Commit graph

39637 commits

Author SHA1 Message Date
Junio C Hamano 6c1249c503 Third batch for 2.5 cycle
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-19 13:24:08 -07:00
Junio C Hamano 4295abc040 Merge branch 'sb/ref-lock-lose-lock-fd'
The refs API uses ref_lock struct which had its own "int fd", even
though the same file descriptor was in the lock struct it contains.
Clean-up the code to lose this redundant field.

* sb/ref-lock-lose-lock-fd:
  refs.c: remove lock_fd from struct ref_lock
2015-05-19 13:17:59 -07:00
Junio C Hamano 3b7d373ae2 Merge branch 'kn/cat-file-literally'
Add the "--allow-unknown-type" option to "cat-file" to allow
inspecting loose objects of an experimental or a broken type.

* kn/cat-file-literally:
  t1006: add tests for git cat-file --allow-unknown-type
  cat-file: teach cat-file a '--allow-unknown-type' option
  cat-file: make the options mutually exclusive
  sha1_file: support reading from a loose object of unknown type
2015-05-19 13:17:58 -07:00
Junio C Hamano 949d16795c Merge branch 'nd/dwim-wildcards-as-pathspecs'
A heuristic to help the "git <cmd> <revs> <pathspec>" command line
convention to catch mistyped paths is to make sure all the non-rev
parameters in the later part of the command line are names of the
files in the working tree, but that means "git grep $str -- \*.c"
must always be disambiguated with "--", because nobody sane will
create a file whose name literally is asterisk-dot-see.  Loosen the
heuristic to declare that with a wildcard string the user likely
meant to give us a pathspec.

* nd/dwim-wildcards-as-pathspecs:
  pathspec: avoid the need of "--" when wildcard is used
2015-05-19 13:17:58 -07:00
Junio C Hamano bcd1ecd08a Merge branch 'jc/merge'
"git merge FETCH_HEAD" learned that the previous "git fetch" could
be to create an Octopus merge, i.e. recording multiple branches
that are not marked as "not-for-merge"; this allows us to lose an
old style invocation "git merge <msg> HEAD $commits..." in the
implementation of "git pull" script; the old style syntax can now
be deprecated.

* jc/merge:
  merge: deprecate 'git merge <message> HEAD <commit>' syntax
  merge: handle FETCH_HEAD internally
  merge: decide if we auto-generate the message early in collect_parents()
  merge: make collect_parents() auto-generate the merge message
  merge: extract prepare_merge_message() logic out
  merge: narrow scope of merge_names
  merge: split reduce_parents() out of collect_parents()
  merge: clarify collect_parents() logic
  merge: small leakfix and code simplification
  merge: do not check argc to determine number of remote heads
  merge: clarify "pulling into void" special case
  t5520: test pulling an octopus into an unborn branch
  t5520: style fixes
  merge: simplify code flow
  merge: test the top-level merge driver
2015-05-19 13:17:57 -07:00
Junio C Hamano eae0216646 Merge branch 'ph/rebase-i-redo'
"git rebase -i" moved the "current" command from "todo" to "done" a
bit too prematurely, losing a step when a "pick" did not even start.

* ph/rebase-i-redo:
  rebase -i: redo tasks that die during cherry-pick
2015-05-19 13:17:56 -07:00
Junio C Hamano 072f391c53 Merge branch 'jc/test-prereq-validate'
Help us to find broken test script that splits the body part of the
test by mistaken use of wrong kind of quotes.

* jc/test-prereq-validate:
  test: validate prerequistes syntax
2015-05-19 13:17:55 -07:00
Junio C Hamano 7a4f891329 Merge branch 'bc/connect-plink'
The connection initiation code for "ssh" transport tried to absorb
differences between the stock "ssh" and Putty-supplied "plink" and
its derivatives, but the logic to tell that we are using "plink"
variants were too loose and falsely triggered when "plink" appeared
anywhere in the path (e.g. "/home/me/bin/uplink/ssh").

* bc/connect-plink:
  connect: improve check for plink to reduce false positives
  t5601: fix quotation error leading to skipped tests
  connect: simplify SSH connection code path
2015-05-19 13:17:55 -07:00
Junio C Hamano da3d507ce0 Merge branch 'jk/test-chain-lint'
Developer support to automatically detect broken &&-chain in the
test scripts is now turned on by default.

* jk/test-chain-lint:
  test-lib: turn on GIT_TEST_CHAIN_LINT by default
  t7502-commit.sh: fix a broken and-chain
2015-05-19 13:17:54 -07:00
Junio C Hamano 3e199decd5 Merge branch 'fg/document-commit-message-stripping'
* fg/document-commit-message-stripping:
  Documentation: clarify how "git commit" cleans up the edited log message
2015-05-19 13:17:53 -07:00
Junio C Hamano 05c39674f3 Merge branch 'jk/stash-require-clean-index'
"git stash pop/apply" forgot to make sure that not just the working
tree is clean but also the index is clean. The latter is important
as a stash application can conflict and the index will be used for
conflict resolution.

* jk/stash-require-clean-index:
  stash: require a clean index to apply
  t3903: avoid applying onto dirty index
  t3903: stop hard-coding commit sha1s
2015-05-19 13:17:52 -07:00
Junio C Hamano 1645dbeff7 Merge branch 'jk/git-no-more-argv0-path-munging'
We have prepended $GIT_EXEC_PATH and the path "git" is installed in
(typically "/usr/bin") to $PATH when invoking subprograms and hooks
for almost eternity, but the original use case the latter tried to
support was semi-bogus (i.e. install git to /opt/foo/git and run it
without having /opt/foo on $PATH), and more importantly it has
become less and less relevant as Git grew more mainstream (i.e. the
users would _want_ to have it on their $PATH).  Stop prepending the
path in which "git" is installed to users' $PATH, as that would
interfere the command search order people depend on (e.g. they may
not like versions of programs that are unrelated to Git in /usr/bin
and want to override them by having different ones in /usr/local/bin
and have the latter directory earlier in their $PATH).

* jk/git-no-more-argv0-path-munging:
  stop putting argv[0] dirname at front of PATH
2015-05-19 13:17:52 -07:00
Junio C Hamano 20cf8b548e Merge branch 'jc/gitignore-precedence'
core.excludesfile (defaulting to $XDG_HOME/git/ignore) is supposed
to be overridden by repository-specific .git/info/exclude file, but
the order was swapped from the beginning. This belatedly fixes it.

* jc/gitignore-precedence:
  ignore: info/exclude should trump core.excludesfile
2015-05-19 13:17:51 -07:00
Junio C Hamano d0c692263f Merge branch 'nd/diff-i-t-a'
After "git add -N", the path appeared in output of "git diff HEAD"
and "git diff --cached HEAD", leading "git status" to classify it
as "Changes to be committed".  Such a path, however, is not yet to
be scheduled to be committed.  "git diff" showed the change to the
path as modification, not as a "new file", in the header of its
output.

Treat such paths as "yet to be added to the index but Git already
know about them"; "git diff HEAD" and "git diff --cached HEAD"
should not talk about them, and "git diff" should show them as new
files yet to be added to the index.

* nd/diff-i-t-a:
  diff-lib.c: adjust position of i-t-a entries in diff
2015-05-19 13:17:49 -07:00
Jeff King a4fb76ce19 progress: treat "no terminal" as being in the foreground
progress: treat "no terminal" as being in the foreground

Commit 85cb890 (progress: no progress in background,
2015-04-13) avoids sending progress from background
processes by checking that the process group id of the
current process is the same as that of the controlling
terminal.

If we don't have a terminal, however, this check never
succeeds, and we print no progress at all (until the final
"done" message). This can be seen when cloning a large
repository; instead of getting progress updates for
"counting objects", it will appear to hang then print the
final count.

We can fix this by treating an error return from tcgetpgrp()
as a signal to show the progress.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-19 09:35:14 -07:00
Mike Hommey 822f0c4ff7 clone: call transport_set_verbosity before anything else on the newly created transport
Commit 2879bc3 made the progress and verbosity options sent to remote helper
earlier than they previously were. But nothing else after that would send
updates if the value is changed later on with transport_set_verbosity.

While for fetch and push, transport_set_verbosity is the first thing that
is done after creating the transport, it was not the case for clone. So
commit 2879bc3 broke changing progress and verbosity for clone, for urls
requiring a remote helper only (so, not git:// urls, for instance).

Moving transport_set_verbosity to just after the transport is created
works around the issue.

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-19 09:05:55 -07:00
Stefan Beller 66d2e04ec9 subdirectory tests: code cleanup, uncomment test
Back when these tests were written, we wanted to make sure that Git
notices it is in a bare repository and "git show -s HEAD" would
refrain from complaining that HEAD might mean a file it sees in its
current working directory (because it does not).  But the version of
Git back then didn't behave well, without (doubly) being told that
it is inside a bare repository by exporting "GIT_DIR=.".  The form
of the test we originally wanted to have was left commented out as
a reminder.

Nowadays the test as originally intended works, so add it to the
test suite.  We'll keep the old test that explicitly sets GIT_DIR=.
to make sure that use case will not regress.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-18 15:22:49 -07:00
Patrick Steinhardt 3890dae970 pack-protocol.txt: fix insconsistent spelling of "packfile"
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-17 11:25:00 -07:00
Patrick Steinhardt 4667391958 git-unpack-objects.txt: fix inconsistent spelling of "packfile"
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-17 11:24:58 -07:00
Patrick Steinhardt d017a450ed git-verify-pack.txt: fix inconsistent spelling of "packfile"
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-17 11:24:57 -07:00
Michael Haggerty f4ab4f3ab1 lock_packed_refs(): allow retries when acquiring the packed-refs lock
Currently, there is only one attempt to acquire any lockfile, and if
the lock is held by another process, the locking attempt fails
immediately.

This is not such a limitation for loose reference files. First, they
don't take long to rewrite. Second, most reference updates have a
known "old" value, so if another process is updating a reference at
the same moment that we are trying to lock it, then probably the
expected "old" value will not longer be valid, and the update will
fail anyway.

But these arguments do not hold for packed-refs:

* The packed-refs file can be large and take significant time to
  rewrite.

* Many references are stored in a single packed-refs file, so it could
  be that the other process was changing a different reference than
  the one that we are interested in.

Therefore, it is much more likely for there to be spurious lock
conflicts in connection to the packed-refs file, resulting in
unnecessary command failures.

So, if the first attempt to lock the packed-refs file fails, continue
retrying for a configurable length of time before giving up. The
default timeout is 1 second.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-14 14:51:51 -07:00
Michael Haggerty 044b6a9efe lockfile: allow file locking to be retried with a timeout
Currently, there is only one attempt to lock a file. If it fails, the
whole operation fails.

But it might sometimes be advantageous to try acquiring a file lock a
few times before giving up. So add a new function,
hold_lock_file_for_update_timeout(), that allows a timeout to be
specified. Make hold_lock_file_for_update() a thin wrapper around the
new function.

If timeout_ms is positive, then retry for at least that many
milliseconds to acquire the lock. On each failed attempt, use select()
to wait for a backoff time that increases quadratically (capped at 1
second) and has a random component to prevent two processes from
getting synchronized. If timeout_ms is negative, retry indefinitely.

In a moment we will switch to using the new function when locking
packed-refs.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-14 14:51:08 -07:00
Paul Tan 19d122bf1b pull: remove --tags error in no merge candidates case
Since 441ed41 ("git pull --tags": error out with a better message.,
2007-12-28), git pull --tags would print a different error message if
git-fetch did not return any merge candidates:

   It doesn't make sense to pull all tags; you probably meant:
        git fetch --tags

This is because at that time, git-fetch --tags would override any
configured refspecs, and thus there would be no merge candidates. The
error message was thus introduced to prevent confusion.

However, since c5a84e9 (fetch --tags: fetch tags *in addition to*
other stuff, 2013-10-30), git fetch --tags would fetch tags in addition
to any configured refspecs. Hence, if any no merge candidates situation
occurs, it is not because --tags was set. As such, this special error
message is now irrelevant.

To prevent confusion, remove this error message.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-14 09:52:51 -07:00
Jeff King d0258b93e6 doc: convert AsciiDoc {?foo} to ifdef::foo[]
The former seems to just be syntactic sugar for the latter.
And as it's sugar that AsciiDoctor doesn't understand, it
would be nice to avoid it. Since there are only two spots,
and the resulting source is not significantly harder to
read, it's worth doing.

Note that this does slightly affect the generated HTML (it
has an extra newline), but the rendered result for both HTML
and docbook should be the same (since the newline is not
syntactically significant there).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-05-14 09:38:29 -07:00
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>
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