741 Commits

Author SHA1 Message Date
Johannes Schindelin
ca8467d498 Introduce helper to create symlinks that knows about index_state
On Windows, symbolic links actually have a type depending on the target:
it can be a file or a directory.

In certain circumstances, this poses problems, e.g. when a symbolic link
is supposed to point into a submodule that is not checked out, so there
is no way for Git to auto-detect the type.

To help with that, we will add support over the course of the next
commits to specify that symlink type via the Git attributes. This
requires an index_state, though, something that Git for Windows'
`symlink()` replacement cannot know about because the function signature
is defined by the POSIX standard and not ours to change.

So let's introduce a helper function to create symbolic links that
*does* know about the index_state.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 01:23:48 +01:00
Ben Peart
aa87b167ee fscache: update fscache to be thread specific instead of global
The threading model for fscache has been to have a single, global cache.
This puts requirements on it to be thread safe so that callers like
preload-index can call it from multiple threads.  This was implemented
with a single mutex and completion events which introduces contention
between the calling threads.

Simplify the threading model by making fscache thread specific.  This allows
us to remove the global mutex and synchronization events entirely and instead
associate a fscache with every thread that requests one. This works well with
the current multi-threading which divides the cache entries into blocks with
a separate thread processing each block.

At the end of each worker thread, if there is a fscache on the primary
thread, merge the cached results from the worker into the primary thread
cache. This enables us to reuse the cache later especially when scanning for
untracked files.

In testing, this reduced the time spent in preload_index() by about 25% and
also reduced the CPU utilization significantly.  On a repo with ~200K files,
it reduced overall status times by ~12%.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
2026-01-16 01:23:43 +01:00
Ben Peart
965494e94c fscache: fscache takes an initial size
Update enable_fscache() to take an optional initial size parameter which is
used to initialize the hashmap so that it can avoid having to rehash as
additional entries are added.

Add a separate disable_fscache() macro to make the code clearer and easier
to read.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 01:23:43 +01:00
Takuto Ikuta
4cf77f3b44 checkout.c: enable fscache for checkout again
This is retry of #1419.

I added flush_fscache macro to flush cached stats after disk writing
with tests for regression reported in #1438 and #1442.

git checkout checks each file path in sorted order, so cache flushing does not
make performance worse unless we have large number of modified files in
a directory containing many files.

Using chromium repository, I tested `git checkout .` performance when I
delete 10 files in different directories.
With this patch:
TotalSeconds: 4.307272
TotalSeconds: 4.4863595
TotalSeconds: 4.2975562
Avg: 4.36372923333333

Without this patch:
TotalSeconds: 20.9705431
TotalSeconds: 22.4867685
TotalSeconds: 18.8968292
Avg: 20.7847136

I confirmed this patch passed all tests in t/ with core_fscache=1.

Signed-off-by: Takuto Ikuta <tikuta@chromium.org>
2026-01-16 01:23:42 +01:00
Jeff Hostetler
b36f5300a9 fscache: make fscache_enabled() public
Make fscache_enabled() function public rather than static.
Remove unneeded fscache_is_enabled() function.
Change is_fscache_enabled() macro to call fscache_enabled().

is_fscache_enabled() now takes a pathname so that the answer
is more precise and mean "is fscache enabled for this pathname",
since fscache only stores repo-relative paths and not absolute
paths, we can avoid attempting lookups for absolute paths.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
2026-01-16 01:23:42 +01:00
Jeff Hostetler
101718ffd0 dir.c: make add_excludes aware of fscache during status
Teach read_directory_recursive() and add_excludes() to
be aware of optional fscache and avoid trying to open()
and fstat() non-existant ".gitignore" files in every
directory in the worktree.

The current code in add_excludes() calls open() and then
fstat() for a ".gitignore" file in each directory present
in the worktree.  Change that when fscache is enabled to
call lstat() first and if present, call open().

This seems backwards because both lstat needs to do more
work than fstat.  But when fscache is enabled, fscache will
already know if the .gitignore file exists and can completely
avoid the IO calls.  This works because of the lstat diversion
to mingw_lstat when fscache is enabled.

This reduced status times on a 350K file enlistment of the
Windows repo on a NVMe SSD by 0.25 seconds.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
2026-01-16 01:23:42 +01:00
Karsten Blees
d5219bf2f3 mingw: add a cache below mingw's lstat and dirent implementations
Checking the work tree status is quite slow on Windows, due to slow
`lstat()` emulation (git calls `lstat()` once for each file in the
index). Windows operating system APIs seem to be much better at scanning
the status of entire directories than checking single files.

Add an `lstat()` implementation that uses a cache for lstat data. Cache
misses read the entire parent directory and add it to the cache.
Subsequent `lstat()` calls for the same directory are served directly
from the cache.

Also implement `opendir()`/`readdir()`/`closedir()` so that they create
and use directory listings in the cache.

The cache doesn't track file system changes and doesn't plug into any
modifying file APIs, so it has to be explicitly enabled for git functions
that don't modify the working copy.

Note: in an earlier version of this patch, the cache was always active and
tracked file system changes via ReadDirectoryChangesW. However, this was
much more complex and had negative impact on the performance of modifying
git commands such as 'git checkout'.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 01:23:41 +01:00
Karsten Blees
52937e3451 mingw: add infrastructure for read-only file system level caches
Add a macro to mark code sections that only read from the file system,
along with a config option and documentation.

This facilitates implementation of relatively simple file system level
caches without the need to synchronize with the file system.

Enable read-only sections for 'git status' and preload_index.

Signed-off-by: Karsten Blees <blees@dcon.de>
2026-01-16 01:23:41 +01:00
Johannes Schindelin
7d52ec07c8 Merge branch 'run-command-be-helpful-when-Git-LFS-fails-on-Windows-7'
Since Git LFS v3.5.x implicitly dropped Windows 7 support, we now want
users to be advised _what_ is going wrong on that Windows version. This
topic branch goes out of its way to provide users with such guidance.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 01:23:37 +01:00
Johannes Schindelin
4d5fb85069 Merge pull request #2504 from dscho/access-repo-via-junction
Handle `git add <file>` where <file> traverses an NTFS junction
2026-01-16 01:02:57 +01:00
Johannes Schindelin
d2ae7c4cba run-command: be helpful with Git LFS fails on Windows 7
Git LFS is now built with Go 1.21 which no longer supports Windows 7.
However, Git for Windows still wants to support Windows 7.

Ideally, Git LFS would re-introduce Windows 7 support until Git for
Windows drops support for Windows 7, but that's not going to happen:
https://github.com/git-for-windows/git/issues/4996#issuecomment-2176152565

The next best thing we can do is to let the users know what is
happening, and how to get out of their fix, at least.

This is not quite as easy as it would first seem because programs
compiled with Go 1.21 or newer will simply throw an exception and fail
with an Access Violation on Windows 7.

The only way I found to address this is to replicate the logic from Go's
very own `version` command (which can determine the Go version with
which a given executable was built) to detect the situation, and in that
case offer a helpful error message.

This addresses https://github.com/git-for-windows/git/issues/4996.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 00:42:57 +01:00
Johannes Schindelin
7240cd0a7a strbuf_realpath(): use platform-dependent API if available
Some platforms (e.g. Windows) provide API functions to resolve paths
much quicker. Let's offer a way to short-cut `strbuf_realpath()` on
those platforms.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 00:25:16 +01:00
Johannes Schindelin
29434e3161 clean: do not traverse mount points
It seems to be not exactly rare on Windows to install NTFS junction
points (the equivalent of "bind mounts" on Linux/Unix) in worktrees,
e.g. to map some development tools into a subdirectory.

In such a scenario, it is pretty horrible if `git clean -dfx` traverses
into the mapped directory and starts to "clean up".

Let's just not do that. Let's make sure before we traverse into a
directory that it is not a mount point (or junction).

This addresses https://github.com/git-for-windows/git/issues/607

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2026-01-16 00:25:13 +01:00
Junio C Hamano
c744b2c16a Merge branch 'jc/c99-fam'
Require C99 style flexible array member support from all platforms.

* jc/c99-fam:
  FLEX_ARRAY: require platforms to support the C99 syntax
2025-12-28 17:36:16 +09:00
Junio C Hamano
4d75f2aea7 FLEX_ARRAY: require platforms to support the C99 syntax
Before C99 syntax to express that the final member in a struct is an
array of unknown number of elements, i.e.,

	struct {
		...
		T flexible_array[];
	};

came along, GNU introduced their own extension to declare such a
member with 0 size, i.e.,

		T flexible_array[0];

and the compilers that did not understand even that were given a way
to emulate it by wasting one element, i.e.,

		T flexible_array[1];

As we are using more and more C99 language features, let's see if
the platforms that still need to resort to the historical forms of
flexible array member support are still there, by forcing all the
flex array definitions to use the C99 syntax and see if anybody
screams (in which case reverting the changes is rather easy).

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-12-12 22:05:19 +09:00
Toon Claes
a67b902c94 git-compat-util: introduce MEMZERO_ARRAY() macro
Introduce a new macro MEMZERO_ARRAY() that zeroes the memory allocated
by ALLOC_ARRAY() and friends. And add coccinelle rule to enforce the use
of this macro.

Signed-off-by: Toon Claes <toon@iotcl.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-12-11 14:44:43 +09:00
Kristoffer Haugsbakk
5a31252702 whatchanged: hint about git-log(1) and aliasing
There have been quite a few `--i-still-use-this` user reports since Git
2.51.0 was released.[1][2]  And it doesn’t seem like they are reading
the man page about the git-log(1) equivalent.

Tell them what options to plug into git-log(1), either as a replacement
command or as an alias.[3]  That template produces almost the same
output[4] and is arguably a plug-in replacement.  Concretely, add
an optional `hint` argument so that we can use it right after the
initial error line.

Also mention the same concrete options in the documentation while we’re
at it.

[1]: E.g.,
    • https://lore.kernel.org/git/e1a69dea-bcb6-45fc-83d3-9e50d32c410b@5y5.one/https://lore.kernel.org/git/1011073f-9930-4360-a42f-71eb7421fe3f@chrispalmer.uk/#thttps://lore.kernel.org/git/9fcbfcc4-79f9-421f-b9a4-dc455f7db485@acm.org/#thttps://lore.kernel.org/git/83241BDE-1E0D-489A-9181-C608E9FCC17B@gmail.com/
[2]: The error message on 2.51.0 does tell them to report it, unconditionally
[3]: We allow aliasing deprecated builtins now for people who are very
    used to the command name or just like it a lot
[4]: You only get different outputs if you happen to have empty
     commits (no changes)[4]
[5]: https://lore.kernel.org/git/20250825085428.GA367101@coredump.intra.peff.net/

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-09-17 13:47:24 -07:00
Junio C Hamano
5ce97021dd Merge branch 'pw/adopt-c99-bool-officially'
Declare weather-balloon we raised for "bool" type 18 months ago a
success and officially allow using the type in our codebase.

* pw/adopt-c99-bool-officially:
  strbuf: convert predicates to return bool
  git-compat-util: convert string predicates to return bool
  CodingGuidelines: allow the use of bool
2025-07-24 16:03:55 -07:00
Phillip Wood
f3ba426e35 git-compat-util: convert string predicates to return bool
Since 8277dbe987 (git-compat-util: convert skip_{prefix,suffix}{,_mem}
to bool, 2023-12-16) a number of our string predicates have been
returning bool instead of int. Now that we've declared that experiment
a success, let's convert the return type of the case-independent
skip_iprefix() and skip_iprefix_mem() functions to match the return
type of their case-dependent equivalents. Returning bool instead of
int makes it clear that these functions are predicates.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-07-16 08:18:06 -07:00
Junio C Hamano
a5cc6a2bc5 Merge branch 'jc/you-still-use-whatchanged'
"git whatchanged" that is longer to type than "git log --raw"
which is its modern rough equivalent has outlived its usefulness
more than 10 years ago.  Plan to deprecate and remove it.

* jc/you-still-use-whatchanged:
  whatschanged: list it in BreakingChanges document
  whatchanged: remove when built with WITH_BREAKING_CHANGES
  whatchanged: require --i-still-use-this
  tests: prepare for a world without whatchanged
  doc: prepare for a world without whatchanged
  you-still-use-that??: help deprecating commands for removal
2025-06-25 14:07:35 -07:00
Phillip Wood
b103881d4f midx repack: avoid integer overflow on 32 bit systems
On a 32 bit system "git multi-pack-index --repack --batch-size=120M"
failed with

    fatal: size_t overflow: 6038786 * 1289

The calculation to estimated size of the objects in the pack referenced
by the multi-pack-index uses st_mult() to multiply the pack size by the
number of referenced objects before dividing by the total number of
objects in the pack. As size_t is 32 bits on 32 bit systems this
calculation easily overflows. Fix this by using 64bit arithmetic instead.

Also fix a potential overflow when caluculating the total size of the
objects referenced by the multipack index with a batch size larger
than SIZE_MAX / 2. In that case

    total_size += estimated_size

can overflow as both total_size and estimated_size can be greater that
SIZE_MAX / 2. This is addressed by using saturating arithmetic for the
addition. Although estimated_size is of type uint64_t by the time we
reach this sum it is bounded by the batch size which is of type size_t
and so casting estimated_size to size_t does not truncate the value.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-05-22 14:48:36 -07:00
Junio C Hamano
4511d56e1a you-still-use-that??: help deprecating commands for removal
Commands slated for removal like "git pack-redundant" now require
an explicit "--i-still-use-this" option to run.  This is to
discourage casual use and surface their pending deprecation to
users.

The warning message is long, so factor it into a helper function
you_still_use_that() to simplify reuse by other commands.

Also add a missing test to ensure this enforcement works for
"pack-redundant".

Helped-by: Elijah Newren <newren@gmail.com>
[en: log message]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-05-12 13:11:43 -07:00
Junio C Hamano
2bc5414c41 Merge branch 'ps/parse-options-integers'
Update parse-options API to catch mistakes to pass address of an
integral variable of a wrong type/size.

* ps/parse-options-integers:
  parse-options: detect mismatches in integer signedness
  parse-options: introduce precision handling for `OPTION_UNSIGNED`
  parse-options: introduce precision handling for `OPTION_INTEGER`
  parse-options: rename `OPT_MAGNITUDE()` to `OPT_UNSIGNED()`
  parse-options: support unit factors in `OPT_INTEGER()`
  global: use designated initializers for options
  parse: fix off-by-one for minimum signed values
2025-04-24 17:25:34 -07:00
Junio C Hamano
36d8035d27 Merge branch 'ps/object-file-cleanup'
Code clean-up.

* ps/object-file-cleanup:
  object-store: merge "object-store-ll.h" and "object-store.h"
  object-store: remove global array of cached objects
  object: split out functions relating to object store subsystem
  object-file: drop `index_blob_stream()`
  object-file: split up concerns of `HASH_*` flags
  object-file: split out functions relating to object store subsystem
  object-file: move `xmmap()` into "wrapper.c"
  object-file: move `git_open_cloexec()` to "compat/open.c"
  object-file: move `safe_create_leading_directories()` into "path.c"
  object-file: move `mkdir_in_gitdir()` into "path.c"
2025-04-24 17:25:33 -07:00
Patrick Steinhardt
791aeddfa2 parse-options: detect mismatches in integer signedness
It was reported that "t5620-backfill.sh" fails on s390x and sparc64 in a
test that exercises the "--min-batch-size" command line option. The
symptom was that the option didn't seem to have an effect: we didn't
fetch objects with a batch size of 20, but instead fetched all objects
at once.

As it turns out, the root cause is that `--min-batch-size` uses
`OPT_INTEGER()` to parse the command line option. While this macro
expects the caller to pass a pointer to an integer, we instead pass a
pointer to a `size_t`. This coincidentally works on most platforms, but
it breaks apart on the mentioned platforms because they are big endian.

This issue isn't specific to git-backfill(1): there are a couple of
other places where we have the same type confusion going on. This
indicates that the issue really is the interface that the parse-options
subsystem provides -- it is simply too easy to get this wrong as there
isn't any kind of compiler warning, and things just work on the most
common systems.

Address the systemic issue by introducing two new build asserts
`BARF_UNLESS_SIGNED()` and `BARF_UNLESS_UNSIGNED()`. As the names
already hint at, those macros will cause a compiler error when passed a
value that is not signed or unsigned, respectively.

Adapt `OPT_INTEGER()`, `OPT_UNSIGNED()` as well as `OPT_MAGNITUDE()` to
use those asserts. This uncovers a small set of sites where we indeed
have the same bug as in git-backfill(1). Adapt all of them to use the
correct option.

Reported-by: Todd Zullinger <tmz@pobox.com>
Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Helped-by: SZEDER Gábor <szeder.dev@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-17 08:15:16 -07:00
Patrick Steinhardt
97dc141fd6 object-file: move git_open_cloexec() to "compat/open.c"
The `git_open_cloexec()` wrapper function provides the ability to open a
file with `O_CLOEXEC` in a platform-agnostic way. This function is
provided by "object-file.c" even though it is not specific to the object
subsystem at all.

Move the file into "compat/open.c". This file already exists before this
commit, but has only been compiled conditionally depending on whether or
not open(3p) may return EINTR. With this change we now unconditionally
compile the object, but wrap `git_open_with_retry()` in an ifdef.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-15 08:24:35 -07:00
Junio C Hamano
6e2a3b8ae0 Merge branch 'ps/reftable-sans-compat-util'
Make the code in reftable library less reliant on the service
routines it used to borrow from Git proper, to make it easier to
use by external users of the library.

* ps/reftable-sans-compat-util:
  Makefile: skip reftable library for Coccinelle
  reftable: decouple from Git codebase by pulling in "compat/posix.h"
  git-compat-util.h: split out POSIX-emulating bits
  compat/mingw: split out POSIX-related bits
  reftable/basics: introduce `REFTABLE_UNUSED` annotation
  reftable/basics: stop using `SWAP()` macro
  reftable/stack: stop using `sleep_millisec()`
  reftable/system: introduce `reftable_rand()`
  reftable/reader: stop using `ARRAY_SIZE()` macro
  reftable/basics: provide wrappers for big endian conversion
  reftable/basics: stop using `st_mult()` in array allocators
  reftable: stop using `BUG()` in trivial cases
  reftable/record: don't `BUG()` in `reftable_record_cmp()`
  reftable/record: stop using `BUG()` in `reftable_record_init()`
  reftable/record: stop using `COPY_ARRAY()`
  reftable/blocksource: stop using `xmmap()`
  reftable/stack: stop using `write_in_full()`
  reftable/stack: stop using `read_in_full()`
2025-04-08 11:43:14 -07:00
Junio C Hamano
b97b360c51 Merge branch 'en/assert-wo-side-effects'
Ensure what we write in assert() does not have side effects,
and introduce ASSERT() macro to mark those that cannot be
mechanically checked for lack of side effects.

* en/assert-wo-side-effects:
  treewide: replace assert() with ASSERT() in special cases
  ci: add build checking for side-effects in assert() calls
  git-compat-util: introduce ASSERT() macro
2025-04-08 11:43:12 -07:00
Junio C Hamano
f76fe4ab06 Merge branch 'jk/use-wunreachable-code-for-devs'
Enable -Wunreachable-code for developer builds.

* jk/use-wunreachable-code-for-devs:
  config.mak.dev: enable -Wunreachable-code
  git-compat-util: add NOT_CONSTANT macro and use it in atfork_prepare()
  run-command: use errno to check for sigfillset() error
2025-03-29 16:39:10 +09:00
Elijah Newren
85e4f762c2 ci: add build checking for side-effects in assert() calls
It is a big no-no to have side-effects in an assertion, because if the
assert() is compiled out, you don't get that side-effect, leading to the
code behaving differently.  That can be a large headache to debug.

We have roughly 566 assert() calls in our codebase (my grep might have
picked up things that aren't actually assert() calls, but most appeared
to be).  All but 9 of them can be determined by gcc to be free of side
effects with a clever redefine of assert() provided by Bruno De Fraine
(from
https://stackoverflow.com/questions/10593492/catching-assert-with-side-effects),
who upon request has graciously placed his two-liner into the public
domain without warranty of any kind.  The current 9 assert() calls
flagged by this clever redefinition of assert() appear to me to be free
of side effects as well, but are too complicated for a compiler/linker
to figure that since each assertion involves some kind of function call.
Add a CI job which will find and report these possibly problematic
assertions, and have the job suggest to the user that they replace these
with ASSERT() calls.

Example output from running:

```
ERROR: The compiler could not verify the following assert()
       calls are free of side-effects.  Please replace with
       ASSERT() calls.
/home/newren/floss/git/diffcore-rename.c:1409
	assert(!dir_rename_count || strmap_empty(dir_rename_count));
/home/newren/floss/git/merge-ort.c:1645
			assert(renames->deferred[side].trivial_merges_okay &&
			       !strset_contains(&renames->deferred[side].target_dirs,
						path));
/home/newren/floss/git/merge-ort.c:794
	assert(omittable_hint ==
	       (!starts_with(type_short_descriptions[type], "CONFLICT") &&
		!starts_with(type_short_descriptions[type], "ERROR")) ||
	       type == CONFLICT_DIR_RENAME_SUGGESTED);
/home/newren/floss/git/merge-recursive.c:1200
	assert(!merge_remote_util(commit));
/home/newren/floss/git/object-file.c:2709
	assert(would_convert_to_git_filter_fd(istate, path));
/home/newren/floss/git/parallel-checkout.c:280
	assert(is_eligible_for_parallel_checkout(pc_item->ce, &pc_item->ca));
/home/newren/floss/git/scalar.c:244
	assert(have_fsmonitor_support());
/home/newren/floss/git/scalar.c:254
	assert(have_fsmonitor_support());
/home/newren/floss/git/sequencer.c:4968
		assert(!(opts->signoff || opts->no_commit ||
			 opts->record_origin || should_edit(opts) ||
			 opts->committer_date_is_author_date ||
			 opts->ignore_date));
```

Note that if there are possibly problematic assertions, not necessarily
all of them will be shown in a single run, because the compiler errors
may include something like "ld: ... more undefined references to
`not_supposed_to_survive' follow" instead of listing each individually.
But in such cases, once you clean up a few that are shown in your first
run, subsequent runs will show (some of) the ones that remain, allowing
you to iteratively remove them all.

Helped-by: Bruno De Fraine <defraine@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-03-21 03:32:04 -07:00
Elijah Newren
07fbc15c20 git-compat-util: introduce ASSERT() macro
Create a ASSERT() macro which is similar to assert(), but will not be
compiled out when NDEBUG is defined, and is thus safe to use even if its
argument has side-effects.

We will use this new macro in a subsequent commit to convert a few
existing assert() invocations to ASSERT().  In particular, we'll
convert the handful of invocations which cannot be proven to be free of
side effects with a simple compiler/linker hack.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-03-21 03:31:47 -07:00
Junio C Hamano
82e79c6364 git-compat-util: add NOT_CONSTANT macro and use it in atfork_prepare()
Our hope is that the number of code paths that falsely trigger
warnings with the -Wunreachable-code compilation option are small,
and they can be worked around case-by-case basis, like we just did
in the previous commit.  If we need such a workaround a bit more
often, however, we may benefit from a more generic and descriptive
facility that helps document the cases we need such workarounds.

    Side note: if we need the workaround all over the place, it
    simply means -Wunreachable-code is not a good tool for us to
    save engineering effort to catch mistakes.  We are still
    exploring if it helps us, so let's assume that it is not the
    case.

Introduce NOT_CONSTANT() macro, with which, the developer can tell
the compiler:

    Do not optimize this expression out, because, despite whatever
    you are told by the system headers, this expression should *not*
    be treated as a constant.

and use it as a replacement for the workaround we used that was
somewhat specific to the sigfillset case.  If the compiler already
knows that the call to sigfillset() cannot fail on a particular
platform it is compiling for and declares that the if() condition
would not hold, it is plausible that the next version of the
compiler may learn that sigfillset() that never fails would not
touch errno and decide that in this sequence:

	errno = 0;
	sigfillset(&all)
	if (errno)
		die_errno("sigfillset");

the if() statement will never trigger.  Marking that the value
returned by sigfillset() cannot be a constant would document our
intention better and would not break with such a new version of
compiler that is even more "clever".  With the marco, the above
sequence can be rewritten:

	if (NOT_CONSTANT(sigfillset(&all)))
		die_errno("sigfillset");

which looks almost like other innocuous annotations we have,
e.g. UNUSED.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-03-17 17:30:49 -07:00
Patrick Steinhardt
75a044f748 git-compat-util.h: split out POSIX-emulating bits
The "git-compat-util.h" header is a treasure trove of various bits and
pieces used throughout the project. It basically mixes two different
things into one:

  - Providing a POSIX-like interface even on platforms that aren't
    POSIX-compliant.

  - Providing low-level functionality that is specific to Git.

This intermixing is a bit of a problem for the reftable library as we
don't want to recreate the POSIX-like interface there. But neither do we
want to pull in the Git-specific functionality, as it is otherwise quite
easy to start depending on the Git codebase again.

Split out a new header "compat/posix.h" that only contains the bits and
pieces relevant for the emulation of POSIX, which we will start using in
the next commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18 10:55:40 -08:00
Junio C Hamano
9d0e81e2ae Merge branch 'ps/zlib-ng'
The code paths to interact with zlib has been cleaned up in
preparation for building with zlib-ng.

* ps/zlib-ng:
  ci: make "linux-musl" job use zlib-ng
  ci: switch linux-musl to use Meson
  compat/zlib: allow use of zlib-ng as backend
  git-zlib: cast away potential constness of `next_in` pointer
  compat/zlib: provide stubs for `deflateSetHeader()`
  compat/zlib: provide `deflateBound()` shim centrally
  git-compat-util: move include of "compat/zlib.h" into "git-zlib.h"
  compat: introduce new "zlib.h" header
  git-compat-util: drop `z_const` define
  compat: drop `uncompress2()` compatibility shim
2025-02-06 14:56:45 -08:00
Patrick Steinhardt
41f1a8435a git-compat-util: move include of "compat/zlib.h" into "git-zlib.h"
We include "compat/zlib.h" in "git-compat-util.h", which is
unnecessarily broad given that we only have a small handful of files
that use the zlib library. Move the header into "git-zlib.h" instead and
adapt users of zlib to include that header.

One exception is the reftable library, as we don't want to use the
Git-specific wrapper of zlib there, so we include "compat/zlib.h"
instead. Furthermore, we move the include into "reftable/system.h" so
that users of the library other than Git can wire up zlib themselves.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-28 13:03:22 -08:00
Patrick Steinhardt
629188ede7 compat: introduce new "zlib.h" header
Introduce a new "compat/zlib-compat.h" header that we include instead of
including <zlib.h> directly. This will allow us to wire up zlib-ng as an
alternative backend for zlib compression in a subsequent commit.

Note that we cannot just call the file "compat/zlib.h", as that may
otherwise cause us to include that file instead of <zlib.h>.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-28 13:03:22 -08:00
Patrick Steinhardt
27e8960037 git-compat-util: drop z_const define
Before including <zlib.h> we explicitly define `z_const` to an empty
value. This has the effect that the `z_const` macro in "zconf.h" itself
will remain empty instead of being defined as `const`, which effectively
adapts a couple of APIs so that their parameters are not marked as being
constants.

It is dubious though whether this is something we actually want: not
marking a parameter as a constant doesn't make it any less constant than
it was. The define was added via 07564773c2 (compat: auto-detect if zlib
has uncompress2(), 2022-01-24), where it was seemingly carried over from
our internal compatibility shim for `uncompress2()` that was removed in
the preceding commit. The commit message doesn't mention why we carry
over the define and make it public, either, and I cannot think of any
reason for why we would want to have it.

Drop the define.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-28 13:03:22 -08:00
Patrick Steinhardt
3656d57bbf compat: drop uncompress2() compatibility shim
Our compat library has an implementation of zlib's `uncompress2()`
function that gets used when linking against an old version of zlib
that doesn't yet have it. The last user of `uncompress2()` got removed
in 15a60b747e (reftable/block: open-code call to `uncompress2()`,
2024-04-08), so the compatibility code is not required anymore. Drop it.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-28 13:03:22 -08:00
Junio C Hamano
0148fd836a usage: add show_usage_if_asked()
Some commands call usage() when they are asked to give the help
message with "git cmd -h", but this has the same problem as we
fixed with callers of usage_with_options() for the same purpose.

Introduce a helper function that captures the common pattern

	if (argc == 2 && !strcmp(argv[1], "-h"))
		usage(usage);

and replaces it with

	show_usage_if_asked(argc, argv, usage);

to help correct these code paths.

Note that this helper function still exits with status 129, and
t0012 insists on it.  After converting all the mistaken callers of
usage_with_options() to call this new helper, we may want to address
it---the end user is asking us to give the help text, and we are
doing exactly as asked, so there is no reason to exit with non-zero
status.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-01-17 13:30:02 -08:00
Patrick Steinhardt
2121a76d71 git-compat-util: introduce macros to disable "-Wsign-compare" warnings
When compiling with DEVELOPER=YesPlease, we explicitly disable the
"-Wsign-compare" warning. This is mostly because our code base is full
of cases where we don't bother at all whether something should be signed
or unsigned, and enabling the warning would thus cause tons of warnings
to pop up.

Unfortunately, disabling this warning also masks real issues. There have
been multiple CVEs in the Git project that would have been flagged by
this warning (e.g. CVE-2022-39260, CVE-2022-41903 and several fixes in
the vicinity of these CVEs). Furthermore, the final audit report by
X41 D-Sec, who are the ones who have discovered some of the CVEs, hinted
that it might be a good idea to become more strict in this context.

Now simply enabling the warning globally does not fly due to the stated
reason above that we simply have too many sites where we use the wrong
integer types. Instead, introduce a new set of macros that allow us to
mark a file as being free of warnings with "-Wsign-compare". The
mechanism is similar to what we do with `USE_THE_REPOSITORY_VARIABLE`:
every file that is not marked with `DISABLE_SIGN_COMPARE_WARNINGS` will
be compiled with those warnings enabled.

These new markings will be wired up in the subsequent commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-06 20:20:01 +09:00
Patrick Steinhardt
52c7dbd036 git-compat-util: drop now-unused UNLEAK() macro
The `UNLEAK()` macro has been introduced with 0e5bba53af (add UNLEAK
annotation for reducing leak false positives, 2017-09-08) to help us
reduce the amount of reported memory leaks in cases we don't care about,
e.g. when exiting immediately afterwards. We have since removed all of
its users in favor of freeing the memory and thus don't need the macro
anymore.

Remove it.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-21 08:23:46 +09:00
Junio C Hamano
a051ca5e65 CodingGuidelines: also mention MAYBE_UNUSED
A function that uses a parameter in one build may lose all uses of
the parameter in another build, depending on the configuration.  A
workaround for such a case, MAYBE_UNUSED, should also be mentioned
when we recommend the use of UNUSED to our developers.

Keep the addition to the guideline short and document the criteria
to choose between UNUSED and MAYBE_UNUSED near their definition.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-29 11:28:07 -07:00
Johannes Schindelin
193eda7507 win32: override fspathcmp() with a directory separator-aware version
On Windows, the backslash is the directory separator, even if the
forward slash can be used, too, at least since Windows NT.

This means that the paths `a/b` and `a\b` are equivalent, and
`fspathcmp()` needs to be made aware of that fact.

Note that we have to override both `fspathcmp()` and `fspathncmp()`, and
the former cannot be a mere pre-processor constant that transforms calls
to `fspathcmp(a, b)` into `fspathncmp(a, b, (size_t)-1)` because the
function `report_collided_checkout()` in `unpack-trees.c` wants to
assign `list.cmp = fspathcmp`.

Also note that `fspatheq()` does _not_ need to be overridden because it
calls `fspathcmp()` internally.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-07-13 16:23:36 -07:00
Junio C Hamano
ec465fcb75 Merge branch 'rs/no-openssl-compilation-fix-on-macos'
Build fix.

* rs/no-openssl-compilation-fix-on-macos:
  git-compat-util: fix NO_OPENSSL on current macOS
2024-04-23 11:52:38 -07:00
René Scharfe
44bdba2fa6 git-compat-util: fix NO_OPENSSL on current macOS
b195aa00c1 (git-compat-util: suppress unavoidable Apple-specific
deprecation warnings, 2014-12-16) started to define
__AVAILABILITY_MACROS_USES_AVAILABILITY in git-compat-util.h.  On
current versions it is already defined (e.g. on macOS 14.4.1).  Undefine
it before redefining it to avoid a compilation error.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-04-15 11:01:31 -07:00
Matthias Aßhauer
2406bf5fc5 Win32: detect unix socket support at runtime
Windows 10 build 17063 introduced support for unix sockets to Windows.
bb390b1 (git-compat-util: include declaration for unix sockets in
windows, 2021-09-14) introduced a way to build git with unix socket
support on Windows, but you still had to decide at build time which
Windows version the compiled executable was supposed to run on.

We can detect at runtime wether the operating system supports unix
sockets and act accordingly for all supported Windows versions.

This fixes https://github.com/git-for-windows/git/issues/3892

Signed-off-by: Matthias Aßhauer <mha1993@live.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-04-03 14:54:28 -07:00
Junio C Hamano
0fea6b73f1 Merge branch 'tb/multi-pack-verbatim-reuse'
Streaming spans of packfile data used to be done only from a
single, primary, pack in a repository with multiple packfiles.  It
has been extended to allow reuse from other packfiles, too.

* tb/multi-pack-verbatim-reuse: (26 commits)
  t/perf: add performance tests for multi-pack reuse
  pack-bitmap: enable reuse from all bitmapped packs
  pack-objects: allow setting `pack.allowPackReuse` to "single"
  t/test-lib-functions.sh: implement `test_trace2_data` helper
  pack-objects: add tracing for various packfile metrics
  pack-bitmap: prepare to mark objects from multiple packs for reuse
  pack-revindex: implement `midx_pair_to_pack_pos()`
  pack-revindex: factor out `midx_key_to_pack_pos()` helper
  midx: implement `midx_preferred_pack()`
  git-compat-util.h: implement checked size_t to uint32_t conversion
  pack-objects: include number of packs reused in output
  pack-objects: prepare `write_reused_pack_verbatim()` for multi-pack reuse
  pack-objects: prepare `write_reused_pack()` for multi-pack reuse
  pack-objects: pass `bitmapped_pack`'s to pack-reuse functions
  pack-objects: keep track of `pack_start` for each reuse pack
  pack-objects: parameterize pack-reuse routines over a single pack
  pack-bitmap: return multiple packs via `reuse_partial_packfile_from_bitmap()`
  pack-bitmap: simplify `reuse_partial_packfile_from_bitmap()` signature
  ewah: implement `bitmap_is_empty()`
  pack-bitmap: pass `bitmapped_pack` struct to pack-reuse functions
  ...
2024-01-12 16:09:56 -08:00
René Scharfe
8277dbe987 git-compat-util: convert skip_{prefix,suffix}{,_mem} to bool
Use the data type bool and its values true and false to document the
binary return value of skip_prefix() and friends more explicitly.

This first use of stdbool.h, introduced with C99, is meant to check
whether there are platforms that claim support for C99, as tested by
7bc341e21b (git-compat-util: add a test balloon for C99 support,
2021-12-01), but still lack that header for some reason.

A fallback based on a wider type, e.g. int, would have to deal with
comparisons somehow to emulate that any non-zero value is true:

   bool b1 = 1;
   bool b2 = 2;
   if (b1 == b2) puts("This is true.");

   int i1 = 1;
   int i2 = 2;
   if (i1 == i2) puts("Not printed.");
   #define BOOLEQ(a, b) (!(a) == !(b))
   if (BOOLEQ(i1, i2)) puts("This is true.");

So we'd be better off using bool everywhere without a fallback, if
possible.  That's why this patch doesn't include any.

Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-12-18 09:08:24 -08:00
Taylor Blau
ed9f41480a git-compat-util.h: implement checked size_t to uint32_t conversion
In a similar fashion as other checked cast functions in this header
(such as `cast_size_t_to_ulong()` and `cast_size_t_to_int()`), implement
a checked cast function for going from a size_t to a uint32_t value.

This function will be utilized in a future commit which needs to make
such a conversion.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-12-14 14:38:08 -08:00
Junio C Hamano
aaf0a421e2 Merge branch 'mp/rebase-label-length-limit'
Overly long label names used in the sequencer machinery are now
chopped to fit under filesystem limitation.

* mp/rebase-label-length-limit:
  rebase: allow overriding the maximal length of the generated labels
  sequencer: truncate labels to accommodate loose refs
2023-08-24 09:32:33 -07:00