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2025-08-12reftable: don't second-guess errors from flock interfacePatrick Steinhardt1-1/+3
The `flock` interface is implemented as part of "reftable/system.c" and thus needs to be implemented by the integrator between the reftable library and its parent code base. As such, we cannot rely on any specific implementation thereof. Regardless of that, users of the `flock` subsystem rely on `errno` being set to specific values. This is fragile and not documented anywhere and doesn't really make for a good interface. Refactor the code so that the implementations themselves are expected to return reftable-specific error codes. Our implementation of the `flock` subsystem already knows to do this for all error paths except one. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-04-29Merge branch 'ps/reftable-api-revamp'Junio C Hamano1-6/+6
Overhaul of the reftable API. * ps/reftable-api-revamp: reftable/table: move printing logic into test helper reftable/constants: make block types part of the public interface reftable/table: introduce iterator for table blocks reftable/table: add `reftable_table` to the public interface reftable/block: expose a generic iterator over reftable records reftable/block: make block iterators reseekable reftable/block: store block pointer in the block iterator reftable/block: create public interface for reading blocks git-zlib: use `struct z_stream_s` instead of typedef reftable/block: rename `block_reader` to `reftable_block` reftable/block: rename `block` to `block_data` reftable/table: move reading block into block reader reftable/block: simplify how we track restart points reftable/blocksource: consolidate code into a single file reftable/reader: rename data structure to "table" reftable: fix formatting of the license header
2025-04-07reftable: fix formatting of the license headerPatrick Steinhardt1-6/+6
The license headers used across the reftable library doesn't follow our typical coding style for multi-line comments. Fix it. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18reftable: ignore file-in-use errors when unlink(3p) fails on WindowsPatrick Steinhardt1-0/+1
Unlinking a file may fail on Windows systems when the file is still held open by another process. This is incompatible with POSIX semantics and by extension with Git's assumed semantics when unlinking files, which is that files can be unlinked regardless of whether they are still open or not. To counteract this incompatibility, we have some custom error handling in the `mingw_unlink()` wrapper that first retries the deletion with some delay, and then asks the user whether we should continue to retry. While this logic might be sensible in many callsites throughout Git, it is less when used in the reftable library. We only use unlink(3) there to delete tables which aren't referenced anymore, and the code is very aware of the limitations on Windows. As such, all calls to unlink(3p) don't perform any error checking at all and are fine with the call failing. Instead, the library provides the `reftable_stack_clean()` function, which Git knows to execute in git-pack-refs(1) after compacting a stack. The effect of this function is that all stale tables will eventually get deleted once they aren't kept open anymore. So while we're fine with unlink(3p) failing, the Windows-emulation of that function will still perform several sleeps and ultimately end up asking the user: $ git pack-refs Unlink of file 'C:/temp/jgittest/jgit/.git/reftable/0x000000000002-0x000000000004-50486d0e.ref' failed. Should I try again? (y/n) n Unlink of file 'C:/temp/jgittest/jgit/.git/reftable/0x000000000002-0x000000000004-50486d0e.ref' failed. Should I try again? (y/n) n Unlink of file 'C:/temp/jgittest/jgit/.git/reftable/0x000000000002-0x000000000004-50486d0e.ref' failed. Should I try again? (y/n) n It even asks multiple times, which is doubly annoying and puzzling to the user: 1. It asks when trying to delete the old file after having written the compacted stack. 2. It asks when reloading the stack, where it will try to unlink now-unreferenced tables. 3. It asks when calling `reftable_stack_clean()`, where it will try to unlink now-stale tables. Fix the issue by making it possible to disable this behaviour with a preprocessor define. As "git-compat-util.h" is only included from "system.h", and given that "system.h" is only ever included by headers and code that are internal to the reftable library, we can set that macro in this header without impacting anything else but the reftable library. Reported-by: Christian Reich <Zottelbart@t-online.de> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18reftable: decouple from Git codebase by pulling in "compat/posix.h"Patrick Steinhardt1-1/+1
The reftable library includes "git-compat-util.h" in order to get a POSIX-like programming environment that papers over various differences between platforms. The header also brings with it a couple of helpers specific to the Git codebase though, and over time we have started to use these helpers in the reftable library, as well. This makes it very hard to use the reftable library as a standalone library without the rest of the Git codebase, so other libraries like e.g. libgit2 cannot easily use it. But now that we have removed all calls to Git-specific functionality and have split out "compat/posix.h" as a separate header we can address this. Stop including "git-compat-util.h" and instead include "compat/posix.h" to finalize the decoupling of the reftable library from the rest of the Git codebase. The only bits which remain specific to Git are "system.h" and "system.c", which projects will have to provide. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18reftable/system: introduce `reftable_rand()`Patrick Steinhardt1-0/+6
Introduce a new system-level `reftable_rand()` function that generates a single unsigned integer for us. The implementation of this function is to be provided by the calling codebase, which allows us to more easily hook into pre-seeded random number generators. Adapt the two callsites where we generated random data. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-06Merge branch 'ps/zlib-ng'Junio C Hamano1-0/+1
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
2025-01-28git-compat-util: move include of "compat/zlib.h" into "git-zlib.h"Patrick Steinhardt1-0/+1
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>
2025-01-21reftable: address trivial -Wsign-compare warningsPatrick Steinhardt1-2/+0
Address the last couple of trivial -Wsign-compare warnings in the reftable library and remove the DISABLE_SIGN_COMPARE_WARNINGS macro that we have in "reftable/system.h". Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-23Merge branch 'ps/build-sign-compare'Junio C Hamano1-0/+2
Start working to make the codebase buildable with -Wsign-compare. * ps/build-sign-compare: t/helper: don't depend on implicit wraparound scalar: address -Wsign-compare warnings builtin/patch-id: fix type of `get_one_patchid()` builtin/blame: fix type of `length` variable when emitting object ID gpg-interface: address -Wsign-comparison warnings daemon: fix type of `max_connections` daemon: fix loops that have mismatching integer types global: trivial conversions to fix `-Wsign-compare` warnings pkt-line: fix -Wsign-compare warning on 32 bit platform csum-file: fix -Wsign-compare warning on 32-bit platform diff.h: fix index used to loop through unsigned integer config.mak.dev: drop `-Wno-sign-compare` global: mark code units that generate warnings with `-Wsign-compare` compat/win32: fix -Wsign-compare warning in "wWinMain()" compat/regex: explicitly ignore "-Wsign-compare" warnings git-compat-util: introduce macros to disable "-Wsign-compare" warnings
2024-12-06global: mark code units that generate warnings with `-Wsign-compare`Patrick Steinhardt1-0/+2
Mark code units that generate warnings with `-Wsign-compare`. This allows for a structured approach to get rid of all such warnings over time in a way that can be easily measured. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19reftable/system: provide thin wrapper for lockfile subsystemPatrick Steinhardt1-1/+44
We use the lockfile subsystem to write lockfiles for "tables.list". As with the tempfile subsystem, the lockfile subsystem also hooks into our infrastructure to prune stale locks via atexit(3p) or signal handlers. Furthermore, the lockfile subsystem also handles locking timeouts, which do add quite a bit of logic. Having to reimplement that in the context of Git wouldn't make a whole lot of sense, and it is quite likely that downstream users of the reftable library may have a better idea for how exactly to implement timeouts. So again, provide a thin wrapper for the lockfile subsystem instead such that the compatibility shim is fully self-contained. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19reftable/system: provide thin wrapper for tempfile subsystemPatrick Steinhardt1-1/+41
We use the tempfile subsystem to write temporary tables, but given that we're in the process of converting the reftable library to become standalone we cannot use this subsystem directly anymore. While we could in theory convert the code to use mkstemp(3p) instead, we'd lose access to our infrastructure that automatically prunes tempfiles via atexit(3p) or signal handlers. Provide a thin wrapper for the tempfile subsystem instead. Like this, the compatibility shim is fully self-contained in "reftable/system.c". Downstream users of the reftable library would have to implement their own tempfile shims by replacing "system.c" with a custom version. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19reftable/system: stop depending on "hash.h"Patrick Steinhardt1-3/+0
We include "hash.h" in "reftable/system.h" such that we can use hash format IDs as well as the raw size of SHA1 and SHA256. As we are in the process of converting the reftable library to become standalone we of course cannot rely on those constants anymore. Introduce a new `enum reftable_hash` to replace internal uses of the hash format IDs and new constants that replace internal uses of the hash size. Adapt the reftable backend to set up the correct hash function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-11-19reftable/system: move "dir.h" to its only userPatrick Steinhardt1-1/+0
We still include "dir.h" in "reftable/system.h" even though it is not used by anything but by a single unit test. Move it over into that unit test so that we don't accidentally use any functionality provided by it in the reftable codebase. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-10-17reftable: convert from `strbuf` to `reftable_buf`Patrick Steinhardt1-1/+0
Convert the reftable library to use the `reftable_buf` interface instead of the `strbuf` interface. This is mostly a mechanical change via sed(1) with some manual fixes where functions for `strbuf` and `reftable_buf` differ. The converted code does not yet handle allocation failures. This will be handled in subsequent commits. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Taylor Blau <me@ttaylorr.com>
2024-06-14hash-ll: merge with "hash.h"Patrick Steinhardt1-1/+1
The "hash-ll.h" header was introduced via d1cbe1e6d8 (hash-ll.h: split out of hash.h to remove dependency on repository.h, 2023-04-22) to make explicit the split between hash-related functions that rely on the global `the_repository`, and those that don't. This split is no longer necessary now that we we have removed the reliance on `the_repository`. Merge "hash-ll.h" back into "hash.h". This causes some code units to not include "repository.h" anymore, which requires us to add some forward declarations. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-03-07reftable/stack: register lockfiles during compactionPatrick Steinhardt1-0/+2
We do not register any of the locks we acquire when compacting the reftable stack via our lockfiles interfaces. These locks will thus not be released when Git gets killed. Refactor the code to register locks as lockfiles. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-24hash-ll.h: split out of hash.h to remove dependency on repository.hElijah Newren1-1/+1
hash.h depends upon and includes repository.h, due to the definition and use of the_hash_algo (defined as the_repository->hash_algo). However, most headers trying to include hash.h are only interested in the layout of the structs like object_id. Move the parts of hash.h that do not depend upon repository.h into a new file hash-ll.h (the "low level" parts of hash.h), and adjust other files to use this new header where the convenience inline functions aren't needed. This allows hash.h and object.h to be fairly small, minimal headers. It also exposes a lot of hidden dependencies on both path.h (which was brought in by repository.h) and repository.h (which was previously implicitly brought in by object.h), so also adjust other files to be more explicit about what they depend upon. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-26compat: auto-detect if zlib has uncompress2()Ævar Arnfjörð Bjarmason1-11/+0
We have a copy of uncompress2() implementation in compat/ so that we can build with an older version of zlib that lack the function, and the build procedure selects if it is used via the NO_UNCOMPRESS2 $(MAKE) variable. This is yet another "annoying" knob the porters need to tweak on platforms that are not common enough to have the default set in the config.mak.uname file. Attempt to instead ask the system header <zlib.h> to decide if we need the compatibility implementation. This is a deviation from the way we have been handling the "compatiblity" features so far, and if it can be done cleanly enough, it could work as a model for features that need compatibility definition we discover in the future. With that goal in mind, avoid expedient but ugly hacks, like shoving the code that is conditionally compiled into an unrelated .c file, which may not work in future cases---instead, take an approach that uses a file that is independently compiled and stands on its own. Compile and link compat/zlib-uncompress2.c file unconditionally, but conditionally hide the implementation behind #if/#endif when zlib version is 1.2.9 or newer, and unconditionally archive the resulting object file in the libgit.a to be picked up by the linker. There are a few things to note in the shape of the code base after this change: - We no longer use NO_UNCOMPRESS2 knob; if the system header <zlib.h> claims a version that is more cent than the library actually is, this would break, but it is easy to add it back when we find such a system. - The object file compat/zlib-uncompress2.o is always compiled and archived in libgit.a, just like a few other compat/ object files already are. - The inclusion of <zlib.h> is done in <git-compat-util.h>; we used to do so from <cache.h> which includes <git-compat-util.h> as the first thing it does, so from the *.c codes, there is no practical change. - Until objects in libgit.a that is already used gains a reference to the function, the reftable code will be the only one that wants it, so libgit.a on the linker command line needs to appear once more at the end to satisify the mutual dependency. - Beat found a trick used by OpenSSL to avoid making the conditionally-compiled object truly empty (apparently because they had to deal with compilers that do not want to see an effectively empty input file). Our compat/zlib-uncompress2.c file borrows the same trick for portabilty. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Helped-by: Beat Bolli <dev+git@drbeat.li> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-08reftable: utility functionsHan-Wen Nienhuys1-0/+32
This commit provides basic utility classes for the reftable library. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>