"git checkout -" is a short-hand for "git checkout @{-1}" and the
"@{nth}" notation for a negative number is to find nth previous
checkout in the reflog of the HEAD to determine the name of the
branch the user was on.  We would want to find the nth most recent
reflog entry that matches "checkout: moving from X to Y" for this.

Unfortunately, reflog is implemented as an append-only file, and the
API to iterate over its entries, for_each_reflog_ent(), reads the
file in order, giving the entries from the oldest to newer.  For the
purpose of finding nth most recent one, this API forces us to record
the last n entries in a rotating buffer and give the result out only
after we read everything.  To optimize for a common case of finding
the nth most recent one for a small value of n, we also have a side
API for_each_recent_reflog_ent() that starts reading near the end of
the file, but it still has to read the entries in the "wrong" order.
The implementation of understanding @{-1} uses this interface.

This all becomes unnecessary if we add an API to let us iterate over
reflog entries in the reverse order, from the newest to older.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Store references hierarchically in a tree that matches the
pseudo-directory structure of the reference names.  Add a new kind of
ref_entry (with flag REF_DIR) to represent a whole subdirectory of
references.  Sort ref_dirs one subdirectory at a time.

NOTE: the dirs can now be sorted as a side-effect of other function
calls.  Therefore, it would be problematic to do something from a
each_ref_fn callback that could provoke the sorting of a directory
that is currently being iterated over (i.e., the directory containing
the entry that is being processed or any of its parents).

This is a bit far-fetched, because a directory is always sorted just
before being iterated over.  Therefore, read-only accesses cannot
trigger the sorting of a directory whose iteration has already
started.  But if a callback function would add a reference to a parent
directory of the reference in the iteration, then try to resolve a
reference under that directory, a re-sort could be triggered and cause
the iteration to work incorrectly.

Nevertheless...add a comment in refs.h warning against modifications
during iteration.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The extra_refs provided a kludgy way to create fake references at a
global level in the hope that they would only affect some particular
code path.  The last user of this API been rewritten, so strip this
stuff out before somebody else gets the bad idea of using it.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add a new function add_packed_ref() that adds a reference directly to
the in-memory packed reference cache.  This will be useful for
creating local references while cloning.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Try consistently to use the name "sha1" for parameters to which a SHA1
will be stored.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Try to consistently use the variable name "refname" when referring to
a string that names a reference.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Instead of keeping this as an internal API, let the callers find
out the reason why resolve_ref() returned NULL is not because there
was no such file in $GIT_DIR but because a file was corrupt.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Make invalidate_ref_cache() an official part of the refs API.  It is
currently a fact of life that code outside of refs.c mucks about with
references.  This change gives such code a way of informing the refs
module that it should no longer trust its cache.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

In add_ref(), verify that the refname is formatted correctly before
adding it to the ref_list.  Here we have to allow refname components
that start with ".", since (for example) the remote protocol uses
synthetic reference name ".have".  So add a new REFNAME_DOT_COMPONENT
flag that can be passed to check_refname_format() to allow leading
dots.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since much of the infrastructure does not work correctly with
unnormalized refnames, change check_refname_format() to reject them.

Similarly, change "git check-ref-format" to reject unnormalized
refnames by default.  But add an option --normalize, which causes "git
check-ref-format" to normalize the refname before checking its format,
and print the normalized refname.  This is exactly the behavior of the
old --print option, which is retained but deprecated.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Change check_ref_format() to take a flags argument that indicates what
is acceptable in the reference name (analogous to "git
check-ref-format"'s "--allow-onelevel" and "--refspec-pattern").  This
is more convenient for callers and also fixes a failure in the test
suite (and likely elsewhere in the code) by enabling "onelevel" and
"refspec-pattern" to be allowed independently of each other.

Also rename check_ref_format() to check_refname_format() to make it
obvious that it deals with refnames rather than references themselves.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When a push specifies deletion of non-existent refs, the post post-receive and
post-update hooks receive them as input/arguments.

For instance, for the following push, where refs/heads/nonexistent is a ref
which does not exist on the remote side:

	git push origin :refs/heads/nonexistent

the post-receive hook receives from standard input:

	<null-sha1> SP <null-sha1> SP refs/heads/nonexistent

and the post-update hook receives as arguments:

	refs/heads/nonexistent

which does not make sense since it is a no-op.

Teach receive-pack not to pass non-existent refs to the post-receive and
post-update hooks. If the push only attempts to delete non-existent refs,
these hooks are not even called.

The update and pre-receive hooks are still notified about attempted
deletion of non-existent refs to give them a chance to inspect the
situation and act on it.

[jc: mild fix-ups to avoid introducing an extra list; also added fixes to
some tests]
Signed-off-by: NPang Yan Han <pangyanhan@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add support for dividing the refs of a single repository into multiple
namespaces, each of which can have its own branches, tags, and HEAD.
Git can expose each namespace as an independent repository to pull from
and push to, while sharing the object store, and exposing all the refs
to operations such as git-gc.

Storing multiple repositories as namespaces of a single repository
avoids storing duplicate copies of the same objects, such as when
storing multiple branches of the same source.  The alternates mechanism
provides similar support for avoiding duplicates, but alternates do not
prevent duplication between new objects added to the repositories
without ongoing maintenance, while namespaces do.

To specify a namespace, set the GIT_NAMESPACE environment variable to
the namespace.  For each ref namespace, git stores the corresponding
refs in a directory under refs/namespaces/.  For example,
GIT_NAMESPACE=foo will store refs under refs/namespaces/foo/.  You can
also specify namespaces via the --namespace option to git.

Note that namespaces which include a / will expand to a hierarchy of
namespaces; for example, GIT_NAMESPACE=foo/bar will store refs under
refs/namespaces/foo/refs/namespaces/bar/.  This makes paths in
GIT_NAMESPACE behave hierarchically, so that cloning with
GIT_NAMESPACE=foo/bar produces the same result as cloning with
GIT_NAMESPACE=foo and cloning from that repo with GIT_NAMESPACE=bar.  It
also avoids ambiguity with strange namespace paths such as
foo/refs/heads/, which could otherwise generate directory/file conflicts
within the refs directory.

Add the infrastructure for ref namespaces: handle the GIT_NAMESPACE
environment variable and --namespace option, and support iterating over
refs in a namespace.
Signed-off-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NJamey Sharp <jamey@minilop.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When create a new branch, we fed "refs/heads/<proposed name>" as a string
to get_sha1() and expected it to fail when a branch already exists.

The right way to check if a ref exists is to check with resolve_ref().

A naïve solution that might appear attractive but does not work is to
forbid slashes in get_describe_name() but that will not work. A describe
name is is in the form of "ANYTHING-g<short sha1>", and that ANYTHING part
comes from a original tag name used in the repository the user ran the
describe command. A sick user could have a confusing hierarchical tag
whose name is "refs/heads/foobar" (stored as refs/tags/refs/heads/foobar")
to generate a describe name "refs/heads/foobar-6-g02ac9837", and we should
be able to use that name to refer to the object whose name is 02ac9837.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

By passing the path to a submodule in opt->submodule, the function can
be used to walk history in the named submodule repository, instead of
the toplevel repository.
Signed-off-by: NHeiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

859c3017 (refs: split log_ref_write logic into log_ref_setup,
2010-05-21) refactors the stack allocation of the log_file array into
the new log_ref_setup() function, but passes it back to the caller.

Since the original intent seems to have been to split the work between
log_ref_setup and log_ref_write, make it the caller's responsibility
to allocate the buffer.
Signed-off-by: NThomas Rast <trast@student.ethz.ch>
Reported-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Separation of the logic for testing and preparing the reflogs from
function log_ref_write to a new non static new function: log_ref_setup.

This allows to be performed from outside the first all reasonable checks
and procedures for writing reflogs.
Signed-off-by: NErick Mattos <erick.mattos@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

With this patch, you can set notes.displayRef to a glob that points at
your favourite notes refs, e.g.,

[notes]
	displayRef = refs/notes/*

Then git-log and friends will show notes from all trees.

Thanks to Junio C Hamano for lots of feedback, which greatly
influenced the design of the entire series and this commit in
particular.
Signed-off-by: NThomas Rast <trast@student.ethz.ch>
Acked-by: NJohan Herland <johan@herland.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since local branch, tags and remote tracking branch namespaces are
most often used, add shortcut notations for globbing those in
manner similar to --glob option.

With this, one can express the "what I have but origin doesn't?"
as:

'git log --branches --not --remotes=origin'
Original-idea-by: NJohannes Sixt <j6t@kdbg.org>
Signed-off-by: NIlari Liusvaara <ilari.liusvaara@elisanet.fi>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add --glob=<glob-pattern> option to rev-parse and everything that
accepts its options. This option matches all refs that match given
shell glob pattern (complete with some DWIM logic).

Example:

'git log --branches --not --glob=remotes/origin'

To show what you have that origin doesn't.
Signed-off-by: NIlari Liusvaara <ilari.liusvaara@elisanet.fi>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Different callers of warn_dangling_symref() may want to control whether its
output goes to stdout or stderr so let it take a FILE argument.
Signed-off-by: NJay Soffian <jaysoffian@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This is some preparation work for the following patches that are using
the "refs/replace/" ref namespace.
Signed-off-by: NChristian Couder <chriscool@tuxfamily.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

In preparation to be used when the ref object is not available
Signed-off-by: NFelipe Contreras <felipe.contreras@gmail.com>
Acked-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add the strict mode of abbreviation to shorten_unambiguous_ref(), i.e. the
resulting ref won't trigger the ambiguous ref warning.

All users of shorten_unambiguous_ref() still use the loose mode.
Signed-off-by: NBert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Often we want to shorten a full ref name to something "prettier"
to show a user. For example, "refs/heads/master" is often shown
simply as "master", or "refs/remotes/origin/master" is shown as
"origin/master".

Many places in the code use a very simple formula: skip common
prefixes like refs/heads, refs/remotes, etc. This is codified in
the prettify_ref function.

for-each-ref has a more correct (but more expensive) approach:
consider the ref lookup rules, and try shortening as much as
possible while remaining unambiguous.

This patch makes the latter strategy globally available as
shorten_unambiguous_ref.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The "for_each_{tag,branch,remote,replace,}_ref" functions are
redefined in terms of "for_each_ref_in" so that we can lose the
hardcoded length of prefix strings from the code.
Signed-off-by: NChristian Couder <chriscool@tuxfamily.org>

The result should be consistent between fetch and push, so we ought to
use the same code in both cases, even though it's short.
Signed-off-by: NDaniel Barkalow <barkalow@iabervon.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

If you prune from the remote "frotz" that deleted the ref your tracking
branch remotes/frotz/HEAD points at, the symbolic ref will become
dangling.  We used to detect this as an error condition and issued a
message every time refs are enumerated.

This stops the error message, but moves the warning to "remote prune".
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This can be used to scan only the last few kilobytes of a reflog, as a
cheap optimization when the data you are looking for is likely to be
found near the end of it.  The caller is expected to fall back to the
full scan if that is not the case.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

These refs can be anything, but they are most likely useful as
pointing to objects that you know are in the object database but don't
have any regular refs for. For example, when cloning with --reference,
the refs in this repository should be listed as objects that we have,
even though we don't have refs in our newly-created repository for
them yet.
Signed-off-by: NDaniel Barkalow <barkalow@iabervon.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This is in preparation to the reflog-expire changes which will
allow updating the ref after expiring the reflog.
Signed-off-by: NBrandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Recent check_ref_format() returns -3 as well as -1 (general
error) and -2 (less than two levels).  The caller was explicitly
checking for -1, to allow "HEAD" but still needed to disallow
bogus refs.

This introduces symbolic constants for the return values from
check_ref_format() to make them read better and more
meaningful.  Normal ref creation codepath can still treat
non-zero return values as errors.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Signed-off-by: NJohannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

A function intended to be called from builtins updating refs
by locking them before write, specially those that came from
scripts using "git update-ref".

[jc: with minor fixups]
Signed-off-by: NCarlos Rica <jasampler@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

git-checkout is also adapted to make use of this new option
instead of the handcrafted command sequence.
Signed-off-by: NSven Verdoolaege <skimo@kotnet.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This new function resolves a ref in *another* git repository.  It's
named for its intended use: to look up the git link to a subproject.

It's not actually wired up to anything yet, but we're getting closer to
having fundamental plumbing support for "links" from one git directory
to another, which is the basis of subproject support.

[jc: amended a FILE* leak]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Currently, the search for all reflogs depends on the existence of
corresponding refs under the .git/refs/ directory.  Let's scan the
.git/logs/ directory directly instead.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

A ref might be pointing to another ref but only the name of the last ref
is remembered.  Let's remember about the first name as well.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

This allows for ref_log_write() to be used in a more flexible way,
and is needed for future changes.

This is only code reorg with no behavior change.
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>