diff --git a/common/filetype.c b/common/filetype.c index 22fc621..8652f1d 100644 --- a/common/filetype.c +++ b/common/filetype.c @@ -48,6 +48,7 @@ [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 +70,53 @@ #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 and EFI PART, 0 otherwise. + * Validity depends on three things: + * 1) MSDOS signature is in the last two bytes of the MBR + * 2) One partition of type 0xEE is found + * 3) EFI GPT signature is at offset 512 + */ +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 +204,13 @@ if (bufsize < 512) return filetype_unknown; + /* + * EFI GPT need to be detected before MBR otherwise + * we will detect a MBR + */ + 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 @@ filetype_bmp, filetype_png, filetype_ext, + filetype_gpt, filetype_max, };