Re: [OSS-Tools] [PATCH] libdt: generalize of_find_device_by_uuid for scoped lookup of all UUIDs

[Roland Hieber <rhi@pengutronix.de>]

On Mon, Jun 05, 2023 at 04:32:36PM +0200, Ahmad Fatoum wrote:
> Despite the generic name, of_find_device_by_uuid only handled
> ID_PART_TABLE_UUID (diskuuid) and ID_PART_ENTRY_UUID (partuuid),
> but not ID_PART_ENTRY_TYPE (GPT Partition Type UUID).
> 
> In preparation for doing Type UUID lookups, adjust of_find_device_by_uuid
> to support all three types of GPT UUIDs.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> This patch is the missing prerequisite for my GPT Type UUID series.
> ---
>  src/libdt.c | 30 +++++++++++++++++++-----------
>  1 file changed, 19 insertions(+), 11 deletions(-)
> 
> diff --git a/src/libdt.c b/src/libdt.c
> index e54d7fb5649d..2c994c647ac9 100644
> --- a/src/libdt.c
> +++ b/src/libdt.c
> @@ -2405,7 +2405,9 @@ out:
>  	return dev;
>  }
>  
> -static struct udev_device *of_find_device_by_uuid(const char *uuid)
> +static struct udev_device *of_find_device_by_uuid(struct udev_device *parent,
> +						  const char *uuid,
> +						  bool type_uuid)
>  {
>  	struct udev *udev;
>  	struct udev_enumerate *enumerate;
> @@ -2418,12 +2420,15 @@ static struct udev_device *of_find_device_by_uuid(const char *uuid)
>  	}
>  
>  	enumerate = udev_enumerate_new(udev);
> +	if (parent)
> +		udev_enumerate_add_match_parent(enumerate, parent);
>  	udev_enumerate_add_match_subsystem(enumerate, "block");
>  	udev_enumerate_scan_devices(enumerate);
>  	devices = udev_enumerate_get_list_entry(enumerate);
>  	udev_list_entry_foreach(dev_list_entry, devices) {
>  		const char *path, *devtype, *dev_uuid;
>  		struct udev_device *device;
> +		const char *property;
>  
>  		path = udev_list_entry_get_name(dev_list_entry);
>  		device = udev_device_new_from_syspath(udev, path);
> @@ -2432,16 +2437,19 @@ static struct udev_device *of_find_device_by_uuid(const char *uuid)
>  		devtype = udev_device_get_devtype(device);
>  		if (!devtype)
>  			continue;
> -		if (!strcmp(devtype, "disk")) {
> -			dev_uuid = udev_device_get_property_value(device, "ID_PART_TABLE_UUID");
> -			if (dev_uuid && !strcasecmp(dev_uuid, uuid))
> -				return device;
> -		} else if (!strcmp(devtype, "partition")) {
> -			dev_uuid = udev_device_get_property_value(device, "ID_PART_ENTRY_UUID");
> -			if (dev_uuid && !strcasecmp(dev_uuid, uuid))
> -				return device;
> -		}
>  
> +		if (type_uuid)
> +			property = "ID_PART_ENTRY_TYPE";
> +		else if (!strcmp(devtype, "disk"))
> +			property = "ID_PART_TABLE_UUID";
> +		else if (!strcmp(devtype, "partition"))
> +			property = "ID_PART_ENTRY_UUID";
> +		else
> +			continue;
> +
> +		dev_uuid = udev_device_get_property_value(device, property);
> +		if (dev_uuid && !strcasecmp(dev_uuid, uuid))
> +			return device;

I wonder if we can't simply add a udev_enumerate_add_match_property
above to do the filtering for us instead of iterating over the match
entries ourselves.

But the patch is correct, so:
Reviewed-by: Roland Hieber <rhi@pengutronix.de>

>  	}
>  	return NULL;
>  }
> @@ -2540,7 +2548,7 @@ int of_get_devicepath(struct device_node *partition_node, char **devpath, off_t
>  					node->full_name);
>  			return -ENODEV;
>  		}
> -		dev = of_find_device_by_uuid(uuid);
> +		dev = of_find_device_by_uuid(NULL, uuid, false);
>  		if (!dev) {
>  			fprintf(stderr, "%s: cannot find device for uuid %s\n", __func__,
>  				uuid);
> -- 
> 2.39.2
> 
> 

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