sha1_file.c:create_tmpfile(): Fix race when creating loose object dirs

There are cases (e.g. when running concurrent fetches in a repo) where
multiple Git processes concurrently attempt to create loose objects
within the same objects/XX/ dir. The creation of the loose object files
is (AFAICS) safe from races, but the creation of the objects/XX/ dir in
which the loose objects reside is unsafe, for example:

Two concurrent fetches - A and B. As part of its fetch, A needs to store
12aaaaa as a loose object. B, on the other hand, needs to store 12bbbbb
as a loose object. The objects/12 directory does not already exist.
Concurrently, both A and B determine that they need to create the
objects/12 directory (because their first call to git_mkstemp_mode()
within create_tmpfile() fails witn ENOENT). One of them - let's say A -
executes the following mkdir() call before the other. This first call
returns success, and A moves on. When B gets around to calling mkdir(),
it fails with EEXIST, because A won the race. The mkdir() error causes B
to return -1 from create_tmpfile(), which propagates all the way,
resulting in the fetch failing with:

  error: unable to create temporary file: File exists
  fatal: failed to write object
  fatal: unpack-objects failed

Although it's hard to add a testcase reproducing this issue, it's easy
to provoke if we insert a sleep after the

  if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
      return -1;

block, and then run two concurrent "git fetch"es against the same repo.

The fix is to simply handle mkdir() failing with EEXIST as a success.
If EEXIST is somehow returned for the wrong reasons (because the relevant
objects/XX is not a directory, or is otherwise unsuitable for object
storage), the following call to adjust_shared_perm(), or ultimately the
retried call to git_mkstemp_mode() will fail, and we end up returning
error from create_tmpfile() in any case.

Note that there are still cases where two users with unsuitable umasks
in a shared repo can end up in two races where one user first wins the
mkdir() race to create an objects/XX/ directory, and then the other user
wins the adjust_shared_perms() race to chmod() that directory, but fails
because it is (transiently, until the first users completes its chmod())
unwriteable to the other user. However, (an equivalent of) this race also
exists before this patch, and is made no worse by this patch.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
unpack-trees: fix "read-tree -u --reset A B" with conflicted index

When we call "read-tree --reset -u HEAD ORIG_HEAD", the first thing we
do with the index is to call read_cache_unmerged.  Originally that
would read the index, leaving aside any unmerged entries.  However, as
of d1a43f2 (reset --hard/read-tree --reset -u: remove unmerged new
paths, 2008-10-15), it actually creates a new cache entry to serve as
a placeholder, so that we later know to update the working tree.

However, we later noticed that the sha1 of that unmerged entry was
just copied from some higher stage, leaving you with random content in
the index.  That was fixed by e11d7b5 ("reset --merge": fix unmerged
case, 2009-12-31), which instead puts the null sha1 into the newly
created entry, and sets a CE_CONFLICTED flag. At the same time, it
teaches the unpack-trees machinery to pay attention to this flag, so
that oneway_merge throws away the current value.

However, it did not update the code paths for twoway_merge, which is
where we end up in the two-way read-tree with --reset. We notice that
the HEAD and ORIG_HEAD versions are the same, and say "oh, we can just
reuse the current version". But that's not true. The current version
is bogus.

Notice this case and make sure we do not keep the bogus entry; either
we do not have that path in the tree we are moving to (i.e. remove
it), or we want to have the cache entry we created for the tree we are
moving to (i.e. resolve by explicitly saying the "newtree" version is
what we want).

[jc: this is from the almost year-old $gmane/212316]

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t1005: reindent

Just to update the style of this ancient test script to match
our house style.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
t1005: add test for "read-tree --reset -u A B"

With a conflicted index, this used to give us an error.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_loose_object_info(): do not return success on missing object

Since 052fe5ea (sha1_loose_object_info: make type lookup optional,
2013-07-12), sha1_loose_object_info() returns happily without
checking if the object in question exists, which is not what the the
caller sha1_object_info_extended() expects; the caller does not even
bother checking the existence of the object itself.

Noticed-by: Sven Brauch <svenbrauch@googlemail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-fetch-pack uses URLs like git-fetch

"git fetch-pack" allows [<host>:]<directory> to point out the source
repository.
Use the term <repository>, which is already used in "git fetch" or "git pull"
to describe URLs supported by Git.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
typofixes: fix misspelt comments

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/technical/http-protocol.txt: typofixes

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
contrib: typofixes

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/git-log: update "--log-size" description

"--log-size" was added in commit 9fa3465, and the commit message
contained a satisfactory explanation; however, the man page entry
for it did not describe the actual output format, what the output
meant and what the option was meant to be used for.

Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Jason St. John <jstjohn@purdue.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/git-log.txt: mark-up fix and minor rephasing

 - typeset options, commands, and paths in monospace;
 - typeset references to sections with emphasis;
 - replace some double quotes with proper AsciiDoc quotes (e.g. ``foo'');
 - use title case when referring to section headings.

Signed-off-by: Jason St. John <jstjohn@purdue.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
State correct usage of literal examples in man pages in the coding standards

The man pages contain inconsistent usage of backticks vs. single quotes
around options, commands, etc. that are in paragraphs. This commit states
that backticks should always be used around literal examples.

This commit states that "--" and friends should not be escaped
(e.g. use `--pretty=oneline` instead of `\--pretty=oneline`).

This commit also states correct usage for typesetting command usage
examples with inline substitutions.

Thanks-to: Ramkumar Ramachandra <artagnon@gmail.com>
Thanks-to: Stuart Rackham <srackham@gmail.com>
Thanks-to: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jason St. John <jstjohn@purdue.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/rev-list-options.txt: fix mark-up

Some the labeled list entries have a blank line between the label
and the body text, and some don't.  Use the latter style for
consistency; incidentally, syntax highlighting in Vim works better
if there is no blank line there.

Typeset literal options, commands, and path names in monospace.
When using `literal string` mark-up to do so, there is no need to
escape AsciiDoc special characters with backslashes, so make sure we
don't do so.

Replace some double quotes with proper AsciiDoc quotes
(e.g. ``foo'').

Signed-off-by: Jason St. John <jstjohn@purdue.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/rev-list-options.txt: fix some grammatical issues and typos

Various fixes:

 - fix typos (e.g. "show" -> "shown")
 - use "regular expression(s)" instead of "regexp" where appropriate
 - reword some sentences for easier reading
 - fix/improve some grammatical issues (e.g. comma usage)
 - add missing articles (e.g. "the")
 - change "E-mail" to "email"

Signed-off-by: Jason St. John <jstjohn@purdue.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff: restrict pathspec limitations to diff b/f case only

builtin_diff_b_f() needs a path, not pathspec. Other modes in diff
can deal with pathspec just fine. But because of the current
GUARD_PATHSPEC() location, other modes also reject :(glob) and
:(icase).

Move GUARD_PATHSPEC(), and the "path" assignment statement, which is
the reason of this GUARD_PATHSPEC(), inside builtin_diff_b_f().

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/gitcli.txt: fix double quotes

Replace double quotes around literal examples with backticks

Signed-off-by: Jason St. John <jstjohn@purdue.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
glossary-content.txt: fix documentation of "**" patterns

"**" means bold in ASCIIDOC, so we need to escape it. This is similar
to 8447dc8 (gitignore.txt: fix documentation of "**" patterns -
2013-11-07)

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
SubmittingPatches: document how to handle multiple patches

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation: revamp git-cherry(1)

git-cherry(1)'s "description" section has never really managed
to explain to me what the command does.  It contains too much
explanation of the algorithm instead of simply saying what
goals it achieves, and too much terminology that we otherwise
do not use (fork-point instead of merge-base).

Try a much more concise approach: state what it finds out, why
this is neat, and how the output is formatted, in a few short
paragraphs.  In return, provide much longer examples of how it
fits into a "format-patch | am" based workflow, and how it
compares to reading the same from git-log.

Also carefully avoid using "merge" in a context where it does
not mean something that comes from git-merge(1).  Instead, say
"apply" in an attempt to further link to patch workflow
concepts.

While there, also omit the language about _which_ upstream
branch we treat as the default.  I literally just learned that
we support having several, so let's not confuse new users
here, especially considering that git-config(1) does not
document this.

Prompted-by: a.huemer@commend.com on #git
Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
cmd_repack(): remove redundant local variable "nr_packs"

Its value is the same as the number of entries in the "names"
string_list, so just use "names.nr" in its place.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Acked-by: Stefan Beller <stefanbeller@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>