t7800: "defaults" is no longer a builtin tool name

073678b8e6324a155fa99f40eee0637941a70a34 reworked the
mergetools/ directory so that every file corresponds to a
difftool-supported tool.  When this happened the "defaults"
file went away as it was no longer needed by mergetool--lib.

t7800 tests that configured commands can override builtins,
but this test was not adjusted when the "defaults" file was
removed because the test continued to pass.

Adjust the test to use the everlasting "vimdiff" tool name
instead of "defaults" so that it correctly tests against a tool
that is known by mergetool--lib.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pkt-line: share buffer/descriptor reading implementation

The packet_read function reads from a descriptor. The
packet_get_line function is similar, but reads from an
in-memory buffer, and uses a completely separate
implementation. This patch teaches the generic packet_read
function to accept either source, and we can do away with
packet_get_line's implementation.

There are two other differences to account for between the
old and new functions. The first is that we used to read
into a strbuf, but now read into a fixed size buffer. The
only two callers are fine with that, and in fact it
simplifies their code, since they can use the same
static-buffer interface as the rest of the packet_read_line
callers (and we provide a similar convenience wrapper for
reading from a buffer rather than a descriptor).

This is technically an externally-visible behavior change in
that we used to accept arbitrary sized packets up to 65532
bytes, and now cap out at LARGE_PACKET_MAX, 65520. In
practice this doesn't matter, as we use it only for parsing
smart-http headers (of which there is exactly one defined,
and it is small and fixed-size). And any extension headers
would be breaking the protocol to go over LARGE_PACKET_MAX
anyway.

The other difference is that packet_get_line would return
on error rather than dying. However, both callers of
strbuf_get_line are actually improved by dying.

The first caller does its own error checking, but we can
drop that; as a result, we'll actually get more specific
reporting about protocol breakage when packet_read dies
internally. The only downside is that packet_read will not
print the smart-http URL that failed, but that's not a big
deal; anybody not debugging can already see the remote's URL
already, and anybody debugging would want to run with
GIT_CURL_VERBOSE anyway to see way more information.

The second caller, which is just trying to skip past any
extra smart-http headers (of which there are none defined,
but which we allow to keep room for future expansion), did
not error check at all. As a result, it would treat an error
just like a flush packet. The resulting mess would generally
cause an error later in get_remote_heads, but now we get
error reporting much closer to the source of the problem.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
teach get_remote_heads to read from a memory buffer

Now that we can read packet data from memory as easily as a
descriptor, get_remote_heads can take either one as a
source. This will allow further refactoring in remote-curl.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
remote-curl: pass buffer straight to get_remote_heads

Until recently, get_remote_heads only knew how to read refs
from a file descriptor. To hack around this, we spawned a
thread (or forked a process) to write the buffer back to us.

Now that we can just pass it our buffer directly, we don't
have to use this hack anymore.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
remote-curl: move ref-parsing code up in file

The ref-parsing functions are static. Let's move them up in
the file to be available to more functions, which will help
us with later refactoring.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
remote-curl: always parse incoming refs

When remote-curl receives a list of refs from a server, it
keeps the whole buffer intact. When we get a "list" command,
we feed the result to get_remote_heads, and when we get a
"fetch" or "push" command, we feed it to fetch-pack or
send-pack, respectively.

If the HTTP response from the server is truncated for any
reason, we will get an incomplete ref advertisement. If we
then feed this incomplete list to fetch-pack, one of a few
things may happen:

  1. If the truncation is in a packet header, fetch-pack
     will notice the bogus line and complain.

  2. If the truncation is inside a packet, fetch-pack will
     keep waiting for us to send the rest of the packet,
     which we never will.

  3. If the truncation is at a packet boundary, fetch-pack
     will keep waiting for us to send the next packet, which
     we never will.

As a result, fetch-pack hangs, waiting for input.  However,
remote-curl believes it has sent all of the advertisement,
and therefore waits for fetch-pack to speak. The two
processes end up in a deadlock.

We do notice the broken ref list if we feed it to
get_remote_heads. So if git asks the helper to do a "list"
followed by a "fetch", we are safe; we'll abort during the
list operation, which parses the refs.

This patch teaches remote-curl to always parse and save the
incoming ref list when we read the ref advertisement from a
server. That means that we will always verify and abort
before even running fetch-pack (or send-pack) when reading a
corrupted list, even if we do not run the "list" command
explicitly.

Since we save the result, in the common case of running
"list" then "fetch", we do not do any extra parsing at all.
In the case of just a "fetch", we do an extra round of
parsing, but only once.

Note also that the "fetch" case will now also initialize
server_capabilities from the remote (in remote-curl; we
already would do so inside fetch-pack).  Doing "list+fetch"
already does this. It doesn't actually matter now, but the
new behavior is arguably more correct, should remote-curl
ever start caring about the server's capability list.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Provide a mechanism to turn off symlink resolution in ceiling paths

Commit 1b77d83cab 'setup_git_directory_gently_1(): resolve symlinks
in ceiling paths' changed the setup code to resolve symlinks in the
entries in GIT_CEILING_DIRECTORIES.  Because those entries are
compared textually to the symlink-resolved current directory, an
entry in GIT_CEILING_DIRECTORIES that contained a symlink would have
no effect.  It was known that this could cause performance problems
if the symlink resolution *itself* touched slow filesystems, but it
was thought that such use cases would be unlikely.  The intention of
the earlier change was to deal with a case when the user has this:

	GIT_CEILING_DIRECTORIES=/home/gitster

but in reality, /home/gitster is a symbolic link to somewhere else,
e.g. /net/machine/home4/gitster. A textual comparison between the
specified value /home/gitster and the location getcwd(3) returns
would not help us, but readlink("/home/gitster") would still be
fast.

After this change was released, Anders Kaseorg <andersk@mit.edu>
reported:

> [...] my computer has been acting so slow when I’m not connected to
> the network.  I put various network filesystem paths in
> $GIT_CEILING_DIRECTORIES, such as
> /afs/athena.mit.edu/user/a/n/andersk (to avoid hitting its parents
> /afs/athena.mit.edu, /afs/athena.mit.edu/user/a, and
> /afs/athena.mit.edu/user/a/n which all live in different AFS
> volumes).  Now when I’m not connected to the network, every
> invocation of Git, including the __git_ps1 in my shell prompt, waits
> for AFS to timeout.

To allow users to work around this problem, give them a mechanism to
turn off symlink resolution in GIT_CEILING_DIRECTORIES entries.  All
the entries that follow an empty entry will not be checked for symbolic
links and used literally in comparison.  E.g. with these:

	GIT_CEILING_DIRECTORIES=:/foo/bar:/xyzzy or
	GIT_CEILING_DIRECTORIES=/foo/bar::/xyzzy

we will not readlink("/xyzzy") because it comes after an empty entry.

With the former (but not with the latter), "/foo/bar" comes after an
empty entry, and we will not readlink it, either.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
index-format.txt: mention of v4 is missing in some places

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read-cache.c: use INDEX_FORMAT_{LB,UB} in verify_hdr()

9d22778 (read-cache.c: write prefix-compressed names in the index -
2012-04-04) defined these. Interestingly, they were not used by
read-cache.c, or anywhere in that patch. They were used in
builtin/update-index.c later for checking supported index
versions. Use them here too.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git.pm: fix cat_blob crashes on large files

Read and write each 1024 byte buffer, rather than trying to buffer
the entire content of the file.  We are only copying the contents to
a file descriptor and do not use it ourselves.

Previous code would crash on all files > 2 Gib, when the offset
variable became negative (perhaps below the level of perl),
resulting in a crash.  On a 32 bit system, or a system with low
memory it might crash before reaching 2 GiB due to memory
exhaustion.

This code may leave a partial file behind in case of failure, where
the old code would leave a completely empty file.  Neither version
verifies the correctness of the content.  Calling code must take
care of verification and cleanup.

Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-commit: populate the edit buffer with 2 blank lines before s-o-b

'commit -s' populates the edit buffer with a blank line before the
Signed-off-by line, to allow the user to immediately start typing
the log message.  But commit 33f2f9ab removed this space, forcing
the user to first push the Signed-off-by line down to open a place
to type the log message.

Fix this regression and let's ensure that the Signed-off-by line is
preceded by two blank lines, instead of just one, to hint that
something should be filled in, and that a blank line should separate
it from the body and the Signed-off-by line.

Add a test for this behavior.

Reported-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'wk/man-deny-current-branch-is-default-these-days' into jch

Will fast-track to 'master'.

* wk/man-deny-current-branch-is-default-these-days:
  user-manual: typofix (ofthe->of the)
Merge branch 'ct/autoconf-htmldir' into jch

An earlier change to config.mak.autogen broke a build driven by the
./configure script when --htmldir is not specified on the command
line of ./configure.

Will fast-track to 'master' (regression fix).

* ct/autoconf-htmldir:
  Bugfix: undefined htmldir in config.mak.autogen
Merge branch 'as/check-ignore' into jch

"git check-ignore ." segfaulted, as a function it calls deep in its
callchain took a string in the <ptr, length> form but did not stop
when given an empty string.

Will fast-track to 'master' (this is a new feature in the upcoming release).

* as/check-ignore:
  name-hash: allow hashing an empty string
  t0008: document test_expect_success_multi
Merge branch 'jn/less-reconfigure' into jch

A change made on v1.8.1.x maintenance track had a nasty regression
to break the build when autoconf is used.

Will fast-track to 'master' and 'maint' (regression fix).

* jn/less-reconfigure:
  Makefile: avoid infinite loop on configure.ac change
Merge branch 'wk/user-manual' into jch

Further updates to the user manual.

Will merge to 'master'.

* wk/user-manual:
  user-manual: Flesh out uncommitted changes and submodule updates
  user-manual: Use request-pull to generate "please pull" text
  user-manual: Reorganize the reroll sections, adding 'git rebase -i'

Conflicts:
	Documentation/user-manual.txt
Merge branch 'nd/count-garbage' into jch

Will cook in 'next'.

* nd/count-garbage:
  count-objects: report how much disk space taken by garbage files
  count-objects: report garbage files in pack directory too
  sha1_file: reorder code in prepare_packed_git_one()
  git-count-objects.txt: describe each line in -v output
Merge branch 'jc/fetch-raw-sha1' into jch

Allows requests to fetch objects at any tip of refs (including
hidden ones).  It seems that there may be use cases even outside
Gerrit (e.g. $gmane/215701).

Will cook in 'next'.

* jc/fetch-raw-sha1:
  fetch: fetch objects by their exact SHA-1 object names
  upload-pack: optionally allow fetching from the tips of hidden refs
  fetch: use struct ref to represent refs to be fetched
  parse_fetch_refspec(): clarify the codeflow a bit

Conflicts:
	cache.h
Merge branch 'jc/remove-treesame-parent-in-simplify-merges' into jch

The --simplify-merges logic did not cull irrelevant parents from a
merge that is otherwise not interesting with respect to the paths
we are following.

This touches a fairly core part of the revision traversal
infrastructure; even though I think this change is correct, please
report immediately if you find any unintended side effect.

Will cook in 'next'.

* jc/remove-treesame-parent-in-simplify-merges:
  simplify-merges: drop merge from irrelevant side branch

Conflicts:
	revision.c
Merge branch 'jc/remove-export-from-config-mak-in' into jch

config.mak.in template had an "export" line to cause a few
common makefile variables to be exported; if they need to be
expoted for autoconf/configure users, they should also be exported
for people who write config.mak the same way.  Move the "export" to
the main Makefile.  Also, stop exporting mandir that used to be
exported (only) when config.mak.autogen was used.  It would have
broken installation of manpages (but not other documentation
formats).

Will cook in 'next'.

* jc/remove-export-from-config-mak-in:
  Makefile: do not export mandir/htmldir/infodir
  config.mak.in: remove unused definitions

Conflicts:
	config.mak.in