Subject: Re: [PATCH] xdiff-interface: stop using the_repository

From: René Scharfe <[email-masked]>
Date: Mon, 9 Feb 2026 16:21:36 +0100

On 2/9/26 12:15 PM, Junio C Hamano wrote:
> René Scharfe <[email-masked]> writes:
> 
>> Use the algorithm-agnostic is_null_oid() and push the dependency of
>> read_mmblob() on the_repository->objects to its callers.  This allows it
>> to be used with arbitrary object databases.
> 
>> diff --git a/xdiff-interface.c b/xdiff-interface.c
>> index 1a35556380..cd7493730b 100644
>> --- a/xdiff-interface.c
>> +++ b/xdiff-interface.c
>> ...
>> -void read_mmblob(mmfile_t *ptr, const struct object_id *oid)
>> +void read_mmblob(mmfile_t *ptr, struct object_database *odb,
>> +		 const struct object_id *oid)
> 
> A possible alternative may be to pass "struct repository *" here,
> but this passes the (current) smallest piece of data necessary to
> drive the helper function odb_read_object(), so it would be fine.
> 
>>  {
>>  	unsigned long size;
>>  	enum object_type type;
>>  
>> -	if (oideq(oid, null_oid(the_hash_algo))) {
>> +	if (is_null_oid(oid)) {
>>  		ptr->ptr = xstrdup("");
>>  		ptr->size = 0;
>>  		return;
>>  	}
>>  
>> -	ptr->ptr = odb_read_object(the_repository->objects, oid, &type, &size);
>> +	ptr->ptr = odb_read_object(odb, oid, &type, &size);
>>  	if (!ptr->ptr || type != OBJ_BLOB)
>>  		die("unable to read blob object %s", oid_to_hex(oid));
>>  	ptr->size = size;

My initial version did that.  Then I realized that read_mmblob() is just
a thin odb_read_object() wrapper that converts null_oid to
empty_blob_oid and dies on non-blobs, though, so requiring a full repo
pointer seemed excessive.  And all callers also use other odb_*
functions already.

René