mbirth/gcd-parser
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Added gcddump to dump parsed GCD to files which can later be reassembled

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into a GCD.
This commit is contained in:
Markus Birth 2018-10-21 01:03:19 +02:00
parent c0a1d833ba
commit 27a90e8b38
Signed by: mbirth
GPG Key ID: A9928D7A098C3A9A
3 changed files with 154 additions and 2 deletions
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21
gcddump.py Normal file
View File

@ -0,0 +1,21 @@
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Dumps the structure of the given GCD file to file.
"""
from grmn import Gcd
import sys
if len(sys.argv) < 3:
print("Syntax: {} GCDFILE DUMPFILE (extension .rcp will be added)".format(sys.argv[0]))
sys.exit(1)
FILE = sys.argv[1]
OUTFILE = sys.argv[2]
print("Opening {}".format(FILE))
gcd = Gcd(FILE)
print("Dumping to {}.rcp".format(OUTFILE))
gcd.dump(OUTFILE)

50
grmn/gcd.py
View File

@ -8,6 +8,7 @@ GCD_SIG = b"G\x41RM\x49Nd\00"
DEFAULT_COPYRIGHT = b"Copyright 1996-2017 by G\x61rm\x69n Ltd. or its subsidiaries."
DEFAULT_FIRST_PADDING = 21
DEFAULT_ALIGN = 0x1000 # second padding block pads until 0x1000
MAX_BLOCK_LENGTH = 0xff00 # binary blocks max len
# Typical structure:
# first 0x1000 Bytes: GCD_SIG > 0x0001 > 0x0002 > 0x0003 > 0x0005 > 0x0001 > 0x0002
@ -27,6 +28,7 @@ class Gcd:
if self.filename is None:
return False
last_tlv6 = None
last_tlv7 = None
with open(self.filename, "rb") as f:
sig = f.read(8)
if sig != GCD_SIG:
@ -46,6 +48,9 @@ class Gcd:
last_tlv6 = tlv
elif tlv.type_id == 0x0007:
tlv.set_tlv6(last_tlv6)
last_tlv7 = tlv
elif tlv.is_binary:
tlv.set_tlv7(last_tlv7)
f.close()
def add_tlv(self, new_tlv: TLV):
@ -98,3 +103,48 @@ class Gcd:
else:
print("☒ ONE OR MORE CHECKSUMS INVALID!")
return all_ok
def write_dump_block(self, f, name):
f.write("\n[BLOCK_{}]\n".format(name))
def write_dump_param(self, f, key, value, comment=None):
if comment is not None:
f.write("# {}\n".format(comment))
f.write("{} = {}\n".format(key, value))
def dump(self, output_basename: str):
output_file = "{}.rcp".format(output_basename)
ctr = 0
last_filename = None
with open(output_file, "wt") as f:
f.write("[GCD_DUMP]\n")
f.write("dump_by = grmn-gcd\n")
f.write("dump_ver = 1\n")
f.write("original_filename = {}\n\n".format(self.filename))
f.write("# [BLOCK_nn] headers are just for parsing/grouping purposes.\n")
f.write("# Lengths are informational only, they will be calculated upon reassembly.\n")
for tlv in self.struct:
if tlv.is_binary:
outfile = "{}_{:04x}.bin".format(output_basename, tlv.type_id)
if outfile != last_filename:
self.write_dump_block(f, str(ctr))
self.write_dump_param(f, "from_file", outfile)
for item in tlv.dump():
self.write_dump_param(f, item[0], item[1], item[2])
last_filename = outfile
with open(outfile, "wb") as of:
of.write(tlv.value)
else:
with open(outfile, "ab") as of:
of.write(tlv.value)
elif tlv.type_id == 0xffff:
# EOF marker
pass
else:
tlvinfo = tlv.dump()
if len(tlvinfo) > 0:
self.write_dump_block(f, str(ctr))
for item in tlvinfo:
self.write_dump_param(f, item[0], item[1], item[2])
ctr += 1
f.close()

85
grmn/tlv.py
View File

@ -1,6 +1,7 @@
# -*- coding: utf-8 -*-
from . import devices
from binascii import hexlify
from struct import pack, unpack
TLV_TYPES = {
@ -22,6 +23,7 @@ TLV_TYPES = {
class TLV:
def __init__(self, type_id: int, expected_length: int, value=None, offset: int=None):
self.type_id = type_id
self.is_binary = False
self.offset = offset
self.comment = TLV_TYPES.get(type_id, "Type {:04x} / {:d}".format(type_id, type_id))
self.length = expected_length
@ -33,10 +35,19 @@ class TLV:
@staticmethod
def factory(header: bytes, offset: int = None):
(type_id, length) = unpack("<HH", header)
if type_id == 0x0006:
if type_id == 0x0001:
new_tlv = TLV1(type_id, length)
elif type_id == 0x0002:
new_tlv = TLV2(type_id, length)
elif type_id == 0x0005:
new_tlv = TLV5(type_id, length)
elif type_id == 0x0006:
new_tlv = TLV6(type_id, length)
elif type_id == 0x0007:
new_tlv = TLV7(type_id, length)
elif type_id in [0x0008, 0x0401, 0x0505, 0x0555, 0x0557, 0x02bd]:
new_tlv = TLVbinary(type_id, length)
new_tlv.is_binary = True
else:
new_tlv = TLV(type_id, length)
new_tlv.offset = offset
@ -73,6 +84,43 @@ class TLV:
return header
return header + self.value
def dump(self):
"""Should return a list of key-value-comment tuples so the object can be recreated using create_from_dump() later."""
data = []
data.append(("type", "0x{:04x}".format(self.type_id), self.comment))
data.append(("length", self.get_actual_length(), None))
if self.value is not None:
hexstr = hexlify(self.value).decode("utf-8")
hexstr = " ".join(hexstr[i:i+2] for i in range(0, len(hexstr), 2))
data.append(("value", hexstr, None))
return data
@staticmethod
def create_from_dump(values):
"""Use data exported with dump() to recreate object."""
pass
class TLV1(TLV):
def dump(self):
data = []
data.append(("type", "0x{:04x}".format(self.type_id), self.comment))
return data
class TLV2(TLV):
def dump(self):
data = []
data.append(("type", "0x{:04x}".format(self.type_id), self.comment))
data.append(("length", self.get_actual_length(), "Length of padding block"))
return data
class TLV5(TLV):
def dump(self):
data = []
data.append(("type", "0x{:04x}".format(self.type_id), self.comment))
data.append(("length", self.get_actual_length(), None))
data.append(("text", self.value.decode("utf-8"), None))
return data
class TLV6(TLV):
"""
Describes following TLV7:
@ -90,7 +138,7 @@ class TLV6(TLV):
0x1014: ["H", "Field 1014"],
0x1015: ["H", "Field 1015"],
0x1016: ["H", "Field 1016 (WiFi fw)"],
0x2015: ["L", "Block size"],
0x2015: ["L", "Binary length"],
0x5003: ["", "End of definition marker"],
}
@ -119,6 +167,10 @@ class TLV6(TLV):
txt += "\n - Field {:d}: {:04x} - {}".format(i+1, fid, self.fields[i])
return txt
def dump(self):
# Dump nothing as important info will be chained in binary dump
return []
class TLV7(TLV):
def __init__(self, type_id: int, expected_length: int, value=None, offset: int=None):
super().__init__(type_id, expected_length, value, offset)
@ -153,3 +205,32 @@ class TLV7(TLV):
txt += "\n - Field {:d}: {:>20}: 0x{:04x} / {:d}".format(i+1, fdesc, v, v)
return txt
def dump(self):
# Dump nothing as important info will be chained in binary dump
return []
class TLVbinary(TLV):
def __init__(self, type_id: int, expected_length: int, value=None, offset: int=None):
super().__init__(type_id, expected_length, value, offset)
self.tlv7 = None
def set_tlv7(self, tlv7: TLV7):
self.tlv7 = tlv7
def dump(self):
data = []
# type is given in fields list from TLV7 already
if not self.tlv7.is_parsed:
self.tlv7.parse()
for i, pair in enumerate(self.tlv7.attr):
fdesc = self.tlv7.tlv6.fields[i]
valtype = self.tlv7.tlv6.format[i]
(fid, v) = pair
if valtype == "B":
valstr = "0x{:02x}".format(v)
elif valtype == "H":
valstr = "0x{:04x}".format(v)
else:
valstr = "0x{:08x}".format(v)
data.append(("0x{:04x}".format(fid), valstr, fdesc))
return data