More tools.

binsum.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# Many thanks to Alex W. who figured this out!
+
+"""
+Calculates the SHA1 of a fw_all.bin until the ending marker.
+"""
+
+from hashlib import sha1
+from struct import unpack
+from grmn import devices
+import sys
+
+FILE = sys.argv[1]
+BLOCKSIZE = 4096
+
+END_MARKER = b"\xff\xff\x5a\xa5\xff\xff\xff\xff"
+
+first_block = True
+past_end = False
+trailer = bytes()
+trailer_pos = -1
+
+csum = sha1()
+print("Reading {} ...".format(FILE))
+with open(FILE, "rb") as f:
+    while True:
+        block = f.read(BLOCKSIZE)
+        if first_block:
+            start = block.find(b"\xff\xff\xff\xff\xf0\xb9\x9d\x38\x0f\x46\x62\xc7")
+            if start < 0:
+                print("No Fenix firmware header found.")
+            else:
+                start += 4
+                hwid = unpack("<H", block[start+24:start+24+2])[0]
+                fver = unpack("<H", block[start+28:start+28+2])[0]
+                print("- Hardware ID: 0x{:04x} / {:d} ({})".format(hwid, hwid, devices.DEVICES.get(hwid, "Unknown device")))
+                print("- Firmware Version: 0x{:04x} / {:04d}".format(fver, fver))
+            first_block = False
+        if END_MARKER in block:
+            end_pos = block.find(END_MARKER)
+            marker_end = end_pos + len(END_MARKER)
+            past_end = True
+            csum.update(block[0:marker_end])
+            block = block[marker_end:]
+            trailer_pos = f.tell() - len(block)
+        if past_end:
+            trailer += block
+        else:
+            csum.update(block)
+        if len(block) < BLOCKSIZE:
+            break
+    f.close()
+print("Calculated SHA1: {}".format(csum.hexdigest()))
+print("SHA1 in file   : {} (offset 0x{:x})".format(trailer[:20].hex(), trailer_pos))