being a
signed entity, and will get sign-extended when then doing the addition in
an 'unsigned long' type.

Since git uses 'unsigned char' pointers extensively, we actually have this
bug in a couple of places.

I may have missed some, but this is the result of looking at

	git grep '[^0-9 	][ 	]*<<[ 	][a-z]' -- '*.c' '*.h'
	git grep '<<[   ]*24'

which catches at least the common byte cases (shifting variables by a
variable amount, and shifting by 24 bits).

I also grepped for just 'unsigned char' variables in general, and
converted the ones that most obviously ended up getting implicitly cast
immediately anyway (eg hash_name(), encode_85()).

In addition to just avoiding 'unsigned char', this patch also tries to use
a common idiom for the delta header size thing. We had three different
variations on it: "& 0x7fUL" in one place (getting the sign extension
right), and "& ~0x80" and "& 0x7f" in two other places (not getting it
right). Apart from making them all just avoid using "unsigned char" at
all, I also unified them to then use a simple "& 0x7f".

I considered making a sparse extension which warns about doing implicit
casts from unsigned types to signed types, but it gets rather complex very
quickly, so this is just a hack.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-06-18 09:22:46 -07:00
Nicolas Pitre 57b73150c4 make patch_delta() error cases a bit more verbose
It is especially important to distinguish between a malloc() failure
from all the other cases.  An out of memory condition is much less
worrisome than a compatibility/corruption problem.

Also make test-delta compilable again.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-12-18 15:30:17 -08:00
Florian Forster 1d7f171c3a Remove all void-pointer arithmetic.
ANSI C99 doesn't allow void-pointer arithmetic. This patch fixes this in
various ways. Usually the strategy that required the least changes was used.

Signed-off-by: Florian Forster <octo@verplant.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-06-20 01:59:46 -07:00
Nicolas Pitre 08abe669c0 split the diff-delta interface
This patch splits the diff-delta interface into index creation and delta
generation.  A wrapper is provided to preserve the diff-delta() call.

This will allow for an optimization in pack-objects.c where the source
object could be fixed and a full window of objects tentatively tried
against
that same source object without recomputing the source index each time.

This patch only restructure things, plus a couple cleanups for good
measure. There is no performance change yet.

Signed-off-by: Nicolas Pitre <nico@cam.org>
2006-04-24 22:27:33 -07:00
Nicolas Pitre 8960844a78 check patch_delta bounds more carefully
Let's avoid going south with invalid delta data.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-04-07 16:31:20 -07:00
Nicolas Pitre d60fc1c864 remove delta-against-self bit
After experimenting with code to add the ability to encode a delta
against part of the deltified file, it turns out that resulting packs
are _bigger_ than when this ability is not used.  The raw delta output
might be smaller, but it doesn't compress as well using gzip with a
negative net saving on average.

Said bit would in fact be more useful to allow for encoding the copying
of chunks larger than 64KB providing more savings with large files.
This will correspond to packs version 3.

While the current code still produces packs version 2, it is made future
proof so pack versions 2 and 3 are accepted.  Any pack version 2 are
compatible with version 3 since the redefined bit was never used before.
When enough time has passed, code to use that bit to produce version 3
packs could be added.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 21:06:38 -08:00
Sergey Vlasov ce726ec8d8 [PATCH] NUL terminate the object data in patch_delta()
At least pretty_print_commit() expects to get NUL-terminated commit data to
work properly.  unpack_sha1_rest(), which reads objects from separate files,
and unpack_non_delta_entry(), which reads non-delta-compressed objects from
pack files, already add the NUL byte after the object data, but patch_delta()
did not do it, which caused problems with, e.g., git-rev-list --pretty when
there are delta-compressed commit objects.

Signed-off-by: Sergey Vlasov <vsu@altlinux.ru>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-09-04 10:28:43 -07:00
Nicolas Pitre dcde55bc58 [PATCH] assorted delta code cleanup
This is a wrap-up patch including all the cleanups I've done to the
delta code and its usage.  The most important change is the
factorization of the delta header handling code.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-29 09:11:38 -07:00
Nicolas Pitre 69a2d426f0 [PATCH] denser delta header encoding
Since the delta data format is not tied to any actual git object
anymore, now is the time to add a small improvement to the delta data
header as it is been done for packed object header.  This patch allows
for reducing the delta header of about 2 bytes and makes for simpler
code.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-28 21:38:47 -07:00
Nicolas Pitre a310d43494 [PATCH] Deltification library work by Nicolas Pitre.
This patch adds the basic library functions to create and replay delta
information.  Also included is a test-delta utility to validate the
code.

diff-delta was based on LibXDiff written by Davide Libenzi

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-19 08:56:22 -07:00