Added gcddump to dump parsed GCD to files which can later be reassembled

into a GCD.

grmn/gcd.py

@@ -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()