Previously, this environment variable was set in the pager_preexec
callback, which is conditionally-compiled only on Unix, because it is not,
and cannot be, called on Windows.

With this patch the env member of struct child_process is used to set
the environment variable, which also works on Windows.

Noticed by Alexey Borzenkov.
Signed-off-by: NJohannes Sixt <j6t@kdbg.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since ea27a18c (spawn pager via run_command interface), the
original git process actually does git work, and the pager
is a child process (actually, on Windows it has always been
that way, since Windows lacks fork). After spawning the
pager, we register an atexit() handler that waits for the
pager to finish.

Unfortunately, that handler does not always run. In
particular, if git is killed by a signal, then we exit
immediately. The calling shell then thinks that git is done;
however, the pager is still trying to run and impact the
terminal. The result can be seen by running a long git
process with a pager (e.g., "git log -p") and hitting ^C.
Depending on your config, you should see the shell prompt,
but pressing a key causes the pager to do any terminal
de-initialization sequence.

This patch just intercepts any death-dealing signals and
waits for the pager before dying. Under typical less
configuration, that means hitting ^C will cause git to stop
generating output, but the pager will keep running.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

An earlier commit 61b80509 (sending errors to stdout under $PAGER,
2008-02-16) avoided losing the error messages that are sent to the
standard error when $PAGER is in effect by dup2'ing fd 2 to the pager.
his way, showing a tag object that points to a bad object:

    $ git show tag-foo

would give the error message to the pager.  However, it was not quite
right if the user did:

    $ git show 2>error.log tag-foo

i.e. use the pager but store the errors in a separate file.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This has two important effects:

 1. The pager is now the _child_ process, instead of the
    parent. This means that whatever spawned git (e.g., the
    shell) will see the exit code of the git process, and
    not the pager.

 2. The mingw and regular code are now unified, which makes
    the setup_pager function much simpler.

There are two caveats:

 1. We used to call execlp directly on the pager, followed
    by trying to exec it via the shall. We now just use the
    shell (which is what mingw has always done). This may
    have different results for pager names which contain
    shell metacharacters.

    It is also slightly less efficient because we
    unnecessarily run the shell; however, pager spawning is
    by definition an interactive task, so it shouldn't be
    a huge problem.

 2. The git process will remain in memory while the user
    looks through the pager. This is potentially wasteful.
    We could get around this by turning the parent into a
    meta-process which spawns _both_ git and the pager,
    collects the exit status from git, waits for both to
    end, and then exits with git's exit code.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since we have neither fork() nor exec(), we have to spawn the pager and
feed it with the program's output.
Signed-off-by: NJohannes Sixt <johannes.sixt@telecom.at>

git_config() only had a function parameter, but no callback data
parameter.  This assumes that all callback functions only modify
global variables.

With this patch, every callback gets a void * parameter, and it is hoped
that this will help the libification effort.
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

If you do this (and you are not an Emacs user who uses PAGER=cat
in your *shell* buffer):

        $ git init
        Initialized empty Git repository in .git/
        $ echo hello world >foo
        $ H=$(git hash-object -w foo)
        $ git tag -a foo-tag -m "Tags $H" $H
        $ echo $H
        3b18e512dba79e4c8300dd08aeb37f8e728b8dad
        $ rm -f .git/objects/3b/18e5*
        $ git show foo-tag
        tag foo-tag
        Tagger: Junio C Hamano <gitster@pobox.com>
        Date:   Sat Feb 16 10:43:23 2008 -0800

        Tags 3b18e512dba79e4c8300dd08aeb37f8e728b8dad

you do not get any indication of error.  If you are careful, you
would notice that no contents from the tagged object is
displayed, but that is about it.  If you run the "show" command
without pager, however, you will see the error:

        $ git --no-pager show foo-tag
        tag foo-tag
        Tagger: Junio C Hamano <gitster@pobox.com>
        Date:   Sat Feb 16 10:43:23 2008 -0800

        Tags 3b18e512dba79e4c8300dd08aeb37f8e728b8dad
        error: Could not read object 3b18e512dba79e4c8300dd08aeb37f8e728b8dad

Because we spawn the pager as the foreground process and feed
its input via pipe from the real command, we cannot affect the
exit status the shell sees from git command when the pager is in
use (I think there is not much gain we can have by working it
around, though).  But at least it may make sense to show the
error message to the user sitting in front of the pager.

[jc: Edgar Toernig suggested a much nicer implementation than
what I originally posted, which I took.]
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When deciding whether or not to turn on automatic color
support, git_config_colorbool checks whether stdout is a
tty. However, because we run a pager, if stdout is not a
tty, we must check whether it is because we started the
pager. This used to be done by checking the pager_in_use
variable.

This variable was set only when the git program being run
started the pager; there was no way for an external program
running git indicate that it had already started a pager.
This patch allows a program to set GIT_PAGER_IN_USE to a
true value to indicate that even though stdout is not a tty,
it is because a pager is being used.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

... since all system headers are pulled in via git-compat-util.h
Signed-off-by: NJohannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

It was very unfortunate that we added core.pager setting to the
configuration file; even when the underlying command does not care
if there is no git repository is involved (think "git diff --no-index"),
the user would now rightfully want the configuration setting to be
honored, which means we would need to read the configuration file before
we launch the pager.

This is a minimum change in the sense that it restores the old
behaviour of not even reading config in setup_git_directory(),
but have the core.pager honored when we know it matters.

Note that this does not cover "git -p --git-dir where command";
the -p option immediately trigger the pager settings before we
even see --git-dir to learn where the configuration file is, so
we will end up reading the configuration from the place where
we would _normally_ find the git repository.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This adds a configuration variable that performs the same function as,
but is overridden by, GIT_PAGER.
Signed-off-by: NBrian Gernhardt <benji@silverinsanity.com>
Acked-by: NJohannes E. Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

If you resize the terminal while less is waiting for input, less
will exit entirely without even showing the output. This is very
noticeable if you do something like "git diff" on a big and
cold-cache tree and git takes a few seconds to think, and then
you resize the window while it's preparing. Boom. No output AT
ALL.

The way to reproduce the problem is to do some pager operation
that takes a while in git, and resizing the window while git is
thinking about the output.  Try

	git diff --stat v2.6.12..

in the kernel tree to do something where it takes a while for git to start
outputting information.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

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

Recent change to paginate "git diff" by default is often irritating
when you do not have any change (or very small change) in your working
tree.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Signed-off-by: NMatthias Lederhofer <matled@gmx.net>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

On one of my systems, the linker is not intelligent enough to link with
pager.o (in libgit.a) when only the variable pager_in_use is needed. The
consequence is that the linker complains about an undefined variable. So,
put the variable into environment.o, where it is linked always.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This allows you to say:

	git -p diff v2.6.16-rc5..

and the command pipes the output of any git command to your pager.

[jc: this resurrects a month old RFC patch with improvement
 suggested by Linus to call it --paginate instead of --less.]
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This patch is a slightly adjusted version of Junio's patch:
http://www.gelato.unsw.edu.au/archives/git/0604/19354.html

However, instead of using a config variable, this patch makes it available
as a diff option.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

When $PAGER is set to 'less -i', we used to fail because we
assumed the $PAGER is a command and simply exec'ed it.

Try exec first, and then run it through shell if it fails.  This
allows even funkier PAGERs like these ;-):

	PAGER='sed -e "s/^/`date`: /" | more'
	PAGER='contrib/colordiff.perl | less -RS'
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Unless the user has a nonstandard "cat" command that does not
meow like a cat, this should not break anything and would save an
extra pipe.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This skips an extra pipe, and helps debugging tremendously.

[jc: PAGER=cat is a questionable hack and should be done as a separate
patch. ]
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This introduces the new function

	void setup_pager(void);

to set up output to be written through a pager applocation.

All in preparation for doing the simple scripts in C.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>