Commit Graph

53050 Commits

Author SHA1 Message Date
nalla
a87f78907c asciidoctor: Fix user-manual to be built by asciidoctor
The `user-manual.txt` ist designed as a `book` but the `Makefile` wants to
build it as an `article`. This seems to be a problem when building the
documentation with `asciidoctor`. Furthermore the parts *Git Glossary*
and *Apendix B* had no subsections which is not allowed when building with
`asciidoctor`. So lets add a *dummy* section.

Signed-off-by: nalla <nalla@hamal.uberspace.de>
2015-05-14 10:05:55 +02:00
Johannes Schindelin
c26e4e7fe7 Handle the branch.<name>.rebase value 'interactive'
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:54 +02:00
Johannes Schindelin
26b7eb409d Teach 'git pull' to handle --rebase=interactive
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:54 +02:00
Jakub Bereżański
ab413060b6 wincred: handle empty username/password correctly
Empty (length 0) usernames and/or passwords, when saved in the Windows
Credential Manager, come back as null when reading the credential.

One use case for such empty credentials is with NTLM authentication, where
empty username and password instruct libcurl to authenticate using the
credentials of the currently logged-on user (single sign-on).

When locating the relevant credentials, make empty username match null.
When outputting the credentials, handle nulls correctly.

Signed-off-by: Jakub Bereżański <kuba@berezanscy.pl>
2015-05-14 10:05:53 +02:00
Jakub Bereżański
326d0eefb4 t0302: check helper can handle empty credentials
Make sure the helper does not crash when blank username and password is
provided. If the helper can save such credentials, it should be able to
read them back.

Signed-off-by: Jakub Bereżański <kuba@berezanscy.pl>
2015-05-14 10:05:53 +02:00
Sebastian Schuberth
3209426cd2 gitk: Use an external icon file on Windows
Git for Windows now ships with the new Git icon from git-scm.com. Use that
icon file if it exists instead of the old procedurally drawn one.

This patch was sent upstream but so far no decision on its inclusion was
made, so commit it to our fork.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
2015-05-14 10:05:52 +02:00
Chris West (Faux)
5c53c59d83 Fix another invocation of git from gitk with an overly long command-line
Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
2015-05-14 10:05:52 +02:00
Johannes Schindelin
2274dc0570 Work around the command line limit on Windows
On Windows, there are dramatic problems when a command line grows
beyond PATH_MAX, which is restricted to 8191 characters on XP and
later (according to http://support.microsoft.com/kb/830473).

Work around this by just cutting off the command line at that length
(actually, at a space boundary) in the hope that only negative
refs are chucked: gitk will then do unnecessary work, but that is
still better than flashing the gitk window and exiting with exit
status 5 (which no Windows user is able to make sense of).

The first fix caused Tcl to fail to compile the regexp, see msysGit issue
427. Here is another fix without using regexp, and using a more relaxed
command line length limit to fix the original issue 387.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:52 +02:00
Johannes Schindelin
9c617fbd4c git gui: set GIT_ASKPASS=git-gui--askpass if not set yet
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:51 +02:00
Heiko Voigt
be028b714d git-gui: provide question helper for retry fallback on Windows
Make use of the new environment variable GIT_ASK_YESNO to support the
recently implemented fallback in case unlink, rename or rmdir fail for
files in use on Windows. The added dialog will present a yes/no question
to the the user which will currently be used by the windows compat layer
to let the user retry a failed file operation.

Signed-off-by: Heiko Voigt <hvoigt@hvoigt.net>
2015-05-14 10:05:51 +02:00
Heiko Voigt
4253aa7896 Revert "git-gui: set GIT_DIR and GIT_WORK_TREE after setup"
This reverts commit a9fa11fe5b.
2015-05-14 10:05:50 +02:00
Johannes Sixt
b3cd0f5f9e criss cross rename failure workaround
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:49 +02:00
Pat Thoyts
f078c010b3 mingw: add tests for the hidden attribute on the git directory
With msysGit the .git directory is supposed to be hidden, unless it is
a bare git repository. Test this.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
2015-05-14 10:05:49 +02:00
Johannes Schindelin
74c09179e2 When initializing .git/, record the current setting of core.hideDotFiles
This is on Windows only, of course.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:48 +02:00
Erik Faye-Lund
3c21fbf5ed core.hideDotFiles: hide '.git' dir by default
At least for cross-platform projects, it makes sense to hide the
files starting with a dot, as this is the behavior on Unix/MacOSX.

However, at least Eclipse has problems interpreting the hidden flag
correctly, so the default is to hide only the .git/ directory.

The config setting core.hideDotFiles therefore supports not only
'true' and 'false', but also 'dotGitOnly'.

[jes: clarified the commit message, made git init respect the setting
by marking the .git/ directory only after reading the config, and added
documentation, and rebased on top of current junio/next]

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:48 +02:00
Karsten Blees
0a175acdfe git-gui:handle the encoding of Git's output correctly
If we use 'eval exec $opt $cmdp $args' to execute git command,
tcl engine will convert the output of the git comand with the rule
system default code page to unicode.

But cp936 -> unicode conversion implicitly done by exec is not reversible.
So we have to use git_read instead.

Bug report and an original reproducer by Cloud Chou:
https://github.com/msysgit/git/issues/302

Karsten Blees writes this code patch.
Cloud Chou find the reason of the bug.

Thanks-to: dscho
Thanks-to: patthoyts
Signed-off-by: Karsten Blees <blees@dcon.de>
Original-test-by: Cloud Chou <515312382@qq.com>
Signed-off-by: Cloud Chou <515312382@qq.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2015-05-14 10:05:47 +02:00
Karsten Blees
1a65c37ae5 Unicode file name support (gitk and git-gui)
Assumes file names in git tree objects are UTF-8 encoded.

On most unix systems, the system encoding (and thus the TCL system
encoding) will be UTF-8, so file names will be displayed correctly.

On Windows, it is impossible to set the system encoding to UTF-8. Changing
the TCL system encoding (via 'encoding system ...', e.g. in the startup
code) is explicitly discouraged by the TCL docs.

Change gitk and git-gui functions dealing with file names to always convert
from and to UTF-8.

Signed-off-by: Karsten Blees <blees@dcon.de>
2015-05-14 10:05:47 +02:00
Johannes Schindelin
b50c89ae8c Start the merging-rebase to v2.4.1
This commit starts the rebase of d74a85f to 2be062d
2015-05-14 10:05:46 +02:00
Junio C Hamano
1ea28e1494 Sync with 2.4.1
* maint:
  Git 2.4.1
2015-05-13 14:35:05 -07:00
Junio C Hamano
aaa7e0d7f8 Git 2.4.1
Signed-off-by: Junio C Hamano <gitster@pobox.com>
v2.4.1
2015-05-13 14:11:43 -07:00
Junio C Hamano
a379f25462 Merge branch 'sb/line-log-plug-pairdiff-leak' into maint
* sb/line-log-plug-pairdiff-leak:
  line-log.c: fix a memleak
2015-05-13 14:05:56 -07:00
Junio C Hamano
071e93a148 Merge branch 'sb/test-bitmap-free-at-end' into maint
* sb/test-bitmap-free-at-end:
  pack-bitmap.c: fix a memleak
2015-05-13 14:05:56 -07:00
Junio C Hamano
36ec67d1ea Merge branch 'nd/t1509-chroot-test' into maint
Correct test bitrot.

* nd/t1509-chroot-test:
  t1509: update prepare script to be able to run t1509 in chroot again
2015-05-13 14:05:55 -07:00
Junio C Hamano
c1c4a878bb Merge branch 'jk/type-from-string-gently' into maint
"git cat-file bl $blob" failed to barf even though there is no
object type that is "bl".

* jk/type-from-string-gently:
  type_from_string_gently: make sure length matches
2015-05-13 14:05:54 -07:00
Junio C Hamano
21b56b9259 Merge branch 'ep/fix-test-lib-functions-report' into maint
* ep/fix-test-lib-functions-report:
  test-lib-functions.sh: fix the second argument to some helper functions
2015-05-13 14:05:53 -07:00
Junio C Hamano
8a1d89745d Merge branch 'cn/bom-in-gitignore' into maint
Teach the codepaths that read .gitignore and .gitattributes files
that these files encoded in UTF-8 may have UTF-8 BOM marker at the
beginning; this makes it in line with what we do for configuration
files already.

* cn/bom-in-gitignore:
  attr: skip UTF8 BOM at the beginning of the input file
  config: use utf8_bom[] from utf.[ch] in git_parse_source()
  utf8-bom: introduce skip_utf8_bom() helper
  add_excludes_from_file: clarify the bom skipping logic
  dir: allow a BOM at the beginning of exclude files
2015-05-13 14:05:51 -07:00
Junio C Hamano
ebb464f0cb Merge branch 'jk/prune-mtime' into maint
Access to objects in repositories that borrow from another one on a
slow NFS server unnecessarily got more expensive due to recent code
becoming more cautious in a naive way not to lose objects to pruning.

* jk/prune-mtime:
  sha1_file: only freshen packs once per run
  sha1_file: freshen pack objects before loose
  reachable: only mark local objects as recent
2015-05-13 14:05:50 -07:00
Junio C Hamano
a60abe10f2 Merge branch 'jk/init-core-worktree-at-root' into maint
We avoid setting core.worktree when the repository location is the
".git" directory directly at the top level of the working tree, but
the code misdetected the case in which the working tree is at the
root level of the filesystem (which arguably is a silly thing to
do, but still valid).

* jk/init-core-worktree-at-root:
  init: don't set core.worktree when initializing /.git
2015-05-13 14:05:49 -07:00
Junio C Hamano
429ad20413 log: do not shorten decoration names too early
The DECORATE_SHORT_REFS option given to load_ref_decorations()
affects the way a copy of the refname is stored for each decorated
commit, and this forces later steps like current_pointed_by_HEAD()
to adjust their behaviour based on this initial settings.

Instead, we can always store the full refname and then shorten them
when producing the output.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-13 12:40:57 -07:00
Junio C Hamano
76c61fbdba log: decorate HEAD with branch name under --decorate=full, too
The previous step to teach "log --decorate" to show "HEAD -> master"
instead of "HEAD, master" when showing the commit at the tip of the
'master' branch, when the 'master' branch is checked out, did not
work for "log --decorate=full".

The commands in the "log" family prepare commit decorations for all
refs upfront, and the actual string used in a decoration depends on
how load_ref_decorations() is called very early in the process.  By
default, "git log --decorate" stores names with common prefixes such
as "refs/heads" stripped; "git log --decorate=full" stores the full
refnames.

When the current_pointed_by_HEAD() function has to decide if "HEAD"
points at the branch a decoration describes, however, what was
passed to load_ref_decorations() to decide to strip (or keep) such a
common prefix is long lost.  This makes it impossible to reliably
tell if a decoration that stores "refs/heads/master", for example,
is the 'master' branch (under "--decorate" with prefix omitted) or
'refs/heads/master' branch (under "--decorate=full").

Keep what was passed to load_ref_decorations() in a global next to
the global variable name_decoration, and use that to decide how to
match what was read from "HEAD" and what is in a decoration.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-13 10:25:18 -07:00
Jeff King
d595bdc17f doc: put example URLs and emails inside literal backticks
This makes sure that AsciiDoc does not turn them into links.
Regular AsciiDoc does not catch these cases, but AsciiDoctor
does treat them as links.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:14:46 -07:00
Jeff King
4538a88256 doc: drop backslash quoting of some curly braces
Text like "{foo}" triggers an AsciiDoc attribute; we have to
write "\{foo}" to suppress this. But when the "foo" is not a
syntactically valid attribute, we can skip the quoting. This
makes the source nicer to read, and looks better under
Asciidoctor. With AsciiDoc itself, this patch produces no
changes.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:14:46 -07:00
Jeff King
1c262bb7b2 doc: convert \--option to --option
Older versions of AsciiDoc would convert the "--" in
"--option" into an emdash. According to 565e135
(Documentation: quote double-dash for AsciiDoc, 2011-06-29),
this is fixed in AsciiDoc 8.3.0. According to bf17126, we
don't support anything older than 8.4.1 anyway, so we no
longer need to worry about quoting.

Even though this does not change the output at all, there
are a few good reasons to drop the quoting:

  1. It makes the source prettier to read.

  2. We don't quote consistently, which may be confusing when
     reading the source.

  3. Asciidoctor does not like the quoting, and renders a
     literal backslash.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:14:46 -07:00
Jeff King
0a3ca9c011 doc/add: reformat --edit option
All of the other options in the list put short and long as
two separate headings.

We can also drop the backslashing of `--`. It isn't used
elsewhere and is unnecessary for modern asciidoc (plus it
confuses asciidoctor).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:13:40 -07:00
Jeff King
a367b8699d doc: fix length of underlined section-title
In AsciiDoc, it is OK to say:

   this is my title
   -------------------------

but AsciiDoctor is more strict. Let's match the underline to
the title (which also makes the source prettier to read).
The output from AsciiDoc is the same either way.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:13:40 -07:00
Jeff King
5a8a19e903 doc: fix hanging "+"-continuation
In list content that wants to continue to a second
paragraph, the "+" continuation and subsequent paragraph
need to be left-aligned. Otherwise AsciiDoc seems to insert
only a linebreak.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:13:40 -07:00
Jeff King
b50bfb8fd5 doc: fix unquoted use of "{type}"
Curly braces open an "attribute" in AsciiDoc; if there's no
such attribute, strange things may happen. In this case, the
unquoted "{type}" causes AsciiDoc to omit an entire line of
text from the output. We can fix it by putting the whole
phrase inside literal backticks (which also lets us get rid
of ugly backslash escaping).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:13:40 -07:00
Jeff King
e08bc7a9ec doc: fix misrendering due to `single quote'
AsciiDoc misparses some text that contains a `literal`
word followed by a fancy `single quote' word, and treats
everything from the start of the literal to the end of the
quote as a single-quoted phrase.

We can work around this by switching the latter to be a
literal, as well. In the first case, this is perhaps what
was intended anyway, as it makes us consistent with the the
earlier literals in the same paragraph. In the second, the
output is arguably better, as we will format our commit
references as <code> blocks.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 22:13:39 -07:00
Jeff King
ad3967a5a2 doc: fix unmatched code fences in git-stripspace
The asciidoctor renderer is more picky than classic asciidoc,
and insists that the start and end of a code fence be the
same size.

Found with this hacky perl script:

    foreach my $fn (@ARGV) {
      open(my $fh, '<', $fn);
      my ($fence, $fence_lineno, $prev);
      while (<$fh>) {
        chomp;
        if (/^----+$/) {
          if ($fence_lineno) {
            if ($_ ne $fence) {
              print "$fn:$fence_lineno:mismatched fence: ",
                    length($fence), " != ", length($_), "\n";
            }
            $fence_lineno = undef;
          }
	  # hacky check to avoid title-underlining
          elsif ($prev eq '' || $prev eq '+') {
            $fence = $_;
            $fence_lineno = $.;
          }
        }
        $prev = $_;
      }
    }

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:33:09 -07:00
Junio C Hamano
185ce3a98c Merge branch 'mh/write-refs-sooner-2.3' into mh/write-refs-sooner-2.4
* mh/write-refs-sooner-2.3:
  ref_transaction_commit(): fix atomicity and avoid fd exhaustion
  ref_transaction_commit(): remove the local flags variable
  ref_transaction_commit(): inline call to write_ref_sha1()
  rename_ref(): inline calls to write_ref_sha1() from this function
  commit_ref_update(): new function, extracted from write_ref_sha1()
  write_ref_to_lockfile(): new function, extracted from write_ref_sha1()
  t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE
  update-ref: test handling large transactions properly
2015-05-12 21:28:54 -07:00
Michael Haggerty
cf018ee0cd ref_transaction_commit(): fix atomicity and avoid fd exhaustion
The old code was roughly

    for update in updates:
        acquire locks and check old_sha
    for update in updates:
        if changing value:
            write_ref_to_lockfile()
            commit_ref_update()
    for update in updates:
        if deleting value:
            unlink()
    rewrite packed-refs file
    for update in updates:
        if reference still locked:
            unlock_ref()

This has two problems.

Non-atomic updates
==================

The atomicity of the reference transaction depends on all pre-checks
being done in the first loop, before any changes have started being
committed in the second loop. The problem is that
write_ref_to_lockfile() (previously part of write_ref_sha1()), which
is called from the second loop, contains two more checks:

* It verifies that new_sha1 is a valid object

* If the reference being updated is a branch, it verifies that
  new_sha1 points at a commit object (as opposed to a tag, tree, or
  blob).

If either of these checks fails, the "transaction" is aborted during
the second loop. But this might happen after some reference updates
have already been permanently committed. In other words, the
all-or-nothing promise of "git update-ref --stdin" could be violated.

So these checks have to be moved to the first loop.

File descriptor exhaustion
==========================

The old code locked all of the references in the first loop, leaving
all of the lockfiles open until later loops. Since we might be
updating a lot of references, this could result in file descriptor
exhaustion.

The solution
============

After this patch, the code looks like

    for update in updates:
        acquire locks and check old_sha
        if changing value:
            write_ref_to_lockfile()
        else:
            close_ref()
    for update in updates:
        if changing value:
            commit_ref_update()
    for update in updates:
        if deleting value:
            unlink()
    rewrite packed-refs file
    for update in updates:
        if reference still locked:
            unlock_ref()

This fixes both problems:

1. The pre-checks in write_ref_to_lockfile() are now done in the first
   loop, before any changes have been committed. If any of the checks
   fails, the whole transaction can now be rolled back correctly.

2. All lockfiles are closed in the first loop immediately after they
   are created (either by write_ref_to_lockfile() or by close_ref()).
   This means that there is never more than one open lockfile at a
   time, preventing file descriptor exhaustion.

To simplify the bookkeeping across loops, add a new REF_NEEDS_COMMIT
bit to update->flags, which keeps track of whether the corresponding
lockfile needs to be committed, as opposed to just unlocked. (Since
"struct ref_update" is internal to the refs module, this change is not
visible to external callers.)

This change fixes two tests in t1400.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:03 -07:00
Michael Haggerty
cbf50f9e3d ref_transaction_commit(): remove the local flags variable
Instead, work directly with update->flags. This has the advantage that
the REF_DELETING bit, set in the first loop, can be read in the second
loop instead of having to be recomputed. Plus, it was potentially
confusing having both update->flags and flags, which sometimes had
different values.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:03 -07:00
Michael Haggerty
61e51e0000 ref_transaction_commit(): inline call to write_ref_sha1()
That was the last caller, so delete function write_ref_sha1().

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:03 -07:00
Michael Haggerty
ba43b7f29c rename_ref(): inline calls to write_ref_sha1() from this function
Most of what it does is unneeded from these call sites.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:02 -07:00
Michael Haggerty
ad4cd6c297 commit_ref_update(): new function, extracted from write_ref_sha1()
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:02 -07:00
Michael Haggerty
e6fd3c6730 write_ref_to_lockfile(): new function, extracted from write_ref_sha1()
This is the first step towards separating the checking and writing of
the new reference value to committing the change.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:02 -07:00
Stefan Beller
fc38a9bb4d t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE
During creation of the patch series our discussion we could have a
more descriptive name for the prerequisite for the test so it stays
unique when other limits of ulimit are introduced.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:02 -07:00
Stefan Beller
d415ad022d update-ref: test handling large transactions properly
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:28:02 -07:00
Junio C Hamano
4ec6591dd7 Merge branch 'mh/write-refs-sooner-2.2' into mh/write-refs-sooner-2.3
* mh/write-refs-sooner-2.2:
  ref_transaction_commit(): fix atomicity and avoid fd exhaustion
  ref_transaction_commit(): remove the local flags variable
  ref_transaction_commit(): inline call to write_ref_sha1()
  rename_ref(): inline calls to write_ref_sha1() from this function
  commit_ref_update(): new function, extracted from write_ref_sha1()
  write_ref_to_lockfile(): new function, extracted from write_ref_sha1()
  t7004: rename ULIMIT test prerequisite to ULIMIT_STACK_SIZE
  update-ref: test handling large transactions properly
2015-05-12 21:26:09 -07:00
Michael Haggerty
6c34492ab4 ref_transaction_commit(): fix atomicity and avoid fd exhaustion
The old code was roughly

    for update in updates:
        acquire locks and check old_sha
    for update in updates:
        if changing value:
            write_ref_to_lockfile()
            commit_ref_update()
    for update in updates:
        if deleting value:
            unlink()
    rewrite packed-refs file
    for update in updates:
        if reference still locked:
            unlock_ref()

This has two problems.

Non-atomic updates
==================

The atomicity of the reference transaction depends on all pre-checks
being done in the first loop, before any changes have started being
committed in the second loop. The problem is that
write_ref_to_lockfile() (previously part of write_ref_sha1()), which
is called from the second loop, contains two more checks:

* It verifies that new_sha1 is a valid object

* If the reference being updated is a branch, it verifies that
  new_sha1 points at a commit object (as opposed to a tag, tree, or
  blob).

If either of these checks fails, the "transaction" is aborted during
the second loop. But this might happen after some reference updates
have already been permanently committed. In other words, the
all-or-nothing promise of "git update-ref --stdin" could be violated.

So these checks have to be moved to the first loop.

File descriptor exhaustion
==========================

The old code locked all of the references in the first loop, leaving
all of the lockfiles open until later loops. Since we might be
updating a lot of references, this could result in file descriptor
exhaustion.

The solution
============

After this patch, the code looks like

    for update in updates:
        acquire locks and check old_sha
        if changing value:
            write_ref_to_lockfile()
        else:
            close_ref()
    for update in updates:
        if changing value:
            commit_ref_update()
    for update in updates:
        if deleting value:
            unlink()
    rewrite packed-refs file
    for update in updates:
        if reference still locked:
            unlock_ref()

This fixes both problems:

1. The pre-checks in write_ref_to_lockfile() are now done in the first
   loop, before any changes have been committed. If any of the checks
   fails, the whole transaction can now be rolled back correctly.

2. All lockfiles are closed in the first loop immediately after they
   are created (either by write_ref_to_lockfile() or by close_ref()).
   This means that there is never more than one open lockfile at a
   time, preventing file descriptor exhaustion.

To simplify the bookkeeping across loops, add a new REF_NEEDS_COMMIT
bit to update->flags, which keeps track of whether the corresponding
lockfile needs to be committed, as opposed to just unlocked. (Since
"struct ref_update" is internal to the refs module, this change is not
visible to external callers.)

This change fixes two tests in t1400.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-12 21:25:27 -07:00