from struct import unpack
import os

def readUnpack(bytes, **options):
    if options.get("type") == 't':
        #print 'DEBUG: In t'
        SOS = SOSfile.read(bytes)
        text_unpacked = unpack('%ss' % bytes, SOS)
        return ''.join(text_unpacked)

    if options.get("type") == 'b':
        #print 'DEBUG: In b', bytes
        SOS = SOSfile.read(bytes)
        #print 'DEBUG: In b2', bytes, SOS
        offset_unpacked = unpack ('< H', SOS)
        #print 'DEBUG: In b3', bytes, SOS
        return int('.'.join(str(x) for x in offset_unpacked))

    if options.get("type") == '1':
        SOS = SOSfile.read(bytes)
        offset_unpacked = unpack ('< B', SOS)
        return int(ord(SOS))

dev_types ={273: 'Character Device, Write-Only, Formatter',
            321: 'Character Device, Write-Only, RS232 Printer',           # Dicionary for Types and SubTypes
            577: 'Character Device, Write-Only, Silentype',
            833: 'Character Device, Write-Only, Parallel Printer',
            323: 'Character Device, Write-Only, Sound Port',
            353: 'Character Device, Read-Write, System Console',
            354: 'Character Device, Read-Write, Graphics Screen',
            355: 'Character Device, Read-Write, Onboard RS232',
            356: 'Character Device, Read-Write, Parallel Card',
            481: 'Block Device, Disk ///',
            721: 'Block Device, PROFile',
            4337: 'Block Device, CFFA3000'}

#Clear SCREEN
print("\033c");

#Is File a SOS DRIVER file?

SOSfile = open('SOSCFFA.DRIVER', 'rb')
filetype = readUnpack(8, type = 't')

if filetype == 'SOS DRVR':
    print "This is a proper SOS file."
    print "Filetype is: %s." % (filetype)
else:
    print "Filetype is: %s." % (filetype)
    print "This is not a proper SOS file"
    exit()

rel_offset = readUnpack(2, type = 'b')                                  # Read two bytes after SOS DRVR to establish first rel_offset value
print "The first relative offset value is", rel_offset, hex(rel_offset) # Print out for debug
drivers = 0                                                             # This is to keep a running total of drivers.
drivers_list=[]                                                         # Initialize a list to hold dictionaries.

loop = True                                                             # Set True for major driver loop
while loop :                                                            # establish loop to find major drivers
    driver = {}                                                         # Intialize a dictionary to hold vaules as we loop
    SOSfile.seek(rel_offset,1)                                          # Jump to location of first driver
    driver['location'] = SOSfile.tell()                                 # add to driver dictionary 52c
    rel_offset = readUnpack(2, type = 'b')                              # 0000 comment length
    if rel_offset == 0xFFFF:                                            # If we encounter FFFF, no more drivers
        loop = False                                                    # Set loop to False to cancel while
    else :
        drivers_list.append(driver)                                     # add to drivers_list list
        SOSfile.seek(rel_offset,1)                                      # seek forward based on contents of rel_offset
        rel_offset = readUnpack(2, type = 'b')                          # read 2 bytes and stick into rel_offset
        SOSfile.seek(rel_offset,1)                                      # seek forward based on contents of rel_offset
        rel_offset = readUnpack(2, type = 'b')                          # read 2 bytes and stick into rel_offset

for i in range(0,len(drivers_list)):                                    # begin loop to grab information from DIB
    SOSfile.seek(drivers_list[i]['location'],0)                         # reference SOF and seek to beginning of major driver
    atell = SOSfile.tell()
    comment_len = readUnpack(2, type = 'b')                             # grab comment length (2 bytes)
    drivers_list[i]['comment_len'] = comment_len                        # store comment length
    if comment_len != 0:                                                # if comment length is not 0000
        comment_txt = readUnpack(comment_len, type = 't')               # comment_len bytes as text
        drivers_list[i]['comment_txt'] = comment_txt                    # place comment in dictionary
    else:
        drivers_list[i]['comment_txt'] = ''                             # else enter comment as nothing
    SOSfile.seek(2,1)                                                   # Skip two bytes immediately following comment or 0000
    link_ptr = readUnpack(2, type = 'b')                                # Grab link pointer
    drivers_list[i]['link_ptr'] = link_ptr                              # Store link pointer
    entry = readUnpack(2, type = 'b')                                   # Grab entry field
    drivers_list[i]['entry'] = entry                                    # Store entry field
    name_len = readUnpack(1, type = '1')                                # Grab one byte for name length
    drivers_list[i]['name_len'] = name_len                              # Store name length
    name = readUnpack(name_len, type = 't')                             # Read name based on length
    drivers_list[i]['name'] = name                                      # Store name
    SOSfile.seek(15 - name_len,1)                                       # Skip past remainder of 15-byte long name field
    flag = readUnpack(1, type = '1')                                    # Grab Flag byte
    if flag == 128:                                                     # Is flag 0x80?
        drivers_list[i]['flag'] = 'ACTIVE'                              # Insert Flag into dictionary with value ACTIVE
    else:                                                               # otherwise...
        drivers_list[i]['flag'] = 'INACTIVE'                            # Insert Flag into dictionary with value INACTIVE
    slot_num = readUnpack(1, type = '1')                                # Grab slot number
    if slot_num == 0:                                                   # Check if device has no slot number...
        drivers_list[i]['slot_num'] = 'None'                            # ... and indicate so.
    else:                                                               # otherwise...
        drivers_list[i]['slot_num'] = slot_num                          # ... enter slot number into the dictionary
    unit = readUnpack(1, type = '1')                                    # get the unit byte
    drivers_list[i]['unit'] = unit                                      # store unit in dictionary
    dev_type = readUnpack(2, type ='b')                                 # Grab bytes for type and subtype
    drivers_list[i]['dev_type'] = dev_types[dev_type]

    print drivers_list[i]['dev_type']
#    print drivers_list[i]['name_len']

SOSfile.close()