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

From: Patrick Steinhardt <[email-masked]>
Date: Wed, 11 Mar 2026 08:44:13 +0100

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