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#!/usr/bin/env python3
#============================================================================
#
#/** @file qgpt.py
#
# GENERAL DESCRIPTION
# Generates QCom GPT header for wrapping Bootblock
#
# Copyright (c) 2018, The Linux Foundation. All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause
#**/
#
import os
import math
import random
import re
import struct
import sys
import tempfile
from binascii import crc32
from optparse import OptionParser
from types import *
def UpdateMBR(options, GPTBlobBuffer):
i = 0x1BE
GPTBlobBuffer[i + 0] = 0x00 # not bootable
GPTBlobBuffer[i + 1] = 0x00 # head
GPTBlobBuffer[i + 2] = 0x01 # sector
GPTBlobBuffer[i + 3] = 0x00 # cylinder
GPTBlobBuffer[i + 4] = 0xEE # type
GPTBlobBuffer[i + 5] = 0xFF # head
GPTBlobBuffer[i + 6] = 0xFF # sector
GPTBlobBuffer[i + 7] = 0xFF # cylinder
GPTBlobBuffer[i + 8:i + 8 + 4] = [0x01, 0x00, 0x00, 0x00]
GPTBlobBuffer[i + 12:i + 16] = [0x00, 0x0f, 0x00, 0x00]
# magic byte for MBR partitioning - always at this location regardless of
# options.sector
GPTBlobBuffer[510:512] = [0x55, 0xAA]
return i
def UpdatePartitionEntry(options, GPTBlobBuffer):
i = 2 * options.sector_size
# GUID of Boot Block
GPTBlobBuffer[i:i + 16] = [0x2c, 0xba, 0xa0, 0xde, 0xdd, 0xcb, 0x05, 0x48,
0xb4, 0xf9, 0xf4, 0x28, 0x25, 0x1c, 0x3e, 0x98]
i += 16
#This is to set Unique Partition GUID. Below Hex Value is : 00ChezaBootblock00
GPTBlobBuffer[i:i + 16] = [0x00, 0x43, 0x68, 0x65, 0x7a, 0x61, 0x42, 0x6f,
0x6f, 0x74, 0x62, 0x6c, 0x6f, 0x63, 0x6b, 0x00]
i += 16
# LBA of BootBlock Start Content
GPTBlobBuffer[i:i + 8] = [0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
i += 8
# End LBA of BootBlock Content
GPTBlobBuffer[i] = options.end_lba & 0xFF
GPTBlobBuffer[i+1] = (options.end_lba>>8) & 0xFF
GPTBlobBuffer[i+2] = (options.end_lba>>16) & 0xFF
GPTBlobBuffer[i+3] = (options.end_lba>>24) & 0xFF
GPTBlobBuffer[i+4] = (options.end_lba>>32) & 0xFF
GPTBlobBuffer[i+5] = (options.end_lba>>40) & 0xFF
GPTBlobBuffer[i+6] = (options.end_lba>>48) & 0xFF
GPTBlobBuffer[i+7] = (options.end_lba>>56) & 0xFF
i += 8
# Attributes
GPTBlobBuffer[i:i + 8] = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
i += 8
# Label
GPTBlobBuffer[i:i + 17] = [0x62, 0x00, 0x6f, 0x00, 0x6f, 0x00, 0x74, 0x00,
0x62, 0x00, 0x6c, 0x00, 0x6f, 0x00, 0x63, 0x00, 0x6b]
return i
def UpdateGPTHeader(options, GPTBlobBuffer):
i = options.sector_size
# Signature and Revision and HeaderSize i.e. "EFI PART" and 00 00 01 00
# and 5C 00 00 00
GPTBlobBuffer[i:i + 16] = [0x45, 0x46, 0x49, 0x20, 0x50, 0x41, 0x52, 0x54,
0x00, 0x00, 0x01, 0x00, 0x5C, 0x00, 0x00, 0x00]
i += 16
# CRC is zeroed out till calculated later
GPTBlobBuffer[i:i + 4] = [0x00, 0x00, 0x00, 0x00]
i += 4
# Reserved, set to 0
GPTBlobBuffer[i:i + 4] = [0x00, 0x00, 0x00, 0x00]
i += 4
# Current LBA
GPTBlobBuffer[i:i + 8] = [0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
i += 8
# Backup LBA, No Backup Gpt Used
GPTBlobBuffer[i:i + 8] = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
i += 8
# First Usuable LBA (qc_sec + bootblock location)
GPTBlobBuffer[i:i + 8] = [0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
i += 8
# Last Usuable LBA (qc_sec + bootblock end location)
GPTBlobBuffer[i] = options.end_lba & 0xFF
GPTBlobBuffer[i+1] = (options.end_lba>>8) & 0xFF
GPTBlobBuffer[i+2] = (options.end_lba>>16) & 0xFF
GPTBlobBuffer[i+3] = (options.end_lba>>24) & 0xFF
GPTBlobBuffer[i+4] = (options.end_lba>>32) & 0xFF
GPTBlobBuffer[i+5] = (options.end_lba>>40) & 0xFF
GPTBlobBuffer[i+6] = (options.end_lba>>48) & 0xFF
GPTBlobBuffer[i+7] = (options.end_lba>>56) & 0xFF
i += 8
# GUID
GPTBlobBuffer[i:i + 16] = [0x32,0x1B,0x10,0x98,0xE2,0xBB,0xF2,0x4B,
0xA0,0x6E,0x2B,0xB3,0x3D,0x00,0x0C,0x20]
i += 16
# Partition Table Entry LBA
GPTBlobBuffer[i:i + 8] = [0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
i += 8
# Number of Partition Entries
GPTBlobBuffer[i:i + 4] = [0x01, 0x00, 0x00, 0x00]
i += 4
# Size of One Partition Entry
GPTBlobBuffer[i:i + 4] = [0x80, 0x00, 0x00, 0x00]
i += 4
# CRC of Partition Entry
PartEntry = GPTBlobBuffer[options.sector_size*2:options.sector_size*2 + 128]
CalcEntryCRC = crc32(b''.join(struct.pack("B", x) for x in PartEntry))
GPTBlobBuffer[i] = CalcEntryCRC & 0xFF
GPTBlobBuffer[i+1] = (CalcEntryCRC>>8) & 0xFF
GPTBlobBuffer[i+2] = (CalcEntryCRC>>16) & 0xFF
GPTBlobBuffer[i+3] = (CalcEntryCRC>>24) & 0xFF
i += 4
# CRC of Partition Table Header
GPTHeader = GPTBlobBuffer[options.sector_size:options.sector_size + 92]
CalcEntryCRC = crc32(b''.join(struct.pack("B", x) for x in GPTHeader))
i = options.sector_size + 16
GPTBlobBuffer[i] = CalcEntryCRC & 0xFF
GPTBlobBuffer[i+1] = (CalcEntryCRC>>8) & 0xFF
GPTBlobBuffer[i+2] = (CalcEntryCRC>>16) & 0xFF
GPTBlobBuffer[i+3] = (CalcEntryCRC>>24) & 0xFF
return i
if __name__ == '__main__':
usage = 'usage: %prog [OPTIONS] INFILE OUTFILE\n\n' + \
'Packages IMAGE in a GPT format.'
parser = OptionParser(usage)
parser.add_option('-s', type="int", dest='sector_size', default=4096,
help='Sector size in bytes [Default:4096(4KB)]',
metavar='SIZE')
(options, args) = parser.parse_args()
if len(args) != 2:
print("Invalid arguments! Exiting...\n")
parser.print_help()
sys.exit(1)
if options.sector_size != 4096 and options.sector_size != 512:
print("Invalid Sector Size")
sys.exit(1)
options.inputfile = args[0]
options.outputfile = args[1]
with open(options.inputfile, 'rb+') as fin:
bb_buffer = fin.read()
# Round up to next sector if bootblock size not evenly divisible
options.end_lba = ((len(bb_buffer) + options.sector_size - 1) //
options.sector_size)
# Add 3 sectors for MBR, GPT header and GPT partition entry
options.end_lba += 3
# Subtract one because this is last usable LBA, not amount of LBAs
options.end_lba -= 1
GPTBlobBuffer = [0] * (options.sector_size*3) #Size of MBR+GPT+PART_ENTRY
UpdateMBR(options, GPTBlobBuffer)
UpdatePartitionEntry(options, GPTBlobBuffer)
UpdateGPTHeader(options, GPTBlobBuffer)
with open(options.outputfile, 'wb') as fout:
for b in GPTBlobBuffer:
fout.write(struct.pack("B", b))
fout.write(bb_buffer)
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