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

Lothar Waßmann
2017-06-26T07:55:47Z

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