Re: [U-Boot] [PATCH v2 3/6] GPT: add accessor function for disk GUID

alison@peloton-tech.com wrote:

From: Alison Chaiken alison@she-devel.com

In order to read the GPT, modify the partition name strings, and then write out a new GPT, the disk GUID is needed. While there is an existing accessor for the partition UUIDs, there is none yet for the disk GUID.

Signed-off-by: Alison Chaiken alison@peloton-tech.com

cmd/gpt.c | 30 +++++++++++++++++++++++++++++- disk/part_efi.c | 31 +++++++++++++++++++++++++++++++ doc/README.gpt | 3 ++- include/part.h | 15 +++++++++++++++ 4 files changed, 77 insertions(+), 2 deletions(-)

diff --git a/cmd/gpt.c b/cmd/gpt.c index 3e98821..3b7d929 100644 --- a/cmd/gpt.c +++ b/cmd/gpt.c @@ -398,6 +398,23 @@ static int gpt_verify(struct blk_desc *blk_dev_desc, const char *str_part) return ret; }

+static int do_disk_guid(struct blk_desc *dev_desc, char * const namestr) +{

• int ret;
• char disk_guid[UUID_STR_LEN + 1];
• ret = get_disk_guid(dev_desc, disk_guid);
• if (ret < 0)

• return 1;
  

Since you are calling this function from a CMD handler and passing its return value as the CMD handlers exit code this should be: return CMD_RET_FAILURE;

• if (namestr)

• setenv(namestr, disk_guid);
  

• else

• printf("%s\n", disk_guid);
  

• return 0;

... and this: return CMD_RET_SUCCESS;

/**

• do_gpt(): Perform GPT operations

@@ -412,7 +429,7 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { int ret = CMD_RET_SUCCESS; int dev = 0;

• char *ep;

• char *ep, *varname = NULL; struct blk_desc *blk_dev_desc = NULL;

  if (argc < 4 || argc > 5)

@@ -436,6 +453,10 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) } else if ((strcmp(argv[1], "verify") == 0)) { ret = gpt_verify(blk_dev_desc, argv[4]); printf("Verify GPT: ");

• } else if (strcmp(argv[1], "guid") == 0) {

• if (argc == 5)
  

•        strcpy(varname, argv[4]);
  
  

You didn't allocate any memory for varname and copy the argument string to a NULL pointer! Maybe use strdup() and free varname after use?

• return do_disk_guid(blk_dev_desc, varname);
  

  } else { return CMD_RET_USAGE; }

@@ -458,4 +479,11 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt, " Example usage:\n" " gpt write mmc 0 $partitions\n" " gpt verify mmc 0 $partitions\n"

• " guid <interface> <dev>\n"
• " - print disk GUID\n"
• " guid <interface> <dev> <varname>\n"
• " - set environment variable to disk GUID\n"
• " Example usage:\n"
• " gpt guid mmc 0\n"
• " gpt guid mmc 0 varname\n"

); diff --git a/disk/part_efi.c b/disk/part_efi.c index 20d33ef..ff9f408 100644 --- a/disk/part_efi.c +++ b/disk/part_efi.c @@ -178,6 +178,37 @@ static void prepare_backup_gpt_header(gpt_header *gpt_h)

• Public Functions (include/part.h)

*/

+/*

• • UUID is displayed as 32 hexadecimal digits, in 5 groups,
• • separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters
• */

+int get_disk_guid(struct blk_desc * dev_desc, char *guid) +{

• ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, dev_desc->blksz);
• gpt_entry *gpt_pte = NULL;
• unsigned char *guid_bin;
• /* This function validates AND fills in the GPT header and PTE */
• if (is_gpt_valid(dev_desc, GPT_PRIMARY_PARTITION_TABLE_LBA,

• 	 gpt_head, &gpt_pte) != 1) {
  

• printf("%s: *** ERROR: Invalid GPT ***\n", __func__);
  

• if (is_gpt_valid(dev_desc, (dev_desc->lba - 1),
  
  

useless '()'

• 		 gpt_head, &gpt_pte) != 1) {
  

• 	printf("%s: *** ERROR: Invalid Backup GPT ***\n",
  

• 	       __func__);
  

• 	return -1;
  

return -EINVAL;?

• } else {
  

• 	printf("%s: ***        Using Backup GPT ***\n",
  

• 	       __func__);
  

• }
  

• }
• guid_bin = (unsigned char *)(gpt_head->disk_guid.b);

disk_guid.b is of type u8 which is the same as unsigned char. No need for a type cast here (and the () around gpt_head->... are unnecessary).

• uuid_bin_to_str(guid_bin, guid, UUID_STR_FORMAT_GUID);
• return 0;

+}

void part_print_efi(struct blk_desc *dev_desc) { ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, dev_desc->blksz); diff --git a/doc/README.gpt b/doc/README.gpt index 3fcd835..c0779a4 100644 --- a/doc/README.gpt +++ b/doc/README.gpt @@ -171,7 +171,8 @@ To restore GUID partition table one needs to: The fields 'uuid' and 'uuid_disk' are optional if CONFIG_RANDOM_UUID is enabled. A random uuid will be used if omitted or they point to an empty/ non-existent environment variable. The environment variable will be set to

• the generated UUID.

• the generated UUID. The 'gpt guid' command reads the current value of the

• uuid_disk from the GPT.

  The field 'bootable' is optional, it is used to mark the GPT partition bootable (set attribute flags "Legacy BIOS bootable").

diff --git a/include/part.h b/include/part.h index 87b1111..16c4a46 100644 --- a/include/part.h +++ b/include/part.h @@ -371,6 +371,21 @@ int gpt_verify_headers(struct blk_desc *dev_desc, gpt_header *gpt_head, int gpt_verify_partitions(struct blk_desc *dev_desc, disk_partition_t *partitions, int parts, gpt_header *gpt_head, gpt_entry **gpt_pte);

+/**

• • get_disk_guid() - Function to read the GUID string from a device's GPT
• • This function reads the GUID string from a block device whose descriptor
• • is provided.
• • @param dev_desc - block device descriptor
• • @param guid - pre-allocated string in which to return the GUID
• • @return - '0' on success, otherwise error
• */

+int get_disk_guid(struct blk_desc *dev_desc, char *guid);

#endif

#if CONFIG_IS_ENABLED(DOS_PARTITION)