[PATCH] cmd/part.c: implement "part name" subcommand

[Quentin Schulz]

Hi Rasmus,

On 10/17/25 10:22 AM, Rasmus Villemoes wrote:
> On Thu, Oct 16 2025, Quentin Schulz <quentin.schulz at cherry.de> wrote:
> 
>> Hi Rasmus,
>>
>> On 10/16/25 2:52 PM, Rasmus Villemoes wrote:
[...]
>>>    cmd/part.c | 16 +++++++++++++++-
>>>    1 file changed, 15 insertions(+), 1 deletion(-)
>>> diff --git a/cmd/part.c b/cmd/part.c
>>> index db7bc5819c0..975a0a08a99 100644
>>> --- a/cmd/part.c
>>> +++ b/cmd/part.c
>>> @@ -25,7 +25,8 @@
>>>    enum cmd_part_info {
>>>    	CMD_PART_INFO_START = 0,
>>>    	CMD_PART_INFO_SIZE,
>>> -	CMD_PART_INFO_NUMBER
>>> +	CMD_PART_INFO_NUMBER,
>>> +	CMD_PART_INFO_NAME,
>>>    };
>>>      static int do_part_uuid(int argc, char *const argv[])
>>> @@ -154,6 +155,9 @@ static int do_part_info(int argc, char *const argv[], enum cmd_part_info param)
>>>    	case CMD_PART_INFO_NUMBER:
>>>    		snprintf(buf, sizeof(buf), "0x%x", part);
>>>    		break;
>>> +	case CMD_PART_INFO_NAME:
>>> +		snprintf(buf, sizeof(buf), "%s", info.name);
>>
>> Is it possible info.name is never set by the fs/blk driver? Should we
>> initialize this field?
>>
> 
> So I took a look, and it seems that all but part_amiga.c do initialize
> it.
> 
> - iso and dos uses part_set_generic_name()
> 
> - mac and efi have real data from the partition table to put in
> 
> - mtd also initializes name, either from a name defined in mtdparts or a
>    size at offset generated one
> 
> - ubi uses the volume name
> 
> I suppose we should make sure info.name is zero-initialized (or, at
> least, that info.name[0] is 0 so there's a valid C string). But I think
> that shouldn't have to be the responsibility of every caller of
> part_get_info(). IOW, I think we should just add
> 
> 	info->name[0] = '\0';
> 	info->type[0] = '\0';
> 
> into part_get_info_by_type(), and then that's a separate patch. WDYT?
> 

Yeah, something like disk_partition_clr_name and disk_partition_clr_type 
for example and call it around the other disk_partition_clr_uuid() calls 
in part_get_info_by_type.

I think this should also be done by *any* caller of drv->get_info? So 
likely in part_get_info_by_uuid as well as part_get_info_by_name. I'm 
also wondering if we shouldn't clear every member when iterating with 
the same disk_partition, e.g. in part_get_info_by_name, 
part_get_info_by_uuid, part_get_bootable so that we don't have leftovers 
from previous failed loops? Essentially what part_get_info_whole_disk() 
does (though it's missing an init for sys_ind and type_flags). Mmmm but 
that would mean also patching the loop in cmd/part.c:do_part_list() for 
example. Or... maybe the whole thing should be a responsibility of the 
get_info implementer (the part_driver) so that calling get_info is 
always "safe"?

That would be a separate patch yes, but likely before this one? Or have 
at least info.name[0] = '\0'; before calling part_get_info*() in 
do_part_info()?

Pfew.. seems like a lot to do here :/

Quentin