[U-Boot] [PATCH 3/3] rename GPT partitions to detect boot failure

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

alison at peloton-tech.com wrote:

> From: Alison Chaiken <alison@she-devel.com>
> 
> This patch provides support in u-boot for renaming GPT
> partitions.  The renaming is accomplished via a new 'gpt flip'
> command.
> 
> The concept for the bootloader state machine is the following:
> 
> -- u-boot renames ‘primary’ partitions as ‘candidate’ and tries
>    to boot them.
> -- Linux, at boot, will rename ‘candidate’ partitions as
>    ‘primary’.
> -- If u-boot sees a ‘candidate’ partition after a boot attempt,
>    it renames it failed’ and renames the ‘backup’ partition as
>    ‘candidate’.
> 
> Logic:
> -- Partitions can go to ‘failed’ only from ‘candidate’ and only
>    via u-boot.  Partitions can go to ‘backup’ only from ‘primary’
>    and vice-versa, only via Linux.  Partitions go to ‘candidate’
>    from ‘primary’ or ‘backup’ only via u-boot.  Only system
>    update software will rename 'failed' partitions.
> 
> 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.
> 
> Signed-off-by: Alison Chaiken <alison@peloton-tech.com>
> ---
>  cmd/gpt.c | 207 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 201 insertions(+), 6 deletions(-)
> 
> diff --git a/cmd/gpt.c b/cmd/gpt.c
> index 128c895..f2c32ae 100644
> --- a/cmd/gpt.c
> +++ b/cmd/gpt.c
> @@ -21,6 +21,9 @@
>  #include <memalign.h>
>  #include <linux/compat.h>
>  
> +/* ONEMIB is 2**20 */
> +#define ONEMIB 1024*1024
>
'()' are missing around the expression!
But anyway, there is no need to reinvent the wheel, since SZ_1M exists
in include/linux/sizes.h.

> +
>  static LIST_HEAD(disk_partitions);
>  
>  /**
> @@ -114,7 +117,6 @@ static char *extract_val(const char *str, const char *key)
>  			break;
>  		}
>  	}
> -
>  	free(strcopy);
>  
>  	return new;
> @@ -158,6 +160,7 @@ static void del_gpt_info(void)
>  {
>  	struct list_head *pos = &disk_partitions;
>  	struct disk_part *curr;
> +
>  	while (!list_empty(pos)) {
>  		curr = list_entry(pos->next, struct disk_part, list);
>  		list_del(pos->next);
> @@ -165,6 +168,11 @@ static void del_gpt_info(void)
>  	}
>  }
>  
> +/*
> + * The number '33' comes from the '32' in the definition of disk_partition_t
> + * in include/part.h.   That file has '37' rather than UUID_STR_LEN + 1, from
> + * include/uuid.h
> + */
>  static struct disk_part *allocate_disk_part(disk_partition_t *info, int partnum)
>  {
>  	struct disk_part *newpart;
> @@ -191,16 +199,33 @@ 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, ONEMIB);
> +	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,
> @@ -212,6 +237,89 @@ static void print_gpt_info(void)
>  	}
>  }
>  
> +static int calc_parts_list_len(int numparts)
> +{
> +	/*
> +	 * prefatory string:
> +	 * doc/README.GPT, suggests that
> +	 * int partlistlen = UUID_STR_LEN + 1 + strlen("partitions=uuid_disk=");
> +	 * is correct, but extract_val() expects "uuid_disk" first.
> +	 */
> +	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=,") + 33);
> +	/* 17 because partstr below is 16 chars */
> +	partlistlen += numparts * (strlen("start=MiB,") + 17);
> +	partlistlen += numparts * (strlen("size=MiB,") + 17);
> +	partlistlen += numparts * (strlen("uuid=;") + UUID_STR_LEN + 1);
> +	/* for the terminating null */
> +	partlistlen ++;
>
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:
> + *    "partitions=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[16];
> +
> +	if (!partitions_list)
> +		return -1;
> +
> +	/*
> +	 * README.gpt specifies starting with "partitions=" like so:
> +	 *      strcpy(partitions_list, "partitions=uuid_disk=");
> +	 * but that breaks extract_val, which doesn't skip over 'partitions='.
> +	 */
> +	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=");
> +		/*
> +		 * name is 32 chars long, per definition of disk_partition_t in part.h,
> +		 * plus one extra byte for NULL
> +		 */
> +		strncat(partitions_list, (const char *)curr->gpt_part_info.name, 33);
>
unnecessary cast. The same holds for all the other (const char *) casts
in this patch.

> +
> +		strcat(partitions_list, ",start=");
> +		prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.start,
> +				      (unsigned long) curr->gpt_part_info.blksz);
> +		strncat(partitions_list, partstr, 17);
> +
> +		strcat(partitions_list, ",size=");
> +		/* lbaint_t is unsigned long, per include/ide.h */
> +		prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.size,
> +				      (unsigned long) curr->gpt_part_info.blksz);
> +		/* one extra byte for NULL */
> +		strncat(partitions_list, partstr, 17);
> +
> +		strcat(partitions_list, ",uuid=");
> +		strncat(partitions_list, (const char *)curr->gpt_part_info.uuid,
> +			UUID_STR_LEN + 1);
> +		strcat(partitions_list, ";");
> +	}
> +	return 0;
> +}
> +
>  /*
>   * read partition info into disk_partitions list where
>   * it can be printed or modified
> @@ -223,8 +331,11 @@ 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);
> @@ -241,7 +352,6 @@ static int get_gpt_info(struct blk_desc *dev_desc)
>  	if (!valid_parts) {
>  		printf("** No valid partitions found **\n");
>  		del_gpt_info();
> -		return -1;
>  	}
>  	return --valid_parts;
>  }
> @@ -295,10 +405,13 @@ 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;
>  	val = extract_val(str, "uuid_disk");
> +
>  	if (!val) {
>  #ifdef CONFIG_RANDOM_UUID
>  		*str_disk_guid = malloc(UUID_STR_LEN + 1);
> @@ -312,6 +425,7 @@ static int set_gpt_info(struct blk_desc *dev_desc,
>  		if (extract_env(val, &p))
>  			p = val;
>  		*str_disk_guid = strdup(p);
> +
>  		free(val);
>  		/* Move s to first partition */
>  		strsep(&s, ";");
> @@ -524,6 +638,83 @@ static int do_disk_guid(struct blk_desc *dev_desc, char * const namestr)
>  	return 0;
>  }
>  
> +static int do_flip_gpt_parts(struct blk_desc *dev_desc)
> +{
> +	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;
> +
> +	ret = get_disk_guid(dev_desc, disk_guid);
> +	if (ret < 0)
> +		return ret;
> +
> +	numparts = get_gpt_info(dev_desc);
> +	if (numparts <  0)
> +		return numparts;
> +	printf("Current partition table with %d partitions is:\n", numparts);
> +	print_gpt_info();
> +
> +	partlistlen = calc_parts_list_len(numparts);
> +	partitions_list = (char *)malloc(partlistlen);
>
Useless cast.


Lothar Waßmann
-- 
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________

-- 
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________

-- 
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________