Python script to inject the EOI marker into panoramic photos created by the S7 camera. In addition the script allows to dump the Samsung specific data that is added to the image

## fix_eoi.py
#!/usr/bin/python

# The Samsung trailer format is based on the implementation from ExifTool
# http://www.sno.phy.queensu.ca/~phil/exiftool/

import mmap
import struct
import os
import sys

if (len(sys.argv) < 2) or (len(sys.argv) > 3):
	print("Usage: fix_eoi.py <filename> [dump]")
	exit()

file = sys.argv[1]

if len(sys.argv) < 3:
	dump = 0
elif sys.argv[2] == "dump":
	dump = 1
else:
	print("Invalid argument")
	print("Usage: fix_eoi.py <filename> [dump]")
	exit()

(file_name, file_ext) = os.path.splitext(file)

with open(file, 'rb') as fh:
	m = mmap.mmap(fh.fileno(), 0, access=mmap.ACCESS_READ)
	b = bytearray(m)

	trailer_tail = b[-4:]

	if trailer_tail != 'SEFT':
		print("No valid Samsung trailer found")
		exit()
	else:
		print("Found SEFT")

	length = struct.unpack_from("<I",b[-8:-4])[0]
	trailer = b[-(8+length):]

	endPos = len(b)
	dirPos = endPos-(8+length)

	if trailer[0:4] != 'SEFH':
		print("No valid Samsung trailer found")
		exit()
	else:
		print("Found SEFH")

	version = struct.unpack_from("<I",trailer[4:8])[0]
	if version != 101:
		print("Unknown Samsung trailer version")
		exit()

	count = struct.unpack_from("<I",trailer[8:12])[0]

	firstBlock = 0
	is_pano = 0

	for index in range(0, count):
		entry = 12 + 12 * index;

		type = struct.unpack_from("<H",trailer[entry+2:entry+4])[0]
		noff = struct.unpack_from("<I",trailer[entry+4:entry+8])[0]
		size = struct.unpack_from("<I",trailer[entry+8:entry+12])[0]

		if firstBlock < noff:
			firstBlock = noff

		entryPos = dirPos - noff
		entryLen = size

		data = b[entryPos:entryPos+entryLen]

		# Validate as the type has to match the SEFH/SEFT entry type
		entry_type = struct.unpack_from("<H",data[2:4])[0]
		if type != entry_type:
			print("Missmatch detected. Aborting!")
			exit()

		entry_offset = struct.unpack_from("<I",data[4:8])[0]
		entry_name = data[8:8+entry_offset].decode("utf-8")

		if entry_name == "Panorama_Shot_Info":
			is_pano = 1

		entry_data = data[8+entry_offset:]

		if dump:
			print("Dumping: %s" % entry_name)
			with open(file_name + '_' + entry_name, 'wb') as f:
				f.write(entry_data)

	if not is_pano:
		print "No Panorama info found"
		exit()

	dataPos = dirPos - firstBlock
	dirLen = endPos - dataPos

	eoi = struct.unpack_from(">H",b[dataPos-2:dataPos])[0]
	if eoi == 0xffd9:
		print("Found EOI")
		exit()
	else:
		print("Inserting EOI")
		with open(file_name + '_pano' + file_ext, 'wb') as f:
				f.write(b[0:dataPos])
				f.write(bytearray(b'\xff\xd9'))
				f.write(b[dataPos:])