git/setup.c, branch v2.30.2

Merge branch 'bc/sha-256-part-3'

2020-08-12T01:04:11Z

The final leg of SHA-256 transition. * bc/sha-256-part-3: (39 commits) t: remove test_oid_init in tests docs: add documentation for extensions.objectFormat ci: run tests with SHA-256 t: make SHA1 prerequisite depend on default hash t: allow testing different hash algorithms via environment t: add test_oid option to select hash algorithm repository: enable SHA-256 support by default setup: add support for reading extensions.objectformat bundle: add new version for use with SHA-256 builtin/verify-pack: implement an --object-format option http-fetch: set up git directory before parsing pack hashes t0410: mark test with SHA1 prerequisite t5308: make test work with SHA-256 t9700: make hash size independent t9500: ensure that algorithm info is preserved in config t9350: make hash size independent t9301: make hash size independent t9300: use $ZERO_OID instead of hard-coded object ID t9300: abstract away SHA-1-specific constants t8011: make hash size independent ...

Merge branch 'jk/reject-newer-extensions-in-v0' into master

2020-07-30T20:20:32Z

With the base fix to 2.27 regresion, any new extensions in a v0 repository would still be silently honored, which is not quite right. Instead, complain and die loudly. * jk/reject-newer-extensions-in-v0: verify_repository_format(): complain about new extensions in v0 repo

setup: add support for reading extensions.objectformat

2020-07-30T16:16:49Z

The transition plan specifies extensions.objectFormat as the indication that we're using a given hash in a certain repo. Read this as one of the extensions we support. If the user has specified an invalid value, fail. Ensure that we reject the extension if the repository format version is 0. Signed-off-by: brian m. carlson Reviewed-by: Eric Sunshine Signed-off-by: Junio C Hamano

Merge branch 'jn/v0-with-extensions-fix' into master

2020-07-17T00:58:42Z

In 2.28-rc0, we corrected a bug that some repository extensions are honored by mistake even in a version 0 repositories (these configuration variables in extensions.* namespace were supposed to have special meaning in repositories whose version numbers are 1 or higher), but this was a bit too big a change. * jn/v0-with-extensions-fix: repository: allow repository format upgrade with extensions Revert "check_repository_format_gently(): refuse extensions for old repositories"

verify_repository_format(): complain about new extensions in v0 repo

2020-07-16T17:39:45Z

We made the mistake in the past of respecting extensions.* even when the repository format version was set to 0. This is bad because forgetting to bump the repository version means that older versions of Git (which do not know about our extensions) won't complain. I.e., it's not a problem in itself, but it means your repository is in a state which does not give you the protection you think you're getting from older versions. For compatibility reasons, we are stuck with that decision for existing extensions. However, we'd prefer not to extend the damage further. We can do that by catching any newly-added extensions and complaining about the repository format. Note that this is a pretty heavy hammer: we'll refuse to work with the repository at all. A lesser option would be to ignore (possibly with a warning) any new extensions. But because of the way the extensions are handled, that puts the burden on each new extension that is added to remember to "undo" itself (because they are handled before we know for sure whether we are in a v1 repo or not, since we don't insist on a particular ordering of config entries). So one option would be to rewrite that handling to record any new extensions (and their values) during the config parse, and then only after proceed to handle new ones only if we're in a v1 repository. But I'm not sure if it's worth the trouble: - ignoring extensions is likely to end up with broken results anyway (e.g., ignoring a proposed objectformat extension means parsing any object data is likely to encounter errors) - this is a sign that whatever tool wrote the extension field is broken. We may be better off notifying immediately and forcefully so that such tools don't even appear to work accidentally. The only downside is that fixing the situation is a little tricky, because programs like "git config" won't want to work with the repository. But: git config --file=.git/config core.repositoryformatversion 1 should still suffice. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

repository: allow repository format upgrade with extensions

2020-07-16T16:36:39Z

Now that we officially permit repository extensions in repository format v0, permit upgrading a repository with extensions from v0 to v1 as well. For example, this means a repository where the user has set "extensions.preciousObjects" can use "git fetch --filter=blob:none origin" to upgrade the repository to use v1 and the partial clone extension. To avoid mistakes, continue to forbid repository format upgrades in v0 repositories with an unrecognized extension. This way, a v0 user using a misspelled extension field gets a chance to correct the mistake before updating to the less forgiving v1 format. While we're here, make the error message for failure to upgrade the repository format a bit shorter, and present it as an error, not a warning. Reported-by: Huan Huan Chen Signed-off-by: Jonathan Nieder Signed-off-by: Junio C Hamano

Revert "check_repository_format_gently(): refuse extensions for old repositories"

2020-07-16T16:36:37Z

This reverts commit 14c7fa269e42df4133edd9ae7763b678ed6594cd. The core.repositoryFormatVersion field was introduced in ab9cb76f661 (Repository format version check., 2005-11-25), providing a welcome bit of forward compatibility, thanks to some welcome analysis by Martin Atukunda. The semantics are simple: a repository with core.repositoryFormatVersion set to 0 should be comprehensible by all Git implementations in active use; and Git implementations should error out early instead of trying to act on Git repositories with higher core.repositoryFormatVersion values representing new formats that they do not understand. A new repository format did not need to be defined until 00a09d57eb8 (introduce "extensions" form of core.repositoryformatversion, 2015-06-23). This provided a finer-grained extension mechanism for Git repositories. In a repository with core.repositoryFormatVersion set to 1, Git implementations can act on "extensions.*" settings that modify how a repository is interpreted. In repository format version 1, unrecognized extensions settings cause Git to error out. What happens if a user sets an extension setting but forgets to increase the repository format version to 1? The extension settings were still recognized in that case; worse, unrecognized extensions settings do *not* cause Git to error out. So combining repository format version 0 with extensions settings produces in some sense the worst of both worlds. To improve that situation, since 14c7fa269e4 (check_repository_format_gently(): refuse extensions for old repositories, 2020-06-05) Git instead ignores extensions in v0 mode. This way, v0 repositories get the historical (pre-2015) behavior and maintain compatibility with Git implementations that do not know about the v1 format. Unfortunately, users had been using this sort of configuration and this behavior change came to many as a surprise: - users of "git config --worktree" that had followed its advice to enable extensions.worktreeConfig (without also increasing the repository format version) would find their worktree configuration no longer taking effect - tools such as copybara[*] that had set extensions.partialClone in existing repositories (without also increasing the repository format version) would find that setting no longer taking effect The behavior introduced in 14c7fa269e4 might be a good behavior if we were traveling back in time to 2015, but we're far too late. For some reason I thought that it was what had been originally implemented and that it had regressed. Apologies for not doing my research when 14c7fa269e4 was under development. Let's return to the behavior we've had since 2015: always act on extensions.* settings, regardless of repository format version. While we're here, include some tests to describe the effect on the "upgrade repository version" code path. [*] https://github.com/google/copybara/commit/ca76c0b1e13c4e36448d12c2aba4a5d9d98fb6e7 Reported-by: Johannes Schindelin Signed-off-by: Jonathan Nieder Signed-off-by: Junio C Hamano

Merge branch 'bc/sha-256-part-2'

2020-07-07T05:09:13Z

SHA-256 migration work continues. * bc/sha-256-part-2: (44 commits) remote-testgit: adapt for object-format bundle: detect hash algorithm when reading refs t5300: pass --object-format to git index-pack t5704: send object-format capability with SHA-256 t5703: use object-format serve option t5702: offer an object-format capability in the test t/helper: initialize the repository for test-sha1-array remote-curl: avoid truncating refs with ls-remote t1050: pass algorithm to index-pack when outside repo builtin/index-pack: add option to specify hash algorithm remote-curl: detect algorithm for dumb HTTP by size builtin/ls-remote: initialize repository based on fetch t5500: make hash independent serve: advertise object-format capability for protocol v2 connect: parse v2 refs with correct hash algorithm connect: pass full packet reader when parsing v2 refs Documentation/technical: document object-format for protocol v2 t1302: expect repo format version 1 for SHA-256 builtin/show-index: provide options to determine hash algo t5302: modernize test formatting ...

check_repository_format_gently(): refuse extensions for old repositories

2020-06-05T17:13:30Z

Previously, extensions were recognized regardless of repository format version. If the user sets an undefined "extensions" value on a repository of version 0 and that value is used by a future git version, they might get an undesired result. Because all extensions now also upgrade repository versions, tightening the check would help avoid this for future extensions. Signed-off-by: Xin Li Signed-off-by: Junio C Hamano

repository: add a helper function to perform repository format upgrade

2020-06-05T17:13:30Z

In version 1 of repository format, "extensions" gained special meaning and it is safer to avoid upgrading when there are pre-existing extensions. Make list-objects-filter to use the helper function instead of setting repository version directly as a prerequisite of exposing the upgrade capability. Signed-off-by: Xin Li Signed-off-by: Junio C Hamano