fmt-merge-msg: show those involved in a merged series

As we already walk the history of the branch that gets merged to
come up with a short log, let's label it with names of the primary
authors, so that the user who summarizes the merge can easily give
credit to them in the log message.

Also infer the names of "lieutents" to help integrators at higher
level of the food-chain to give credit to them, by counting:

 * The committer of the 'tip' commit that is merged
 * The committer of merge commits that are merged

Often the first one gives the owner of the history being pulled, but
his last pull from his sublieutenants may have been a fast-forward,
in which case the first one would not be.  The latter rule will
count the integrator of the history, so together it might be a
reasonable heuristics.

There are two special cases:

 - The "author" credit is omitted when the series is written solely
   by the same author who is making the merge. The name can be seen
   on the "Author" line of the "git log" output to view the log
   message anyway.

 - The "lieutenant" credit is omitted when there is only one key
   committer in the merged branch and it is the committer who is
   making the merge. Typically this applies to the case where the
   developer merges his own branch.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
clean: preserve nested git worktree in subdirectories

remove_dir_recursively() has a check to avoid removing the directory it
was asked to remove without recursing into it and report success when the
directory is the top level of a working tree of a nested git repository,
to protect such a repository from "clean -f" (without double -f). If a
working tree of a nested git repository is in a subdirectory of a toplevel
project, however, this protection did not apply by mistake; we forgot to
pass the REMOVE_DIR_KEEP_NESTED_GIT down to the recursive removal
codepath.

This requires us to also teach the higher level not to remove the
directory it is asked to remove, when the recursed invocation did not
remove the directory it was asked to remove due to a nested git
repository, as it is not an error to leave the parent directories of such
a nested repository.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
push: Provide situational hints for non-fast-forward errors

Pushing a non-fast-forward update to a remote repository will result in
an error, but the hint text doesn't provide the correct resolution in
every case. Give better resolution advice in three push scenarios:

1) If you push your current branch and it triggers a non-fast-forward
error, you should merge remote changes with 'git pull' before pushing
again.

2) If you push to a shared repository others push to, and your local
tracking branches are not kept up to date, the 'matching refs' default
will generate non-fast-forward errors on outdated branches. If this is
your workflow, the 'matching refs' default is not for you. Consider
setting the 'push.default' configuration variable to 'current' or
'upstream' to ensure only your current branch is pushed.

3) If you explicitly specify a ref that is not your current branch or
push matching branches with ':', you will generate a non-fast-forward
error if any pushed branch tip is out of date. You should checkout the
offending branch and merge remote changes before pushing again.

Teach transport.c to recognize these scenarios and configure push.c
to hint for them. If 'git push's default behavior changes or we
discover more scenarios, extension is easy. Standardize on the
advice API and add three new advice variables, 'pushNonFFCurrent',
'pushNonFFDefault', and 'pushNonFFMatching'. Setting any of these
to 'false' will disable their affiliated advice. Setting
'pushNonFastForward' to false will disable all three, thus preserving the
config option for users who already set it, but guaranteeing new
users won't disable push advice accidentally.

Based-on-patch-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Christopher Tiwald <christiwald@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
rebase -i: remind that the lines are top-to-bottom

Nelson Benitez Leon opened a discussion with a patch with this in the
note:

    Hi, I was using git rebase -i for some time now and never occured to
    me I could reorder the commit lines to affect the order the commits
    are applied, learnt that recently from a git tutorial.

Nelson's patch was to stress the fact that the lines in the insn sheet can
be re-ordered in a much more verbose way.  Let's add a one-liner reminder
and also remind that the lines in the insn sheet is read from top to
bottom, unlike the "git log" output.

Discussion-triggered-by: Nelson Benitez Leon
Signed-off-by: Junio C Hamano <gitster@pobox.com>
drop casts from users EMPTY_TREE_SHA1_BIN

This macro already evaluates to the correct type, as it
casts the string literal to "unsigned char *" itself
(and callers who want the literal can use the _LITERAL
form).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
make is_empty_blob_sha1 available everywhere

The read-cache implementation defines this static function,
but it is a generally useful concept in git. Let's give
the empty blob the same treatment as the empty tree,
providing both hex and binary forms of the sha1.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
teach diffcore-rename to optionally ignore empty content

Our rename detection is a heuristic, matching pairs of
removed and added files with similar or identical content.
It's unlikely to be wrong when there is actual content to
compare, and we already take care not to do inexact rename
detection when there is not enough content to produce good
results.

However, we always do exact rename detection, even when the
blob is tiny or empty. It's easy to get false positives with
an empty blob, simply because it is an obvious content to
use as a boilerplate (e.g., when telling git that an empty
directory is worth tracking via an empty .gitignore).

This patch lets callers specify whether or not they are
interested in using empty files as rename sources and
destinations. The default is "yes", keeping the original
behavior. It works by detecting the empty-blob sha1 for
rename sources and destinations.

One more flexible alternative would be to allow the caller
to specify a minimum size for a blob to be "interesting" for
rename detection. But that would catch small boilerplate
files, not large ones (e.g., if you had the GPL COPYING file
in many directories).

A better alternative would be to allow a "-rename"
gitattribute to allow boilerplate files to be marked as
such. I'll leave the complexity of that solution until such
time as somebody actually wants it. The complaints we've
seen so far revolve around empty files, so let's start with
the simple thing.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge-recursive: don't detect renames of empty files

Merge-recursive detects renames so that if one side modifies
"foo" and the other side moves it to "bar", the modification
is applied to "bar". However, our rename detection is based
on content analysis, it can be wrong (i.e., two files were
not intended as a rename, but just happen to have the same
or similar content).

This is quite rare if the files actually contain content,
since two unrelated files are unlikely to have exactly the
same content.  However, empty files present a problem, in
that there is nothing to analyze. An uninteresting
placeholder file with zero bytes may or may not be related
to a placeholder file with another name.

The result is that adding content to an empty file may cause
confusion if the other side of a merge removed it; your
content may end up in another random placeholder file that
was added.

Let's err on the side of caution and not consider empty
files as renames. This will cause a modify/delete conflict
on the merge, which will let the user sort it out
themselves.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
combine-diff: fix loop index underflow

If both la and context are zero at the start of the loop, la wraps around
and we end up reading from memory far away.  Skip the loop in that case
instead.

Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
configure: move definitions of private m4 macros before AC_INIT invocation

This way, no spurious comments nor whitespace will be propagated in the
generated configure script.

This change is a pure code movement (plus addition of a comment line).

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
configure: avoid some code repetitions thanks to m4_{push,pop}def

This change is just cosmetic, and should cause no semantic change, nor
any change in the generated configure script.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
configure: be more idiomatic

Lots of code in Git's configure.ac doesn't follow the typical formatting,
idioms and best practices for Autoconf input files.  Improve the situation.

There are probably many more similar improvements to be done, but trying
to clump all of them in a single change would make it unreviewable, so we
content ourselves with a partial improvement.

This change is just cosmetic, and should cause no semantic change.

The most relevant of the changes introduced by this patch are:

 - Do not add trailing '\' characters for line continuation where they
   are not truly needed.

 - In several (but not all) macro calls, properly quote the arguments.

 - Few cosmetic changes in spacing and comments.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
clean up struct ref's nonfastforward field

Each ref structure contains a "nonfastforward" field which
is set during push to show whether the ref rewound history.
Originally this was a single bit, but it was changed in
f25950f (push: Provide situational hints for non-fast-forward
errors) to an enum differentiating a non-ff of the current
branch versus another branch.

However, we never actually set the member according to the
enum values, nor did we ever read it expecting anything but
a boolean value. But we did use the side effect of declaring
the enum constants to store those values in a totally
different integer variable. The code as-is isn't buggy, but
the enum declaration inside "struct ref" is somewhat
misleading.

Let's convert nonfastforward back into a single bit, and
then define the NON_FF_* constants closer to where they
would be used (they are returned via the "int *nonfastforward"
parameter to transport_push, so we can define them there).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
checkout: suppress tracking message with "-q"

Like the "switched to..." message (which is already
suppressed by "-q"), this message is purely informational.
Let's silence it if the user asked us to be quiet.

This patch is slightly more than a one-liner, because we
have to teach create_branch to propagate the flag all the
way down to install_branch_config.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
teach "git branch" a --quiet option

There's currently no way to suppress the informational
"deleted branch..." or "set up tracking..." messages.  This
patch provides a "-q" option to do so.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
am -3: list the paths that needed 3-way fallback

When applying a patch that was based on an older release with "am -3", I
often wonder changes to which files need to be reviewed with extra care to
spot mismerges, but there is no good indication.

The paths that needed 3-way fallback can easily be obtained by comparing
the synthesized (partial) base tree and the current HEAD and noticing only
additions and modifications (removals only show the sparseness of the fake
ancestor tree, which is not useful information at all).  List them in the
usual --name-status format.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
am: support --include option

am supports a number of pass-through options
to apply, like --exclude and --directory. Add
--include to this list.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
gitweb: add `status` headers to git_feed() responses.

The git_feed() method was not setting a `Status` header unless it was
responding to an If-Modified-Since request with `304 Not Modified`.
Now, when it is serving successful responses, it sets status to `200
OK`.

Signed-off-by: W Trevor King <wking@drexel.edu>
Acked-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
gitweb: refactor If-Modified-Since handling

The current gitweb only generates Last-Modified and handles
If-Modified-Since headers for the git_feed action.  This patch breaks
the Last-Modified and If-Modified-Since handling code out from
git_feed into a new function exit_if_unmodified_since.  This makes the
code easy to reuse for other actions.

Only gitweb actions which can easily calculate a modification time
should use exit_if_unmodified_since, as the goal is to balance local
processing time vs. upload bandwidth.

Signed-off-by: W Trevor King <wking@drexel.edu>
Acked-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
gitweb: add If-Modified-Since handling to git_snapshot().

Because snapshots can be large, you can save some bandwidth by
supporting caching via If-Modified-Since.  This patch adds support for
the i-m-s request to git_snapshot() if the request is a commit.
Requests for snapshots of trees, which lack well defined timestamps,
are still handled as they were before.

Signed-off-by: W Trevor King <wking@drexel.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>