merge: a random object may not necssarily be a commit

The user could have said "git merge $(git rev-parse v1.0.0)"; we
shouldn't mark it as "Merge commit '15999998fb...'" as the merge
name, even though such an invocation might be crazy.

We could even read the "tag " header from the tag object and replace
the object name the user gave us, but let's not lose the information
by doing so, at least not yet.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply --whitespace=fix: avoid running over the postimage buffer

Originally update-pre-post-images could assume that any whitespace
fixing will make the result only shorter by unexpanding runs of
leading SPs into HTs and removing trailing whitespaces at the end of
lines.  Updating the post-image we read from the patch to match the
actual result can be performed in-place under this assumption.
These days, however, we have tab-in-indent (aka Python) rule whose
result can be longer than the original, and we do need to allocate
a larger buffer than the input and replace the result.

Fortunately the support for lengthening rewrite was already added
when we began supporting "match while ignoring whitespace
differences" mode in 86c91f91794c (git apply: option to ignore
whitespace differences, 2009-08-04).  We only need to correctly
count the number of bytes necessary to hold the updated result and
tell the function to allocate a new buffer.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
combine-diff: coalesce lost lines optimally

This replaces the greedy implementation to coalesce lost lines by using
dynamic programming to find the Longest Common Subsequence.

The O(n²) time complexity is obviously bigger than previous
implementation but it can produce shorter diff results (and most likely
easier to read).

List of lost lines is now doubly-linked because we reverse-read it when
reading the direction matrix.

Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
attr.c::path_matches(): the basename is part of the pathname

The function takes two strings (pathname and basename) as if they
are independent strings, but in reality, the latter is always
pointing into a substring in the former.

Clarify this relationship by expressing the latter as an offset into
the former.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
checkout: avoid unnecessary match_pathspec calls

In checkout_paths() we do this

 - for all updated items, call match_pathspec
 - for all items, call match_pathspec (inside unmerge_cache)
 - for all items, call match_pathspec (for showing "path .. is unmerged)
 - for updated items, call match_pathspec and update paths

That's a lot of duplicate match_pathspec(s) and the function is not
exactly cheap to be called so many times, especially on large indexes.
This patch makes it call match_pathspec once per updated index entry,
save the result in ce_flags and reuse the results in the following
loops.

The changes in 0a1283b (checkout $tree $path: do not clobber local
changes in $path not in $tree - 2011-09-30) limit the affected paths
to ones we read from $tree. We do not do anything to other modified
entries in this case, so the "for all items" above could be modified
to "for all updated items". But..

The command's behavior now is modified slightly: unmerged entries that
match $path, but not updated by $tree, are now NOT touched.  Although
this should be considered a bug fix, not a regression. A new test is
added for this change.

And while at there, free ps_matched after use.

The following command is tested on webkit, 215k entries. The pattern
is chosen mainly to make match_pathspec sweat:

git checkout -- "*[a-zA-Z]*[a-zA-Z]*[a-zA-Z]*"

        before      after
real    0m3.493s    0m2.737s
user    0m2.239s    0m1.586s
sys     0m1.252s    0m1.151s

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
stream_blob_to_fd: detect errors reading from stream

We call read_istream, but never check its return value for
errors. This can lead to us looping infinitely, as we just
keep trying to write "-1" bytes (and we do not notice the
error, as we simply check that write_in_full reports the
same number of bytes we fed it, which of course is also -1).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
check_sha1_signature: check return value from read_istream

It's possible for read_istream to return an error, in which
case we just end up in an infinite loop (aside from EOF, we
do not even look at the result, but just feed it straight
into our running hash).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read_istream_filtered: propagate read error from upstream

The filter istream pulls data from an "upstream" stream,
running it through a filter function. However, we did not
properly notice when the upstream filter yielded an error,
and just returned what we had read. Instead, we should
propagate the error.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
avoid infinite loop in read_istream_loose

The read_istream_loose function loops on inflating a chunk of data
from an mmap'd loose object. We end the loop when we run out
of space in our output buffer, or if we see a zlib error.

We need to treat Z_BUF_ERROR specially, though, as it is not
fatal; it is just zlib's way of telling us that we need to
either feed it more input or give it more output space. It
is perfectly normal for us to hit this when we are at the
end of our buffer.

However, we may also get Z_BUF_ERROR because we have run out
of input. In a well-formed object, this should not happen,
because we have fed the whole mmap'd contents to zlib. But
if the object is truncated or corrupt, we will loop forever,
never giving zlib any more data, but continuing to ask it to
inflate.

We can fix this by considering it an error when zlib returns
Z_BUF_ERROR but we still have output space left (which means
it must want more input, which we know is a truncation
error). It would not be sufficient to just check whether
zlib had consumed all the input at the start of the loop, as
it might still want to generate output from what is in its
internal state.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
add test for streaming corrupt blobs

We do not have many tests for handling corrupt objects. This
new test at least checks that we detect a byte error in a
corrupt blob object while streaming it out with cat-file.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
streaming_write_entry: propagate streaming errors

When we are streaming an index blob to disk, we store the
error from stream_blob_to_fd in the "result" variable, and
then immediately overwrite that with the return value of
"close". That means we catch errors on close (e.g., problems
committing the file to disk), but miss anything which
happened before then.

We can fix this by using bitwise-OR to accumulate errors in
our result variable.

While we're here, we can also simplify the error handling
with an early return, which makes it easier to see under
which circumstances we need to clean up.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
add tests for cloning corrupted repositories

We try not to let corruption pass unnoticed over fetches and
clones. For the most part, this works, but there are some
broken corner cases, including:

  1. We do not detect missing objects over git-aware
     transports. This is a little hard to test, because the
     sending side will actually complain about the missing
     object.

     To fool it, we corrupt a repository such that we have a
     "misnamed" object: it claims to be sha1 X, but is
     really Y. This lets the sender blindly transmit it, but
     it is the receiver's responsibility to verify that what
     it got is sane (and it does not).

  2. We do not detect missing or misnamed blobs during the
     checkout phase of clone.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
clone: die on errors from unpack_trees

When clone is populating the working tree, it ignores the
return status from unpack_trees; this means we may report a
successful clone, even when the checkout fails.

When checkout fails, we may want to leave the $GIT_DIR in
place, as it might be possible to recover the data through
further use of "git checkout" (e.g., if the checkout failed
due to a transient error, disk full, etc). However, we
already die on a number of other checkout-related errors, so
this patch follows that pattern.

In addition to marking a now-passing test, we need to adjust
t5710, which blindly assumed it could make bogus clones of
very deep alternates hierarchies. By using "--bare", we can
avoid it actually touching any objects.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
clone: run check_everything_connected

When we fetch from a remote, we do a revision walk to make
sure that what we received is connected to our existing
history. We do not do the same check for clone, which should
be able to check that we received an intact history graph.

The upside of this patch is that it will make clone more
resilient against propagating repository corruption. The
downside is that we will now traverse "rev-list --objects
--all" down to the roots, which may take some time (it is
especially noticeable for a "--local --bare" clone).

Note that we need to adjust t5710, which tries to make such
a bogus clone. Rather than checking after the fact that our
clone is bogus, we can simplify it to just make sure "git
clone" reports failure.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t5516: test interaction between pushURL and pushInsteadOf correctly

1c2eafb89bca (Add url.<base>.pushInsteadOf: URL rewriting for push
only, 2009-09-07) wants to make sure that a push destination read
from URL is not rewritten by pushInsteadOf because an explicit
pushURL exists; for that, a pushInsteadOf rewrite rule for the value
of remote.r.URL is set to a non-existent is set up.

We would also want to make sure that pushInsteadOf rewrite rule is
not applied to the location read from pushURL.

This way, we will make sure that

 - "testrepo/" (pushURL) gets updated;

 - the push does not try to update "trash2/" (the result of applying
   pushInsteadOf to pushURL);

 - the push does not try to update "trash3/" (the result of applying
   pushInsteadOf to URL).

Signed-off-by: Junio C Hamano <gitster@pobox.com>
attr.c::path_matches(): special case paths that end with a slash

The function is given a string that ends with a slash to signal that
the path is a directory to make sure that a pattern that ends with a
slash (i.e. MUSTBEDIR) can tell directories and non-directories
apart.  However, the pattern itself (pat->pattern and
pat->patternlen) that came from such a MUSTBEDIR pattern is
represented as a string that ends with a slash, but patternlen does
not count that trailing slash. A MUSTBEDIR pattern "element/" is
represented as a counted string <"element/", 7> and this must match
match pathname "element/".

Because match_basename() and match_pathname() want to see pathname
"element" to match against the pattern <"element/", 7>, reduce the
length of the path to exclude the trailing slash when calling
these functions.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dir.c::match_basename(): pay attention to the length of string parameters

The function takes two counted strings (<basename, basenamelen> and
<pattern, patternlen>) as parameters, together with prefix (the
length of the prefix in pattern that is to be matched literally
without globbing against the basename) and EXC_* flags that tells it
how to match the pattern against the basename.

However, it did not pay attention to the length of these counted
strings.  Update them to do the following:

 * When the entire pattern is to be matched literally, the pattern
   matches the basename only when the lengths of them are the same,
   and they match up to that length.

 * When the pattern is "*" followed by a string to be matched
   literally, make sure that the basenamelen is equal or longer than
   the "literal" part of the pattern, and the tail of the basename
   string matches that literal part.

 * Otherwise, use the new fnmatch_icase_mem helper to make
   sure we only lookmake sure we use only look at the
   counted part of the strings.  Because these counted strings are
   full strings most of the time, we check for termination
   to avoid unnecessary allocation.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dir.c::match_pathname(): adjust patternlen when shifting pattern

If we receive a pattern that starts with "/", we shift it
forward to avoid looking at the "/" part. Since the prefix
and patternlen parameters are counts of what is in the
pattern, we must decrement them as we increment the pointer.

We remembered to handle prefix, but not patternlen. This
didn't cause any bugs, though, because the patternlen
parameter is not actually used. Since it will be used in
future patches, let's correct this oversight.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dir.c::match_pathname(): pay attention to the length of string parameters

This function takes two counted strings: a <pattern, patternlen> pair
and a <pathname, pathlen> pair. But we end up feeding the result to
fnmatch, which expects NUL-terminated strings.

We can fix this by calling the fnmatch_icase_mem function, which
handles re-allocating into a NUL-terminated string if necessary.

While we're at it, we can avoid even calling fnmatch in some cases. In
addition to patternlen, we get "prefix", the size of the pattern that
contains no wildcard characters. We do a straight match of the prefix
part first, and then use fnmatch to cover the rest. But if there are
no wildcards in the pattern at all, we do not even need to call
fnmatch; we would simply be comparing two empty strings.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t: check that a pattern without trailing slash matches a directory

Prior to v1.8.1.1, with:

  git init
  echo content >foo &&
  mkdir subdir &&
  echo content >subdir/bar &&
  echo "subdir export-ignore" >.gitattributes
  git add . &&
  git commit -m one &&
  git archive HEAD | tar tf -

the resulting archive would contain only "foo" and ".gitattributes",
not subdir.  This was broken with a recent change that intended to
allow "subdir/ export-ignore" to also exclude the directory, but
instead ended up _requiring_ the trailing slash by mistake.

A pattern "subdir" should match any path "subdir", whether it is a
directory or a non-directory.  A pattern "subdir/" insists that a
path "subdir" must be a directory for it to match.

This patch adds test not just for this simple case, but also for
deeper cross-directory cases, as well as cases with wildcards.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>