git: Add strict checks for supported extensions by pjbgf · Pull Request #1850

git: Add strict checks for supported extensions by pjbgf · Pull Request #1850 · go-git/go-git

AI review requested due to automatic review settings

February 16, 2026 16:56

Git extensions may be Storer-specific, like reftables or objectformat. By implementing
this interface, the Storers will be able to tell the core go-git precisely what extensions
they support.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Feb 16, 2026

The SHA256 implementation introduced a temporary ObjectFormatGetter interface
that had two key goals:
- Provide a way to access the ObjectFormat from a storer.Storer, without
  changing the existing API.
- Be able to distinguish between storer.Storer implementations that support
  the objectformat extension.

The PR go-git#1850 ensures that the storer.Storer being used supports the required
objectformat. With that, this interface can be replaced by config.ConfigStorer,
making the config the single source of truth for the objectformat.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf mentioned this pull request

Feb 16, 2026

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Feb 16, 2026

The SHA256 implementation introduced a temporary ObjectFormatGetter interface
that had two key goals:
- Provide a way to access the ObjectFormat from a storer.Storer, without
  changing the existing API.
- Be able to distinguish between storer.Storer implementations that support
  the objectformat extension.

The PR go-git#1850 ensures that the storer.Storer being used supports the required
objectformat. With that, this interface can be replaced by config.ConfigStorer,
making the config the single source of truth for the objectformat.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

The upstream Git enforces fail-safe heuristics to ensure that older git versions
will avoid handling repositories using extensions they are unaware of.

The logic is largely based on the value of core.repositoryformatversion. As per
official Git docs:
> This version specifies the rules for operating on the on-disk repository data.
> An implementation of git which does not understand a particular version
> advertised by an on-disk repository MUST NOT operate on that repository;
> doing so risks not only producing wrong results, but actually losing data.

Now go-git will ensure that:
- The git.Open logic will verify and enforces the extension support rules.
- go-git will keep track of built-in extensions that it supports.
- Any extension that is Storer-specific (e.g. objectformat, reftables),
  will be confirmed by the specific Storer via new x/storage.ExtensionChecker
  interface. Failing to do so, it will be assumed that the extension is
  unsupported and the Open operation will return an error.

This is a breaking change and it will force go-git to not be able to open
repositories that it in fact doesn't really support. Conversaly, the error
messages will be more useful (e.g. unknown extension vs object not found).

Upstream refs:
- https://git-scm.com/docs/git-config#Documentation/git-config.txt-extensions
- https://git-scm.com/docs/gitrepository-layout#_git_repository_format_versions

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf mentioned this pull request

Feb 23, 2026

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Feb 26, 2026

The SHA256 implementation introduced a temporary ObjectFormatGetter interface
that had two key goals:
- Provide a way to access the ObjectFormat from a storer.Storer, without
  changing the existing API.
- Be able to distinguish between storer.Storer implementations that support
  the objectformat extension.

The PR go-git#1850 ensures that the storer.Storer being used supports the required
objectformat. With that, this interface can be replaced by config.ConfigStorer,
making the config the single source of truth for the objectformat.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Feb 26, 2026

The SHA256 implementation introduced a temporary ObjectFormatGetter interface
that had two key goals:
- Provide a way to access the ObjectFormat from a storer.Storer, without
  changing the existing API.
- Be able to distinguish between storer.Storer implementations that support
  the objectformat extension.

The PR go-git#1850 ensures that the storer.Storer being used supports the required
objectformat. With that, this interface can be replaced by config.ConfigStorer,
making the config the single source of truth for the objectformat.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Mar 2, 2026

Previous to go-git#1850, go-git was oblivious to Git extensions, which
meant that at times it would try to handle repositories where the
underlying feature was not fully supported.

An example of that being worktreeConfig, meaning that any worktree
specific config were being ignored.

This commit adds that support to storage/filesystem, resulting into
worktree configs being overlayed the local config, providing upstream
parity with upstream Git.

References:
- https://git-scm.com/docs/git-worktree#_configuration_file

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Mar 2, 2026

Previous to go-git#1850, go-git was oblivious to Git extensions, which
meant that at times it would try to handle repositories where the
underlying feature was not fully supported.

An example of that being worktreeConfig, meaning that any worktree
specific config were being ignored.

This commit adds that support to storage/filesystem, resulting into
worktree configs being overlayed the local config, providing upstream
parity with upstream Git.

References:
- https://git-scm.com/docs/git-worktree#_configuration_file

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Mar 2, 2026

Previous to go-git#1850, go-git was oblivious to Git extensions, which
meant that at times it would try to handle repositories where the
underlying feature was not fully supported.

An example of that being worktreeConfig, meaning that any worktree
specific config were being ignored.

This commit adds that support to storage/filesystem, resulting into
worktree configs being overlayed the local config, providing upstream
parity with upstream Git.

References:
- https://git-scm.com/docs/git-worktree#_configuration_file

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Mar 2, 2026

Previous to go-git#1850, go-git was oblivious to Git extensions, which
meant that at times it would try to handle repositories where the
underlying feature was not fully supported.

An example of that being worktreeConfig, meaning that any worktree
specific config were being ignored.

This commit adds that support to storage/filesystem, resulting into
worktree configs being overlayed the local config, providing upstream
parity with upstream Git.

References:
- https://git-scm.com/docs/git-worktree#_configuration_file

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf mentioned this pull request

Mar 2, 2026

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Mar 3, 2026

Previous to go-git#1850, go-git was oblivious to Git extensions, which
meant that at times it would try to handle repositories where the
underlying feature was not fully supported.

An example of that being worktreeConfig, meaning that any worktree
specific config were being ignored.

This commit adds that support to storage/filesystem, resulting into
worktree configs being overlayed the local config, providing upstream
parity with upstream Git.

References:
- https://git-scm.com/docs/git-worktree#_configuration_file

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

pjbgf added a commit to pjbgf/go-git that referenced this pull request

Mar 3, 2026

Previous to go-git#1850, go-git was oblivious to Git extensions, which
meant that at times it would try to handle repositories where the
underlying feature was not fully supported.

An example of that being worktreeConfig, meaning that any worktree
specific config were being ignored.

This commit adds that support to storage/filesystem, resulting into
worktree configs being overlayed the local config, providing upstream
parity with upstream Git.

References:
- https://git-scm.com/docs/git-worktree#_configuration_file

Signed-off-by: Paulo Gomes <pjbgf@linux.com>