Subject: Re: [PATCH v5] clone: add clone.<url>.defaultObjectFilter config

From: "Alan Braithwaite" <[email-masked]>
Date: Sat, 14 Mar 2026 18:33:38 -0700

Thanks for the review, Patrick.

> `url_normalize()` will return a `NULL` pointer in case
> it cannot parse the URL.  We need to be prepared for
> this, otherwise we might segfault.

Good catch.  The updated patch guards on the return value
and skips the urlmatch lookup entirely when the URL cannot
be normalized.  Today `match_urls()` happens to handle
this safely (it returns 0 when `url->url` is NULL), but an
explicit NULL check guards against future regressions in
that code path.

> Do we want to "test_when_finished rm -rf
> default-filter-clone" here and for all the subsequent
> tests?

Done -- added `test_when_finished` cleanup to each test.

Patch incoming. :)

Thanks,
- Alan

On Wed, Mar 11, 2026, at 00:44, Patrick Steinhardt wrote:
> On Sat, Mar 07, 2026 at 01:33:56AM +0000, Alan Braithwaite via 
> GitGitGadget wrote:
>> diff --git a/Documentation/config/clone.adoc b/Documentation/config/clone.adoc
>> index 0a10efd174..1d6c0957a0 100644
>> --- a/Documentation/config/clone.adoc
>> +++ b/Documentation/config/clone.adoc
>> @@ -21,3 +21,37 @@ endif::[]
>>  	If a partial clone filter is provided (see `--filter` in
>>  	linkgit:git-rev-list[1]) and `--recurse-submodules` is used, also apply
>>  	the filter to submodules.
>> +
>> +`clone.defaultObjectFilter`::
>> +`clone.<url>.defaultObjectFilter`::
>> +	When set to a filter spec string (e.g., `blob:limit=1m`,
>> +	`blob:none`, `tree:0`), linkgit:git-clone[1] will automatically
>> +	use `--filter=<value>` to enable partial clone behavior.
>> +	Objects matching the filter are excluded from the initial
>> +	transfer and lazily fetched on demand (e.g., during checkout).
>> +	Subsequent fetches inherit the filter via the per-remote config
>> +	that is written during the clone.
>> ++
>> +The bare `clone.defaultObjectFilter` applies to all clones.  The
>> +URL-qualified form `clone.<url>.defaultObjectFilter` restricts the
>> +setting to clones whose URL matches `<url>`, following the same
>> +rules as `http.<url>.*` (see linkgit:git-config[1]).  The most
>> +specific URL match wins.  You can match a domain, a namespace, or a
>> +specific project:
>> ++
>> +----
>> +[clone]
>> +    defaultObjectFilter = blob:limit=1m
>> +
>> +[clone "https://github.com/"]
>> +    defaultObjectFilter = blob:limit=5m
>> +
>> +[clone "https://internal.corp.com/large-project/"]
>> +    defaultObjectFilter = blob:none
>> +----
>> ++
>> +An explicit `--filter` option on the command line takes precedence
>> +over this config, and `--no-filter` defeats it entirely to force a
>> +full clone.  Only affects the initial clone; it has no effect on
>> +later fetches into an existing repository.  If the server does not
>> +support object filtering, the setting is silently ignored.
>
> This all reads good to me.
>
>> diff --git a/builtin/clone.c b/builtin/clone.c
>> index 45d8fa0eed..1207655815 100644
>> --- a/builtin/clone.c
>> +++ b/builtin/clone.c
>> @@ -757,6 +758,47 @@ static int git_clone_config(const char *k, const char *v,
>>  	return git_default_config(k, v, ctx, cb);
>>  }
>>  
>> +static int clone_filter_collect(const char *var, const char *value,
>> +				const struct config_context *ctx UNUSED,
>> +				void *cb)
>> +{
>> +	char **filter_spec_p = cb;
>> +
>> +	if (!strcmp(var, "clone.defaultobjectfilter")) {
>> +		if (!value)
>> +			return config_error_nonbool(var);
>> +		free(*filter_spec_p);
>> +		*filter_spec_p = xstrdup(value);
>> +	}
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Look up clone.defaultObjectFilter or clone.<url>.defaultObjectFilter
>> + * using the urlmatch infrastructure.  A URL-qualified entry that matches
>> + * the clone URL takes precedence over the bare form, following the same
>> + * rules as http.<url>.* configuration variables.
>> + */
>> +static char *get_default_object_filter(const char *url)
>> +{
>> +	struct urlmatch_config config = URLMATCH_CONFIG_INIT;
>> +	char *filter_spec = NULL;
>> +	char *normalized_url;
>> +
>> +	config.section = "clone";
>> +	config.key = "defaultobjectfilter";
>> +	config.collect_fn = clone_filter_collect;
>> +	config.cb = &filter_spec;
>> +
>> +	normalized_url = url_normalize(url, &config.url);
>
> `url_normalize()` will return a `NULL` pointer in case it cannot parse
> the URL. We need to be prepared for this, otherwise we might segfault.
> I guess the best route is to simply ignore the URL in that case --
> otherwise, we would always error out in case the remote has a weird URL
> configured.
>
>> diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
>> index 1e354e057f..1254901f3e 100755
>> --- a/t/t5616-partial-clone.sh
>> +++ b/t/t5616-partial-clone.sh
>> @@ -722,6 +722,124 @@ test_expect_success 'after fetching descendants of non-promisor commits, gc work
>>  	git -C partial gc --prune=now
>>  '
>>  
>> +# Test clone.<url>.defaultObjectFilter config
>> +
>> +test_expect_success 'setup for clone.defaultObjectFilter tests' '
>> +	git init default-filter-src &&
>> +	echo "small" >default-filter-src/small.txt &&
>> +	dd if=/dev/zero of=default-filter-src/large.bin bs=1024 count=100 2>/dev/null &&
>> +	git -C default-filter-src add . &&
>> +	git -C default-filter-src commit -m "initial" &&
>> +
>> +	git clone --bare "file://$(pwd)/default-filter-src" default-filter-srv.bare &&
>> +	git -C default-filter-srv.bare config --local uploadpack.allowfilter 1 &&
>> +	git -C default-filter-srv.bare config --local uploadpack.allowanysha1inwant 1
>> +'
>> +
>> +test_expect_success 'clone with clone.<url>.defaultObjectFilter applies filter' '
>> +	SERVER_URL="file://$(pwd)/default-filter-srv.bare" &&
>> +	git -c "clone.$SERVER_URL.defaultObjectFilter=blob:limit=1k" clone \
>> +		"$SERVER_URL" default-filter-clone &&
>
> Do we want to "test_when_finished rm -rf default-filter-clone" here and
> for all the subsequent tests?
>
> Patrick