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The code to maintain mapping between object names in multiple hash
functions is being added, written in Rust.
* bc/sha1-256-interop-02:
object-file-convert: always make sure object ID algo is valid
rust: add a small wrapper around the hashfile code
rust: add a new binary object map format
rust: add functionality to hash an object
rust: add a build.rs script for tests
rust: fix linking binaries with cargo
hash: expose hash context functions to Rust
write-or-die: add an fsync component for the object map
csum-file: define hashwrite's count as a uint32_t
rust: add additional helpers for ObjectID
hash: add a function to look up hash algo structs
rust: add a hash algorithm abstraction
rust: add a ObjectID struct
hash: use uint32_t for object_id algorithm
conversion: don't crash when no destination algo
repository: require Rust support for interoperability
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The following command reports that some header files are included twice:
$ git grep '#include' '*.c' | sort | uniq -cd
Remove the second #include line in each case, as it has no effect.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In some cases, we zero-initialize our object IDs, which sets the algo
member to zero as well, which is not a valid algorithm number. This is
a bad practice, but we typically paper over it in many cases by simply
substituting the repository's hash algorithm.
However, our new Rust loose object map code doesn't handle this
gracefully and can't find object IDs when the algorithm is zero because
they don't compare equal to those with the correct algo field. In
addition, the comparison code doesn't have any knowledge of what the
main algorithm is because that's global state, so we can't adjust the
comparison.
To make our code function properly and to avoid propagating these bad
entries, if we get a source object ID with a zero algo, just make a copy
of it with the fixed algorithm. This has the benefit of also fixing the
object IDs if we're in a single algorithm mode as well.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we set up a repository that doesn't have a compatibility hash
algorithm, we set the destination algorithm object to NULL. In such a
case, we want to silently do nothing instead of crashing, so simply
treat the operation as a no-op and copy the object ID.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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