Re: [PATCH 4/5] commands: create createnv command

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 02.06.25 15:28, Sascha Hauer wrote:
> We want to move away from describing the barebox environment explicitly
> in the device tree and instead motivate usage of GPT partitions for the
> envrionment. This patch creates a createnv command to facilitate this.
> It creates an environment partition on the specified device and if
> necessary also a GPT partition table. In the simplest case a "createnv"
> without arguments will create a partition on the device barebox itself
> booted from. Both the device and the size of the partition can be
> specified on the command line.
> 
> We can't create environment partitions on a device containing a MBR
> partition table, so a MBR partitioned device won't be touched.
> 
> As an additional safety net the command will ask the user if altering
> the partition table is really desired. This behaviour can be overwritten
> by specifying -f on the command line.

Could we have saveenv/loadenv nudge the user towards createnv if CMD_CREATENV
is enabled?

Something along the lines of:

  saveenv: no environment was registered
  saveenv: run createnv to create an ad-hoc environment

Cheers,
Ahmad

> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  commands/Kconfig    |  18 ++++++
>  commands/Makefile   |   1 +
>  commands/createnv.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 198 insertions(+)
> 
> diff --git a/commands/Kconfig b/commands/Kconfig
> index 0f3155d123ab6eebd6a8b4585ff8c496318c9efe..27a935d4d2e55f0384a28ab1d8718c0cf90fb746 100644
> --- a/commands/Kconfig
> +++ b/commands/Kconfig
> @@ -771,6 +771,24 @@ endmenu
>  
>  menu "Environment"
>  
> +config CMD_CREATENV
> +	tristate
> +	depends on PARTITION_DISK_EFI
> +	select PARTITION_MANIPULATION
> +	prompt "createnv"
> +	help
> +	  createnv - Create a barebox environment partition
> +
> +	  Usage: createnv [-sf] [device]
> +
> +	  Create a barebox environment partition.
> +	  This creates a barebox environment partition and eventually
> +	  a GPT partition table when it does not exist.
> +
> +	  Options:
> +		-s <size>       specify partition size (default 1MiB)
> +		-f      force. Do not ask
> +
>  config CMD_NV
>  	depends on NVVAR
>  	tristate
> diff --git a/commands/Makefile b/commands/Makefile
> index 8c2749b5ebddb5ef22691d2007f556af195b432b..2780a26dc2daf86ebdc11011fed0849bafaa982a 100644
> --- a/commands/Makefile
> +++ b/commands/Makefile
> @@ -157,6 +157,7 @@ obj-$(CONFIG_CMD_BTHREAD)	+= bthread.o
>  obj-$(CONFIG_CMD_UBSAN)		+= ubsan.o
>  obj-$(CONFIG_CMD_SELFTEST)	+= selftest.o
>  obj-$(CONFIG_CMD_TUTORIAL)	+= tutorial.o
> +obj-$(CONFIG_CMD_CREATENV)	+= createnv.o
>  obj-$(CONFIG_CMD_STACKSMASH)	+= stacksmash.o
>  obj-$(CONFIG_CMD_PARTED)	+= parted.o
>  obj-$(CONFIG_CMD_EFI_HANDLE_DUMP)	+= efi_handle_dump.o
> diff --git a/commands/createnv.c b/commands/createnv.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..df03664be11251165287bd2291d09bee7408f553
> --- /dev/null
> +++ b/commands/createnv.c
> @@ -0,0 +1,179 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <command.h>
> +#include <malloc.h>
> +#include <stdlib.h>
> +#include <partitions.h>
> +#include <driver.h>
> +#include <disks.h>
> +#include <xfuncs.h>
> +#include <getopt.h>
> +#include <efi/partition.h>
> +#include <bootsource.h>
> +#include <linux/kstrtox.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <envfs.h>
> +
> +static int do_createnv(int argc, char *argv[])
> +{
> +	uint64_t start, size = SZ_1M;
> +	struct cdev *cdev;
> +	struct block_device *blk;
> +	struct partition *part;
> +	struct partition_desc *pdesc = NULL;
> +	enum filetype filetype;
> +	guid_t partition_barebox_env_guid = PARTITION_BAREBOX_ENVIRONMENT_GUID;
> +	void *buf = NULL;
> +	bool force = false;
> +	int opt, ret;
> +
> +	while ((opt = getopt(argc, argv, "s:f")) > 0) {
> +		switch (opt) {
> +		case 's':
> +			size = strtoull_suffix(optarg, NULL, 0);
> +			break;
> +		case 'f':
> +			force = true;
> +			break;
> +		default:
> +			return COMMAND_ERROR_USAGE;
> +		}
> +        }
> +
> +	argc -= optind;
> +	argv += optind;
> +
> +	if (argc < 1) {
> +		cdev = bootsource_of_cdev_find();
> +		if (!cdev) {
> +			printf("Cannot find bootsource cdev\n");
> +			return COMMAND_ERROR;
> +		}
> +		ret = cdev_open(cdev, O_RDWR);
> +		if (ret) {
> +			printf("Cannot open %s: %pe\n", cdev->name, ERR_PTR(ret));
> +			return COMMAND_ERROR;
> +		}
> +	} else {
> +		cdev = cdev_open_by_path_name(argv[0], O_RDWR);
> +		if (!cdev) {
> +			printf("Cannot open %s\n", argv[0]);
> +			return COMMAND_ERROR;
> +		}
> +	}
> +
> +	blk = cdev_get_block_device(cdev);
> +	if (!blk) {
> +		ret = -ENOENT;
> +		goto err;
> +	}
> +
> +	buf = xzalloc(2 * SECTOR_SIZE);
> +
> +	ret = cdev_read(cdev, buf, 2 * SECTOR_SIZE, 0, 0);
> +	if (ret < 0) {
> +		printf("Cannot read from %s: %pe\n", cdev->name, ERR_PTR(ret));
> +		goto err;
> +	}
> +
> +	filetype = file_detect_partition_table(buf, 2 * SECTOR_SIZE);
> +
> +	switch (filetype) {
> +	case filetype_gpt:
> +		pdesc = partition_table_read(blk);
> +		if (!pdesc) {
> +			printf("Cannot read partition table\n");
> +			ret = -EINVAL;
> +			goto err;
> +		}
> +		break;
> +	case filetype_mbr:
> +		printf("%s contains a DOS partition table. Cannot create a barebox environment here\n",
> +		       cdev->name);
> +		ret = -EINVAL;
> +		goto err;
> +	default:
> +		printf("Will create a GPT on %s\n", cdev->name);
> +		pdesc = partition_table_new(blk, "gpt");
> +		break;
> +	}
> +
> +	list_for_each_entry(part, &pdesc->partitions, list) {
> +		if (guid_equal(&part->typeuuid, &partition_barebox_env_guid)) {
> +			printf("%s already contains a barebox environment partition\n",
> +			       cdev->name);
> +			ret = -EINVAL;
> +			goto err;
> +		}
> +	}
> +
> +	size >>= SECTOR_SHIFT;
> +
> +	ret = partition_find_free_space(pdesc, size, &start);
> +	if (ret) {
> +		printf("No free space available\n");
> +		goto err;
> +	}
> +
> +	ret = partition_create(pdesc, "barebox-environment", "bbenv", start, start + size - 1);
> +	if (ret) {
> +		printf("Creating partition failed: %pe\n", ERR_PTR(ret));
> +		goto err;
> +	}
> +
> +	printf("Will create a barebox environment partition of size %llu bytes on %s\n",
> +	       size << SECTOR_SHIFT, cdev->name);
> +
> +	if (!force) {
> +		char c;
> +
> +		printf("Do you wish to continue? (y/n)\n");
> +
> +		c = getchar();
> +		if (c != 'y') {
> +			ret = -EINTR;
> +			goto err;
> +		}
> +	}
> +
> +	ret = partition_table_write(pdesc);
> +	if (ret) {
> +		printf("Cannot write partition table: %pe\n", ERR_PTR(ret));
> +		goto err;
> +	}
> +
> +	if (!default_environment_path_get()) {
> +		char *path = xasprintf("/dev/%s.barebox-environment", cdev->name);
> +		default_environment_path_set(path);
> +		free(path);
> +	}
> +
> +	printf("Created barebox environment partition on %s\n", cdev->name);
> +
> +	ret = 0;
> +err:
> +	if (pdesc)
> +		partition_table_free(pdesc);
> +
> +	free(buf);
> +	cdev_close(cdev);
> +
> +	return ret ? COMMAND_ERROR : 0;
> +}
> +
> +BAREBOX_CMD_HELP_START(createnv)
> +BAREBOX_CMD_HELP_TEXT("Create a barebox environment partition.")
> +BAREBOX_CMD_HELP_TEXT("This creates a barebox environment partition and eventually")
> +BAREBOX_CMD_HELP_TEXT("a GPT partition table when it does not exist.")
> +BAREBOX_CMD_HELP_OPT("-s <size>", "specify partition size (default 1MiB)")
> +BAREBOX_CMD_HELP_OPT("-f\t", "force. Do not ask")
> +BAREBOX_CMD_HELP_END
> +
> +BAREBOX_CMD_START(createnv)
> +        .cmd            = do_createnv,
> +        BAREBOX_CMD_DESC("Create a barebox environment partition")
> +        BAREBOX_CMD_OPTS("[-sf] [device]")
> +        BAREBOX_CMD_GROUP(CMD_GRP_CONSOLE)
> +        BAREBOX_CMD_HELP(cmd_createnv_help)
> +BAREBOX_CMD_END
> 


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