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

Of course, it still ignores the fact that not all grep's support some of
the flags like -F/-L/-A/-C etc, but for those cases, the external grep
itself will happily just say "unrecognized option -F" or similar.

So with this change, "git grep" should handle all the flags the native
grep handles, which is really quite fine. We don't _need_ to expose
anything more, and if you do want our extensions, you can get them with
"--uncached" and an up-to-date index.

No configuration necessary, and we automatically take advantage of any
native grep we have, if possible.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This reverts 518920b7 commit.
Linus has a more portable alternative.

Some implementations do not know what to do with -H; define
NO_H_OPTION_IN_GREP when you build git if your grep lacks -H.

Most of the time, it can be worked around by prepending
/dev/null to the argument list, but that causes -L and -c to
slightly misbehave (they both expose /dev/null is given), so
when these options are given, do not run external grep that does
not understand -H.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The "-F" flag apparently got mis-translated due to some over-eager
copy-paste work into a duplicate "-H" when using the external grep.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The earlier one to use external grep missed some often used options.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

It's not perfect, but it gets the "git grep some-random-string" down to
the good old half-a-second range for the kernel.

It should convert more of the argument flags for "grep", that should be
trivial to expand (I did a few just as an example). It should also bother
to try to return the right "hit" value (which it doesn't, right now - the
code is kind of there, but I didn't actually bother to do it _right_).

Also, right now it _just_ limits by number of arguments, but it should
also strictly speaking limit by total argument size (ie add up the length
of the filenames, and do the "exec_grep()" flush call if it's bigger than
some random value like 32kB).

But I think that it's _conceptually_ doing all the right things, and it
seems to work. So maybe somebody else can do some of the final polish.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

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

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

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

I mistyped

	git grep next -e '"^@"' '*.c'

and got many hits that contain "next" without complaint.
Obviously what I meant to say was:

	git grep -e '"^@"' next -- '*.c'

This tightens the argument parsing rule a bit:

 - All "grep" parameters should come first;

 - If there is no -e nor -f to specify pattern, the first non
   option string is the parameter;

 - After that, zero or more revs can follow.

 - An optional '--' can be present, and is skipped.

 - All the rest are pathspecs.  If '--' was not there, they must
   be paths that exist in the working tree.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

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

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

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

It barfed and segfaulted with an incomplete line.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The earlier code descended into Documentation/technical when
given "Documentation/how*" as the pattern, which was too loose.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

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

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

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

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

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

Grep may want to grok multiple revisions, but it does not make
much sense to walk revisions while doing so.  This stops calling
the code to parse parameters for the revision walker.  The
parameter parsing for the optional "-e" option becomes a lot
simpler with it as well.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

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

This tweaks the pathspec wildcard used in builtin-grep to match
that of ls-files.  With this:

	git grep -e DEBUG -- '*/Kconfig*'

would work like the shell script version, and you could even do:

	git grep -e DEBUG --cached -- '*/Kconfig*' ;# from index
	git grep -e DEBUG v2.6.12 -- '*/Kconfig*' ;# from rev
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This attempts to set up built-in "git grep" to further reduce
our dependence on the shell, while at the same time optionally
allowing to run grep against object database.  You could do
funky things like these:

	git grep --cached -e pattern	;# grep from index
	git grep -e pattern master	;# or in a rev
	git grep -e pattern master next ;# or in multiple revs
	git grep -e pattern pu^@	;# even like this with an
					;# extension from another topic ;-)
	git grep -e pattern master..next ;# or even from rev ranges
	git grep -e pattern master~20:Documentation
					;# or an arbitrary tree
	git grep -e pattern next:git-commit.sh
        				;# or an arbitrary blob

Right now, it does not understand and/or obey many options grep
should accept, and the pattern must be given with -e option due
to the way the parameter parser is structured, both of which
obviously need to be fixed for usability.

But this is going in the right direction.  The shell script
version is one of the worst Portability offender in the git
barebone Porcelainish; it uses xargs -0 to pass paths around and
shell arrays to sift flags and parameters.
Signed-off-by: NJunio C Hamano <junkio@cox.net>