test: rename $satisfied to $satisfied_prereq

All other shell variables that are used to globally keep track of
states related to prerequisite have "prereq" somewhere in their
names.  Be consistent and avoid potential name crashes with other
kinds of satisfaction in the future.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
test: allow prerequisite to be evaluated lazily

The test prerequisite mechanism is a useful way to allow some tests
in a test script to be skipped in environments that do not support
certain features (e.g. it is pointless to attempt checking how well
symbolic links are handled by Git on filesystems that do not support
them).  It is OK for commonly used prerequisites to be always tested
during start-up of a test script by having a codeblock that tests a
feature and calls test_set_prereq, but for an uncommon feature,
forcing 90% of scripts to pay the same probing overhead for
prerequisite they do not care about is wasteful.

Introduce a mechanism to probe the prerequiste lazily.  Changes are:

 - test_lazy_prereq () function, which takes the name of the
   prerequisite it probes and the script to probe for it, is
   added.  This only registers the name of the prerequiste that can
   be lazily probed and the script to eval (without running).

 - test_have_prereq() function (which is used by test_expect_success
   and also can be called directly by test scripts) learns to look
   at the list of prerequisites that can be lazily probed, and the
   prerequisites that have already been probed that way.  When asked
   for a prerequiste that can be but haven't been probed, the script
   registered with an earlier call to test_lazy_prereq is evaluated
   and the prerequisite is set.

 - test_run_lazy_prereq_() function is a helper to run the probe
   script with the same kind of sandbox as regular tests, helped by
   Jeff King.

Update the codeblock to probe and set SYMLINKS prerequisite using
the new mechanism as an example.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
test-lib: provide case insensitivity as a prerequisite

Case insensitivity plays a role in several tests and is tested in several
tests. Therefore, move the test from t003 into the test lib and use the
prerequisite in t0003.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t0050: use the CASE_INSENSITIVE_FS test prereq

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t0050: use the SYMLINKS test prereq

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
test-lib: provide UTF8 behaviour as a prerequisite

UTF8 behaviour of the filesystem (conversion from nfd to nfc)  plays a
role in several tests and is tested in several tests. Therefore, move
the test from t0050 into the test lib and use the prerequisite in t0050.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff: do not use null sha1 as a sentinel value

The diff code represents paths using the diff_filespec
struct. This struct has a sha1 to represent the sha1 of the
content at that path, as well as a sha1_valid member which
indicates whether its sha1 field is actually useful. If
sha1_valid is not true, then the filespec represents a
working tree file (e.g., for the no-index case, or for when
the index is not up-to-date).

The diff_filespec is only used internally, though. At the
interfaces to the diff subsystem, callers feed the sha1
directly, and we create a diff_filespec from it. It's at
that point that we look at the sha1 and decide whether it is
valid or not; callers may pass the null sha1 as a sentinel
value to indicate that it is not.

We should not typically see the null sha1 coming from any
other source (e.g., in the index itself, or from a tree).
However, a corrupt tree might have a null sha1, which would
cause "diff --patch" to accidentally diff the working tree
version of a file instead of treating it as a blob.

This patch extends the edges of the diff interface to accept
a "sha1_valid" flag whenever we accept a sha1, and to use
that flag when creating a filespec. In some cases, this
means passing the flag through several layers, making the
code change larger than would be desirable.

One alternative would be to simply die() upon seeing
corrupted trees with null sha1s. However, this fix more
directly addresses the problem (while bogus sha1s in a tree
are probably a bad thing, it is really the sentinel
confusion sending us down the wrong code path that is what
makes it devastating). And it means that git is more capable
of examining and debugging these corrupted trees. For
example, you can still "diff --raw" such a tree to find out
when the bogus entry was introduced; you just cannot do a
"--patch" diff (just as you could not with any other
corrupted tree, as we do not have any content to diff).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
do not write null sha1s to on-disk index

We should never need to write the null sha1 into an index
entry (short of the 1 in 2^160 chance that somebody actually
has content that hashes to it). If we attempt to do so, it
is much more likely that it is a bug, since we use the null
sha1 as a sentinel value to mean "not valid".

The presence of null sha1s in the index (which can come
from, among other things, "update-index --cacheinfo", or by
reading a corrupted tree) can cause problems for later
readers, because they cannot distinguish the literal null
sha1 from its use a sentinel value.  For example, "git
diff-files" on such an entry would make it appear as if it
is stat-dirty, and until recently, the diff code assumed
such an entry meant that we should be diffing a working tree
file rather than a blob.

Ideally, we would stop such entries from entering even our
in-core index. However, we do sometimes legitimately add
entries with null sha1s in order to represent these sentinel
situations; simply forbidding them in add_index_entry breaks
a lot of the existing code. However, we can at least make
sure that our in-core sentinel representation never makes it
to disk.

To be thorough, we will test an attempt to add both a blob
and a submodule entry. In the former case, we might run into
problems anyway because we will be missing the blob object.
But in the latter case, we do not enforce connectivity
across gitlink entries, making this our only point of
enforcement. The current implementation does not care which
type of entry we are seeing, but testing both cases helps
future-proof the test suite in case that changes.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fsck: detect null sha1 in tree entries

Short of somebody happening to beat the 1 in 2^160 odds of
actually generating content that hashes to the null sha1, we
should never see this value in a tree entry. So let's have
fsck warn if it it seen.

As in the previous commit, we test both blob and submodule
entries to future-proof the test suite against the
implementation depending on connectivity to notice the
error.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
config: "git config baa" should exit with status 1

We instead failed with an undocumented exit status 255.
Also define a "catch-all" status and document it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
t7406: fix misleading "rev-parse --max-count=1 HEAD"

The test happened to use "rev-parse --max-count=1 HEAD" consistently
to prepare the expected output and the actual output, so the
comparison between them gave us a correct success/failure because
both output had irrelevant "--max-count=1" in it.

But that is not an excuse to keep it broken.  Replace it a more
meaningful construct "rev-parse --verify HEAD".

Noticed by Daniel Graña while working on his submodule tests.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
sane_execvp(): ignore non-directory on $PATH

When you have a non-directory on your PATH, a funny thing happens:

	$ PATH=$PATH:/bin/sh git foo
	fatal: cannot exec 'git-foo': Not a directory?

Worse yet, as real commands always take precedence over aliases,
this behaviour interacts rather badly with them:

	$ PATH=$PATH:/bin/sh git -c alias.foo=show git foo -s
	fatal: cannot exec 'git-foo': Not a directory?

This is because an ENOTDIR error from the underlying execvp(2) is
reported back to the caller of our sane_execvp() wrapper as-is.

Translating it to ENOENT, just like the case where we _might_ have
the command in an unreadable directory, fixes it.  Without an alias,
we would get

	git: 'foo' is not a git command. See 'git --help'.

and we use the 'foo' alias when it is available, of course.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
send-email: improve RFC2047 quote parsing

The RFC2047 unquoting, used to parse email addresses in From and Cc
headers, is broken in several ways:

* It erroneously substitutes ' ' for '_' in *the whole* header, even
  outside the quoted field. [Noticed by Christoph.]

* It is too liberal in its matching, and happily matches the start
  of one quoted chunk against the end of another, or even just
  something that looks like such an end. [Noticed by Junio.]

* It fundamentally cannot cope with encodings that are not a
  superset of ASCII, nor several (incompatible) encodings in the
  same header.

This patch fixes the first two by doing a more careful decoding of
the outer quoting (e.g. "=AB" to represent an octet whose value is
0xAB).  Fixing the fundamental issues is left for a future, more
intrusive, patch.

Noticed-by: Christoph Miebach <christoph.miebach@web.de>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
setup: clarify error messages for file/revisions ambiguity

The previous "Use '--' to separate filenames from revisions" may sound
obvious for an old-time Unix user, but does not make it clear how to use
this '--'. In addition to mentionning this '--', give an idea of what the
new command should look like.

Ideally, we could provide cut-and-paste ready commands based on the
command that just failed, but we have no easy access to argv[] in this
place of the code.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff_setup_done(): return void

diff_setup_done() has historically returned an error code, but lost
the last nonzero return in 943d5b7 (allow diff.renamelimit to be set
regardless of -M/-C, 2006-08-09).  The callers were in a pretty
confused state: some actually checked for the return code, and some
did not.

Let it return void, and patch all callers to take this into account.
This conveniently also gets rid of a handful of different(!) error
messages that could never be triggered anyway.

Note that the function can still die().

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge-recursive: eliminate flush_buffer() in favor of write_in_full()

flush_buffer() is a thin wrapper around write_in_full() with two very
confusing properties:

* It runs a loop to handle short reads, ensuring that we write
  everything.  But that is precisely what write_in_full() does!

* It checks for a return value of 0 from write_in_full(), which cannot
  happen: it returns this value only if count=0, but flush_buffer()
  will never call write_in_full() in this case.

Remove it.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
include agent identifier in capability string

Instead of having the client advertise a particular version
number in the git protocol, we have managed extensions and
backwards compatibility by having clients and servers
advertise capabilities that they support. This is far more
robust than having each side consult a table of
known versions, and provides sufficient information for the
protocol interaction to complete.

However, it does not allow servers to keep statistics on
which client versions are being used. This information is
not necessary to complete the network request (the
capabilities provide enough information for that), but it
may be helpful to conduct a general survey of client
versions in use.

We already send the client version in the user-agent header
for http requests; adding it here allows us to gather
similar statistics for non-http requests.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix '\ No newline...' annotation in rewrite diffs

When a file that ends with an incomplete line is expressed as a
complete rewrite with the -B option, git diff incorrectly
appends the incomplete line indicator "\ No newline at end of
file" after such a line, rather than writing it on a line of its
own (the output codepath for normal output without -B does not
have this problem).  Add a LF after the incomplete line before
writing the "\ No newline ..." out to fix this.

Add a couple of tests to confirm that the indicator comment is
generated on its own line in both plain diff and rewrite mode.

Signed-off-by: Adam Butcher <dev.lists@jessamine.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
apply: delete unused deflate_origlen from patch struct

It hasn't been used since 2006, as of commit 3cd4f5e8

    "git-apply --binary: clean up and prepare for --reverse"

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read_index_from: remove bogus errno assignments

These assignments comes from the very first commit e83c516 (Initial
revision of "git", the information manager from hell - 2005-04-07).
Back then we did not die() when errors happened so correct errno was
required.

Since 5d1a5c0 ([PATCH] Better error reporting for "git status" -
2005-10-01), read_index_from() learned to die rather than just return
-1 and these assignments became irrelevant. Remove them.

While at it, move die_errno() next to xmmap() call because it's the
mmap's error code that we care about. Otherwise if close(fd); fails,
it could overwrite mmap's errno.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>