dir.c: use the cache_* macro to access the current index

These codepaths always start from the_index and use index_*
functions, but there is no reason to do so.  Use the compatibility
cache_* macro to access the current in-core index like everybody
else.

While at it, fix typo in the comment for a function to check if a
path within a directory appears in the index.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
ls-files -k: a directory only can be killed if the index has a non-directory

"ls-files -o" and "ls-files -k" both traverse the working tree down
to find either all untracked paths or those that will be "killed"
(removed from the working tree to make room) when the paths recorded
in the index are checked out.  It is necessary to traverse the
working tree fully when enumerating all the "other" paths, but when
we are only interested in "killed" paths, we can take advantage of
the fact that paths that do not overlap with entries in the index
can never be killed.

The treat_one_path() helper function, which is called during the
recursive traversal, is the ideal place to implement an
optimization.

When we are looking at a directory P in the working tree, there are
three cases:

 (1) P exists in the index.  Everything inside the directory P in
     the working tree needs to go when P is checked out from the
     index.

 (2) P does not exist in the index, but there is P/Q in the index.
     We know P will stay a directory when we check out the contents
     of the index, but we do not know yet if there is a directory
     P/Q in the working tree to be killed, so we need to recurse.

 (3) P does not exist in the index, and there is no P/Q in the index
     to require P to be a directory, either.  Only in this case, we
     know that everything inside P will not be killed without
     recursing.

Note that this helper is called by treat_leading_path() that decides
if we need to traverse only subdirectories of a single common
leading directory, which is essential for this optimization to be
correct.  This caller checks each level of the leading path
component from shallower directory to deeper ones, and that is what
allows us to only check if the path appears in the index.  If the
call to treat_one_path() weren't there, given a path P/Q/R, the real
traversal may start from directory P/Q/R, even when the index
records P as a regular file, and we would end up having to check if
any leading subpath in P/Q/R, e.g. P, appears in the index.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
t3010: update to demonstrate "ls-files -k" optimization pitfalls

An earlier draft of the previous step used cache_name_exists() to
check the directory we were looking at, which missed the second case
described in its log message.  Demonstrate why it is not sufficient.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
move setup_alternate_shallow and write_shallow_commits to shallow.c

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
rebase -i: fix cases ignoring core.commentchar

180bad3d (rebase -i: respect core.commentchar, 2013-02-11) updated
"rebase -i" to honor core.commentchar but missed one instance of
hard-coded '#' comment character in skip_unnecessary_picks().

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
rebase --preserve-merges: ignore "merge.log" config

When "merge.log" config is set, "rebase --preserve-merges" will add
the log lines to the message of the rebased merge commit.  A rebase
should not modify a commit message automatically.

Teach "git-rebase" to ignore that configuration by passing
"--no-log" to the git-merge call.

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dir.c::test_one_path(): work around directory_exists_in_index_icase() breakage

directory_exists_in_index() takes pathname and its length, but its
helper function directory_exists_in_index_icase() reads one byte
beyond the end of the pathname and expects there to be a '/'.

This needs to be fixed, as that one-byte-beyond-the-end location may
not even be readable, possibly by not registering directories to
name hashes with trailing slashes.  In the meantime, update the new
caller added recently to treat_one_path() to make sure that the path
buffer it gives the function is one byte longer than the path it is
asking the function about by appending a slash to it.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit: search author pattern against mailmap

"git commit --author=$name" sets the author to one whose name
matches the given string from existing commits, when $name is not in
the "Name <e-mail>" format. However, it does not honor the mailmap
to use the canonical name for the author found this way.

Fix it by telling the logic to find a matching existing author to
honor the mailmap, and use the name and email after applying the
mailmap.

Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t3404: make tests more self-contained

As its very first action, t3404 installs (via set_fake_editor) a
specialized $EDITOR which simplifies automated 'rebase -i' testing. Many
tests rely upon this setting, thus tests which need a different editor
must take extra care upon completion to restore $EDITOR in order to
avoid breaking following tests. This places extra burden upon such tests
and requires that they undesirably have extra knowledge about
surrounding tests. Ease this burden by having each test install the
$EDITOR it requires, rather than relying upon a global setting.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t3404: rebase -i: demonstrate short SHA-1 collision

The 'todo' sheet for interactive rebase shows abbreviated SHA-1's and
then performs its operations upon those shortened values. This can lead
to an abort if the SHA-1 of a reworded or edited commit is no longer
unique within the abbreviated SHA-1 space and a subsequent SHA-1 in the
todo list has the same abbreviated value.

For example:

  edit f00dfad first
  pick badbeef second

If, after editing, the new SHA-1 of "first" also has prefix badbeef,
then the subsequent 'pick badbeef second' will fail since badbeef is no
longer a unique SHA-1 abbreviation:

  error: short SHA1 badbeef is ambiguous.
  fatal: Needed a single revision
  Invalid commit name: badbeef

Demonstrate this problem with a couple of specially crafted commits
which initially have distinct abbreviated SHA-1's, but for which the
abbreviated SHA-1's collide after a simple rewording of the first
commit's message.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
rebase -i: fix short SHA-1 collision

The 'todo' sheet for interactive rebase shows abbreviated SHA-1's and
then performs its operations upon those shortened values. This can lead
to an abort if the SHA-1 of a reworded or edited commit is no longer
unique within the abbreviated SHA-1 space and a subsequent SHA-1 in the
todo list has the same abbreviated value.

For example:

  edit f00dfad first
  pick badbeef second

If, after editing, the new SHA-1 of "first" also has prefix badbeef,
then the subsequent 'pick badbeef second' will fail since badbeef is no
longer a unique SHA-1 abbreviation:

  error: short SHA1 badbeef is ambiguous.
  fatal: Needed a single revision
  Invalid commit name: badbeef

Fix this problem by expanding the SHA-1's in the todo list before
performing the operations.

[es: also collapse & expand SHA-1's for --edit-todo; respect
core.commentchar in transform_todo_ids(); compose commit message]

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
shallow: only add shallow graft points to new shallow file

for_each_commit_graft() goes through all graft points, and shallow
boundaries are just one special kind of grafting.

If $GIT_DIR/shallow and $GIT_DIR/info/grafts are both present,
write_shallow_commits() may catch both sets, accidentally turning
some graft points to shallow boundaries.  Don't do that.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
shallow: add setup_temporary_shallow()

This function is like setup_alternate_shallow() except that it does
not lock $GIT_DIR/shallow.  It is supposed to be used when a program
generates temporary shallow for use by another program, then throw
the shallow file away.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
upload-pack: delegate rev walking in shallow fetch to pack-objects

upload-pack has a special revision walking code for shallow
recipients. It works almost like the similar code in pack-objects
except:

1. in upload-pack, graft points could be added for deepening;

2. also when the repository is deepened, the shallow point will be
   moved further away from the tip, but the old shallow point will be
   marked as edge to produce more efficient packs. See 6523078 (make
   shallow repository deepening more network efficient - 2009-09-03).

Pass the file to pack-objects via --shallow-file. This will override
$GIT_DIR/shallow and give pack-objects the exact repository shape
that upload-pack has.

mark edge commits by revision command arguments. Even if old shallow
points are passed as "--not" revisions as in this patch, they will not
be picked up by mark_edges_uninteresting() because this function looks
up to parents for edges, while in this case the edge is the children,
in the opposite direction. This will be fixed in an later patch when
all given uninteresting commits are marked as edges.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
list-objects: reduce one argument in mark_edges_uninteresting

mark_edges_uninteresting() is always called with this form

  mark_edges_uninteresting(revs->commits, revs, ...);

Remove the first argument and let mark_edges_uninteresting figure that
out by itself. It helps answer the question "are this commit list and
revs related in any way?" when looking at mark_edges_uninteresting
implementation.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
list-objects: mark more commits as edges in mark_edges_uninteresting

The purpose of edge commits is to let pack-objects know what objects
it can use as base, but does not need to include in the thin pack
because the other side is supposed to already have them. So far we
mark uninteresting parents of interesting commits as edges. But even
an unrelated uninteresting commit (that the other side has) may
become a good base for pack-objects and help produce more efficient
packs.

This is especially true for shallow clone, when the client issues a
fetch with a depth smaller or equal to the number of commits the
server is ahead of the client. For example, in this commit history
the client has up to "A" and the server has up to "B":

    -------A---B
     have--^   ^
              /
       want--+

If depth 1 is requested, the commit list to send to the client
includes only B. The way m_e_u is working, it checks if parent
commits of B are uninteresting, if so mark them as edges.  Due to
shallow effect, commit B is grafted to have no parents and the
revision walker never sees A as the parent of B. In fact it marks no
edges at all in this simple case and sends everything B has to the
client even if it could have excluded what A and also the client
already have.

In a slightly different case where A is not a direct parent of B
(iow there are commits in between A and B), marking A as an edge can
still save some because B may still have stuff from the far ancestor
A.

There is another case from the earlier patch, when we deepen a ref
from C->E to A->E:

    ---A---B   C---D---E
     want--^   ^       ^
       shallow-+      /
          have-------+

In this case we need to send A and B to the client, and C (i.e. the
current shallow point that the client informs the server) is a very
good base because it's closet to A and B. Normal m_e_u won't recognize
C as an edge because it only looks back to parents (i.e. A<-B) not the
opposite way B->C even if C is already marked as uninteresting commit
by the previous patch.

This patch includes all uninteresting commits from command line as
edges and lets pack-objects decide what's best to do. The upside is we
have better chance of producing better packs in certain cases. The
downside is we may need to process some extra objects on the server
side.

For the shallow case on git.git, when the client is 5 commits behind
and does "fetch --depth=3", the result pack is 99.26 KiB instead of
4.92 MiB.

Reported-and-analyzed-by: Matthijs Kooijman <matthijs@stdin.nl>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add testcase for needless objects during a shallow fetch

This is a testcase that checks for a problem where, during a specific
shallow fetch where the client does not have any commits that are a
successor of the new shallow root (i.e., the fetch creates a new
detached piece of history), the server would simply send over _all_
objects, instead of taking into account the objects already present in
the client.

The actual problem was fixed by a recent patch series by Nguyễn Thái
Ngọc Duy already.

Signed-off-by: Matthijs Kooijman <matthijs@stdin.nl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
has_sha1_file: re-check pack directory before giving up

When we read a sha1 file, we first look for a packed
version, then a loose version, and then re-check the pack
directory again before concluding that we cannot find it.
This lets us handle a process that is writing to the
repository simultaneously (e.g., receive-pack writing a new
pack followed by a ref update, or git-repack packing
existing loose objects into a new pack).

However, we do not do the same trick with has_sha1_file; we
only check the packed objects once, followed by loose
objects. This means that we might incorrectly report that we
do not have an object, even though we could find it if we
simply re-checked the pack directory.

By itself, this is usually not a big deal. The other process
is running simultaneously, so we may run has_sha1_file
before it writes, anyway. It is a race whether we see the
object or not.  However, we may also see other things
the writing process has done (like updating refs); and in
that case, we must be able to also see the new objects.

For example, imagine we are doing a for_each_ref iteration,
and somebody simultaneously pushes. Receive-pack may write
the pack and update a ref after we have examined the
objects/pack directory, but before the iteration gets to the
updated ref. When we do finally see the updated ref,
for_each_ref will call has_sha1_file to check whether the
ref is broken. If has_sha1_file returns the wrong answer, we
erroneously will think that the ref is broken.

For a normal iteration without DO_FOR_EACH_INCLUDE_BROKEN,
this means that the caller does not see the ref at all
(neither the old nor the new value).  So not only will we
fail to see the new value of the ref (which is acceptable,
since we are running simultaneously with the writer, and we
might well read the ref before the writer commits its
write), but we will not see the old value either. For
programs that act on reachability like pack-objects or
prune, this can cause data loss, as we may see the objects
referenced by the original ref value as dangling (and either
omit them from the pack, or delete them via prune).

There's no test included here, because the success case is
two processes running simultaneously forever. But you can
replicate the issue with:

  # base.sh
  # run this in one terminal; it creates and pushes
  # repeatedly to a repository
  git init parent &&
  (cd parent &&

    # create a base commit that will trigger us looking at
    # the objects/pack directory before we hit the updated ref
    echo content >file &&
    git add file &&
    git commit -m base &&

    # set the unpack limit abnormally low, which
    # lets us simulate full-size pushes using tiny ones
    git config receive.unpackLimit 1
  ) &&
  git clone parent child &&
  cd child &&
  n=0 &&
  while true; do
    echo $n >file && git add file && git commit -m $n &&
    git push origin HEAD:refs/remotes/child/master &&
    n=$(($n + 1))
  done

  # fsck.sh
  # now run this simultaneously in another terminal; it
  # repeatedly fscks, looking for us to consider the
  # newly-pushed ref broken. We cannot use for-each-ref
  # here, as it uses DO_FOR_EACH_INCLUDE_BROKEN, which
  # skips the has_sha1_file check (and if it wants
  # more information on the object, it will actually read
  # the object, which does the proper two-step lookup)
  cd parent &&
  while true; do
    broken=`git fsck 2>&1 | grep remotes/child`
    if test -n "$broken"; then
      echo $broken
      exit 1
    fi
  done

Without this patch, the fsck loop fails within a few seconds
(and almost instantly if the test repository actually has a
large number of refs). With it, the two can run
indefinitely.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make setup_git_env() resolve .git file when $GIT_DIR is not specified

This makes reinitializing on a .git file repository work.

This is probably the only case that setup_git_env() (via
set_git_dir()) is called on a .git file. Other cases in
setup_git_dir_gently() and enter_repo() both cover .git file case
explicitly because they need to verify the target repo is valid.

Reported-by: Ximin Luo <infinity0@gmx.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
add--interactive: fix external command invocation on Windows

Back in 21e9757e (Hack git-add--interactive to make it work with
ActiveState Perl, 2007-08-01), the invocation of external commands was
changed to use qx{} on Windows. The rationale was that the command
interpreter on Windows is not a POSIX shell, but rather Windows's CMD.
That patch was wrong to include 'msys' in the check whether to use qx{}
or not: 'msys' identifies MSYS perl as shipped with Git for Windows,
which does not need the special treatment; qx{} should be used only with
ActiveState perl, which is identified by 'MSWin32'.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>