Commit Graph

526 Commits

Author SHA1 Message Date
Ævar Arnfjörð Bjarmason
bc40dfb10a string-list.h users: change to use *_{nodup,dup}()
Change all in-tree users of the string_list_init(LIST, BOOL) API to
use string_list_init_{nodup,dup}(LIST) instead.

As noted in the preceding commit let's leave the now-unused
string_list_init() wrapper in-place for any in-flight users, it can be
removed at some later date.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-01 12:32:22 -07:00
Han-Wen Nienhuys
617480d75b refs: make explicit that ref_iterator_peel returns boolean
Use -1 as error return value throughout.

This removes spurious differences in the GIT_TRACE_REFS output, depending on the
ref storage backend active.

Before, the cached ref_iterator (but only that iterator!) would return
peel_object() output directly. No callers relied on the peel_status values
beyond success/failure. All calls to these functions go through
peel_iterated_oid(), which returns peel_object() as a fallback, but also
squashing the error values.

The iteration interface already passes REF_ISSYMREF and REF_ISBROKEN through the
flags argument, so the additional error values in enum peel_status provide no
value.

The ref iteration interface provides a separate peel() function because certain
formats (eg. packed-refs and reftable) can store the peeled object next to the
tag SHA1. Passing the peeled SHA1 as an optional argument to each_ref_fn maps
more naturally to the implementation of ref databases. Changing the code in this
way is left for a future refactoring.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-20 07:54:12 +09:00
Junio C Hamano
16f91451fa Merge branch 'wc/packed-ref-removal-cleanup'
When "git update-ref -d" removes a ref that is packed, it left
empty directories under $GIT_DIR/refs/ for

* wc/packed-ref-removal-cleanup:
  refs: cleanup directories when deleting packed ref
2021-05-16 21:05:24 +09:00
Will Chandler
5f03e5126d refs: cleanup directories when deleting packed ref
When deleting a packed ref via 'update-ref -d', a lockfile is made in
the directory that would contain the loose copy of that ref, creating
any directories in the ref's path that do not exist. When the
transaction completes, the lockfile is deleted, but any empty parent
directories made when creating the lockfile are left in place.  These
empty directories are not removed by 'pack-refs' or other housekeeping
tasks and will accumulate over time.

When deleting a loose ref, we remove all empty parent directories at the
end of the transaction.

This commit applies the parent directory cleanup logic used when
deleting loose refs to packed refs as well.

Signed-off-by: Will Chandler <wfc@wfchandler.org>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-11 13:59:57 +09:00
Junio C Hamano
aaa3c8065d Merge branch 'bc/hash-transition-interop-part-1'
SHA-256 transition.

* bc/hash-transition-interop-part-1:
  hex: print objects using the hash algorithm member
  hex: default to the_hash_algo on zero algorithm value
  builtin/pack-objects: avoid using struct object_id for pack hash
  commit-graph: don't store file hashes as struct object_id
  builtin/show-index: set the algorithm for object IDs
  hash: provide per-algorithm null OIDs
  hash: set, copy, and use algo field in struct object_id
  builtin/pack-redundant: avoid casting buffers to struct object_id
  Use the final_oid_fn to finalize hashing of object IDs
  hash: add a function to finalize object IDs
  http-push: set algorithm when reading object ID
  Always use oidread to read into struct object_id
  hash: add an algo member to struct object_id
2021-05-10 16:59:46 +09:00
Junio C Hamano
a850356d1b Merge branch 'hn/trace-reflog-expiry'
The reflog expiry machinery has been taught to emit trace events.

* hn/trace-reflog-expiry:
  refs/debug: trace into reflog expiry too
2021-05-07 12:47:38 +09:00
brian m. carlson
14228447c9 hash: provide per-algorithm null OIDs
Up until recently, object IDs did not have an algorithm member, only a
hash.  Consequently, it was possible to share one null (all-zeros)
object ID among all hash algorithms.  Now that we're going to be
handling objects from multiple hash algorithms, it's important to make
sure that all object IDs have a correct algorithm field.

Introduce a per-algorithm null OID, and add it to struct hash_algo.
Introduce a wrapper function as well, and use it everywhere we used to
use the null_oid constant.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-27 16:31:39 +09:00
Han-Wen Nienhuys
34c319970d refs/debug: trace into reflog expiry too
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-27 15:59:39 +09:00
Han-Wen Nienhuys
2a2112a429 refs: print errno for read_raw_ref if GIT_TRACE_REFS is set
The ref backend API uses errno as a sideband error channel.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-12 14:42:37 -07:00
René Scharfe
ca56dadb4b use CALLOC_ARRAY
Add and apply a semantic patch for converting code that open-codes
CALLOC_ARRAY to use it instead.  It shortens the code and infers the
element size automatically.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-13 16:00:09 -08:00
Martin Ågren
7f0dc7998b refs/files-backend: don't peek into struct lock_file
Similar to the previous commits, avoid peeking into the `struct
lock_file`. Use the lock file API instead. Note how we obtain the path
to the lock file if `fdopen_lock_file()` failed and that this is not a
problem: as documented in lockfile.h, failure to "fdopen" does not roll
back the lock file and we're free to, e.g., query it for its path.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-06 13:53:32 -08:00
Junio C Hamano
c9a04f036f Merge branch 'hn/refs-trace-backend'
Developer support.

* hn/refs-trace-backend:
  refs: add GIT_TRACE_REFS debugging mechanism
2020-09-22 12:36:28 -07:00
Han-Wen Nienhuys
4441f42707 refs: add GIT_TRACE_REFS debugging mechanism
When set in the environment, GIT_TRACE_REFS makes git print operations and
results as they flow through the ref storage backend. This helps debug
discrepancies between different ref backends.

Example:

    $ GIT_TRACE_REFS="1" ./git branch
    15:42:09.769631 refs/debug.c:26         ref_store for .git
    15:42:09.769681 refs/debug.c:249        read_raw_ref: HEAD: 0000000000000000000000000000000000000000 (=> refs/heads/ref-debug) type 1: 0
    15:42:09.769695 refs/debug.c:249        read_raw_ref: refs/heads/ref-debug: 3a238e539b (=> refs/heads/ref-debug) type 0: 0
    15:42:09.770282 refs/debug.c:233        ref_iterator_begin: refs/heads/ (0x1)
    15:42:09.770290 refs/debug.c:189        iterator_advance: refs/heads/b4 (0)
    15:42:09.770295 refs/debug.c:189        iterator_advance: refs/heads/branch3 (0)

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-09 12:58:37 -07:00
Han-Wen Nienhuys
63c0567365 refs: move REF_LOG_ONLY to refs-internal.h
REF_LOG_ONLY is used in the transaction preparation: if a symref is involved in
a transaction, the referent of the symref should be updated, and the symref
itself should only be updated in the reflog.

Other ref backends will need to duplicate this logic too, so move it to a
central place.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-08 15:51:07 -07:00
Han-Wen Nienhuys
5085aef4c8 refs: move gitdir into base ref_store
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-19 14:08:04 -07:00
Han-Wen Nienhuys
4877c6c738 refs: fix comment about submodule ref_stores
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-19 14:08:03 -07:00
Han-Wen Nienhuys
e39620f07e refs: split off reading loose ref data in separate function
This prepares for handling FETCH_HEAD (which is not a regular ref)
separately from the ref backend.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-19 14:08:03 -07:00
Han-Wen Nienhuys
25429fed5c refs: move the logic to add \t to reflog to the files backend
523fa69c (reflog: cleanse messages in the refs.c layer, 2020-07-10)
centralized reflog normalizaton.  However, the normalizaton added a
leading "\t" to the message. This is an artifact of the reflog
storage format in the files backend, so it should be added there.

Routines that parse back the reflog (such as grab_nth_branch_switch)
expect the "\t" to not be in the message, so without this fix, git
with reftable cannot process the "@{-1}" syntax.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-31 10:21:51 -07:00
Junio C Hamano
523fa69c36 reflog: cleanse messages in the refs.c layer
Regarding reflog messages:

 - We expect that a reflog message consists of a single line.  The
   file format used by the files backend may add a LF after the
   message as a delimiter, and output by commands like "git log -g"
   may complete such an incomplete line by adding a LF at the end,
   but philosophically, the terminating LF is not a part of the
   message.

 - We however allow callers of refs API to supply a random sequence
   of NUL terminated bytes.  We cleanse caller-supplied message by
   squashing a run of whitespaces into a SP, and by trimming trailing
   whitespace, before storing the message.  This is how we tolerate,
   instead of erring out, a message with LF in it (be it at the end,
   in the middle, or both).

Currently, the cleansing of the reflog message is done by the files
backend, before the log is written out.  This is sufficient with the
current code, as that is the only backend that writes reflogs.  But
new backends can be added that write reflogs, and we'd want the
resulting log message we would read out of "log -g" the same no
matter what backend is used, and moving the code to do so to the
generic layer is a way to do so.

An added benefit is that the "cleansing" function could be updated
later, independent from individual backends, to e.g. allow
multi-line log messages if we wanted to, and when that happens, it
would help a lot to ensure we covered all bases if the cleansing
function (which would be updated) is called from the generic layer.

Side note: I am not interested in supporting multi-line reflog
messages right at the moment (nobody is asking for it), but I
envision that instead of the "squash a run of whitespaces into a SP
and rtrim" cleansing, we can %urlencode problematic bytes in the
message *AND* append a SP at the end, when a new version of Git that
supports multi-line and/or verbatim reflog messages writes a reflog
record.  The reading side can detect the presense of SP at the end
(which should have been rtrimmed out if it were written by existing
versions of Git) as a signal that decoding %urlencode recovers the
original reflog message.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-10 13:53:37 -07:00
Han-Wen Nienhuys
84ee4ca10d refs: improve documentation for ref iterator
Document some of the flag options in refs_ref_iterator_begin, and explain how
ref_iterator_advance_fn should handle them.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-05-20 10:39:02 -07:00
Patrick Steinhardt
edc30691e5 refs: fix segfault when aborting empty transaction
When cleaning up a transaction that has no updates queued, then the
transaction's backend data will not have been allocated. We correctly
handle this for the packed backend, where the cleanup function checks
whether the backend data has been allocated at all -- if not, then there
is nothing to clean up. For the files backend we do not check this and
as a result will hit a segfault due to dereferencing a `NULL` pointer
when cleaning up such a transaction.

Fix the issue by checking whether `backend_data` is set in the files
backend, too.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-30 10:34:11 -07:00
Junio C Hamano
145136a95a C: use skip_prefix() to avoid hardcoded string length
We often skip an optional prefix in a string with a hardcoded
constant, e.g.

	if (starts_with(string, "prefix"))
		string += 6;

which is less error prone when written

	skip_prefix(string, "prefix", &string);

Note that this changes a few error messages from "git reflog expire
--expire=nonsense.timestamp", which used to complain by saying

    '--expire=nonsense.timestamp' is not a valid timestamp

but with this change, we say

    'nonsense.timestamp' is not a valid timestamp

which is more technically correct (the string with --expire= as
a prefix obviously cannot be a valid timestamp, but the error is
about the part of the input without that prefix).

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 13:03:45 -08:00
René Scharfe
e0ae2447d6 refs: pass NULL to refs_read_ref_full() because object ID is not needed
refs_read_ref_full() wraps refs_resolve_ref_unsafe(), which handles a
NULL oid pointer of callers not interested in the resolved object ID.
Pass NULL from files_copy_or_rename_ref() to clarify that it is one
such caller.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-11 13:48:42 -08:00
Elijah Newren
15beaaa3d1 Fix spelling errors in code comments
Reported-by: Jens Schleusener <Jens.Schleusener@fossies.org>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-10 16:00:54 +09:00
Junio C Hamano
207ad3cb20 Merge branch 'sc/pack-refs-deletion-racefix'
"git pack-refs" can lose refs that are created while running, which
is getting corrected.

* sc/pack-refs-deletion-racefix:
  pack-refs: always refresh after taking the lock file
2019-08-22 12:34:10 -07:00
René Scharfe
9b7b0295f9 dir-iterator: release strbuf after use
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-07 12:25:35 -07:00
Sun Chao
a613d4f817 pack-refs: always refresh after taking the lock file
When a packed ref is deleted, the whole packed-refs file is
rewritten to omit the ref that no longer exists. However if another
gc command is running and calls `pack-refs --all` simultaneously,
there is a chance that a ref that was just updated lose the newly
created commits.

Through these steps, losing commits on newly updated refs can be
demonstrated:

  # step 1: compile git without `USE_NSEC` option
  Some kernel releases do enable it by default while some do
  not. And if we compile git without `USE_NSEC`, it will be easier
  demonstrated by the following steps.

  # step 2: setup a repository and add the first commit
  git init repo &&
  (cd repo &&
   git config core.logallrefupdates true &&
   git commit --allow-empty -m foo)

  # step 3: in one terminal, repack the refs repeatedly
  cd repo &&
  while true
  do
    git pack-refs --all
  done

  # step 4: in another terminal, simultaneously update the
  # master with update-ref, and create and delete an
  # unrelated ref also with update-ref
  cd repo &&
  while true
  do
    us=$(git commit-tree -m foo -p HEAD HEAD^{tree}) &&
    git update-ref refs/heads/newbranch $us &&
    git update-ref refs/heads/master $us &&
    git update-ref -d refs/heads/newbranch &&
    them=$(git rev-parse master) &&
    if test "$them" != "$us"
    then
      echo >&2 "lost commit: $us"
      exit 1
    fi
    # eye candy
    printf .
  done

Though we have the packed-refs lock file and loose refs lock
files to avoid updating conflicts, a ref will lost its newly
commits if racy stat-validity of `packed-refs` file happens
(which is quite same as the racy-git described in
`Documentation/technical/racy-git.txt`), the following
specific set of operations demonstrates the problem:

  1. Call `pack-refs --all` to pack all the loose refs to
     packed-refs, and let say the modify time of the
     packed-refs is DATE_M.

  2. Call `update-ref` to update a new commit to master while
     it is already packed.  the old value (let us call it
     OID_A) remains in the packed-refs file and write the new
     value (let us call it OID_B) to $GIT_DIR/refs/heads/master.

  3. Call `update-ref -d` within the same DATE_M from the 1th
     step to delete a different ref newbranch which is packed
     in the packed-refs file. It check newbranch's oid from
     packed-refs file without locking it.

     Meanwhile it keeps a snapshot of the packed-refs file in
     memory and record the file's attributes with the snapshot.
     The oid of master in the packed-refs's snapshot is OID_A.

  4. Call a new `pack-refs --all` to pack the loose refs, the
     oid of master in packe-refs file is OID_B, and the loose
     refs $GIT_DIR/refs/heads/master is removed. Let's say
     the `pack-refs --all` is very quickly done and the new
     packed-refs file's modify time is still DATE_M, and it
     has the same file size, even the same inode.

  5. 3th step now goes on after checking the newbranch, it
     begin to rewrite the packed-refs file. After get the
     lock file of packed-ref file, it checks it's on-disk
     file attributes with the snapshot, suck as the timestamp,
     the file size and the inode value. If they are both the
     same values, and the snapshot is not refreshed.

     Because the loose ref of master is removed by 4th step,
     `update-ref -d` will updates the new packed-ref to disk
     which contains master with the oid OID_A. So now the
     newly commit OID_B of master is lost.

The best path forward is just always refreshing after take
the lock file of `packed-refs` file. Traditionally we avoided
that because refreshing it implied parsing the whole file.
But these days we mmap it, so it really is just an extra
open()/mmap() and a quick read of the header. That doesn't seem
like an outrageous cost to pay when we're already taking the lock.

Signed-off-by: Sun Chao <sunchao9@huawei.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Sun Chao <sunchao9@huawei.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-02 09:59:05 -07:00
Matheus Tavares
fa1da7d2ee dir-iterator: add flags parameter to dir_iterator_begin
Add the possibility of giving flags to dir_iterator_begin to initialize
a dir-iterator with special options.

Currently possible flags are:
- DIR_ITERATOR_PEDANTIC, which makes dir_iterator_advance abort
immediately in the case of an error, instead of keep looking for the
next valid entry;
- DIR_ITERATOR_FOLLOW_SYMLINKS, which makes the iterator follow
symlinks and include linked directories' contents in the iteration.

These new flags will be used in a subsequent patch.

Also add tests for the flags' usage and adjust refs/files-backend.c to
the new dir_iterator_begin signature.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-07-11 13:52:15 -07:00
Matheus Tavares
3012397e03 dir-iterator: refactor state machine model
dir_iterator_advance() is a large function with two nested loops. Let's
improve its readability factoring out three functions and simplifying
its mechanics. The refactored model will no longer depend on
level.initialized and level.dir_state to keep track of the iteration
state and will perform on a single loop.

Also, dir_iterator_begin() currently does not check if the given string
represents a valid directory path. Since the refactored model will have
to stat() the given path at initialization, let's also check for this
kind of error and make dir_iterator_begin() return NULL, on failures,
with errno appropriately set. And add tests for this new behavior.

Improve documentation at dir-iteration.h and code comments at
dir-iterator.c to reflect the changes and eliminate possible
ambiguities.

Finally, adjust refs/files-backend.c to check for now possible
dir_iterator_begin() failures.

Original-patch-by: Daniel Ferreira <bnmvco@gmail.com>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-07-11 13:52:15 -07:00
Junio C Hamano
2e08c892a7 Merge branch 'jk/refs-double-abort'
A corner case bug in the refs API has been corrected.

* jk/refs-double-abort:
  refs/files-backend: don't look at an aborted transaction
  refs/files-backend: handle packed transaction prepare failure
2019-04-16 19:28:11 +09:00
Junio C Hamano
917f2cd1c2 Merge branch 'nd/rewritten-ref-is-per-worktree'
"git rebase" uses the refs/rewritten/ hierarchy to store its
intermediate states, which inherently makes the hierarchy per
worktree, but it didn't quite work well.

* nd/rewritten-ref-is-per-worktree:
  Make sure refs/rewritten/ is per-worktree
  files-backend.c: reduce duplication in add_per_worktree_entries_to_dir()
  files-backend.c: factor out per-worktree code in loose_fill_ref_dir()
2019-04-10 02:14:23 +09:00
Jeff King
d3322eb28b refs/files-backend: don't look at an aborted transaction
When deleting refs, we hold packed-refs.lock and prepare a packed
transaction to drop the refs from the packed-refs file. If it turns out
that we don't need to rewrite the packed refs (e.g., because none of the
deletions were present in the file), then we abort the transaction.

If that abort succeeds, then the transaction struct will have been
freed, and we set our local pointer to NULL so we don't look at it
again.

However, if it fails, then the struct will _still_ have been freed
(because ref_transaction_abort() always frees). But we don't clean up
the pointer, and will jump to our cleanup code, which will try to abort
it again, causing a use-after-free.

It's actually impossible for this to trigger in practice, since
packed_transaction_abort() will never return anything but success. But
let's fix it anyway, since that's more than we should assume about the
packed-refs code (after all, we are already bothering to check for an
error result which cannot be triggered).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-22 15:52:54 +09:00
Jeff King
249e8dc73e refs/files-backend: handle packed transaction prepare failure
In files_transaction_prepare(), if we have to delete some refs, we use a
subordinate packed_transaction to do so. It's rare for that
sub-transaction's prepare step to fail, since we hold the packed-refs
lock. But if it does, we trigger a BUG() due to these steps:

  - we've attached the packed transaction to the files transaction as
    backend_data->packed_transaction

  - when the prepare step fails, the packed transaction cleans itself
    up, putting itself into the CLOSED state

  - the error value from preparing the packed transaction lets us know
    in files_transaction_prepare() that we should also clean up and
    return an error. We call files_transaction_cleanup(), which tries to
    abort backend_data->packed_transaction. Since it's already CLOSED,
    that triggers an assertion in ref_transaction_abort().

We can fix that by disconnecting the packed transaction from the outer
files transaction, and then free-ing (not aborting!) it ourselves.

A few other options/alternatives I considered:

  - we could just make it a noop to abort a CLOSED transaction. But that
    seems less safe, since clearly this code expects (and enforces) a
    particular set of state transitions.

  - we could have files_transaction_cleanup() selectively call abort()
    vs free() based on the state of the on the packed transaction.
    That's basically a more restricted version of the above, but also
    potentially unsafe.

  - instead of disconnecting backend_data->packed_transaction on error,
    we could wait to install it until we successfully prepare. That
    might make the flow a little simpler, but it introduces a hassle.
    Earlier parts of files_transaction_prepare() that encounter an error
    will jump to the cleanup label, and expect that cleaning up the
    outer transaction will clean up the packed transaction, too. We'd
    have to adjust those sites to clean up the packed transaction.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-22 15:52:49 +09:00
Nguyễn Thái Ngọc Duy
b9317d55a3 Make sure refs/rewritten/ is per-worktree
a9be29c981 (sequencer: make refs generated by the `label` command
worktree-local, 2018-04-25) adds refs/rewritten/ as per-worktree
reference space. Unfortunately (my bad) there are a couple places that
need update to make sure it's really per-worktree.

 - add_per_worktree_entries_to_dir() is updated to make sure ref listing
   look at per-worktree refs/rewritten/ instead of per-repo one [1]

 - common_list[] is updated so that git_path() returns the correct
   location. This includes "rev-parse --git-path".

This mess is created by me. I started trying to fix it with the
introduction of refs/worktree, where all refs will be per-worktree
without special treatments. Unfortunate refs/rewritten came before
refs/worktree so this is all we can do.

This also fixes logs/refs/worktree not being per-worktree.

[1] note that ref listing still works sometimes. For example, if you
    have .git/worktrees/foo/refs/rewritten/bar AND the directory
    .git/worktrees/refs/rewritten, refs/rewritten/bar will show up.
    add_per_worktree_entries_to_dir() is only needed when the directory
    .git/worktrees/refs/rewritten is missing.

Reported-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-08 11:57:47 +09:00
Nguyễn Thái Ngọc Duy
90d31ff5d4 files-backend.c: reduce duplication in add_per_worktree_entries_to_dir()
This function is duplicated to handle refs/bisect/ and refs/worktree/
and a third prefix is coming. Time to clean up.

This also fixes incorrect "refs/worktrees/" length in this code. The
correct length is 14 not 11. The test in the next patch will also cover
this.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-08 11:57:47 +09:00
Nguyễn Thái Ngọc Duy
09e65645e3 files-backend.c: factor out per-worktree code in loose_fill_ref_dir()
This is the first step for further cleaning up and extending this
function.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-08 11:57:47 +09:00
Jeff King
10dee40ed3 files-backend: drop refs parameter from split_symref_update()
This parameter was added in fcc42ea0c9 (split_symref_update(): add a
files_ref_store argument, 2016-09-04) without comment, but never used.
The splitting is purely mechanical, and doesn't depend on the particular
ref-store. Let's drop this parameter in the name of simplicity.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-02-14 15:26:15 -08:00
Junio C Hamano
a1598010f7 Merge branch 'nd/per-worktree-ref-iteration'
Build fix.

* nd/per-worktree-ref-iteration:
  files-backend.c: fix build error on Solaris
2018-11-26 23:13:43 +09:00
Nguyễn Thái Ngọc Duy
46c0eb5843 files-backend.c: fix build error on Solaris
This function files_reflog_path returns void, which usually means
"return;" not returning "void value" from another function.

Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-11-26 15:22:58 +09:00
Junio C Hamano
e146cc97be Merge branch 'nd/per-worktree-ref-iteration'
The code to traverse objects for reachability, used to decide what
objects are unreferenced and expendable, have been taught to also
consider per-worktree refs of other worktrees as starting points to
prevent data loss.

* nd/per-worktree-ref-iteration:
  git-worktree.txt: correct linkgit command name
  reflog expire: cover reflog from all worktrees
  fsck: check HEAD and reflog from other worktrees
  fsck: move fsck_head_link() to get_default_heads() to avoid some globals
  revision.c: better error reporting on ref from different worktrees
  revision.c: correct a parameter name
  refs: new ref types to make per-worktree refs visible to all worktrees
  Add a place for (not) sharing stuff between worktrees
  refs.c: indent with tabs, not spaces
2018-11-13 22:37:26 +09:00
Junio C Hamano
d829d491ee Merge branch 'bc/hash-transition-part-15'
More codepaths are moving away from hardcoded hash sizes.

* bc/hash-transition-part-15:
  rerere: convert to use the_hash_algo
  submodule: make zero-oid comparison hash function agnostic
  apply: rename new_sha1_prefix and old_sha1_prefix
  apply: replace hard-coded constants
  tag: express constant in terms of the_hash_algo
  transport: use parse_oid_hex instead of a constant
  upload-pack: express constants in terms of the_hash_algo
  refs/packed-backend: express constants using the_hash_algo
  packfile: express constants in terms of the_hash_algo
  pack-revindex: express constants in terms of the_hash_algo
  builtin/fetch-pack: remove constants with parse_oid_hex
  builtin/mktree: remove hard-coded constant
  builtin/repack: replace hard-coded constants
  pack-bitmap-write: use GIT_MAX_RAWSZ for allocation
  object_id.cocci: match only expressions of type 'struct object_id'
2018-10-30 15:43:42 +09:00
Nguyễn Thái Ngọc Duy
3a3b9d8cde refs: new ref types to make per-worktree refs visible to all worktrees
One of the problems with multiple worktree is accessing per-worktree
refs of one worktree from another worktree. This was sort of solved by
multiple ref store, where the code can open the ref store of another
worktree and has access to the ref space of that worktree.

The problem with this is reporting. "HEAD" in another ref space is
also called "HEAD" like in the current ref space. In order to
differentiate them, all the code must somehow carry the ref store
around and print something like "HEAD from this ref store".

But that is not feasible (or possible with a _lot_ of work). With the
current design, we pass a reference around as a string (so called
"refname"). Extending this design to pass a string _and_ a ref store
is a nightmare, especially when handling extended SHA-1 syntax.

So we do it another way. Instead of entering a separate ref space, we
make refs from other worktrees available in the current ref space. So
"HEAD" is always HEAD of the current worktree, but then we can have
"worktrees/blah/HEAD" to denote HEAD from a worktree named
"blah". This syntax coincidentally matches the underlying directory
structure which makes implementation a bit easier.

The main worktree has to be treated specially because well... it's
special from the beginning. So HEAD from the main worktree is
acccessible via the name "main-worktree/HEAD" instead of
"worktrees/main/HEAD" because "main" could be just another secondary
worktree.

This patch also makes it possible to specify refs from one worktree in
another one, e.g.

    git log worktrees/foo/HEAD

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-10-22 13:32:29 +09:00
Junio C Hamano
ff6bbce6e3 Merge branch 'rj/header-check'
Header files clean-up.

* rj/header-check:
  delta-islands.h: add missing forward declarations (hdr-check)
  midx.h: add missing forward declarations (hdr-check)
  refs/refs-internal.h: add missing declarations (hdr-check)
  refs/packed-backend.h: add missing declaration (hdr-check)
  refs/ref-cache.h: add missing declarations (hdr-check)
  ewah/ewok_rlw.h: add missing include (hdr-check)
  json-writer.h: add missing include (hdr-check)
  Makefile: add a hdr-check target
2018-10-16 16:16:00 +09:00
Junio C Hamano
eea5e03a5a Merge branch 'tq/refs-internal-comment-fix'
Fix for typo in a sample code in comment.

* tq/refs-internal-comment-fix:
  refs: docstring typo
2018-10-16 16:15:59 +09:00
Junio C Hamano
6d8f8ebb74 Merge branch 'ds/commit-graph-with-grafts'
The recently introduced commit-graph auxiliary data is incompatible
with mechanisms such as replace & grafts that "breaks" immutable
nature of the object reference relationship.  Disable optimizations
based on its use (and updating existing commit-graph) when these
incompatible features are in use in the repository.

* ds/commit-graph-with-grafts:
  commit-graph: close_commit_graph before shallow walk
  commit-graph: not compatible with uninitialized repo
  commit-graph: not compatible with grafts
  commit-graph: not compatible with replace objects
  test-repository: properly init repo
  commit-graph: update design document
  refs.c: upgrade for_each_replace_ref to be a each_repo_ref_fn callback
  refs.c: migrate internal ref iteration to pass thru repository argument
2018-10-16 16:15:59 +09:00
brian m. carlson
49d166081b refs/packed-backend: express constants using the_hash_algo
Switch uses of GIT_SHA1_HEXSZ to use the_hash_algo so that they are
appropriate for the any given hash length.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-10-15 12:53:15 +09:00
Nguyễn Thái Ngọc Duy
8aff1a9ca5 Add a place for (not) sharing stuff between worktrees
When multiple worktrees are used, we need rules to determine if
something belongs to one worktree or all of them. Instead of keeping
adding rules when new stuff comes (*), have a generic rule:

- Inside $GIT_DIR, which is per-worktree by default, add
  $GIT_DIR/common which is always shared. New features that want to
  share stuff should put stuff under this directory.

- Inside refs/, which is shared by default except refs/bisect, add
  refs/worktree/ which is per-worktree. We may eventually move
  refs/bisect to this new location and remove the exception in refs
  code.

(*) And it may also include stuff from external commands which will
    have no way to modify common/per-worktree rules.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-10-07 08:21:18 +09:00
Ramsay Jones
4eb4416d37 refs/refs-internal.h: add missing declarations (hdr-check)
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-20 11:50:00 -07:00
Ramsay Jones
611023f88f refs/packed-backend.h: add missing declaration (hdr-check)
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-20 11:50:00 -07:00
Ramsay Jones
440984b2d6 refs/ref-cache.h: add missing declarations (hdr-check)
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-20 11:50:00 -07:00
Tao Qingyun
7b6057c852 refs: docstring typo
Signed-off-by: Tao Qingyun <taoqy@ls-a.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-17 10:17:22 -07:00
Jeff King
9001dc2a74 convert "oidcmp() != 0" to "!oideq()"
This is the flip side of the previous two patches: checking
for a non-zero oidcmp() can be more strictly expressed as
inequality. Like those patches, we write "!= 0" in the
coccinelle transformation, which covers by isomorphism the
more common:

  if (oidcmp(E1, E2))

As with the previous two patches, this patch can be achieved
almost entirely by running "make coccicheck"; the only
differences are manual line-wrap fixes to match the original
code.

There is one thing to note for anybody replicating this,
though: coccinelle 1.0.4 seems to miss the case in
builtin/tag.c, even though it's basically the same as all
the others. Running with 1.0.7 does catch this, so
presumably it's just a coccinelle bug that was fixed in the
interim.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-29 11:32:49 -07:00
Jeff King
4a7e27e957 convert "oidcmp() == 0" to oideq()
Using the more restrictive oideq() should, in the long run,
give the compiler more opportunities to optimize these
callsites. For now, this conversion should be a complete
noop with respect to the generated code.

The result is also perhaps a little more readable, as it
avoids the "zero is equal" idiom. Since it's so prevalent in
C, I think seasoned programmers tend not to even notice it
anymore, but it can sometimes make for awkward double
negations (e.g., we can drop a few !!oidcmp() instances
here).

This patch was generated almost entirely by the included
coccinelle patch. This mechanical conversion should be
completely safe, because we check explicitly for cases where
oidcmp() is compared to 0, which is what oideq() is doing
under the hood. Note that we don't have to catch "!oidcmp()"
separately; coccinelle's standard isomorphisms make sure the
two are treated equivalently.

I say "almost" because I did hand-edit the coccinelle output
to fix up a few style violations (it mostly keeps the
original formatting, but sometimes unwraps long lines).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-29 11:32:49 -07:00
Stefan Beller
4a6067cda5 refs.c: migrate internal ref iteration to pass thru repository argument
In 60ce76d358 (refs: add repository argument to for_each_replace_ref,
2018-04-11) and 0d296c57ae (refs: allow for_each_replace_ref to handle
arbitrary repositories, 2018-04-11), for_each_replace_ref learned how
to iterate over refs by a given arbitrary repository.
New attempts in the object store conversion have shown that it is useful
to have the repository handle available that the refs iteration is
currently iterating over.

To achieve this goal we will need to add a repository argument to
each_ref_fn in refs.h. However as many callers rely on the signature
such a patch would be too large.

So convert the internals of the ref subsystem first to pass through a
repository argument without exposing the change to the user. Assume
the_repository for the passed through repository, although it is not
used anywhere yet.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-21 10:22:50 -07:00
Junio C Hamano
7d020f5a78 Merge branch 'jk/size-t'
Code clean-up to use size_t/ssize_t when they are the right type.

* jk/size-t:
  strbuf_humanise: use unsigned variables
  pass st.st_size as hint for strbuf_readlink()
  strbuf_readlink: use ssize_t
  strbuf: use size_t for length in intermediate variables
  reencode_string: use size_t for string lengths
  reencode_string: use st_add/st_mult helpers
2018-08-15 15:08:25 -07:00
Junio C Hamano
3a2a1dc170 Merge branch 'sb/object-store-lookup'
lookup_commit_reference() and friends have been updated to find
in-core object for a specific in-core repository instance.

* sb/object-store-lookup: (32 commits)
  commit.c: allow lookup_commit_reference to handle arbitrary repositories
  commit.c: allow lookup_commit_reference_gently to handle arbitrary repositories
  tag.c: allow deref_tag to handle arbitrary repositories
  object.c: allow parse_object to handle arbitrary repositories
  object.c: allow parse_object_buffer to handle arbitrary repositories
  commit.c: allow get_cached_commit_buffer to handle arbitrary repositories
  commit.c: allow set_commit_buffer to handle arbitrary repositories
  commit.c: migrate the commit buffer to the parsed object store
  commit-slabs: remove realloc counter outside of slab struct
  commit.c: allow parse_commit_buffer to handle arbitrary repositories
  tag: allow parse_tag_buffer to handle arbitrary repositories
  tag: allow lookup_tag to handle arbitrary repositories
  commit: allow lookup_commit to handle arbitrary repositories
  tree: allow lookup_tree to handle arbitrary repositories
  blob: allow lookup_blob to handle arbitrary repositories
  object: allow lookup_object to handle arbitrary repositories
  object: allow object_as_type to handle arbitrary repositories
  tag: add repository argument to deref_tag
  tag: add repository argument to parse_tag_buffer
  tag: add repository argument to lookup_tag
  ...
2018-08-02 15:30:42 -07:00
Junio C Hamano
37aac3e408 Merge branch 'bc/object-id'
Conversion from uchar[40] to struct object_id continues.

* bc/object-id:
  pretty: switch hard-coded constants to the_hash_algo
  sha1-file: convert constants to uses of the_hash_algo
  log-tree: switch GIT_SHA1_HEXSZ to the_hash_algo->hexsz
  diff: switch GIT_SHA1_HEXSZ to use the_hash_algo
  builtin/merge-recursive: make hash independent
  builtin/merge: switch to use the_hash_algo
  builtin/fmt-merge-msg: make hash independent
  builtin/update-index: simplify parsing of cacheinfo
  builtin/update-index: convert to using the_hash_algo
  refs/files-backend: use the_hash_algo for writing refs
  sha1-name: use the_hash_algo when parsing object names
  strbuf: allocate space with GIT_MAX_HEXSZ
  commit: express tree entry constants in terms of the_hash_algo
  hex: switch to using the_hash_algo
  tree-walk: replace hard-coded constants with the_hash_algo
  cache: update object ID functions for the_hash_algo
2018-08-02 15:30:39 -07:00
Junio C Hamano
9cb10ca9df Merge branch 'bp/log-ref-write-fd-with-strbuf'
Code clean-up.

* bp/log-ref-write-fd-with-strbuf:
  convert log_ref_write_fd() to use strbuf
2018-07-24 14:50:47 -07:00
Junio C Hamano
00da9b2091 Merge branch 'bb/pedantic'
The codebase has been updated to compile cleanly with -pedantic
option.

* bb/pedantic:
  utf8.c: avoid char overflow
  string-list.c: avoid conversion from void * to function pointer
  sequencer.c: avoid empty statements at top level
  convert.c: replace "\e" escapes with "\033".
  fixup! refs/refs-internal.h: avoid forward declaration of an enum
  refs/refs-internal.h: avoid forward declaration of an enum
  fixup! connect.h: avoid forward declaration of an enum
  connect.h: avoid forward declaration of an enum
2018-07-24 14:50:47 -07:00
Jeff King
765b496dc6 pass st.st_size as hint for strbuf_readlink()
When we initially added the strbuf_readlink() function in
b11b7e13f4 (Add generic 'strbuf_readlink()' helper function,
2008-12-17), the point was that we generally have a _guess_
as to the correct size based on the stat information, but we
can't necessarily trust it.

Over the years, a few callers have grown up that simply pass
in 0, even though they have the stat information. Let's have
them pass in their hint for consistency (and in theory
efficiency, since it may avoid an extra resize/syscall loop,
but neither location is probably performance critical).

Note that st.st_size is actually an off_t, so in theory we
need xsize_t() here. But none of the other callsites use it,
and since this is just a hint, it doesn't matter either way
(if we wrap we'll simply start with a too-small hint and
then eventually complain when we cannot allocate the
memory).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-24 10:19:29 -07:00
brian m. carlson
2ae2e2a1ca refs/files-backend: use the_hash_algo for writing refs
In order to ensure we write the correct amount, use the_hash_algo to
find the correct number of bytes for the current hash.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-16 14:27:39 -07:00
Ben Peart
80a6c2073b convert log_ref_write_fd() to use strbuf
Since we don't care about how many bytes were written, simplify the return
value logic.

log_ref_write_fd() was written long before strbuf was fleshed out. Remove
the old manual buffer management code and replace it with strbuf(). Also
update copy_reflog_msg() which is called only by log_ref_write_fd() to use
strbuf as it keeps things consistent.

Signed-off-by: Ben Peart <Ben.Peart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-10 14:22:44 -07:00
Junio C Hamano
13f925f3e4 fixup! refs/refs-internal.h: avoid forward declaration of an enum 2018-07-09 14:36:12 -07:00
Beat Bolli
91c2f2040a refs/refs-internal.h: avoid forward declaration of an enum
Include iterator.h to define enum iterator_selection.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-09 14:35:52 -07:00
Stefan Beller
109cd76dd3 object: add repository argument to parse_object
Add a repository argument to allow the callers of parse_object
to be more specific about which repository to act on. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.

As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-29 10:43:38 -07:00
Stefan Beller
09427e8366 refs/packed-backend.c: close fd of empty file
Signed-off-by: Stefan Beller <sbeller@google.com>
Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-06-01 10:49:53 +09:00
Junio C Hamano
50f08db594 Merge branch 'js/use-bug-macro'
Developer support update, by using BUG() macro instead of die() to
mark codepaths that should not happen more clearly.

* js/use-bug-macro:
  BUG_exit_code: fix sparse "symbol not declared" warning
  Convert remaining die*(BUG) messages
  Replace all die("BUG: ...") calls by BUG() ones
  run-command: use BUG() to report bugs, not die()
  test-tool: help verifying BUG() code paths
2018-05-30 14:04:07 +09:00
Junio C Hamano
2f76ebc93c Merge branch 'ma/lockfile-cleanup'
Code clean-up to adjust to a more recent lockfile API convention that
allows lockfile instances kept on the stack.

* ma/lockfile-cleanup:
  lock_file: move static locks into functions
  lock_file: make function-local locks non-static
  refs.c: do not die if locking fails in `delete_pseudoref()`
  refs.c: do not die if locking fails in `write_pseudoref()`
  t/helper/test-write-cache: clean up lock-handling
2018-05-30 14:04:05 +09:00
Martin Ågren
b227586831 lock_file: make function-local locks non-static
Placing `struct lock_file`s on the stack used to be a bad idea, because
the temp- and lockfile-machinery would keep a pointer into the struct.
But after 076aa2cbd (tempfile: auto-allocate tempfiles on heap,
2017-09-05), we can safely have lockfiles on the stack. (This applies
even if a user returns early, leaving a locked lock behind.)

These `struct lock_file`s are local to their respective functions and we
can drop their staticness.

For good measure, I have inspected these sites and come to believe that
they always release the lock, with the possible exception of bailing out
using `die()` or `exit()` or by returning from a `cmd_foo()`.

As pointed out by Jeff King, it would be bad if someone held on to a
`struct lock_file *` for some reason. After some grepping, I agree with
his findings: no-one appears to be doing that.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-10 14:54:45 +09:00
Junio C Hamano
174774cd51 Merge branch 'sb/object-store-replace'
The effort to pass the repository in-core structure throughout the
API continues.  This round deals with the code that implements the
refs/replace/ mechanism.

* sb/object-store-replace:
  replace-object: allow lookup_replace_object to handle arbitrary repositories
  replace-object: allow do_lookup_replace_object to handle arbitrary repositories
  replace-object: allow prepare_replace_object to handle arbitrary repositories
  refs: allow for_each_replace_ref to handle arbitrary repositories
  refs: store the main ref store inside the repository struct
  replace-object: add repository argument to lookup_replace_object
  replace-object: add repository argument to do_lookup_replace_object
  replace-object: add repository argument to prepare_replace_object
  refs: add repository argument to for_each_replace_ref
  refs: add repository argument to get_main_ref_store
  replace-object: check_replace_refs is safe in multi repo environment
  replace-object: eliminate replace objects prepared flag
  object-store: move lookup_replace_object to replace-object.h
  replace-object: move replace_map to object store
  replace_object: use oidmap
2018-05-08 15:59:21 +09:00
Johannes Schindelin
033abf97fc Replace all die("BUG: ...") calls by BUG() ones
In d8193743e0 (usage.c: add BUG() function, 2017-05-12), a new macro
was introduced to use for reporting bugs instead of die(). It was then
subsequently used to convert one single caller in 588a538ae5
(setup_git_env: convert die("BUG") to BUG(), 2017-05-12).

The cover letter of the patch series containing this patch
(cf 20170513032414.mfrwabt4hovujde2@sigill.intra.peff.net) is not
terribly clear why only one call site was converted, or what the plan
is for other, similar calls to die() to report bugs.

Let's just convert all remaining ones in one fell swoop.

This trick was performed by this invocation:

	sed -i 's/die("BUG: /BUG("/g' $(git grep -l 'die("BUG' \*.c)

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-06 19:06:13 +09:00
Stefan Beller
64a741619d refs: store the main ref store inside the repository struct
This moves the 'main_ref_store', which was a global variable in refs.c
into the repository struct.

This patch does not deal with the parts in the refs subsystem which deal
with the submodules there. A later patch needs to get rid of the submodule
exposure in the refs API, such as 'get_submodule_ref_store(path)'.

Acked-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-12 11:38:56 +09:00
Jeff King
fb9c2d2703 refs: use chdir_notify to update cached relative paths
Commit f57f37e2e1 (files-backend: remove the use of
git_path(), 2017-03-26) introduced a regression when a
relative $GIT_DIR is used in a working tree:

  - when we initialize the ref backend, we make a copy of
    get_git_dir(), which may be relative

  - later, we may call setup_work_tree() and chdir to the
    root of the working tree

  - further calls to the ref code will use the stored git
    directory, but relative paths will now point to the
    wrong place

The new test in t1501 demonstrates one such instance (the
bug causes us to write the ref update to the nonsense
"relative/relative/.git").

Since setup_work_tree() now uses chdir_notify, we can just
ask it update our relative paths when necessary.

Reported-by: Rafael Ascensao <rafa.almas@gmail.com>
Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-30 12:50:03 -07:00
Junio C Hamano
9db22910f7 Merge branch 'kg/packed-ref-cache-fix'
Avoid mmapping small files while using packed refs (especially ones
with zero size, which would cause later munmap() to fail).

* kg/packed-ref-cache-fix:
  packed_ref_cache: don't use mmap() for small files
  load_contents(): don't try to mmap an empty file
  packed_ref_iterator_begin(): make optimization more general
  find_reference_location(): make function safe for empty snapshots
  create_snapshot(): use `xmemdupz()` rather than a strbuf
  struct snapshot: store `start` rather than `header_len`
2018-02-15 14:55:42 -08:00
Junio C Hamano
cbf0240f82 Merge branch 'sg/cocci-move-array'
Code clean-up.

* sg/cocci-move-array:
  Use MOVE_ARRAY
2018-02-13 13:39:13 -08:00
Junio C Hamano
2b72ea0a48 Merge branch 'mr/packed-ref-store-fix'
Crash fix for a corner case where an error codepath tried to unlock
what it did not acquire lock on.

* mr/packed-ref-store-fix:
  files_initial_transaction_commit(): only unlock if locked
2018-02-13 13:39:11 -08:00
Kim Gybels
ba41a8b600 packed_ref_cache: don't use mmap() for small files
Take a hint from commit ea68b0ce9f (hash-object: don't use mmap() for
small files, 2010-02-21) and use read() instead of mmap() for small
packed-refs files.

Signed-off-by: Kim Gybels <kgybels@infogroep.be>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-24 12:55:26 -08:00
Michael Haggerty
01caf20d57 load_contents(): don't try to mmap an empty file
We don't actually create zero-length `packed-refs` files, but they are
valid and we should handle them correctly. The old code `xmmap()`ed
such files, which led to an error when `munmap()` was called. So, if
the `packed-refs` file is empty, leave the snapshot at its zero values
and return 0 without trying to read or mmap the file.

Returning 0 also makes `create_snapshot()` exit early, which avoids
the technically undefined comparison `NULL < NULL`.

Reported-by: Kim Gybels <kgybels@infogroep.be>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-24 12:55:26 -08:00
Michael Haggerty
f34242975f packed_ref_iterator_begin(): make optimization more general
We can return an empty iterator not only if the `packed-refs` file is
missing, but also if it is empty or if there are no references whose
names succeed `prefix`. Optimize away those cases as well by moving
the call to `find_reference_location()` higher in the function and
checking whether the determined start position is the same as
`snapshot->eof`. (This is possible now because the previous commit
made `find_reference_location()` robust against empty snapshots.)

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-24 12:55:26 -08:00
Michael Haggerty
4a14f8d093 find_reference_location(): make function safe for empty snapshots
This function had two problems if called for an empty snapshot (i.e.,
`snapshot->start == snapshot->eof == NULL`):

* It checked `NULL < NULL`, which is undefined by C (albeit highly
  unlikely to fail in the real world).

* (Assuming the above comparison behaved as expected), it returned
  NULL when `mustexist` was false, contrary to its docstring.

Change the check and fix the docstring.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-24 12:55:26 -08:00
Michael Haggerty
27a41841ec create_snapshot(): use xmemdupz() rather than a strbuf
It's lighter weight.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-24 12:55:26 -08:00
Michael Haggerty
4a2854f77c struct snapshot: store start rather than header_len
Store a pointer to the start of the actual references within the
`packed-refs` contents rather than storing the length of the header.
This is more convenient for most users of this field.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-24 12:55:26 -08:00
SZEDER Gábor
f919ffebed Use MOVE_ARRAY
Use the helper macro MOVE_ARRAY to move arrays.  This is shorter and
safer, as it automatically infers the size of elements.

Patch generated by Coccinelle and contrib/coccinelle/array.cocci in
Travis CI's static analysis build job.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-22 11:32:51 -08:00
Mathias Rav
81fcb698e0 files_initial_transaction_commit(): only unlock if locked
Running git clone --single-branch --mirror -b TAGNAME previously
triggered the following error message:

	fatal: multiple updates for ref 'refs/tags/TAGNAME' not allowed.

This error condition is handled in files_initial_transaction_commit().

42c7f7ff9 ("commit_packed_refs(): remove call to `packed_refs_unlock()`", 2017-06-23)
introduced incorrect unlocking in the error path of this function,
which changes the error message to

	fatal: BUG: packed_refs_unlock() called when not locked

Move the call to packed_refs_unlock() above the "cleanup:" label
since the unlocking should only be done in the last error path.

Signed-off-by: Mathias Rav <m@git.strova.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-19 14:16:56 -08:00
Junio C Hamano
02abc6be8e Merge branch 'mh/avoid-rewriting-packed-refs' into maint
Recent update to the refs infrastructure implementation started
rewriting packed-refs file more often than before; this has been
optimized again for most trivial cases.

* mh/avoid-rewriting-packed-refs:
  files-backend: don't rewrite the `packed-refs` file unnecessarily
  t1409: check that `packed-refs` is not rewritten unnecessarily
2017-12-06 09:08:50 -08:00
Junio C Hamano
a97222978a Merge branch 'mh/tidy-ref-update-flags'
Code clean-up in refs API implementation.

* mh/tidy-ref-update-flags:
  refs: update some more docs to use "oid" rather than "sha1"
  write_packed_entry(): take `object_id` arguments
  refs: rename constant `REF_ISPRUNING` to `REF_IS_PRUNING`
  refs: rename constant `REF_NODEREF` to `REF_NO_DEREF`
  refs: tidy up and adjust visibility of the `ref_update` flags
  ref_transaction_add_update(): remove a check
  ref_transaction_update(): die on disallowed flags
  prune_ref(): call `ref_transaction_add_update()` directly
  files_transaction_prepare(): don't leak flags to packed transaction
2017-11-15 12:14:29 +09:00
Junio C Hamano
ffb0b5762e Merge branch 'mh/avoid-rewriting-packed-refs'
Recent update to the refs infrastructure implementation started
rewriting packed-refs file more often than before; this has been
optimized again for most trivial cases.

* mh/avoid-rewriting-packed-refs:
  files-backend: don't rewrite the `packed-refs` file unnecessarily
  t1409: check that `packed-refs` is not rewritten unnecessarily
2017-11-15 12:14:27 +09:00
Junio C Hamano
e7e456f500 Merge branch 'bc/object-id'
Conversion from uchar[20] to struct object_id continues.

* bc/object-id: (25 commits)
  refs/files-backend: convert static functions to object_id
  refs: convert read_raw_ref backends to struct object_id
  refs: convert peel_object to struct object_id
  refs: convert resolve_ref_unsafe to struct object_id
  worktree: convert struct worktree to object_id
  refs: convert resolve_gitlink_ref to struct object_id
  Convert remaining callers of resolve_gitlink_ref to object_id
  sha1_file: convert index_path and index_fd to struct object_id
  refs: convert reflog_expire parameter to struct object_id
  refs: convert read_ref_at to struct object_id
  refs: convert peel_ref to struct object_id
  builtin/pack-objects: convert to struct object_id
  pack-bitmap: convert traverse_bitmap_commit_list to object_id
  refs: convert dwim_log to struct object_id
  builtin/reflog: convert remaining unsigned char uses to object_id
  refs: convert dwim_ref and expand_ref to struct object_id
  refs: convert read_ref and read_ref_full to object_id
  refs: convert resolve_refdup and refs_resolve_refdup to struct object_id
  Convert check_connected to use struct object_id
  refs: update ref transactions to use struct object_id
  ...
2017-11-06 14:24:27 +09:00
Michael Haggerty
78fb457968 refs: update some more docs to use "oid" rather than "sha1"
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:08 +09:00
Michael Haggerty
4170188262 write_packed_entry(): take object_id arguments
Change `write_packed_entry()` to take `struct object_id *` rather than
`unsigned char *` arguments.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:08 +09:00
Michael Haggerty
acedcde76d refs: rename constant REF_ISPRUNING to REF_IS_PRUNING
Underscores are cheap, and help readability.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:08 +09:00
Michael Haggerty
91774afcc3 refs: rename constant REF_NODEREF to REF_NO_DEREF
Even after working with this code for years, I still see this constant
name as "ref node ref". Rename it to make it's meaning clearer.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:08 +09:00
Michael Haggerty
5ac95fee3d refs: tidy up and adjust visibility of the ref_update flags
The constants used for `ref_update::flags` were rather disorganized:

* The definitions in `refs.h` were not close to the functions that
  used them.

* Maybe constants were defined in `refs-internal.h`, making them
  visible to the whole refs module, when in fact they only made sense
  for the files backend.

* Their documentation wasn't very consistent and partly still referred
  to sha1s rather than oids.

* The numerical values followed no rational scheme

Fix all of these problems. The main functional improvement is that
some constants' visibility is now limited to `files-backend.c`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:07 +09:00
Michael Haggerty
62c72d1fd0 ref_transaction_add_update(): remove a check
We want to make `REF_ISPRUNING` internal to the files backend. For
this to be possible, `ref_transaction_add_update()` mustn't know about
it. So move the check that `REF_ISPRUNING` is only used with
`REF_NODEREF` from this function to `files_transaction_prepare()`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:07 +09:00
Michael Haggerty
b00f3cfa92 prune_ref(): call ref_transaction_add_update() directly
`prune_ref()` needs to use the `REF_ISPRUNING` flag, but we want to
make that flag private to the files backend. So instead of calling
`ref_transaction_delete()`, which is a public function and therefore
shouldn't allow the `REF_ISPRUNING` flag, change `prune_ref()` to call
`ref_transaction_add_update()`, which is private to the refs
module. (Note that we don't need any of the other services provided by
`ref_transaction_delete()`.)

This allows us to change `ref_transaction_update()` to reject the
`REF_ISPRUNING` flag. Do so by adjusting
`REF_TRANSACTION_UPDATE_ALLOWED_FLAGS`. Also add parentheses to its
definition to avoid potential future mishaps.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:07 +09:00
Michael Haggerty
b0ca411051 files_transaction_prepare(): don't leak flags to packed transaction
The files backend uses `ref_update::flags` for several internal flags.
But those flags have no meaning to the packed backend. So when adding
updates for the packed-refs transaction, only use flags that make
sense to the packed backend.

`REF_NODEREF` is part of the public interface, and it's logically what
we want, so include it. In fact it is actually ignored by the packed
backend (which doesn't support symbolic references), but that's its
own business.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-06 10:31:07 +09:00
Michael Haggerty
7c6bd25c7d files-backend: don't rewrite the packed-refs file unnecessarily
Even when we are deleting references, we needn't overwrite the
`packed-refs` file if the references that we are deleting only exist
as loose references. Implement this optimization as follows:

* Add a function `is_packed_transaction_needed()`, which checks
  whether a given packed-refs transaction actually needs to be carried
  out (i.e., it returns false if the transaction obviously wouldn't
  have any effect). This function must be called while holding the
  `packed-refs` lock to avoid races.

* Change `files_transaction_prepare()` to check whether the
  packed-refs transaction is actually needed. If not, squelch it, but
  continue holding the `packed-refs` lock until the end of the
  transaction to avoid races.

This fixes a mild regression caused by dc39e09942 (files_ref_store:
use a transaction to update packed refs, 2017-09-08). Before that
commit, unnecessary rewrites of `packed-refs` were suppressed by
`repack_without_refs()`. But the transaction-based writing introduced
by that commit didn't perform that optimization.

Note that the pre-dc39e09942 code still had to *read* the whole
`packed-refs` file to determine that the rewrite could be skipped, so
the performance for the cases that the write could be elided was
`O(N)` in the number of packed references both before and after
dc39e09942. But after that commit the constant factor increased.

This commit reimplements the optimization of eliding unnecessary
`packed-refs` rewrites. That, plus the fact that since
cfa2e29c34 (packed_ref_store: get rid of the `ref_cache` entirely,
2017-03-17) we don't necessarily have to read the whole `packed-refs`
file at all, means that deletes of one or a few loose references can
now be done with `O(n lg N)` effort, where `n` is the number of loose
references being deleted and `N` is the total number of packed
references.

This commit fixes two tests in t1409.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-30 09:45:15 +09:00
Michael Haggerty
ff08e56cde Merge branch 'bc/object-id' into base 2017-10-28 09:27:15 +02:00
Junio C Hamano
4e40fb302e Merge branch 'mh/ref-locking-fix'
Transactions to update multiple references that involves a deletion
was quite broken in an error codepath and did not abort everything
correctly.

* mh/ref-locking-fix:
  files_transaction_prepare(): fix handling of ref lock failure
  t1404: add a bunch of tests of D/F conflicts
2017-10-26 12:29:23 +09:00
Michael Haggerty
da5267f1b6 files_transaction_prepare(): fix handling of ref lock failure
Since dc39e09942 (files_ref_store: use a transaction to update packed
refs, 2017-09-08), failure to lock a reference has been handled
incorrectly by `files_transaction_prepare()`. If
`lock_ref_for_update()` fails in the lock-acquisition loop of that
function, it sets `ret` then breaks out of that loop. Prior to
dc39e09942, that was OK, because the only thing following the loop was
the cleanup code. But dc39e09942 added another blurb of code between
the loop and the cleanup. That blurb sometimes resets `ret` to zero,
making the cleanup code think that the locking was successful.

Specifically, whenever

* One or more reference deletions have been processed successfully in
  the lock-acquisition loop. (Processing the first such reference
  causes a packed-ref transaction to be initialized.)

* Then `lock_ref_for_update()` fails for a subsequent reference. Such
  a failure can happen for a number of reasons, such as the old SHA-1
  not being correct, lock contention, etc. This causes a `break` out
  of the lock-acquisition loop.

* The `packed-refs` lock is acquired successfully and
  `ref_transaction_prepare()` succeeds for the packed-ref transaction.
  This has the effect of resetting `ret` back to 0, and making the
  cleanup code think that lock acquisition was successful.

In that case, any reference updates that were processed prior to
breaking out of the loop would be carried out (loose and packed), but
the reference that couldn't be locked and any subsequent references
would silently be ignored.

This can easily cause data loss if, for example, the user was trying
to push a new name for an existing branch while deleting the old name.
After the push, the branch could be left unreachable, and could even
subsequently be garbage-collected.

This problem was noticed in the context of deleting one reference and
creating another in a single transaction, when the two references D/F
conflict with each other, like

    git update-ref --stdin <<EOF
    delete refs/foo
    create refs/foo/bar HEAD
    EOF

This triggers the above bug because the deletion is processed
successfully for `refs/foo`, then the D/F conflict causes
`lock_ref_for_update()` to fail when `refs/foo/bar` is processed. In
this case the transaction *should* fail, but instead it causes
`refs/foo` to be deleted without creating `refs/foo`. This could
easily result in data loss.

The fix is simple: instead of just breaking out of the loop, jump
directly to the cleanup code. This fixes some tests in t1404 that were
added in the previous commit.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-25 15:08:26 +09:00
brian m. carlson
4f01e5080c refs/files-backend: convert static functions to object_id
Convert several static functions to take pointers to struct object_id.
Change the relevant parameters to write_packed_entry to be const, as we
don't modify them.  Rename lock_ref_sha1_basic to lock_ref_oid_basic to
reflect its new argument.  Update the docstring for verify lock to
account for the new parameter name, and note additionally that the
old_oid may be NULL.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:52 +09:00
brian m. carlson
99afe91a6c refs: convert read_raw_ref backends to struct object_id
Convert the unsigned char * parameter to struct object_id * for
files_read_raw_ref and packed_read_raw_ref.  Update the documentation.
Switch from using get_sha1_hex and a hard-coded 40 to using
parse_oid_hex.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:52 +09:00
brian m. carlson
ac2ed0d7d5 refs: convert peel_object to struct object_id
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:52 +09:00
brian m. carlson
49e61479be refs: convert resolve_ref_unsafe to struct object_id
Convert resolve_ref_unsafe to take a pointer to struct object_id by
converting one remaining caller to use struct object_id, removing the
temporary NULL pointer check in expand_ref, converting the declaration
and definition, and applying the following semantic patch:

@@
expression E1, E2, E3, E4;
@@
- resolve_ref_unsafe(E1, E2, E3.hash, E4)
+ resolve_ref_unsafe(E1, E2, &E3, E4)

@@
expression E1, E2, E3, E4;
@@
- resolve_ref_unsafe(E1, E2, E3->hash, E4)
+ resolve_ref_unsafe(E1, E2, E3, E4)

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:51 +09:00
brian m. carlson
0155f710b8 refs: convert reflog_expire parameter to struct object_id
reflog_expire already used struct object_id internally, but it did not
take it as a parameter.  Adjust the parameter (and the callers) to pass
a pointer to struct object_id instead of a pointer to unsigned char.
Remove the temporary inserted earlier as it is no longer required.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:51 +09:00
brian m. carlson
34c290a6fc refs: convert read_ref and read_ref_full to object_id
All but two of the call sites already have parameters using the hash
parameter of struct object_id, so convert them to take a pointer to the
struct directly.  Also convert refs_read_refs_full, the underlying
implementation.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:50 +09:00
brian m. carlson
89f3bbdd3b refs: update ref transactions to use struct object_id
Update the ref transaction code to use struct object_id.  Remove one
NULL pointer check which was previously inserted around a dereference;
since we now pass a pointer to struct object_id directly through, the
code we're calling handles this for us.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:50 +09:00
brian m. carlson
2616a5e508 refs: convert delete_ref and refs_delete_ref to struct object_id
Convert delete_ref and refs_delete_ref to take a pointer to struct
object_id.  Update the documentation accordingly, including referring to
null_oid in lowercase, as it is not a #define constant.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:50 +09:00
brian m. carlson
49e9958869 refs/files-backend: convert struct ref_to_prune to object_id
Change the member of this struct to be a struct object_id.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-16 11:05:50 +09:00
Junio C Hamano
e46ebc2754 Merge branch 'rs/cleanup-strbuf-users'
Code clean-up.

* rs/cleanup-strbuf-users:
  graph: use strbuf_addchars() to add spaces
  use strbuf_addstr() for adding strings to strbufs
  path: use strbuf_add_real_path()
2017-10-05 13:48:19 +09:00
Junio C Hamano
efe9d6ce33 Merge branch 'rs/resolve-ref-optional-result'
Code clean-up.

* rs/resolve-ref-optional-result:
  refs: pass NULL to resolve_refdup() if hash is not needed
  refs: pass NULL to refs_resolve_refdup() if hash is not needed
2017-10-05 13:48:19 +09:00
Junio C Hamano
1a2e1a76ec Merge branch 'mh/mmap-packed-refs'
Operations that do not touch (majority of) packed refs have been
optimized by making accesses to packed-refs file lazy; we no longer
pre-parse everything, and an access to a single ref in the
packed-refs does not touch majority of irrelevant refs, either.

* mh/mmap-packed-refs: (21 commits)
  packed-backend.c: rename a bunch of things and update comments
  mmapped_ref_iterator: inline into `packed_ref_iterator`
  ref_cache: remove support for storing peeled values
  packed_ref_store: get rid of the `ref_cache` entirely
  ref_store: implement `refs_peel_ref()` generically
  packed_read_raw_ref(): read the reference from the mmapped buffer
  packed_ref_iterator_begin(): iterate using `mmapped_ref_iterator`
  read_packed_refs(): ensure that references are ordered when read
  packed_ref_cache: keep the `packed-refs` file mmapped if possible
  packed-backend.c: reorder some definitions
  mmapped_ref_iterator_advance(): no peeled value for broken refs
  mmapped_ref_iterator: add iterator over a packed-refs file
  packed_ref_cache: remember the file-wide peeling state
  read_packed_refs(): read references with minimal copying
  read_packed_refs(): make parsing of the header line more robust
  read_packed_refs(): only check for a header at the top of the file
  read_packed_refs(): use mmap to read the `packed-refs` file
  die_unterminated_line(), die_invalid_line(): new functions
  packed_ref_cache: add a backlink to the associated `packed_ref_store`
  prefix_ref_iterator: break when we leave the prefix
  ...
2017-10-03 15:42:50 +09:00
Junio C Hamano
cb1083ca23 Merge branch 'jk/read-in-full'
Code clean-up to prevent future mistakes by copying and pasting
code that checks the result of read_in_full() function.

* jk/read-in-full:
  worktree: check the result of read_in_full()
  worktree: use xsize_t to access file size
  distinguish error versus short read from read_in_full()
  avoid looking at errno for short read_in_full() returns
  prefer "!=" when checking read_in_full() result
  notes-merge: drop dead zero-write code
  files-backend: prefer "0" for write_in_full() error check
2017-10-03 15:42:49 +09:00
Junio C Hamano
3b48045c6c Merge branch 'sd/branch-copy'
"git branch" learned "-c/-C" to create a new branch by copying an
existing one.

* sd/branch-copy:
  branch: fix "copy" to never touch HEAD
  branch: add a --copy (-c) option to go with --move (-m)
  branch: add test for -m renaming multiple config sections
  config: create a function to format section headers
2017-10-03 15:42:48 +09:00
René Scharfe
72d4a9a721 use strbuf_addstr() for adding strings to strbufs
Use strbuf_addstr() instead of strbuf_addf() for adding strings.  That's
simpler and makes the intent clearer.

Patch generated by Coccinelle and contrib/coccinelle/strbuf.cocci;
adjusted indentation in refs/packed-backend.c manually.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-02 13:13:46 +09:00
René Scharfe
872ccb2c69 refs: pass NULL to refs_resolve_refdup() if hash is not needed
This gets us rid of a write-only variable.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-01 17:26:58 +09:00
Junio C Hamano
73ecdc606e Merge branch 'rs/resolve-ref-optional-result'
Code clean-up.

* rs/resolve-ref-optional-result:
  refs: pass NULL to resolve_ref_unsafe() if hash is not needed
  refs: pass NULL to refs_resolve_ref_unsafe() if hash is not needed
  refs: make sha1 output parameter of refs_resolve_ref_unsafe() optional
2017-09-28 14:47:56 +09:00
Jeff King
88780c37b3 files-backend: prefer "0" for write_in_full() error check
Commit 06f46f237a (avoid "write_in_full(fd, buf, len) !=
len" pattern, 2017-09-13) converted this callsite from:

  write_in_full(...) != 1

to

  write_in_full(...) < 0

But during the conflict resolution in c50424a6f0 (Merge
branch 'jk/write-in-full-fix', 2017-09-25), this morphed
into

  write_in_full(...) < 1

This behaves as we want, but we prefer to avoid modeling the
"less than length" error-check which can be subtly buggy, as
shown in efacf609c8 (config: avoid "write_in_full(fd, buf,
len) < len" pattern, 2017-09-13).

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-26 12:54:43 +09:00
Michael Haggerty
cff28ca94c packed-backend.c: rename a bunch of things and update comments
We've made huge changes to this file, and some of the old names and
comments are no longer very fitting. So rename a bunch of things:

* `struct packed_ref_cache` → `struct snapshot`
* `acquire_packed_ref_cache()` → `acquire_snapshot()`
* `release_packed_ref_buffer()` → `clear_snapshot_buffer()`
* `release_packed_ref_cache()` → `release_snapshot()`
* `clear_packed_ref_cache()` → `clear_snapshot()`
* `struct packed_ref_entry` → `struct snapshot_record`
* `cmp_packed_ref_entries()` → `cmp_packed_ref_records()`
* `cmp_entry_to_refname()` → `cmp_record_to_refname()`
* `sort_packed_refs()` → `sort_snapshot()`
* `read_packed_refs()` → `create_snapshot()`
* `validate_packed_ref_cache()` → `validate_snapshot()`
* `get_packed_ref_cache()` → `get_snapshot()`
* Renamed local variables and struct members accordingly.

Also update a bunch of comments to reflect the renaming and the
accumulated changes that the code has undergone.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:46 +09:00
Michael Haggerty
523ee2d785 mmapped_ref_iterator: inline into packed_ref_iterator
Since `packed_ref_iterator` is now delegating to
`mmapped_ref_iterator` rather than `cache_ref_iterator` to do the
heavy lifting, there is no need to keep the two iterators separate. So
"inline" `mmapped_ref_iterator` into `packed_ref_iterator`. This
removes a bunch of boilerplate.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:46 +09:00
Michael Haggerty
a6e19bcdad ref_cache: remove support for storing peeled values
Now that the `packed-refs` backend doesn't use `ref_cache`, there is
nobody left who might want to store peeled values of references in
`ref_cache`. So remove that feature.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:46 +09:00
Michael Haggerty
9dd389f3d8 packed_ref_store: get rid of the ref_cache entirely
Now that everything has been changed to read what it needs directly
out of the `packed-refs` file, `packed_ref_store` doesn't need to
maintain a `ref_cache` at all. So get rid of it.

First of all, this will save a lot of memory and lots of little
allocations. Instead of needing to store complicated parsed data
structures in memory, we just mmap the file (potentially sharing
memory with other processes) and parse only what we need.

Moreover, since the mmapped access to the file reads only the parts of
the file that it needs, this might save reading all of the data from
disk at all (at least if the file starts out sorted).

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:46 +09:00
Michael Haggerty
ba1c052fa6 ref_store: implement refs_peel_ref() generically
We're about to stop storing packed refs in a `ref_cache`. That means
that the only way we have left to optimize `peel_ref()` is by checking
whether the reference being peeled is the one currently being iterated
over (in `current_ref_iter`), and if so, using `ref_iterator_peel()`.
But this can be done generically; it doesn't have to be implemented
per-backend.

So implement `refs_peel_ref()` in `refs.c` and remove the `peel_ref()`
method from the refs API.

This removes the last callers of a couple of functions, so delete
them. More cleanup to come...

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:46 +09:00
Michael Haggerty
f3987ab36d packed_read_raw_ref(): read the reference from the mmapped buffer
Instead of reading the reference from the `ref_cache`, read it
directly from the mmapped buffer.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
d1cf15516f packed_ref_iterator_begin(): iterate using mmapped_ref_iterator
Now that we have an efficient way to iterate, in order, over the
mmapped contents of the `packed-refs` file, we can use that directly
to implement reference iteration for the `packed_ref_store`, rather
than iterating over the `ref_cache`. This is the next step towards
getting rid of the `ref_cache` entirely.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
02b920f3f7 read_packed_refs(): ensure that references are ordered when read
It doesn't actually matter now, because the references are only
iterated over to fill the associated `ref_cache`, which itself puts
them in the correct order. But we want to get rid of the `ref_cache`,
so we want to be able to iterate directly over the `packed-refs`
buffer, and then the iteration will need to be ordered correctly.

In fact, we already write the `packed-refs` file sorted, but it is
possible that other Git clients don't get it right. So let's not
assume that a `packed-refs` file is sorted unless it is explicitly
declared to be so via a `sorted` trait in its header line.

If it is *not* declared to be sorted, then scan quickly through the
file to check. If it is found to be out of order, then sort the
records into a new memory-only copy. This checking and sorting is done
quickly, without parsing the full file contents. However, it needs a
little bit of care to avoid reading past the end of the buffer even if
the `packed-refs` file is corrupt.

Since *we* always write the file correctly sorted, include that trait
when we write or rewrite a `packed-refs` file. This means that the
scan described in the previous paragraph should only have to be done
for `packed-refs` files that were written by older versions of the Git
command-line client, or by other clients that haven't yet learned to
write the `sorted` trait.

If `packed-refs` was already sorted, then (if the system allows it) we
can use the mmapped file contents directly. But if the system doesn't
allow a file that is currently mmapped to be replaced using
`rename()`, then it would be bad for us to keep the file mmapped for
any longer than necessary. So, on such systems, always make a copy of
the file contents, either as part of the sorting process, or
afterwards.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
5b633610ec packed_ref_cache: keep the packed-refs file mmapped if possible
Keep a copy of the `packed-refs` file contents in memory for as long
as a `packed_ref_cache` object is in use:

* If the system allows it, keep the `packed-refs` file mmapped.

* If not (either because the system doesn't support `mmap()` at all,
  or because a file that is currently mmapped cannot be replaced via
  `rename()`), then make a copy of the file's contents in
  heap-allocated space, and keep that around instead.

We base the choice of behavior on a new build-time switch,
`MMAP_PREVENTS_DELETE`. By default, this switch is set for Windows
variants.

After this commit, `MMAP_NONE` and `MMAP_TEMPORARY` are still handled
identically. But the next commit will introduce a difference.

This whole change is still pointless, because we only read the
`packed-refs` file contents immediately after instantiating the
`packed_ref_cache`. But that will soon change.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
14b3c344ea packed-backend.c: reorder some definitions
No code has been changed. This will make subsequent patches more
self-contained.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
81b9b5aea7 mmapped_ref_iterator_advance(): no peeled value for broken refs
If a reference is broken, suppress its peeled value.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
9cfb3dc0d1 mmapped_ref_iterator: add iterator over a packed-refs file
Add a new `mmapped_ref_iterator`, which can iterate over the
references in an mmapped `packed-refs` file directly. Use this
iterator from `read_packed_refs()` to fill the packed refs cache.

Note that we are not yet willing to promise that the new iterator
generates its output in order. That doesn't matter for now, because
the packed refs cache doesn't care what order it is filled.

This change adds a lot of boilerplate without providing any obvious
benefits. The benefits will come soon, when we get rid of the
`ref_cache` for packed references altogether.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
daa45408c1 packed_ref_cache: remember the file-wide peeling state
Rather than store the peeling state (i.e., the one defined by traits
in the `packed-refs` file header line) in a local variable in
`read_packed_refs()`, store it permanently in `packed_ref_cache`. This
will be needed when we stop reading all packed refs at once.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Michael Haggerty
6a9bc4034a read_packed_refs(): read references with minimal copying
Instead of copying data from the `packed-refs` file one line at time
and then processing it, process the data in place as much as possible.

Also, instead of processing one line per iteration of the main loop,
process a reference line plus its corresponding peeled line (if
present) together.

Note that this change slightly tightens up the parsing of the
`packed-refs` file. Previously, the parser would have accepted
multiple "peeled" lines for a single reference (ignoring all but the
last one). Now it would reject that.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-25 18:02:45 +09:00
Junio C Hamano
c50424a6f0 Merge branch 'jk/write-in-full-fix'
Many codepaths did not diagnose write failures correctly when disks
go full, due to their misuse of write_in_full() helper function,
which have been corrected.

* jk/write-in-full-fix:
  read_pack_header: handle signed/unsigned comparison in read result
  config: flip return value of store_write_*()
  notes-merge: use ssize_t for write_in_full() return value
  pkt-line: check write_in_full() errors against "< 0"
  convert less-trivial versions of "write_in_full() != len"
  avoid "write_in_full(fd, buf, len) != len" pattern
  get-tar-commit-id: check write_in_full() return against 0
  config: avoid "write_in_full(fd, buf, len) < len" pattern
2017-09-25 15:24:06 +09:00
René Scharfe
e691b027b6 refs: pass NULL to refs_resolve_ref_unsafe() if hash is not needed
This allows us to get rid of two write-only variables, one of them
being a SHA1 buffer.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-24 10:18:18 +09:00
Junio C Hamano
07f0542da3 Merge branch 'mh/packed-ref-transactions'
Implement transactional update to the packed-ref representation of
references.

* mh/packed-ref-transactions:
  files_transaction_finish(): delete reflogs before references
  packed-backend: rip out some now-unused code
  files_ref_store: use a transaction to update packed refs
  t1404: demonstrate two problems with reference transactions
  files_initial_transaction_commit(): use a transaction for packed refs
  prune_refs(): also free the linked list
  files_pack_refs(): use a reference transaction to write packed refs
  packed_delete_refs(): implement method
  packed_ref_store: implement reference transactions
  struct ref_transaction: add a place for backends to store data
  packed-backend: don't adjust the reference count on lock/unlock
2017-09-19 10:47:56 +09:00
Junio C Hamano
89563ec379 Merge branch 'jk/incore-lockfile-removal'
The long-standing rule that an in-core lockfile instance, once it
is used, must not be freed, has been lifted and the lockfile and
tempfile APIs have been updated to reduce the chance of programming
errors.

* jk/incore-lockfile-removal:
  stop leaking lock structs in some simple cases
  ref_lock: stop leaking lock_files
  lockfile: update lifetime requirements in documentation
  tempfile: auto-allocate tempfiles on heap
  tempfile: remove deactivated list entries
  tempfile: use list.h for linked list
  tempfile: release deactivated strbufs instead of resetting
  tempfile: robustify cleanup handler
  tempfile: factor out deactivation
  tempfile: factor out activation
  tempfile: replace die("BUG") with BUG()
  tempfile: handle NULL tempfile pointers gracefully
  tempfile: prefer is_tempfile_active to bare access
  lockfile: do not rollback lock on failed close
  tempfile: do not delete tempfile on failed close
  always check return value of close_tempfile
  verify_signed_buffer: prefer close_tempfile() to close()
  setup_temporary_shallow: move tempfile struct into function
  setup_temporary_shallow: avoid using inactive tempfile
  write_index_as_tree: cleanup tempfile on error
2017-09-19 10:47:53 +09:00
Junio C Hamano
8a044c7f1d Merge branch 'nd/prune-in-worktree'
"git gc" and friends when multiple worktrees are used off of a
single repository did not consider the index and per-worktree refs
of other worktrees as the root for reachability traversal, making
objects that are in use only in other worktrees to be subject to
garbage collection.

* nd/prune-in-worktree:
  refs.c: reindent get_submodule_ref_store()
  refs.c: remove fallback-to-main-store code get_submodule_ref_store()
  rev-list: expose and document --single-worktree
  revision.c: --reflog add HEAD reflog from all worktrees
  files-backend: make reflog iterator go through per-worktree reflog
  revision.c: --all adds HEAD from all worktrees
  refs: remove dead for_each_*_submodule()
  refs.c: move for_each_remote_ref_submodule() to submodule.c
  revision.c: use refs_for_each*() instead of for_each_*_submodule()
  refs: add refs_head_ref()
  refs: move submodule slash stripping code to get_submodule_ref_store
  refs.c: refactor get_submodule_ref_store(), share common free block
  revision.c: --indexed-objects add objects from all worktrees
  revision.c: refactor add_index_objects_to_pending()
  refs.c: use is_dir_sep() in resolve_gitlink_ref()
  revision.h: new flag in struct rev_info wrt. worktree-related refs
2017-09-19 10:47:53 +09:00
Junio C Hamano
dafbe1993e Merge branch 'ma/split-symref-update-fix'
A leakfix.

* ma/split-symref-update-fix:
  refs/files-backend: add `refname`, not "HEAD", to list
  refs/files-backend: correct return value in lock_ref_for_update
  refs/files-backend: fix memory leak in lock_ref_for_update
  refs/files-backend: add longer-scoped copy of string to list
2017-09-19 10:47:53 +09:00
Michael Haggerty
a8811695e3 read_packed_refs(): make parsing of the header line more robust
The old code parsed the traits in the `packed-refs` header by looking
for the string " trait " (i.e., the name of the trait with a space on
either side) in the header line. This is fragile, because if any other
implementation of Git forgets to write the trailing space, the last
trait would silently be ignored (and the error might never be
noticed).

So instead, use `string_list_split_in_place()` to split the traits
into tokens then use `unsorted_string_list_has_string()` to look for
the tokens we are interested in. This means that we can read the
traits correctly even if the header line is missing a trailing
space (or indeed, if it is missing the space after the colon, or if it
has multiple spaces somewhere).

However, older Git clients (and perhaps other Git implementations)
still require the surrounding spaces, so we still have to output the
header with a trailing space.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
36f23534ae read_packed_refs(): only check for a header at the top of the file
This tightens up the parsing a bit; previously, stray header-looking
lines would have been processed.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
49a03ef466 read_packed_refs(): use mmap to read the packed-refs file
It's still done in a pretty stupid way, involving more data copying
than necessary. That will improve in future commits.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
735267aa10 die_unterminated_line(), die_invalid_line(): new functions
Extract some helper functions for reporting errors. While we're at it,
prevent them from spewing unlimited output to the terminal. These
functions will soon have more callers.

These functions accept the problematic line as a `(ptr, len)` pair
rather than a NUL-terminated string, and `die_invalid_line()` checks
for an EOL itself, because these calling conventions will be
convenient for future callers. (Efficiency is not a concern here
because these functions are only ever called if the `packed-refs` file
is corrupt.)

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
f0a7dc86d2 packed_ref_cache: add a backlink to the associated packed_ref_store
It will prove convenient in upcoming patches.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Jeff King
157113c614 prefix_ref_iterator: break when we leave the prefix
If the underlying iterator is ordered, then `prefix_ref_iterator` can
stop as soon as it sees a refname that comes after the prefix. This
will rarely make a big difference now, because `ref_cache_iterator`
only iterates over the directory containing the prefix (and usually
the prefix will span a whole directory anyway). But if *hint, hint* a
future reference backend doesn't itself know where to stop the
iteration, then this optimization will be a big win.

Note that there is no guarantee that the underlying iterator doesn't
include output preceding the prefix, so we have to skip over any
unwanted references before we get to the ones that we want.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Michael Haggerty
8738a8a4df ref_iterator: keep track of whether the iterator output is ordered
References are iterated over in order by refname, but reflogs are not.
Some consumers of reference iteration care about the difference. Teach
each `ref_iterator` to keep track of whether its output is ordered.

`overlay_ref_iterator` is one of the picky consumers. Add a sanity
check in `overlay_ref_iterator_begin()` to verify that its inputs are
ordered.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:19:07 +09:00
Jeff King
564bde9ae6 convert less-trivial versions of "write_in_full() != len"
The prior commit converted many sites to check the return
value of write_in_full() for negativity, rather than a
mismatch with the input length. This patch covers similar
cases, but where the return value is stored in an
intermediate variable. These should get the same treatment,
but they need to be reviewed more carefully since it would
be a bug if the return value is stored in an unsigned type
(which indeed, it is in one of the cases).

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Jeff King
06f46f237a avoid "write_in_full(fd, buf, len) != len" pattern
The return value of write_in_full() is either "-1", or the
requested number of bytes[1]. If we make a partial write
before seeing an error, we still return -1, not a partial
value. This goes back to f6aa66cb95 (write_in_full: really
write in full or return error on disk full., 2007-01-11).

So checking anything except "was the return value negative"
is pointless. And there are a couple of reasons not to do
so:

  1. It can do a funny signed/unsigned comparison. If your
     "len" is signed (e.g., a size_t) then the compiler will
     promote the "-1" to its unsigned variant.

     This works out for "!= len" (unless you really were
     trying to write the maximum size_t bytes), but is a
     bug if you check "< len" (an example of which was fixed
     recently in config.c).

     We should avoid promoting the mental model that you
     need to check the length at all, so that new sites are
     not tempted to copy us.

  2. Checking for a negative value is shorter to type,
     especially when the length is an expression.

  3. Linus says so. In d34cf19b89 (Clean up write_in_full()
     users, 2007-01-11), right after the write_in_full()
     semantics were changed, he wrote:

       I really wish every "write_in_full()" user would just
       check against "<0" now, but this fixes the nasty and
       stupid ones.

     Appeals to authority aside, this makes it clear that
     writing it this way does not have an intentional
     benefit. It's a historical curiosity that we never
     bothered to clean up (and which was undoubtedly
     cargo-culted into new sites).

So let's convert these obviously-correct cases (this
includes write_str_in_full(), which is just a wrapper for
write_in_full()).

[1] A careful reader may notice there is one way that
    write_in_full() can return a different value. If we ask
    write() to write N bytes and get a return value that is
    _larger_ than N, we could return a larger total. But
    besides the fact that this would imply a totally broken
    version of write(), it would already invoke undefined
    behavior. Our internal remaining counter is an unsigned
    size_t, which means that subtracting too many byte will
    wrap it around to a very large number. So we'll instantly
    begin reading off the end of the buffer, trying to write
    gigabytes (or petabytes) of data.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Martin Ågren
276d0e35c0 refs/files-backend: add refname, not "HEAD", to list
An earlier patch rewrote `split_symref_update()` to add a copy of a
string to a string list instead of adding the original string. That was
so that the original string could be freed in a later patch, but it is
also conceptually cleaner, since now all calls to `string_list_insert()`
and `string_list_append()` add `update->refname`. --- Except a literal
"HEAD" is added in `split_head_update()`.

Restructure `split_head_update()` in the same way as the earlier patch
did for `split_symref_update()`. This does not correct any practical
problem, but makes things conceptually cleaner. The downside is a call
to `string_list_has_string()`, which should be relatively cheap.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00
Martin Ågren
3f5ef95b5e refs/files-backend: correct return value in lock_ref_for_update
In one code path we return a literal -1 and not a symbolic constant. The
value -1 would be interpreted as TRANSACTION_NAME_CONFLICT, which is
wrong. Use TRANSACTION_GENERIC_ERROR instead (that is the only other
return value we have to choose from).

Noticed-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00
Martin Ågren
851e1fbd01 refs/files-backend: fix memory leak in lock_ref_for_update
After the previous patch, none of the functions we call hold on to
`referent.buf`, so we can safely release the string buffer before
returning.

Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-10 16:36:58 +09:00