xdiff: add hunk_func()

Add a way to register a callback function that is gets passed the
start line and line count of each hunk of a diff.  Only standard
types are used.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
blame: use hunk_func(), part 1

Use blame_chunk_cb() directly as hunk_func() callback, without detour
through xdi_diff_hunks().

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
blame: use hunk_func(), part 2

Use handle_split_cb() directly as hunk_func() callback, without going
through xdi_diff_hunks().

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
blame: factor out helper for calling xdi_diff()

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
xdiff: remove emit_func() and xdi_diff_hunks()

The functions are unused now, remove them.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
xdiff: remove unused functions

The functions xdl_cha_first(), xdl_cha_next() and xdl_atol() are not used
by us.  While removing them increases the difference to the upstream
version of libxdiff, it only adds a bit to the more than 600 differing
lines in xutils.c (mmfile_t management was simplified significantly when
the library was imported initially).  Besides, if upstream modifies these
functions in the future, we won't need to think about importing those
changes, so in that sense it makes tracking modifications easier.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tests: move code to run tests under bash into a helper library

The following patch will add tests for the bash prompt functions as a
new test script, which also has to be run under bash.

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tests: add tests for the bash prompt functions in the completion script

The tests cover the discovery of the '.git' directory in the
__gitdir() function in different scenarios, and the prompt itself,
i.e. branch name, detached heads, operations (rebase, merge,
cherry-pick, bisect), and status indicators (dirty, stash, untracked
files; but not the upstream status).

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
completion: use __gitdir() in _git_log()

The standard way to find out the path to the repository in the
completion script is the __gitdir() helper function, because that
handles the repository path given on the command line (i.e. git
--git-dir=/path/to/repo log --<TAB>).  However, there is one
exception: the completion function for 'git log' still uses 'git
rev-parse --git-dir' directly, and could offer (or not) the '--merge'
option erroneously when the repository is specified on the command
line.

Use __gitdir() there, too.

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
completion: respect $GIT_DIR

The __gitdir() helper function finds out the path of the git
repository by running 'git rev-parse --git-dir'.  However, it has a
shortcut first to avoid the overhead of running a git command in a
subshell when the current directory is at the top of the work tree,
i.e. when it contains a '.git' subdirectory.

If the 'GIT_DIR' environment variable is set then it specifies the
path to the git repository, and the autodetection of the '.git'
directory is not necessary.  However, $GIT_DIR is only taken into
acocunt by 'git rev-parse --git-dir', and the check for the '.git'
subdirectory is performed first, so it wins over the path given in
$GIT_DIR.

There are several completion (helper) functions that depend on
__gitdir(), and when the above case triggers the completion script
will do weird things, like offering refs, aliases, or stashes from a
different repository, or displaying wrong or broken prompt, etc.

So check first whether $GIT_DIR is set, and only proceed with checking
the '.git' directory in the current directory if it isn't.  'git
rev-parse' would also check whether the path in $GIT_DIR is a proper
'.git' directory, i.e. 'HEAD', 'refs/', and 'objects/' are present and
accessible, but we don't have to be that thorough for the bash prompt.
And we've lived with an equally permissive check for '.git' in the
current working directory for years anyway.

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: reformat comment

With the "--reject" option, apply_fragments() can return 0, while marking
the fragment that was rejected as such, and there was a comment for that,
but it was stated rather poorly.

Update the comment and enclose it in a block, as this part will be getting
new code in later patches.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: accept --threeway command line option

This is the beginning of teaching the three-way merge fallback logic "git
am -3" uses to the underlying "git apply".  It only implements the command
line parsing part, and does not do anything interesting yet.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: split load_preimage() helper function out

The function apply_data() gets a patch for a single path, reads the
preimage in core, and applies the change represented in the patch.

Separate out the first part that reads the preimage into a separate
helper function load_preimage().

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: clear_image() clears things a bit more

The clear_image() function did not clear the line table in the image
structure; this does not matter for the current callers, as the function
is only called from the codepaths that deal with binary patches where the
line table is never populated, and the codepaths that do populate the line
table free it themselves.

But it will start to matter when we introduce a codepath to retry a failed
patch, so make sure it clears and frees everything.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: refactor read_file_or_gitlink()

Reading a blob out of the object store does not have to require that the
caller has a cache entry for it.

Create a read_blob_object() helper function that takes the object name and
mode, and use it to reimplement the original function as a thin wrapper to
it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: fall back on three-way merge

Grab the preimage blob the patch claims to be based on out of the object
store, apply the patch, and then call three-way-merge function.

This step does not plug the actual three-way merge logic yet, but we are
getting there.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: plug the three-way merge logic in

When a patch does not apply to what we have, but we know the preimage the
patch was made against, we apply the patch to the preimage to compute what
the patch author wanted the result to look like, and attempt a three-way
merge between the result and our version, using the intended preimage as
the base version.

When we are applying the patch using the index, we would additionally need
to add the object names of these three blobs involved in the merge, which
is not yet done in this step, but we add a field to "struct patch" so that
later write-out step can use it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: register conflicted stages to the index

Now we have all the necessary logic to fall back on three-way merge when
the patch does not cleanly apply, insert the conflicted entries to the
index as appropriate.  This obviously triggers only when the "--index"
option is used.

When we fall back to three-way merge and some of the merges fail, just
like the case where the "--reject" option was specified and we had to
write some "*.rej" files out for unapplicable patches, exit the command
with non-zero status without showing the diffstat and summary.  Otherwise
they would make the list of problematic paths scroll off the display.

This wraps up the series, at least for now.  We might want to also arrange
to call into the rerere machinery to clean things up, but that is left for
later updates.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'nd/i18n-branch-lego' into jch

Fix yet another message construction by concatenating pieces of sentenes,
which is unfriendly to i18n.

Will merge to 'master'.

By Nguyễn Thái Ngọc Duy
* nd/i18n-branch-lego:
  branch: remove lego in i18n tracking info strings
Merge branch 'jk/maint-reflog-walk-count-vs-time' (early part) into jch

By Jeff King
* 'jk/maint-reflog-walk-count-vs-time' (early part):
  reflog-walk: always make HEAD@{0} show indexed selectors
  reflog-walk: clean up "flag" field of commit_reflog struct
  log: respect date_mode_explicit with --format:%gd
  t1411: add more selector index/date tests