[U-Boot] [PATCH v7 9/9] GPT: provide commands to selectively rename partitions

["Lothar Waßmann" <LW@KARO-electronics.de>]

Hi,

On Sun, 25 Jun 2017 16:43:25 -0700 alison at peloton-tech.com wrote:
> From: Alison Chaiken <alison@peloton-tech.com>
> 
> This patch provides support in u-boot for renaming GPT
> partitions.  The renaming is accomplished via new 'gpt swap'
> and 'gpt rename' commands.
> 
> The 'swap' mode returns an error if no matching partition names
> are found, or if the number of partitions with one name does not equal
> the number with the second name.   The 'rename' variant always
> succeeds as long as a partition with the provided number exists.
> 
> Rewriting the partition table has the side-effect that all partitions
> end up with "msftdata" flag set.  The reason is that partition type
> PARTITION_BASIC_DATA_GUID is hard-coded in the gpt_fill_pte()
> function.  This does not appear to cause any harm.
> 
> Changes since v7:
> 
> -- Removed several casts in create_gpt_partitions_list() and
>    do_rename_gpt_parts() as suggested by Lothar Waßmann.  The cast of
>    gpt_part_info.name to char* is needed to silence a compiler
>    warning.
> 
> -- Substituted simple_strtol() for atoi() in do_gpt_rename_parts() as
>    suggested by Tom Rini and Wolfgang Denk.
> 
> -- Fixed bug in do_rename_gpt_parts() where 0 was returned as a valid
>    number of partitions with which to continue.
> 
> -- Added a comment to do_rename_gpt_parts() noting that the debug()
>    string it optionally prints is useful as input to the pre-existing
>    'gpt write' and 'gpt verify' commands.
> 
> -- Changed some -1 return values to -ENODEV and -EINVAL as suggested
>    by Tom Rini.
> 
> 
> Signed-off-by: Alison Chaiken <alison@peloton-tech.com>
> ---
>  cmd/Kconfig    |   8 ++
>  cmd/gpt.c      | 239 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  doc/README.gpt |  20 ++++-
>  3 files changed, 261 insertions(+), 6 deletions(-)
> 
> diff --git a/cmd/Kconfig b/cmd/Kconfig
> index 07b0e3b..ae61b96 100644
> --- a/cmd/Kconfig
> +++ b/cmd/Kconfig
> @@ -595,6 +595,14 @@ config CMD_GPT
>  	  Enable the 'gpt' command to ready and write GPT style partition
>  	  tables.
>  
> +config CMD_GPT_RENAME
> +	bool "GPT partition renaming commands"
> +	depends on CMD_GPT
> +	help
> +	  Enables the 'gpt' command to interchange names on two GPT
> +	  partitions via the 'gpt swap' command or to rename single
> +	  partitions via the 'rename' command.
> +
>  config CMD_ARMFLASH
>  	#depends on FLASH_CFI_DRIVER
>  	bool "armflash"
> diff --git a/cmd/gpt.c b/cmd/gpt.c
> index 9934ef4..8c0441f 100644
> --- a/cmd/gpt.c
> +++ b/cmd/gpt.c
> @@ -20,6 +20,8 @@
>  #include <div64.h>
>  #include <memalign.h>
>  #include <linux/compat.h>
> +#include <linux/sizes.h>
> +#include <stdlib.h>
>  
>  static LIST_HEAD(disk_partitions);
>  
> @@ -194,16 +196,33 @@ static struct disk_part *allocate_disk_part(disk_partition_t *info, int partnum)
>  	return newpart;
>  }
>  
> +static void prettyprint_part_size(char *sizestr, unsigned long partsize,
> +				  unsigned long blksize)
> +{
> +	unsigned long long partbytes;
> +	unsigned long partmegabytes;
> +
> +	partbytes = partsize * blksize;
> +	partmegabytes = lldiv(partbytes, SZ_1M);
> +	snprintf(sizestr, 16, "%luMiB", partmegabytes);
> +}
> +
>  static void print_gpt_info(void)
>  {
>  	struct list_head *pos;
>  	struct disk_part *curr;
> +	char partstartstr[16];
> +	char partsizestr[16];
>  
>  	list_for_each(pos, &disk_partitions) {
>  		curr = list_entry(pos, struct disk_part, list);
> +		prettyprint_part_size(partstartstr, (unsigned long)curr->gpt_part_info.start,
> +				      (unsigned long) curr->gpt_part_info.blksz);
> +		prettyprint_part_size(partsizestr, (unsigned long)curr->gpt_part_info.size,
> +				      (unsigned long) curr->gpt_part_info.blksz);
> +
>  		printf("Partition %d:\n", curr->partnum);
> -		printf("1st block %x, size %x\n", (unsigned)curr->gpt_part_info.start,
> -		       (unsigned)curr->gpt_part_info.size);
> +		printf("Start %s, size %s\n", partstartstr, partsizestr);
>  		printf("Block size %lu, name %s\n", curr->gpt_part_info.blksz,
>  		       curr->gpt_part_info.name);
>  		printf("Type %s, bootable %d\n", curr->gpt_part_info.type,
> @@ -215,6 +234,74 @@ static void print_gpt_info(void)
>  	}
>  }
>  
> +#ifdef CONFIG_CMD_GPT_RENAME
> +static int calc_parts_list_len(int numparts)
> +{
> +	int partlistlen = UUID_STR_LEN + 1 + strlen("uuid_disk=");
> +	/* for the comma */
> +	partlistlen++;
> +
> +	/* per-partition additions; numparts starts at 1, so this should be correct */
> +	partlistlen += numparts * (strlen("name=,") + PART_NAME_LEN + 1);
> +	/* see part.h for definition of struct disk_partition */
> +	partlistlen += numparts * (strlen("start=MiB,") + sizeof(lbaint_t) + 1);
> +	partlistlen += numparts * (strlen("size=MiB,") + sizeof(lbaint_t) + 1);
> +	partlistlen += numparts * (strlen("uuid=;") + UUID_STR_LEN + 1);
> +	/* for the terminating null */
> +	partlistlen++;
> +	debug("Length of partitions_list is %d for %d partitions\n", partlistlen,
> +	       numparts);
> +	return partlistlen;
> +}
> +
> +/*
> + * create the string that upstream 'gpt write' command will accept as an
> + * argument
> + *
> + * From doc/README.gpt, Format of partitions layout:
> + *    "uuid_disk=...;name=u-boot,size=60MiB,uuid=...;
> + *	name=kernel,size=60MiB,uuid=...;"
> + * The fields 'name' and 'size' are mandatory for every partition.
> + * The field 'start' is optional. The fields 'uuid' and 'uuid_disk'
> + * are optional if CONFIG_RANDOM_UUID is enabled.
> + */
> +static int create_gpt_partitions_list(int numparts, const char *guid, char *partitions_list)
> +{
> +	struct list_head *pos;
> +	struct disk_part *curr;
> +	char partstr[PART_NAME_LEN + 1];
> +
> +	if (!partitions_list)
> +		return -EINVAL;
> +
> +	strcpy(partitions_list, "uuid_disk=");
> +	strncat(partitions_list, guid, UUID_STR_LEN + 1);
> +	strcat(partitions_list, ";");
> +
> +	list_for_each(pos, &disk_partitions) {
> +		curr = list_entry(pos, struct disk_part, list);
> +		strcat(partitions_list, "name=");
> +		strncat(partitions_list, (const char *)curr->gpt_part_info.name, PART_NAME_LEN + 1);
> +		strcat(partitions_list, ",start=");
> +		prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.start,
> +				      (unsigned long) curr->gpt_part_info.blksz);
> +		/* one extra byte for NULL */
> +		strncat(partitions_list, partstr, PART_NAME_LEN + 1);
> +		strcat(partitions_list, ",size=");
> +		/* lbaint_t is unsigned long, per include/ide.h */
>
AFAICT lbaint_t is declared in include/blk.h and may be uint64_t or
ulong depending on CONFIG_SYS_64BIT_LBA.

> +		prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.size,
> +				      (unsigned long) curr->gpt_part_info.blksz);
> +		strncat(partitions_list, partstr, PART_NAME_LEN + 1);
> +
> +		strcat(partitions_list, ",uuid=");
> +		strncat(partitions_list, curr->gpt_part_info.uuid,
> +			UUID_STR_LEN + 1);
> +		strcat(partitions_list, ";");
> +	}
> +	return 0;
> +}
> +#endif
> +
>  /*
>   * read partition info into disk_partitions list where
>   * it can be printed or modified
> @@ -226,8 +313,11 @@ static int get_gpt_info(struct blk_desc *dev_desc)
>  	disk_partition_t info;
>  	struct disk_part *new_disk_part;
>  
> -	if (disk_partitions.next == NULL)
> -		INIT_LIST_HEAD(&disk_partitions);
> +	/*
> +	 * Always re-read partition info from device, in case
> +	 * it has changed
> +	 */
> +	INIT_LIST_HEAD(&disk_partitions);
>  
>  	for (p = 1; p <= MAX_SEARCH_PARTITIONS; p++) {
>  		ret = part_get_info(dev_desc, p, &info);
> @@ -301,6 +391,8 @@ static int set_gpt_info(struct blk_desc *dev_desc,
>  		return -1;
>  
>  	str = strdup(str_part);
> +	if (str == NULL)
> +		return -ENOMEM;
>  
>  	/* extract disk guid */
>  	s = str;
> @@ -530,6 +622,127 @@ static int do_disk_guid(struct blk_desc *dev_desc, char * const namestr)
>  	return ret;
>  }
>  
> +#ifdef CONFIG_CMD_GPT_RENAME
> +static int do_rename_gpt_parts(struct blk_desc *dev_desc, char *subcomm,
> +			       char *name1, char *name2)
> +{
> +	struct list_head *pos;
> +	struct disk_part *curr;
> +	disk_partition_t *new_partitions = NULL;
> +	char disk_guid[UUID_STR_LEN + 1];
> +	char *partitions_list, *str_disk_guid;
> +	u8 part_count = 0;
> +	int partlistlen, ret, numparts = 0, partnum, i = 1, ctr1 = 0, ctr2 = 0;
> +
> +	if ((subcomm == NULL) || (name1 == NULL) || (name2 == NULL) ||
> +	    (strcmp(subcomm, "swap") && (strcmp(subcomm, "rename"))))
> +		return -EINVAL;
> +
> +	ret = get_disk_guid(dev_desc, disk_guid);
> +	if (ret < 0)
> +		return ret;
> +	numparts = get_gpt_info(dev_desc);
> +	if (numparts <=  0)
> +		return numparts ? numparts: -ENODEV;
> +
> +	partlistlen = calc_parts_list_len(numparts);
> +	partitions_list = malloc(partlistlen);
> +	memset(partitions_list, '\0', partlistlen);
> +
> +	ret = create_gpt_partitions_list(numparts, (const char *) disk_guid,
>
unnecessary type cast. A function that takes a 'const' argument may well
be passed a non-'const' value.

> +					 partitions_list);
> +	if (ret < 0)
> +		return ret;
> +	/*
> +	 * Uncomment the following line to print a string that 'gpt write'
> +	 * or 'gpt verify' will accept as input.
> +	 */
> +	debug("OLD partitions_list is %s with %u chars\n", partitions_list,
> +	      (unsigned)strlen(partitions_list));
> +
> +	ret = set_gpt_info(dev_desc, (const char *)partitions_list, &str_disk_guid,
>
dto.

[...]
> +		list_for_each(pos, &disk_partitions) {
> +			curr = list_entry(pos, struct disk_part, list);
> +			if (i == partnum) {
> +				strcpy((char *)curr->gpt_part_info.name, name2);
> +				break;
> +			}
> +			i++;
> +		}
> +	}
> +
> +	ret = create_gpt_partitions_list(numparts, (const char *) disk_guid, partitions_list);
>
dto.

> +	if (ret < 0)
> +		return ret;
> +	debug("NEW partitions_list is %s with %u chars\n", partitions_list,
> +	      (unsigned)strlen(partitions_list));
> +
> +	ret = set_gpt_info(dev_desc, (const char *)partitions_list, &str_disk_guid,
dto.

> @@ -547,7 +760,7 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
>  	char *ep;
>  	struct blk_desc *blk_dev_desc = NULL;
>  
> -	if (argc < 4 || argc > 5)
> +	if (argc < 4 || argc > 6)
>
Other subcommands still accept only 4 parameters, so this check should
possibly be done after checking the subcommand name, or at least made
conditional on CONFIG_CMD_GPT_RENAME which enables the new subcommands.

>  		return CMD_RET_USAGE;
>  
>  	dev = (int)simple_strtoul(argv[3], &ep, 10);
> @@ -572,6 +785,11 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
>  		ret = do_disk_guid(blk_dev_desc, argv[4]);
>  	} else if (strcmp(argv[1], "read") == 0) {
>  		ret = do_get_gpt_info(blk_dev_desc);
> +#ifdef CONFIG_CMD_GPT_RENAME
> +	} else if ((strcmp(argv[1], "swap") == 0) ||
> +		   (strcmp(argv[1], "rename") == 0)) {
> +		ret = do_rename_gpt_parts(blk_dev_desc, argv[1], argv[4], argv[5]);
> +#endif
>  	} else {
>  		return CMD_RET_USAGE;
>  	}
> @@ -603,4 +821,15 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt,
>  	" Example usage:\n"
>  	" gpt guid mmc 0\n"
>  	" gpt guid mmc 0 varname\n"
> +#ifdef CONFIG_CMD_GPT_RENAME
> +	"gpt partition renaming commands:\n"
> +	"gpt swap <interface> <dev> <name1> <name2>\n"
> +	"    - change all partitions named name1 to name2\n"
> +	"      and vice-versa\n"
> +	"gpt rename <interface> <dev> <part> <name>\n"
> +	"    - rename the specified partition\n"
> +	" Example usage:\n"
> +	" gpt swap mmc 0 foo bar\n"
> +	" gpt rename mmc 0 3 foo\n"
> +#endif
>  );
> diff --git a/doc/README.gpt b/doc/README.gpt
> index 6c5ab78..d3db8bc 100644
> --- a/doc/README.gpt
> +++ b/doc/README.gpt
> @@ -210,6 +210,24 @@ Following line can be used to assess if GPT verification has succeed:
>  U-BOOT> gpt verify mmc 0 $partitions
>  U-BOOT> if test $? = 0; then echo "GPT OK"; else echo "GPT ERR"; fi
>  
> +Renaming GPT partitions from U-Boot:
> +====================================
> +
> +GPT partition names are a mechanism via which userspace and U-Boot can
> +communicate about software updates and boot failure.  The 'gpt guid',
> +'gpt read', 'gpt rename' and 'gpt swap' commands facilitate
> +programmatic renaming of partitions from bootscripts by generating and
> +modifying the partitions layout string.  Here is an illustration of
> +employing 'swap' to exchange 'primary' and 'backup' partition names:
> +
> +U-BOOT> gpt swap mmc 0 primary backup
> +
> +Afterwards, all partitions previously named 'primary' will be named
> +'backup', and vice-versa.  Alternatively, single partitions may be
> +renamed.  In this example, mmc0's first partition will be renamed
> +'primary':
> +
> +U-BOOT> gpt rename mmc 0 1 primary
>  
>  The GPT functionality may be tested with the 'sandbox' board by
>  creating a disk image as described under 'Block Device Emulation' in
> @@ -218,7 +236,7 @@ board/sandbox/README.sandbox:
>  =>host bind 0 ./disk.raw
>  => gpt read host 0
>  [ . . . ]
> -=> gpt flip host 0
> +=> gpt swap host 0 name othername
>  [ . . . ]
>  
>  Partition type GUID:


Lothar Waßmann