Re: [PATCH v2 2/4] parted: add support for gpt-location

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Apr 23, 2025 at 04:09:11PM +0200, Marco Felsch wrote:
> Add support to place the GPT partition entries to random places instead
> of LBA2.
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> ---
> v2:
> - new
> 
>  commands/parted.c | 29 +++++++++++++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/commands/parted.c b/commands/parted.c
> index 90cee1ede10e..895c06524d4c 100644
> --- a/commands/parted.c
> +++ b/commands/parted.c
> @@ -224,6 +224,30 @@ static int do_mklabel(struct block_device *blk, int argc, char *argv[])
>  		return -EINVAL;
>  	}
>  
> +	if (argc == 3) {
> +		uint64_t mult;
> +		int ret;
> +
> +		if (!strcmp(argv[1], "msdos")) {
> +			printf("gpt-location not supported for msdos partitions\n");
> +			return -EINVAL;
> +		}
> +
> +		ret = parted_strtoull(argv[2], &gpt_location, &mult);
> +		if (ret)
> +			return ret;
> +
> +		if (!mult)
> +			mult = gunit;
> +
> +		gpt_location *= mult;
> +
> +		/* Ensure alignment */
> +		gpt_location = ALIGN(gpt_location, SECTOR_SIZE);
> +		/* convert to LBA */
> +		gpt_location >>= SECTOR_SHIFT;
> +	}
> +
>  	pdesc = partition_table_new(blk, argv[1], gpt_location);
>  	if (IS_ERR(pdesc)) {
>  		printf("Error: Cannot create partition table: %pe\n", pdesc);
> @@ -236,7 +260,7 @@ static int do_mklabel(struct block_device *blk, int argc, char *argv[])
>  		partition_table_free(gpdesc);
>  	gpdesc = pdesc;
>  
> -	return 2;
> +	return argc > 2 ? 3 : 2;

Optional arguments are not supported by parted. You can pass multiple
commands to parted, e.g.

parted /dev/mmc0 mklabel gpt mkpart foo ext4 4MiB 1024MiB

argc will contain the remaining arguments, when another command follows
it won't be exactly three and you can't tell if the argument belongs to
this command or is the start of the next one.

You could implement it as an option.

Sascha

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