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2025-03-10object-file-convert: stop depending on `the_repository`Patrick Steinhardt1-13/+16
There are multiple sites in "object-file-convert.c" where we use the global `the_repository` variable, either explicitly or implicitly by using `the_hash_algo`. All of these callsites are transitively called from `convert_object_file()`, which indeed has no repo as input. Refactor the function so that it receives a repository as a parameter and pass it through to all internal functions to get rid of the dependency. Remove the `USE_THE_REPOSITORY_VARIABLE` define. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-12-06global: mark code units that generate warnings with `-Wsign-compare`Patrick Steinhardt1-0/+1
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>
2024-06-14hash-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>
2024-06-14global: introduce `USE_THE_REPOSITORY_VARIABLE` macroPatrick Steinhardt1-0/+2
Use of the `the_repository` variable is deprecated nowadays, and we slowly but steadily convert the codebase to not use it anymore. Instead, callers should be passing down the repository to work on via parameters. It is hard though to prove that a given code unit does not use this variable anymore. The most trivial case, merely demonstrating that there is no direct use of `the_repository`, is already a bit of a pain during code reviews as the reviewer needs to manually verify claims made by the patch author. The bigger problem though is that we have many interfaces that implicitly rely on `the_repository`. Introduce a new `USE_THE_REPOSITORY_VARIABLE` macro that allows code units to opt into usage of `the_repository`. The intent of this macro is to demonstrate that a certain code unit does not use this variable anymore, and to keep it from new dependencies on it in future changes, be it explicit or implicit For now, the macro only guards `the_repository` itself as well as `the_hash_algo`. There are many more known interfaces where we have an implicit dependency on `the_repository`, but those are not guarded at the current point in time. Over time though, we should start to add guards as required (or even better, just remove them). Define the macro as required in our code units. As expected, most of our code still relies on the global variable. Nearly all of our builtins rely on the variable as there is no way yet to pass `the_repository` to their entry point. For now, declare the macro in "biultin.h" to keep the required changes at least a little bit more contained. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-06-14hash: require hash algorithm in `oidread()` and `oidclr()`Patrick Steinhardt1-1/+1
Both `oidread()` and `oidclr()` use `the_repository` to derive the hash function that shall be used. Require callers to pass in the hash algorithm to get rid of this implicit dependency. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02object-file-convert: convert commits that embed signed tagsEric W. Biederman1-22/+82
As mentioned in the hash function transition plan commit mergetag lines need to be handled. The commit mergetag lines embed an entire tag object in a commit object. Keep the implementation sane if not fast by unembedding the tag object, converting the tag object, and embedding the new tag object, in the new commit object. In the long run I don't expect any other approach is maintainable, as tag objects may be extended in ways that require additional translation. To keep the implementation of convert_commit_object maintainable I have modified convert_commit_object to process the lines in any order, and to fail on unknown lines. We can't know ahead of time if a new line might embed something that needs translation or not so it is better to fail and require the code to be updated instead of silently mistranslating objects. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02object-file-convert: convert commit objects when writingbrian m. carlson1-1/+45
When writing a commit object in a repository with both SHA-1 and SHA-256, we'll need to convert our commit objects so that we can write the hash values for both into the repository. To do so, let's add a function to convert commit objects. Read the commit object and map the tree value and any of the parent values, and copy the rest of the commit through unmodified. Note that we don't need to modify the signature headers, because they are the same under both algorithms. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02object-file-convert: don't leak when converting tag objectsEric W. Biederman1-20/+25
Upon close examination I discovered that while brian's code to convert tag objects was functionally correct, it leaked memory. Rearrange the code so that all error checking happens before any memory is allocated. Add code to release the temporary strbufs the code uses. The code pretty much assumes the tag object ends with a newline, so add an explict test to verify that is the case. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02object-file-convert: convert tag objects when writingbrian m. carlson1-1/+51
When writing a tag object in a repository with both SHA-1 and SHA-256, we'll need to convert our commit objects so that we can write the hash values for both into the repository. To do so, let's add a function to convert tag objects. Note that signatures for tag objects in the current algorithm trail the message, and those for the alternate algorithm are in headers. Therefore, we parse the tag object for both a trailing signature and a header and then, when writing the other format, swap the two around. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02object-file-convert: add a function to convert trees between algorithmsbrian m. carlson1-1/+50
In the future, we're going to want to provide SHA-256 repositories that have compatibility support for SHA-1 as well. In order to do so, we'll need to be able to convert tree objects from SHA-256 to SHA-1 by writing a tree with each SHA-256 object ID mapped to a SHA-1 object ID. We implement a function, convert_tree_object, that takes an existing tree buffer and writes it to a new strbuf, converting between algorithms. Let's make this function generic, because while we only need it to convert from the main algorithm to the compatibility algorithm now, we may need to do the other way around in the future, such as for transport. We avoid reusing the code in decode_tree_entry because that code normalizes data, and we don't want that here. We want to produce a complete round trip of data, so if, for example, the old entry had a wrongly zero-padded mode, we'd want to preserve that when converting to ensure a stable hash value. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02loose: add a mapping between SHA-1 and SHA-256 for loose objectsbrian m. carlson1-1/+13
As part of the transition plan, we'd like to add a file in the .git directory that maps loose objects between SHA-1 and SHA-256. Let's implement the specification in the transition plan and store this data on a per-repository basis in struct repository. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-02object-file-convert: stubs for converting from one object format to anotherEric W. Biederman1-0/+57
Two basic functions are provided: - convert_object_file Takes an object file it's type and hash algorithm and converts it into the equivalent object file that would have been generated with hash algorithm "to". For blob objects there is no conversation to be done and it is an error to use this function on them. For commit, tree, and tag objects embedded oids are replaced by the oids of the objects they refer to with those objects and their object ids reencoded in with the hash algorithm "to". Signatures are rearranged so that they remain valid after the object has been reencoded. - repo_oid_to_algop which takes an oid that refers to an object file and returns the oid of the equivalent object file generated with the target hash algorithm. The pair of files object-file-convert.c and object-file-convert.h are introduced to hold as much of this logic as possible to keep this conversion logic cleanly separated from everything else and in the hopes that someday the code will be clean enough git can support compiling out support for sha1 and the various conversion functions. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>