Some file systems that can host git repositories and their working copies
do not support symbolic links. But then if the repository contains a symbolic
link, it is impossible to check out the working copy.

This patch enables partial support of symbolic links so that it is possible
to check out a working copy on such a file system.  A new flag
core.symlinks (which is true by default) can be set to false to indicate
that the filesystem does not support symbolic links. In this case, symbolic
links that exist in the trees are checked out as small plain files, and
checking in modifications of these files preserve the symlink property in
the database (as long as an entry exists in the index).

Of course, this does not magically make symbolic links work on such defective
file systems; hence, this solution does not help if the working copy relies
on that an entry is a real symbolic link.
Signed-off-by: NJohannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

diff sets the exit status to 0 when no changes were found, to 1
when changes were found, and 2 means error.

We imitate this to be able to use "git diff" in the test scripts.
(Actually, keeping in line with the rest of git, -1 is returned
on error, which corresponds to an exit status 255).

To find out if the diff is not empty, a member called
"found_changes" was introduced in struct diff_options, which is
set in builtin_diff() and fn_out_consume().
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

"git-diff-files --cc" to show conflicts during merge did not pass
the correct mode information for the working tree down, and showed
bogus combined diff.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

With this flag and given two paths, git-diff-files behaves as a GNU diff
lookalike (plus the git goodies like --check, colour, etc.).  This flag
is also available in git-diff.  It also works outside of a git repository.

In addition, if git-diff{,-files} is called without revision or stage
parameter, and with exactly two paths at least one of which is not tracked,
the default is --no-index.

So, you can now say

	git diff /etc/inittab /etc/fstab

and it actually works!

This also unifies the duplicated argument parsing between cmd_diff_files()
and builtin_diff_files().
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

They used to open and read index themselves, but they now expect
their callers to do so.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

When we do not trust executable bit from lstat(2), we copied
existing ce_mode bits without checking if the filesystem object
is a regular file (which is the only thing we apply the "trust
executable bit" business) nor if the blob in the index is a
regular file (otherwise, we should do the same as registering a
new regular file, which is to default non-executable).

Noticed by Johannes Sixt.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Warning: this changes the semantics.

This makes "git blame" without any positive rev to start digging
from the working tree copy, which is made into a fake commit
whose sole parent is the HEAD.

It also adds --contents <file> option to pretend as if the
working tree copy has the contents of the named file.  You can
use '-' to make the command read from the standard input.

If you want the command to start annotating from the HEAD
commit, you need to explicitly give HEAD parameter.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This updates the way diffcore represents an unmerged pair
somewhat.  It used to be that entries with mode=0 on both sides
were used to represent an unmerged pair, but now it has an
explicit flag.  This is to allow diff-index --cached to report
the entry from the tree when the path is unmerged in the index.

This is used in updating "git reset <tree> -- <path>" to restore
absense of the path in the index from the tree.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This implements a 3-way diff between the HEAD commit, the state in the
index, and the working directory.  This is like the n-way diff for a
merge, and uses much of the same code.  It is invoked with the -c flag
to git-diff-index, which it already accepted and did nothing with.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

In the same spirit as hashcmp() and hashcpy().
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This abstracts away the size of the hash values when copying them
from memory location to memory location, much as the introduction
of hashcmp abstracted away hash value comparsion.

A few call sites were using char* rather than unsigned char* so
I added the cast rather than open hashcpy to be void*.  This is a
reasonable tradeoff as most call sites already use unsigned char*
and the existing hashcmp is also declared to be unsigned char*.

[jc: Splitted the patch to "master" part, to be followed by a
 patch for merge-recursive.c which is not in "master" yet.

 Fixed the cast in the latter hunk to combine-diff.c which was
 wrong in the original.

 Also converted ones left-over in combine-diff.c, diff-lib.c and
 upload-pack.c ]
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Introduces global inline:

	hashcmp(const unsigned char *sha1, const unsigned char *sha2)

Uses memcmp for comparison and returns the result based on the length of
the hash name (a future runtime decision).
Acked-by: NAlex Riesen <raa.lkml@gmail.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

We've had this notion of a "object_list" for a long time, which eventually
grew a "name" member because some users (notably git-rev-list) wanted to
name each object as it is generated.

That object_list is great for some things, but it isn't all that wonderful
for others, and the "name" member is generally not used by everybody.

This patch splits the users of the object_list array up into two: the
traditional list users, who want the list-like format, and who don't
actually use or want the name. And another class of users that really used
the list as an extensible array, and generally wanted to name the objects.

The patch is fairly straightforward, but it's also biggish. Most of it
really just cleans things up: switching the revision parsing and listing
over to the array makes things like the builtin-diff usage much simpler
(we now see exactly how many members the array has, and we don't get the
objects reversed from the order they were on the command line).

One of the main reasons for doing this at all is that the malloc overhead
of the simple object list was actually pretty high, and the array is just
a lot denser. So this patch brings down memory usage by git-rev-list by
just under 3% (on top of all the other memory use optimizations) on the
mozilla archive.

It does add more lines than it removes, and more importantly, it adds a
whole new infrastructure for maintaining lists of objects, but on the
other hand, the new dynamic array code is pretty obvious. The change to
builtin-diff-tree.c shows a fairly good example of why an array interface
is sometimes more natural, and just much simpler for everybody.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Since structures with `flexible array members' are an incomplete datatype ANSI
C99 forbids creating instances of them. This patch removes such an instance
from `diff-lib.c' and replaces it with a pointer to a `struct
combine_diff_path'. Since all neccessary memory is allocated at once the number
of calls to `xmalloc' is not increased.
Signed-off-by: NFlorian Forster <octo@verplant.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

"diff-index -m" does not mean "do not ignore merges", but means
"pretend missing files match the index".

The previous round tried to address this, but failed because
setup_revisions() ate "-m" flag before the caller had a chance
to intervene.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The second installment to libify diff brothers.  The pathname
arguments are checked more strictly than before because we now
use the revision.c::setup_revisions() infrastructure.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This is the first installment to libify diff brothers.

The updated diff-files uses revision.c::setup_revisions()
infrastructure to parse its command line arguments, which means
the pathname arguments are checked more strictly than before.
The tests are adjusted to separate possibly missing paths from
the rest of arguments with double-dashes, to show the kosher
way.

As Linus pointed out, renaming diff.c to diff-lib.c was simply
stupid, so I am renaming it back.  The new diff-lib.c is to
contain pieces extracted from diff brothers.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

When a verbatim rename or copy is detected, we did not show
anything on the "diff --stat" for the filepair.  This makes it
to show the rename information.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Now I am not doing any real "git-diff in C" yet, but this would
help before doing so.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Set maximum filename length for binary files so that scaling won't be
triggered and result in invalid string access.
Signed-off-by: NJonas Fonseca <fonseca@diku.dk>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Just like "patch" format always needs recursive, "diffstat"
format does not make sense without setting recursive.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Just like "patch" format always needs recursive, "diffstat"
format does not make sense without setting recursive.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

With this option, git prepends a diffstat in front of the patch.

Since I really, really do not know what a diffstat of a combined diff
("merge diff") should look like, the diffstat is not generated for these.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Signed-off-by: NJunio C Hamano <junkio@cox.net>

I missed that "git-diff-* --stat" spits out three-dash separator
on its own without being asked.  Remove it.

When we output commit log followed by diff, perhaps --patch-with-stat,
for downstream consumer, we _would_ want the three-dash between
the message and the diff material, but that logic belongs to the
caller, not diff generator.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Signed-off-by: NJunio C Hamano <junkio@cox.net>

... and a fix for an invalid free():
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Now, you can say "git diff --stat" (to get an idea how many changes are
uncommitted), or "git log --stat".
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

More friendly for human reading I believe, and possibly friendlier to some
parsers (although only by an epsilon).
Signed-off-by: NPetr Baudis <pasky@suse.cz>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This new flag outputs the diff-raw output and diff-patch output
at the same time.  Requested by Cogito.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Nobody except diff-stages used it -- the callers instead filtered
the input to diffcore themselves.  Make diff-stages do that as
well and retire diffcore-pathspec.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

We did not read in the file data before emitting the
total-rewrite diff.  Noticed by Pasky.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

We were leaking filepairs when output-format was set to
NO_OUTPUT.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-diff-* --pickaxe-regex will change the -S pickaxe to match
POSIX extended regular expressions instead of fixed strings.

The regex.h library is a rather stupid interface and I like pcre too, but
with any luck it will be everywhere we will want to run Git on, it being
POSIX.2 and all. I'm not sure if we can expect platforms like AIX to
conform to POSIX.2 or if win32 has regex.h. We might add a flag to
Makefile if there is a portability trouble potential.
Signed-off-by: NPetr Baudis <pasky@suse.cz>

Introduce tree-walk.[ch] and move "struct tree_desc" and
associated functions from various places.

Rename DIFF_FILE_CANON_MODE(mode) macro to canon_mode(mode) and
move it to cache.h.  This macro returns the canonicalized
st_mode value in the host byte order for files, symlinks and
directories -- to be compared with a tree_desc entry.
create_ce_mode(mode) in cache.h is similar but is intended to be
used for index entries (so it does not work for directories) and
returns the value in the network byte order.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The speed of the built-in diff generator is nice; but the function names
shown by `diff -p' are /really/ nice.  And I hate having to choose.  So,
we hack xdiff to find the function names and print them.

xdiff has grown a flag to say whether to dig up the function names.  The
builtin_diff function passes this flag unconditionally.  I suppose it
could parse GIT_DIFF_OPTS, but it doesn't at the moment.  I've also
reintroduced the `function name' into the test suite, from which it was
removed in commit 3ce8f089.

The function names are parsed by a particularly stupid algorithm at the
moment: it just tries to find a line in the `old' file, from before the
start of the hunk, whose first character looks plausible.  Still, it's
most definitely a start.
Signed-off-by: NMark Wooding <mdw@distorted.org.uk>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This stops using temporary files when we are using the built-in
diff (including the complete rewrite).
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This fixes up a couple of minor issues with the real built-in
diff to be more usable:

 - Omit ---/+++ header unless we emit diff output;

 - Detect and punt binary diff like GNU does;

 - Honor GIT_DIFF_OPTS minimally (only -u<number> and
   --unified=<number> are currently supported);

 - Omit line count of 1 from "@@ -l,k +m,n @@" hunk header
   (i.e. when k == 1 or n == 1)

 - Adjust testsuite for the lack of -p support.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This uses a simplified libxdiff setup to generate unified diffs _without_
doing  fork/execve of GNU "diff".

This has several huge advantages, for example:

Before:

	[torvalds@g5 linux]$ time git diff v2.6.16.. > /dev/null

	real    0m24.818s
	user    0m13.332s
	sys     0m8.664s

After:

	[torvalds@g5 linux]$ time git diff v2.6.16.. > /dev/null

	real    0m4.563s
	user    0m2.944s
	sys     0m1.580s

and the fact that this should be a lot more portable (ie we can ignore all
the issues with doing fork/execve under Windows).

Perhaps even more importantly, this allows us to do diffs without actually
ever writing out the git file contents to a temporary file (and without
any of the shell quoting issues on filenames etc etc).

NOTE! THIS PATCH DOES NOT DO THAT OPTIMIZATION YET! I was lazy, and the
current "diff-core" code actually will always write the temp-files,
because it used to be something that you simply had to do. So this current
one actually writes a temp-file like before, and then reads it into memory
again just to do the diff. Stupid.

But if this basic infrastructure is accepted, we can start switching over
diff-core to not write temp-files, which should speed things up even
further, especially when doing big tree-to-tree diffs.

Now, in the interest of full disclosure, I should also point out a few
downsides:

 - the libxdiff algorithm is different, and I bet GNU diff has gotten a
   lot more testing. And the thing is, generating a diff is not an exact
   science - you can get two different diffs (and you will), and they can
   both be perfectly valid. So it's not possible to "validate" the
   libxdiff output by just comparing it against GNU diff.

 - GNU diff does some nice eye-candy, like trying to figure out what the
   last function was, and adding that information to the "@@ .." line.
   libxdiff doesn't do that.

 - The libxdiff thing has some known deficiencies. In particular, it gets
   the "\No newline at end of file" case wrong. So this is currently for
   the experimental branch only. I hope Davide will help fix it.

That said, I think the huge performance advantage, and the fact that it
integrates better is definitely worth it. But it should go into a
development branch at least due to the missing newline issue.

Technical note: this is based on libxdiff-0.17, but I did some surgery to
get rid of the extraneous fat - stuff that git doesn't need, and seriously
cutting down on mmfile_t, which had much more capabilities than the diff
algorithm either needed or used. In this version, "mmfile_t" is just a
trivial <pointer,length> tuple.

That said, I tried to keep the differences to simple removals, so that you
can do a diff between this and the libxdiff origin, and you'll basically
see just things getting deleted. Even the mmfile_t simplifications are
left in a state where the diffs should be readable.

Apologies to Davide, whom I'd love to get feedback on this all from (I
wrote my own "fill_mmfile()" for the new simpler mmfile_t format: the old
complex format had a helper function for that, but I did my surgery with
the goal in mind that eventually we _should_ just do

	mmfile_t mf;

	buf = read_sha1_file(sha1, type, &size);
	mf->ptr = buf;
	mf->size = size;
	.. use "mf" directly ..

which was really a nightmare with the old "helpful" mmfile_t, and really
is that easy with the new cut-down interfaces).

[ Btw, as any hawk-eye can see from the diff, this was actually generated
  with itself, so it is "self-hosting". That's about all the testing it
  has gotten, along with the above kernel diff, which eye-balls correctly,
  but shows the newline issue when you double-check it with "git-apply" ]
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>