git/Documentation/config/transfer.txt

transfer.fsckObjects::
	When `fetch.fsckObjects` or `receive.fsckObjects` are
	not set, the value of this variable is used instead.
	Defaults to false.
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When set, the fetch or receive will abort in the case of a malformed
object or a link to a nonexistent object. In addition, various other
issues are checked for, including legacy issues (see `fsck.<msg-id>`),
and potential security issues like the existence of a `.GIT` directory
or a malicious `.gitmodules` file (see the release notes for v2.2.1
and v2.17.1 for details). Other sanity and security checks may be
added in future releases.
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On the receiving side, failing fsckObjects will make those objects
unreachable, see "QUARANTINE ENVIRONMENT" in
linkgit:git-receive-pack[1]. On the fetch side, malformed objects will
instead be left unreferenced in the repository.
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Due to the non-quarantine nature of the `fetch.fsckObjects`
implementation it can not be relied upon to leave the object store
clean like `receive.fsckObjects` can.
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As objects are unpacked they're written to the object store, so there
can be cases where malicious objects get introduced even though the
"fetch" failed, only to have a subsequent "fetch" succeed because only
new incoming objects are checked, not those that have already been
written to the object store. That difference in behavior should not be
relied upon. In the future, such objects may be quarantined for
"fetch" as well.
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For now, the paranoid need to find some way to emulate the quarantine
environment if they'd like the same protection as "push". E.g. in the
case of an internal mirror do the mirroring in two steps, one to fetch
the untrusted objects, and then do a second "push" (which will use the
quarantine) to another internal repo, and have internal clients
consume this pushed-to repository, or embargo internal fetches and
only allow them once a full "fsck" has run (and no new fetches have
happened in the meantime).

transfer.hideRefs::
	String(s) `receive-pack` and `upload-pack` use to decide which
	refs to omit from their initial advertisements.  Use more than
	one definition to specify multiple prefix strings. A ref that is
	under the hierarchies listed in the value of this variable is
	excluded, and is hidden when responding to `git push` or `git
	fetch`.  See `receive.hideRefs` and `uploadpack.hideRefs` for
	program-specific versions of this config.
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You may also include a `!` in front of the ref name to negate the entry,
explicitly exposing it, even if an earlier entry marked it as hidden.
If you have multiple hideRefs values, later entries override earlier ones
(and entries in more-specific config files override less-specific ones).
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If a namespace is in use, the namespace prefix is stripped from each
reference before it is matched against `transfer.hiderefs` patterns.
For example, if `refs/heads/master` is specified in `transfer.hideRefs` and
the current namespace is `foo`, then `refs/namespaces/foo/refs/heads/master`
is omitted from the advertisements but `refs/heads/master` and
`refs/namespaces/bar/refs/heads/master` are still advertised as so-called
"have" lines. In order to match refs before stripping, add a `^` in front of
the ref name. If you combine `!` and `^`, `!` must be specified first.
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Even if you hide refs, a client may still be able to steal the target
objects via the techniques described in the "SECURITY" section of the
linkgit:gitnamespaces[7] man page; it's best to keep private data in a
separate repository.

transfer.unpackLimit::
	When `fetch.unpackLimit` or `receive.unpackLimit` are
	not set, the value of this variable is used instead.
	The default value is 100.