The implementation of "get_sha1_hex()" that reads a hexadecimal
string that spells a full object name has been extended to cope
with any hash function used in the repository, but the "sha1" in
its name survived. Rename it to get_hash_hex(), a name that is
more consistent within its friends like get_hash_hex_algop().
* jc/retire-get-sha1-hex:
hex: retire get_sha1_hex()
Various offset computation in the code that accesses the packfiles
and other data in the object layer has been hardened against
arithmetic overflow, especially on 32-bit systems.
* tb/object-access-overflow-protection:
commit-graph.c: prevent overflow in `verify_commit_graph()`
commit-graph.c: prevent overflow in `write_commit_graph()`
commit-graph.c: prevent overflow in `merge_commit_graph()`
commit-graph.c: prevent overflow in `split_graph_merge_strategy()`
commit-graph.c: prevent overflow in `load_tree_for_commit()`
commit-graph.c: prevent overflow in `fill_commit_in_graph()`
commit-graph.c: prevent overflow in `fill_commit_graph_info()`
commit-graph.c: prevent overflow in `load_oid_from_graph()`
commit-graph.c: prevent overflow in add_graph_to_chain()
commit-graph.c: prevent overflow in `write_commit_graph_file()`
pack-bitmap.c: ensure that eindex lookups don't overflow
midx.c: prevent overflow in `fill_included_packs_batch()`
midx.c: prevent overflow in `write_midx_internal()`
midx.c: store `nr`, `alloc` variables as `size_t`'s
midx.c: prevent overflow in `nth_midxed_offset()`
midx.c: prevent overflow in `nth_midxed_object_oid()`
midx.c: use `size_t`'s for fanout nr and alloc
packfile.c: use checked arithmetic in `nth_packed_object_offset()`
packfile.c: prevent overflow in `load_idx()`
packfile.c: prevent overflow in `nth_packed_object_id()`
The naming convention around get_sha1_hex() and its friends is
awkward these days, after "struct object_id" was introduced.
There are three public functions around this area:
* get_sha1_hex() - use the implied the_hash_algo, fill uchar *
* get_oid_hex() - use the implied the_hash_algo, fill oid *
* get_oid_hex_algop() - use the passed algop, fill oid *
Between the latter two, the "_algop" suffix signals whether the
the_hash_algo is used as the implied algorithm or the caller should
pass an algorithm explicitly. That is very much understandable and
is a good convention.
Between the former two, however, the "SHA1" vs "OID" in the names
differentiate in what type of variable the result is stored.
We could argue that it makes sense to use "SHA1" to mean "flat byte
buffer" to honor the historical practice in the days before "struct
object_id" was invented, but the natural fourth friend of the above
group would take an algop and fill a flat byte buffer, and it would
be strange to name it get_sha1_hex_algop(). Do we use the passed in
algo, or are we limited to SHA-1 ;-)?
In fact, such a function exists, albeit as a private helper function
used by the implementation of these functions, and is named a lot
more sensibly: get_hash_hex_algop().
Correct the misnomer of get_sha1_hex() and use "hash", instead of
"sha1", as "flat byte buffer that stores binary (as opposed to
hexadecimal) representation of the hash".
The four (2x2) friends now become:
* get_hash_hex() - use the implied the_hash_algo, fill uchar *
* get_oid_hex() - use the implied the_hash_algo, fill oid *
* get_hash_hex_algop() - use the passed algop, fill uchar *
* get_oid_hex_algop() - use the passed algop, fill oid *
As there are only two remaining calls to get_sha1_hex() in the
codebase right now, the blast radious of this change is fairly
small.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In a similar spirit as the previous commits, ensure that we use
`st_add()` or `st_mult()` when computing values that may overflow the
32-bit unsigned limit.
Note that in each of these instances, we prevent 32-bit overflow
already since we have explicit casts to `size_t`.
So this code is OK as-is, but let's clarify it by using the `st_xyz()`
helpers to make it obvious that we are performing the relevant
computations using 64 bits.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Prevent an overflow when locating a pack's CRC offset when the number
of packed items is greater than 2^32-1/hashsz by guarding the
computation with an `st_mult()`.
Note that to avoid truncating the result, the `crc_offset` member must
itself become a `size_t`. The only usage of this variable (besides the
assignment in `load_idx()`) is in `read_v2_anomalous_offsets()` in the
index-pack code. There we use the `crc_offset` as a pointer offset, so
we are already equipped to handle the type change.
Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 37fec86a83 (packfile: abstract away hash constant values,
2018-05-02), `nth_packed_object_id()` started using the variable
`the_hash_algo->rawsz` instead of a fixed constant when trying to
compute an offset into the ".idx" file for some object position.
This can lead to surprising truncation when looking for an object
towards the end of a large enough pack, like the following:
(gdb) p hashsz
$1 = 20
(gdb) p n
$2 = 215043814
(gdb) p hashsz * n
$3 = 5908984
, which is a debugger session broken on a known-bad call to the
`nth_packed_object_id()` function.
This behavior predates 37fec86a83, and is original to the v2 index
format, via: 74e34e1fca (sha1_file.c: learn about index version 2,
2007-04-09).
This is due to §6.4.4.1 of the C99 standard, which states that an
untyped integer constant will take the first type in which the value can
be accurately represented, among `int`, `long int`, and `long long int`.
Since 20 can be represented as an `int`, and `n` is a 32-bit unsigned
integer, the resulting computation is defined by §6.3.1.8, and the
(signed) integer value representing `n` is converted to an unsigned
type, meaning that `20 * n` (for `n` having type `uint32_t`) is
equivalent to a multiplication between two unsigned 32-bit integers.
When multiplying a sufficiently large `n`, the resulting value can
exceed 2^32-1, wrapping around and producing an invalid result. Let's
follow the example in f86f769550 (compute pack .idx byte offsets using
size_t, 2020-11-13) and replace this computation with `st_mult()`, which
will ensure that the computation is done using 64-bits.
While here, guard the corresponding computation for packs with v1
indexes, too. Though the likelihood of seeing a bug there is much
smaller, since (a) v1 indexes are generated far less frequently than v2
indexes, and (b) they all correspond to packs no larger than 2 GiB, so
having enough objects to trigger this overflow is unlikely if not
impossible.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
alloc_nr, ALLOC_GROW, and ALLOC_GROW_BY are commonly used macros for
dynamic array allocation. Moving these macros to git-compat-util.h with
the other alloc macros focuses alloc.[ch] to allocation for Git objects
and additionally allows us to remove inclusions to alloc.h from files
that solely used the above macros.
Signed-off-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Header files cleanup.
* en/header-split-cache-h-part-3: (28 commits)
fsmonitor-ll.h: split this header out of fsmonitor.h
hash-ll, hashmap: move oidhash() to hash-ll
object-store-ll.h: split this header out of object-store.h
khash: name the structs that khash declares
merge-ll: rename from ll-merge
git-compat-util.h: remove unneccessary include of wildmatch.h
builtin.h: remove unneccessary includes
list-objects-filter-options.h: remove unneccessary include
diff.h: remove unnecessary include of oidset.h
repository: remove unnecessary include of path.h
log-tree: replace include of revision.h with simple forward declaration
cache.h: remove this no-longer-used header
read-cache*.h: move declarations for read-cache.c functions from cache.h
repository.h: move declaration of the_index from cache.h
merge.h: move declarations for merge.c from cache.h
diff.h: move declaration for global in diff.c from cache.h
preload-index.h: move declarations for preload-index.c from elsewhere
sparse-index.h: move declarations for sparse-index.c from cache.h
name-hash.h: move declarations for name-hash.c from cache.h
run-command.h: move declarations for run-command.c from cache.h
...
We create .pack and then .idx, we consider only packfiles that have
.idx usable (those with only .pack are not ready yet), so we should
remove .idx before removing .pack for consistency.
* ds/remove-idx-before-pack:
packfile: delete .idx files before .pack files
The vast majority of files including object-store.h did not need dir.h
nor khash.h. Split the header into two files, and let most just depend
upon object-store-ll.h, while letting the two callers that need it
depend on the full object-store.h.
After this patch:
$ git grep -h include..object-store | sort | uniq -c
2 #include "object-store.h"
129 #include "object-store-ll.h"
Diff best viewed with `--color-moved`.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When installing a packfile, we place the .pack file before the .idx
file. The intention is that Git scans for .idx files in the pack
directory and then loads the .pack files from that list.
However, when we delete packfiles, we do not do this in the reverse
order as we should. The unlink_pack_path() method deletes the .pack
followed by the .idx.
This creates a window where the process could be interrupted between
the .pack deletion and the .idx deletion, leaving the repository in a
state that looks strange, but isn't actually too problematic if we
assume the pack was safe to delete. The .idx without a .pack will cause
some overhead, but will not interrupt other Git processes.
This ordering was introduced into the 'git repack' builtin by
a1bbc6c017 (repack: rewrite the shell script in C, 2013-09-15), though
we must be careful to track history through the code move in 8434e85d5f
(repack: refactor pack deletion for future use, 2019-06-10) to see that.
This became more important after 73320e49ad (builtin/repack.c: only
collect fully-formed packs, 2023-06-07) changed how 'git repack' scanned
for packfiles for use in the cruft pack process. It previously looked
for .pack files, but that was problematic due to the order that packs
are installed: repacks between the creation of a .pack and the creation
of its .idx would result in hard failures.
There is an independent proposal about what to do in the case of a .idx
without a .pack during this 'git repack' scenario, but this change is
focused on deleting .pack files more safely.
Modify the order to delete the .idx before the .pack. The rest of the
modifiers on the .pack should still come after the .pack so we know all
of the presumed properties of the packfile as long as it exists in the
filesystem, in case we wish to reinstate it by re-indexing the .pack
file.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
More header clean-up.
* en/header-split-cache-h-part-2: (22 commits)
reftable: ensure git-compat-util.h is the first (indirect) include
diff.h: reduce unnecessary includes
object-store.h: reduce unnecessary includes
commit.h: reduce unnecessary includes
fsmonitor: reduce includes of cache.h
cache.h: remove unnecessary headers
treewide: remove cache.h inclusion due to previous changes
cache,tree: move basic name compare functions from read-cache to tree
cache,tree: move cmp_cache_name_compare from tree.[ch] to read-cache.c
hash-ll.h: split out of hash.h to remove dependency on repository.h
tree-diff.c: move S_DIFFTREE_IFXMIN_NEQ define from cache.h
dir.h: move DTYPE defines from cache.h
versioncmp.h: move declarations for versioncmp.c functions from cache.h
ws.h: move declarations for ws.c functions from cache.h
match-trees.h: move declarations for match-trees.c functions from cache.h
pkt-line.h: move declarations for pkt-line.c functions from cache.h
base85.h: move declarations for base85.c functions from cache.h
copy.h: move declarations for copy.c functions from cache.h
server-info.h: move declarations for server-info.c functions from cache.h
packfile.h: move pack_window and pack_entry from cache.h
...
The on-disk reverse index that allows mapping from the pack offset
to the object name for the object stored at the offset has been
enabled by default.
* tb/pack-revindex-on-disk:
t: invert `GIT_TEST_WRITE_REV_INDEX`
config: enable `pack.writeReverseIndex` by default
pack-revindex: introduce `pack.readReverseIndex`
pack-revindex: introduce GIT_TEST_REV_INDEX_DIE_ON_DISK
pack-revindex: make `load_pack_revindex` take a repository
t5325: mark as leak-free
pack-write.c: plug a leak in stage_tmp_packfiles()
In a future commit, we will introduce a `pack.readReverseIndex`
configuration, which forces Git to generate the reverse index from
scratch instead of loading it from disk.
In order to avoid reading this configuration value more than once, we'll
use the `repo_settings` struct to lazily load this value.
In order to access the `struct repo_settings`, add a repository argument
to `load_pack_revindex`, and update all callers to pass the correct
instance (in all cases, `the_repository`).
In certain instances, a new function-local variable is introduced to
take the place of a `struct repository *` argument to the function
itself to avoid propagating the new parameter even further throughout
the tree.
Co-authored-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Dozens of files made use of trace and trace2 functions, without
explicitly including trace.h or trace2.h. This made it more difficult
to find which files could remove a dependence on cache.h. Make C files
explicitly include trace.h or trace2.h if they are using them.
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Split key function and data structure definitions out of cache.h to
new header files and adjust the users.
* en/header-split-cleanup:
csum-file.h: remove unnecessary inclusion of cache.h
write-or-die.h: move declarations for write-or-die.c functions from cache.h
treewide: remove cache.h inclusion due to setup.h changes
setup.h: move declarations for setup.c functions from cache.h
treewide: remove cache.h inclusion due to environment.h changes
environment.h: move declarations for environment.c functions from cache.h
treewide: remove unnecessary includes of cache.h
wrapper.h: move declarations for wrapper.c functions from cache.h
path.h: move function declarations for path.c functions from cache.h
cache.h: remove expand_user_path()
abspath.h: move absolute path functions from cache.h
environment: move comment_line_char from cache.h
treewide: remove unnecessary cache.h inclusion from several sources
treewide: remove unnecessary inclusion of gettext.h
treewide: be explicit about dependence on gettext.h
treewide: remove unnecessary cache.h inclusion from a few headers
Code clean-up around the use of the_repository.
* ab/remove-implicit-use-of-the-repository:
libs: use "struct repository *" argument, not "the_repository"
post-cocci: adjust comments for recent repo_* migration
cocci: apply the "revision.h" part of "the_repository.pending"
cocci: apply the "rerere.h" part of "the_repository.pending"
cocci: apply the "refs.h" part of "the_repository.pending"
cocci: apply the "promisor-remote.h" part of "the_repository.pending"
cocci: apply the "packfile.h" part of "the_repository.pending"
cocci: apply the "pretty.h" part of "the_repository.pending"
cocci: apply the "object-store.h" part of "the_repository.pending"
cocci: apply the "diff.h" part of "the_repository.pending"
cocci: apply the "commit.h" part of "the_repository.pending"
cocci: apply the "commit-reach.h" part of "the_repository.pending"
cocci: apply the "cache.h" part of "the_repository.pending"
cocci: add missing "the_repository" macros to "pending"
cocci: sort "the_repository" rules by header
cocci: fix incorrect & verbose "the_repository" rules
cocci: remove dead rule from "the_repository.pending.cocci"
* ab/remove-implicit-use-of-the-repository:
libs: use "struct repository *" argument, not "the_repository"
post-cocci: adjust comments for recent repo_* migration
cocci: apply the "revision.h" part of "the_repository.pending"
cocci: apply the "rerere.h" part of "the_repository.pending"
cocci: apply the "refs.h" part of "the_repository.pending"
cocci: apply the "promisor-remote.h" part of "the_repository.pending"
cocci: apply the "packfile.h" part of "the_repository.pending"
cocci: apply the "pretty.h" part of "the_repository.pending"
cocci: apply the "object-store.h" part of "the_repository.pending"
cocci: apply the "diff.h" part of "the_repository.pending"
cocci: apply the "commit.h" part of "the_repository.pending"
cocci: apply the "commit-reach.h" part of "the_repository.pending"
cocci: apply the "cache.h" part of "the_repository.pending"
cocci: add missing "the_repository" macros to "pending"
cocci: sort "the_repository" rules by header
cocci: fix incorrect & verbose "the_repository" rules
cocci: remove dead rule from "the_repository.pending.cocci"
Apply the part of "the_repository.pending.cocci" pertaining to
"promisor-remote.h".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
With the change in the last commit to move several functions to
write-or-die.h, csum-file.h no longer needs to include cache.h.
However, removing that include forces several other C files, which
directly or indirectly dependend upon csum-file.h's inclusion of
cache.h, to now be more explicit about their dependencies.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Dozens of files made use of gettext functions, without explicitly
including gettext.h. This made it more difficult to find which files
could remove a dependence on cache.h. Make C files explicitly include
gettext.h if they are using it.
However, while compat/fsmonitor/fsm-ipc-darwin.c should also gain an
include of gettext.h, it was left out to avoid conflicting with an
in-flight topic.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Once we start running, we assumed that the list of alternate object
databases would never change. Hook into the machinery used to
update the list of packfiles during runtime to update this list as
well.
* ds/reprepare-alternates-when-repreparing-packfiles:
object-file: reprepare alternates when necessary
More work towards -Wunused.
* jk/unused-post-2.39-part2: (21 commits)
help: mark unused parameter in git_unknown_cmd_config()
run_processes_parallel: mark unused callback parameters
userformat_want_item(): mark unused parameter
for_each_commit_graft(): mark unused callback parameter
rewrite_parents(): mark unused callback parameter
fetch-pack: mark unused parameter in callback function
notes: mark unused callback parameters
prio-queue: mark unused parameters in comparison functions
for_each_object: mark unused callback parameters
list-objects: mark unused callback parameters
mark unused parameters in signal handlers
run-command: mark error routine parameters as unused
mark "pointless" data pointers in callbacks
ref-filter: mark unused callback parameters
http-backend: mark unused parameters in virtual functions
http-backend: mark argc/argv unused
object-name: mark unused parameters in disambiguate callbacks
serve: mark unused parameters in virtual functions
serve: use repository pointer to get config
ls-refs: drop config caching
...
When an object is not found in a repository's object store, we sometimes
call reprepare_packed_git() to see if the object was temporarily moved
into a new pack-file (and its old pack-file or loose object was
deleted). This process does a scan of each pack directory within each
odb, but does not reevaluate if the odb list needs updating.
Extend reprepare_packed_git() to also reprepare the alternate odb list
by setting loaded_alternates to zero and calling prepare_alt_odb(). This
will add newly-discoverd odbs to the linked list, but will not duplicate
existing ones nor will it remove existing ones that are no longer listed
in the alternates file. Do this under the object read lock to avoid
readers from interacting with a potentially incomplete odb being added
to the odb list.
If the alternates file was edited to _remove_ some alternates during the
course of the Git process, Git will continue to see alternates that were
ever valid for that repository. ODBs are not removed from the list, the
same as the existing behavior before this change. Git already has
protections against an alternate directory disappearing from the
filesystem during the lifetime of a process, and those are still in
effect.
This change is specifically for concurrent changes to the repository, so
it is difficult to create a test that guarantees this behavior is
correct. I manually verified by introducing a reprepare_packed_git() call
into get_revision() and stepped into that call in a debugger with a
parent 'git log' process. Multiple runs of prepare_alt_odb() kept
the_repository->objects->odb as a single-item chain until I added a
.git/objects/info/alternates file in a different process. The next run
added the new odb to the chain and subsequent runs did not add to the
chain.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The for_each_{loose,packed}_object interface uses callback functions,
but not every callback needs all of the parameters. Mark the unused ones
to satisfy -Wunused-parameter.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This allows us to replace includes of cache.h with includes of the much
smaller alloc.h in many places. It does mean that we also need to add
includes of alloc.h in a number of C files.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the pack code was split into its own file[1], it got a copy of the
static read_object() function. But there's only one caller here, so we
could just inline it. And it's worth doing so, as the name read_object()
invites comparisons to the public read_object_file(), but the two don't
behave quite the same.
[1] The move happened over several commits, but the relevant one here is
f1d8130be0 (pack: move clear_delta_base_cache(), packed_object_info(),
unpack_entry(), 2017-08-18).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Undoes 'jk/unused-annotation' topic and redoes it to work around
Coccinelle rules misfiring false positives in unrelated codepaths.
* ab/unused-annotation:
git-compat-util.h: use "deprecated" for UNUSED variables
git-compat-util.h: use "UNUSED", not "UNUSED(var)"
Annotate function parameters that are not used (but cannot be
removed for structural reasons), to prepare us to later compile
with -Wunused warning turned on.
* jk/unused-annotation:
is_path_owned_by_current_uid(): mark "report" parameter as unused
run-command: mark unused async callback parameters
mark unused read_tree_recursive() callback parameters
hashmap: mark unused callback parameters
config: mark unused callback parameters
streaming: mark unused virtual method parameters
transport: mark bundle transport_options as unused
refs: mark unused virtual method parameters
refs: mark unused reflog callback parameters
refs: mark unused each_ref_fn parameters
git-compat-util: add UNUSED macro
As reported in [1] the "UNUSED(var)" macro introduced in
2174b8c75d (Merge branch 'jk/unused-annotation' into next,
2022-08-24) breaks coccinelle's parsing of our sources in files where
it occurs.
Let's instead partially go with the approach suggested in [2] of
making this not take an argument. As noted in [1] "coccinelle" will
ignore such tokens in argument lists that it doesn't know about, and
it's less of a surprise to syntax highlighters.
This undoes the "help us notice when a parameter marked as unused is
actually use" part of 9b24034754 (git-compat-util: add UNUSED macro,
2022-08-19), a subsequent commit will further tweak the macro to
implement a replacement for that functionality.
1. https://lore.kernel.org/git/220825.86ilmg4mil.gmgdl@evledraar.gmail.com/
2. https://lore.kernel.org/git/220819.868rnk54ju.gmgdl@evledraar.gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
An earlier optimization discarded a tree-object buffer that is
still in use, which has been corrected.
* jk/is-promisor-object-keep-tree-in-use:
is_promisor_object(): fix use-after-free of tree buffer
Hashmap comparison functions must conform to a particular callback
interface, but many don't use all of their parameters. Especially the
void cmp_data pointer, but some do not use keydata either (because they
can easily form a full struct to pass when doing lookups). Let's mark
these to make -Wunused-parameter happy.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git fsck" reads mode from tree objects but canonicalizes the mode
before passing it to the logic to check object sanity, which has
hid broken tree objects from the checking logic. This has been
corrected, but to help exiting projects with broken tree objects
that they cannot fix retroactively, the severity of anomalies this
code detects has been demoted to "info" for now.
* jk/fsck-tree-mode-bits-fix:
fsck: downgrade tree badFilemode to "info"
fsck: actually detect bad file modes in trees
tree-walk: add a mechanism for getting non-canonicalized modes
Since commit fcc07e980b (is_promisor_object(): free tree buffer after
parsing, 2021-04-13), we'll always free the buffers attached to a
"struct tree" after searching them for promisor links. But there's an
important case where we don't want to do so: if somebody else is already
using the tree!
This can happen during a "rev-list --missing=allow-promisor" traversal
in a partial clone that is missing one or more trees or blobs. The
backtrace for the free looks like this:
#1 free_tree_buffer tree.c:147
#2 add_promisor_object packfile.c:2250
#3 for_each_object_in_pack packfile.c:2190
#4 for_each_packed_object packfile.c:2215
#5 is_promisor_object packfile.c:2272
#6 finish_object__ma builtin/rev-list.c:245
#7 finish_object builtin/rev-list.c:261
#8 show_object builtin/rev-list.c:274
#9 process_blob list-objects.c:63
#10 process_tree_contents list-objects.c:145
#11 process_tree list-objects.c:201
#12 traverse_trees_and_blobs list-objects.c:344
[...]
We're in the middle of walking through the entries of a tree object via
process_tree_contents(). We see a blob (or it could even be another tree
entry) that we don't have, so we call is_promisor_object() to check it.
That function loops over all of the objects in the promisor packfile,
including the tree we're currently walking. When we're done with it
there, we free the tree buffer. But as we return to the walk in
process_tree_contents(), it's still holding on to a pointer to that
buffer, via its tree_desc iterator, and it accesses the freed memory.
Even a trivial use of "--missing=allow-promisor" triggers this problem,
as the included test demonstrates (it's just a vanilla --blob:none
clone).
We can detect this case by only freeing the tree buffer if it was
allocated on our behalf. This is a little tricky since that happens
inside parse_object(), and it doesn't tell us whether the object was
already parsed, or whether it allocated the buffer itself. But by
checking for an already-parsed tree beforehand, we can distinguish the
two cases.
That feels a little hacky, and does incur an extra lookup in the
object-hash table. But that cost is fairly minimal compared to actually
loading objects (and since we're iterating the whole pack here, we're
likely to be loading most objects, rather than reusing cached results).
It may also be a good direction for this function in general, as there
are other possible optimizations that rely on doing some analysis before
parsing:
- we could detect blobs and avoid reading their contents; they can't
link to other objects, but parse_object() doesn't know that we don't
care about checking their hashes.
- we could avoid allocating object structs entirely for most objects
(since we really only need them in the oidset), which would save
some memory.
- promisor commits could use the commit-graph rather than loading the
object from disk
This commit doesn't do any of those optimizations, but I think it argues
that this direction is reasonable, rather than relying on parse_object()
and trying to teach it to give us more information about whether it
parsed.
The included test fails reliably under SANITIZE=address just when
running "rev-list --missing=allow-promisor". Checking the output isn't
strictly necessary to detect the bug, but it seems like a reasonable
addition given the general lack of coverage for "allow-promisor" in the
test suite.
Reported-by: Andrew Olsen <andrew.olsen@koordinates.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When using init_tree_desc() and tree_entry() to iterate over a tree, we
always canonicalize the modes coming out of the tree. This is a good
thing to prevent bugs or oddities in normal code paths, but it's
counter-productive for tools like fsck that want to see the exact
contents.
We can address this by adding an option to avoid the extra
canonicalization. A few notes on the implementation:
- I've attached the new option to the tree_desc struct itself. The
actual code change is in decode_tree_entry(), which is in turn
called by the public update_tree_entry(), tree_entry(), and
init_tree_desc() functions, plus their "gently" counterparts.
By letting it ride along in the struct, we can avoid changing the
signature of those functions, which are called many times. Plus it's
conceptually simpler: you really want a particular iteration of a
tree to be "raw" or not, rather than individual calls.
- We still have to set the new option somewhere. The struct is
initialized by init_tree_desc(). I added the new flags field only to
the "gently" version. That avoids disturbing the much more numerous
non-gentle callers, and it makes sense that anybody being careful
about looking at raw modes would also be careful about bogus trees
(i.e., the caller will be something like fsck in the first place).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make our mergesort implementation type-safe.
* rs/mergesort:
mergesort: remove llist_mergesort()
packfile: use DEFINE_LIST_SORT
fetch-pack: use DEFINE_LIST_SORT
commit: use DEFINE_LIST_SORT
blame: use DEFINE_LIST_SORT
test-mergesort: use DEFINE_LIST_SORT
test-mergesort: use DEFINE_LIST_SORT_DEBUG
mergesort: add macros for typed sort of linked lists
mergesort: tighten merge loop
mergesort: unify ranks loops
Build a typed sort function for packed_git lists using DEFINE_LIST_SORT
instead of calling llist_mergesort(). This gets rid of the next pointer
accessor functions and their calling overhead at the cost of slightly
increased object text size.
Before:
__TEXT __DATA __OBJC others dec hex
20218 320 0 110936 131474 20192 packfile.o
With this patch:
__TEXT __DATA __OBJC others dec hex
20430 320 0 112619 133369 208f9 packfile.o
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Collection of what is referenced by objects in promisor packs have
been optimized to inspect these objects in the in-pack order.
* jk/optim-promisor-object-enumeration:
is_promisor_object(): walk promisor packs in pack-order
When we generate the list of promisor objects, we walk every pack with a
.promisor file and examine its objects for any links to other objects.
By default, for_each_packed_object() will go in pack .idx order.
This is the worst case with respect to our delta base cache. If we have
a delta chain of A->B->C->D, then visiting A may require reconstructing
both B and C, unless we also visited B recently, in which case we may
have cached its value. Because .idx order is based on sha1, it's random
with respect to the actual object contents and deltas, and thus we're
unlikely to get many cache hits.
If we instead traverse in pack order, then we get the optimal case:
packs are written to keep delta families together, and to place bases
before their children.
Even on a modest repository like git.git, this has a noticeable speedup
on p5600.4, which runs "fsck" on a partial clone with blob:none (so lots
of trees which need to be walked, and which delta well):
Test HEAD^ HEAD
-------------------------------------------------------
5600.4: 17.87(17.83+0.04) 15.42(15.35+0.06) -13.7%
On a larger repository like linux.git, the speedup is even more
pronounced:
Test HEAD^ HEAD
-----------------------------------------------------------
5600.4: 322.47(322.01+0.42) 186.41(185.76+0.63) -42.2%
Any other operations that call is_promisor_object(), like "rev-list
--exclude-promisor-objects", would similarly benefit, but the
invocations in p5600 don't actually trigger any such cases.
Note that we may pay a small price to build a rev-index in-memory to do
the pack-order traversal. But it's still a big net win, and even that
small cost goes away if you are using pack.writeReverseIndex.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A mechanism to pack unreachable objects into a "cruft pack",
instead of ejecting them into loose form to be reclaimed later, has
been introduced.
* tb/cruft-packs:
sha1-file.c: don't freshen cruft packs
builtin/gc.c: conditionally avoid pruning objects via loose
builtin/repack.c: add cruft packs to MIDX during geometric repack
builtin/repack.c: use named flags for existing_packs
builtin/repack.c: allow configuring cruft pack generation
builtin/repack.c: support generating a cruft pack
builtin/pack-objects.c: --cruft with expiration
reachable: report precise timestamps from objects in cruft packs
reachable: add options to add_unseen_recent_objects_to_traversal
builtin/pack-objects.c: --cruft without expiration
builtin/pack-objects.c: return from create_object_entry()
t/helper: add 'pack-mtimes' test-tool
pack-mtimes: support writing pack .mtimes files
chunk-format.h: extract oid_version()
pack-write: pass 'struct packing_data' to 'stage_tmp_packfiles'
pack-mtimes: support reading .mtimes files
Documentation/technical: add cruft-packs.txt
To store the individual mtimes of objects in a cruft pack, introduce a
new `.mtimes` format that can optionally accompany a single pack in the
repository.
The format is defined in Documentation/technical/pack-format.txt, and
stores a 4-byte network order timestamp for each object in name (index)
order.
This patch prepares for cruft packs by defining the `.mtimes` format,
and introducing a basic API that callers can use to read out individual
mtimes.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
