[PATCH 2/5] filetype: add GPT support

[Sascha Hauer]

On Fri, Feb 15, 2013 at 02:35:14PM +0100, Jean-Christophe PLAGNIOL-VILLARD wrote:
> GPT need to be check before MBR
> 
> Cc: Rob Herring <rob.herring at calxeda.com>
> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
> ---
>  common/filetype.c  |   47 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/filetype.h |    1 +
>  2 files changed, 48 insertions(+)
> 
> diff --git a/common/filetype.c b/common/filetype.c
> index 22fc621..06fa803 100644
> --- a/common/filetype.c
> +++ b/common/filetype.c
> @@ -48,6 +48,7 @@ static const struct filetype_str filetype_str[] = {
>  	[filetype_bmp] = { "BMP image", "bmp" },
>  	[filetype_png] = { "PNG image", "png" },
>  	[filetype_ext] = { "ext filesystem", "ext" },
> +	[filetype_gpt] = { "GUID Partition Table", "gpt" },
>  };
>  
>  const char *file_type_to_string(enum filetype f)
> @@ -69,9 +70,52 @@ const char *file_type_to_short_string(enum filetype f)
>  #define MBR_StartSector		8	/* MBR: Offset of Starting Sector in Partition Table Entry */
>  #define BS_55AA			510	/* Boot sector signature (2) */
>  #define MBR_Table		446	/* MBR: Partition table offset (2) */
> +#define MBR_partition_size	16	/* MBR: Partition table offset (2) */
>  #define BS_FilSysType32		82	/* File system type (1) */
>  #define BS_FilSysType		54	/* File system type (1) */
>  
> +#define MBR_PART_sys_ind	4
> +#define MBR_PART_start_sect	8
> +#define MBR_OSTYPE_EFI_GPT	0xee
> +
> +static inline int pmbr_part_valid(const uint8_t *buf)
> +{
> +	if (buf[MBR_PART_sys_ind] == MBR_OSTYPE_EFI_GPT &&
> +		get_unaligned_le32(&buf[MBR_PART_start_sect]) == 1UL) {
> +		return 1;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * is_gpt_valid(): test Protective MBR for validity and EFI PART
> + * @mbr: pointer to a legacy mbr structure
> + *
> + * Description: Returns 1 if PMBR is valid, 0 otherwise.
> + * Validity depends on two things:
> + *  1) MSDOS signature is in the last two bytes of the MBR
> + *  2) One partition of type 0xEE is found

Still wrong. This describes is_pmbr_valid, but the function is named and
implements is_gpt_valid. I suggest implemting a real is_pmbr_valid
function and call it from is_gpt_valid which additionally checks for the
gpt header.

Sascha


> + */
> +static int is_gpt_valid(const uint8_t *buf)
> +{
> +	int i;
> +
> +	if (get_unaligned_le16(&buf[BS_55AA]) != 0xAA55)
> +		return 0;
> +
> +	if (strncmp(&buf[512], "EFI PART", 8))
> +		return 0;
> +
> +	buf += MBR_Table;
> +
> +	for (i = 0; i < 4; i++, buf += MBR_partition_size) {
> +		if (pmbr_part_valid(buf))
> +			return 1;
> +	}
> +	return 0;
> +}
> +
>  enum filetype is_fat_or_mbr(const unsigned char *sector, unsigned long *bootsec)
>  {
>  	/*
> @@ -159,6 +203,9 @@ enum filetype file_detect_type(const void *_buf, size_t bufsize)
>  	if (bufsize < 512)
>  		return filetype_unknown;
>  
> +	if (bufsize >= 520 && is_gpt_valid(buf8))
> +		return filetype_gpt;
> +
>  	type = is_fat_or_mbr(buf8, NULL);
>  	if (type != filetype_unknown)
>  		return type;
> diff --git a/include/filetype.h b/include/filetype.h
> index 4d43757..78ca5d2 100644
> --- a/include/filetype.h
> +++ b/include/filetype.h
> @@ -23,6 +23,7 @@ enum filetype {
>  	filetype_bmp,
>  	filetype_png,
>  	filetype_ext,
> +	filetype_gpt,
>  	filetype_max,
>  };
>  
> -- 
> 1.7.10.4
> 
> 
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