checkout: fix bug with ambiguous refs

The usual dwim_ref lookup prefers tags to branches. Because
checkout primarily works on branches, though, we switch that
behavior to prefer branches.

However, there was a bug in the implementation in which we
used lookup_commit_reference (which used the regular lookup
rules) to get the actual commit to checkout. Checking out an
ambiguous ref therefore ended up putting us in an extremely
broken state in which we wrote the branch ref into HEAD, but
actually checked out the tree for the tag.

This patch fixes the bug by always attempting to pull the
commit to be checked out from the branch-ified version of
the name we were given.

Patch by Junio, tests and commit message from Jeff King.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Demonstrate breakage: checkout overwrites untracked symlink with directory

This adds tests where an untracked file and an untracked symlink are in the
way where a directory should be created by 'git checkout'. Commit b1735b1a
(do not overwrite files in leading path, 2010-12-14) fixed the case where
a file is in the way, but the untracked symlink is still removed silently.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
branch/checkout --track: Ensure that upstream branch is indeed a branch

When creating a new branch using the --track option, we must make sure that
we don't try to set an upstream that does not make sense to follow (using
'git pull') or update (using 'git push'). The current code checks against
using HEAD as upstream (since tracking a symref doesn't make sense). However,
tracking a tag doesn't make sense either. Indeed, tracking _any_ ref that is
not a (local or remote) branch doesn't make sense, and should be disallowed.

This patch achieves this by checking that the ref we're trying to --track
resides within refs/heads/* or refs/remotes/*. This new check replaces the
previous check against HEAD.

A couple of testcases are also added, verifying that we cannot create
branches with tags as upstreams.

Finally, some selftests relying on using a non-branch as an upstream have
been reworked or removed:

- t6040: Reverse the meaning of two tests that depend on the ability to
use (lightweight and annotated) tags as upstreams. These two tests were
originally added in commits 1be570f and 57ffc5f, and this patch reverts the
intention of those two commits.

- t7201: Remove part of a test (introduced in 9188ed8) relying on a
non-branch as upstream.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
do not overwrite untracked symlinks

Git traditionally overwrites untracked symlinks silently. This will
generally not cause massive data loss, but it is inconsistent with
the behavior for regular files, which are not silently overwritten.

With this change, git refuses to overwrite untracked symlinks by
default. If the user really wants to overwrite the untracked
symlink, he has git-clean and git-checkout -f at his disposal.

Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
doc: technical details about the index file format

This bases on the original work by Robin Rosenberg.

Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-cvsimport.perl: Bail out right away when reading from the server fails

If the CVS server is down, this reduced the git-cvsimport output from:

ssh: connect to host ijbswa.cvs.sourceforge.net port 22: Connection refused
Use of uninitialized value $rep in scalar chomp at /usr/local/libexec/git-core/git-cvsimport line 369.
Use of uninitialized value $rep in substitution (s///) at /usr/local/libexec/git-core/git-cvsimport line 370.
Expected Valid-requests from server, but got: <unknown>

to the less noisy:

ssh: connect to host ijbswa.cvs.sourceforge.net port 22: Connection refused
Failed to read from server at /usr/local/libexec/git-core/git-cvsimport line 370.

In this case a silent exit() instead of the die() would probably do,
but I assume that there could be cases where the connection attempt
succeeds, but reading from the server fails for other reasons.

Signed-off-by: Fabian Keil <fk@fabiankeil.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: do not patch lines that were already patched

When looking for a place to apply a hunk, we used to check lines that
match the preimage of it, starting from the line that the patch wants to
apply the hunk at, looking forward and backward with increasing offsets
until we find a match.

Colin Guthrie found an interesting case where this misapplied a patch that
wanted to touch a preimage that consists of

                        }
                }

                return 0;
        }

which is a rather unfortunately common pattern.

The target version of the file originally had only one such location, but
the hunk immediately before that created another instance of such block of
lines, and find_pos() happily reported that the preimage of the hunk
matched what it wanted to modify.

Oops.

By marking the lines application of earlier hunks touched and preventing
match_fragment() from considering them as a match with preimage of other
hunks, we can reduce such an accident.

I also considered to teach apply_one_fragment() to take the offset we have
found while applying the previous hunk into account when looking for a
match with find_pos(), but dismissed that approach, because it would
sometimes work better but sometimes worse, depending on the difference
between the version the patch was created against and the version the
patch is being applied.

This does _not_ prevent misapplication of patches to a file that has many
similar looking blocks of lines and a preimage cannot identify which one
of them should be applied.  For that, we would need to scan beyond the
first match in find_pos(), and issue a warning (or error out).  That will
be a separate topic.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply -v: show offset count when patch did not apply exactly

When the line number the patch intended to touch does not match
the line in the version being patched, GNU patch reports that
it applied the hunk at a different line number, with how big an
offset.

Teach "git apply" to do the same under --verbose option.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
git stash: show status relative to current directory

git status shows modified paths relative to current directory, so it's
possible to copy&paste them directly, even if you're in a subdirectory.

But "git stash apply" always shows status from root of git repository.
This is misleading because you can't use the paths without modifications.

This is caused by changing directory to root of repository at the
beginning of git stash.

This patch makes git stash show status relative to current directory.
Instead of removing the "cd to toplevel", which would affect whole
script and might have other side-effects, the fix is to change directory
temporarily back to original dir just before displaying status.

Signed-off-by: Piotr Krukowiecki <piotr.krukowiecki@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-bisect.txt: streamline run presentation

Streamline the presentation of "bisect run" by removing one example
which does not introduce new concepts.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-bisect.txt: example for bisecting with hot-fix

Give an example on how to bisect when older revisions need a hot-fix to
build, run or test. Triggered by the binutils/kernel issue at

http://thread.gmane.org/gmane.comp.gnu.binutils/52601/focus=1112779

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --quiet: disable optimization when --diff-filter=X is used

The code notices that the caller does not want any detail of the changes
and only wants to know if there is a change or not by specifying --quiet.
And it breaks out of the loop when it knows it already found any change.

When you have a post-process filter (e.g. --diff-filter), however, the
path we found to be different in the previous round and set HAS_CHANGES
bit may end up being uninteresting, and there may be no output at the end.
The optimization needs to be disabled for such case.

Note that the f245194 (diff: change semantics of "ignore whitespace"
options, 2009-05-22) already disables this optimization by refraining
from setting HAS_CHANGES when post-process filters that need to inspect
the contents of the files (e.g. -S, -w) in diff_change() function.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
stash: fix incorrect quoting in cleanup of temporary files

The * was inside the quotes, so that the pattern was never expanded and the
temporary files were never removed. As a consequence, 'stash -p' left a
.git-stash-*-patch file in $GIT_DIR. Other code paths did not leave files
behind because they removed the temporary file themselves, at least in
non-error paths.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
stash: copy the index using --index-output instead of cp -p

'git stash create' must operate with a temporary index. For this purpose,
it used 'cp -p' to create a copy. -p is needed to preserve the timestamp
of the index file. Now Jakob Pfender reported a certain combination of
a Linux NFS client, OpenBSD NFS server, and cp implementation where this
operation failed.

Luckily, the first operation in git-stash after copying the index is to
call 'git read-tree'. Therefore, use --index-output instead of 'cp -p'
to write the copy of the index.

--index-output requires that the specified file is on the same volume as
the source index, so that the lock file can be rename()d. For this reason,
the name of the temporary index is constructed in a way different from the
other temporary files. The code path of 'stash -p' also needs a temporary
index, but we do not use the new name because it does not depend on the
same precondition as --index-output.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add test: git stash shows status relative to current dir

[jc: moved "cd subdir" inside subshell and fixed comparison with expected]

Signed-off-by: Piotr Krukowiecki <piotr.krukowiecki@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
doc: technical details about the index file format

 * Clarify "string of unsigned bytes";

 * Blob has two variants (regular file vs symlink), not (blob vs symlink);

 * Clarify permission mode bits;

 * Clarify ce_namelen() "too long to fit in the length field" case;

 * Clarify "." etc are forbidden as path components;

 * Match the description with the internal wording "cache-tree";

 * All types of extension begin with signature and length as explained in
   the first part. Don't repeat the "length" part in the description of
   each extension (can be mistaken as if there is a separate 32-bit size
   field inside the extension), but state what the signature for each
   extension is.

 * Don't say "Extension tag", as we have said "Extension signature" in the
   first part---be consistent;

 * Clarify the invalidation of cache-tree entries;

 * Correct description on subtree_nr field in the cache-tree;

 * Clarify the order of entries in cache-tree;

Signed-off-by: Junio C Hamano <gitster@pobox.com>
grep: Add the option '--line-number'

This is a synonym for the existing '-n' option, matching GNU grep.

Signed-off-by: Joe Ratterman <jratt0@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git tag documentation grammar fixes and readability updates

... with help from Eric Raible.

In addition, describe the use of GIT_COMMITTER_DATE more comprehensively
by including "date-formats.txt"

Signed-off-by: Michael Witten <mfwitten@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
HOME must be set before calling git-init when creating test repositories

Otherwise the created test repositories will be affected by users ~/.gitconfig.
For example, setting core.logAllrefupdates in users config will make all
calls to "git config --unset core.logAllrefupdates" fail which will break
the first test which uses the statement and expects it to succeed.

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse-remote: replace unnecessary sed invocation

Just use parameter expansion instead.

Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>