One caller of deref_tag() was not careful enough to make sure
what deref_tag() returned was not NULL (i.e. we found a tag
object that points at an object we do not have).  Fix it, and
warn about refs that point at such an incomplete tag where
needed.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The client side support for multi_ack.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

When git-fetch-pack gets the remote refs, it does not need to filter them
right away, but it can see which refs are common (taking advantage of the
patch which makes git-fetch-pack not use git-rev-list).

This means that we ask get_remote_heads() to return all remote refs,
including the funny refs, and filtering them with a separate function later.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The code used to call git-rev-list to enumerate the local revisions.
A disadvantage of that method was that git-rev-list, lacking a
control apart from the command line, would happily enumerate
ancestors of acknowledged common commits, which was just taking
unnecessary bandwidth.

Therefore, do not use git-rev-list on the fetching side, but rather
construct the list on the go. Send the revisions starting from the
local heads, ignoring the revisions known to be common.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Let's have it simmer a bit longer in the proposed updates branch
and shake the problems out.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This patch concludes the series, which makes
git-fetch-pack/git-upload-pack negotiate a potentially better set of
common revs. It should make a difference when fetching from a repository
with a few branches.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The code used to call git-rev-list to enumerate the local revisions. A
disadvantage of that method was that git-rev-list, lacking a control apart
from the command line, would happily enumerate ancestors of acknowledged
common commits, which was just taking unnecessary bandwidth.

Therefore, do not use git-rev-list on the fetching side, but rather
construct the list on the go. Send the revisions starting from the local
heads, ignoring the revisions known to be common.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Also Johannes noticed we use parse_object to look up if we know that
object already -- we should just ask the in-core object registry with
lookup_object() for that.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

The previous round to optimize fetch-pack has a small bug that
feeds SHA1^ ("parent commit") before making sure SHA1 is
actually a commit (or a tag that eventually dereferences to a
commit).  Also it did not help culling the known-to-be-common
parents if the common one was a merge.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

It was all good and well to check if all remote refs are complete (local
refs or descendants thereof), but we can just as easily use the same
information to avoid sending "want" lines just for the complete objects in
the case that not all remote refs are complete (or their names differ).

Also, git-fetch-pack does not have to ask for descendants of remote refs
which are complete (for now, git-rev-list is told to ignore only the first
parent). That change also eliminates a code path where a popen()ed handle
was not pclose()ed.
Signed-off-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

On top of optimization by Linus not to ask refs that already match, we
can walk our refs and not issue "want" for things that are known to be
reachable from them.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

On top of optimization by Linus not to ask refs that already match, we
can walk our refs and not issue "want" for things that are known to be
reachable from them.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

If everything is up-to-date locally, we don't need to even ask for a
pack-file from the remote, or try to unpack it.

This is especially important for tags - since the pack-file common commit
logic is based purely on the commit history, it will never be able to find
a common tag, and will thus always end up re-fetching them.

Especially notably, if the tag points to a non-commit (eg a tagged tree),
the pack-file would be unnecessarily big, just because it cannot any most
recent common point between commits for pruning.

Short-circuiting the case where we already have that reference means that
we avoid a lot of these in the common case.

NOTE! This only matches remote ref names against the same local name,
which works well for tags, but is not as generic as it could be. If we
ever need to, we could match against _any_ local ref (if we have it, we
have it), but this "match against same name" is simpler and more
efficient, and covers the common case.

Renaming of refs is common for branch heads, but since those are always
commits, the pack-file generation can optimize that case.

In some cases we might still end up fetching pack-files unnecessarily, but
this at least avoids the re-fetching of tags over and over if you use a
regular

	git fetch --tags ...

which was the main reason behind the change.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This allows the remote side (most notably, upload-pack) to show
additional information without affecting the downloader.  Peek-remote
does not ignore them -- this is to make it useful for Pasky's
automatic tag following.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This is a beginning of resurrecting the multi-head pulling support
for git-fetch-pack command.  The git-fetch-script wrapper still
only knows about fetching a single head, without renaming, so it is
not very useful unless you directly call git-fetch-pack itself yet.

It also fixes a longstanding obsolete description of how the command
discovers the list of local commits.

It really just boils down to one "get_remote_heads()" function, and a
common "struct ref" structure definition.

This adds documentation for 'smarter pull' family of commands.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Oh, well..  FC4 has UTF-8 as the default environment, and I applaud
that, but then it sometimes results in these characters that aren't
actually visible as a problem.

With the socket case, the input and output fd's might end up being the same,
so we want to dup the other before we close either of them.

git-clone-pack will want it too. Soon.

It was a misguided attempt to mix fetching and cloning. I'll make
a separate clone thing.

"git_path()" returns a static pathname pointer into the git directory
using a printf-like format specifier.

"head_ref()" works like "for_each_ref()", except for just the HEAD.

It returns the result SHA1 on stdout, so you can do

	remote=$(git-fetch-pack host:dir branchname)

and it will unpack the objects and "remote" will be the SHA1 name of the
branch on the other side.  You can then save that off, or merge it, or
whatever.

Now the only piece missing is actually generating the pack-file.

It's meant to be used by "git fetch" for the local and ssh case.

It doesn't actually do the fetching now, but it does discover the common
commit point.