Add a simple script to add a capsule header

This may be helpful for OEMs and ODMs shipping 'bare' firmware.

contrib/add-capsule-header.py

@@ -0,0 +1,71 @@
+#!/usr/bin/python3
+#
+# Copyright (C) 2019 Richard Hughes <richard@hughsie.com>
+#
+# SPDX-License-Identifier: LGPL-2.1+
+
+import sys
+import uuid
+import argparse
+import struct
+
+CAPSULE_FLAGS_PERSIST_ACROSS_RESET = 0x00010000
+CAPSULE_FLAGS_POPULATE_SYSTEM_TABLE = 0x00020000
+CAPSULE_FLAGS_INITIATE_RESET = 0x00040000
+
+def main(args):
+
+    # parse GUID from command line
+    try:
+        guid = uuid.UUID(args.guid)
+    except ValueError as e:
+        print(e)
+        return 1
+    try:
+        with open(args.bin, 'rb') as f:
+            bin_data = f.read()
+    except FileNotFoundError as e:
+        print(e)
+        return 1
+
+    # check if already has header
+    hdrsz = struct.calcsize('<16sIII')
+    if len(bin_data) >= hdrsz:
+        hdr = struct.unpack('<16sIII', bin_data[:hdrsz])
+        imgsz = hdr[3]
+        if imgsz == len(bin_data):
+            print('Replacing existing CAPSULE_HEADER of:')
+            guid_mixed = uuid.UUID(bytes_le=hdr[0])
+            hdrsz_old = hdr[1]
+            flags = hdr[2]
+            print('GUID:      %s' % guid_mixed)
+            print('HdrSz:     0x%04x' % hdrsz_old)
+            print('Flags:     0x%04x' % flags)
+            print('PayloadSz: 0x%04x' % imgsz)
+            bin_data = bin_data[hdrsz_old:]
+
+    # set header flags
+    flags = CAPSULE_FLAGS_PERSIST_ACROSS_RESET | CAPSULE_FLAGS_INITIATE_RESET
+    if hasattr(args, 'flags'):
+        flags = int(args.flags, 16)
+
+    # build update capsule header
+    imgsz = hdrsz + len(bin_data)
+    hdr = struct.pack('<16sIII', guid.bytes_le, hdrsz, flags, imgsz)
+    with open(args.cap, 'wb') as f:
+        f.write(hdr + bin_data)
+    print('Wrote capsule %s' % args.cap)
+    print('GUID:      %s' % guid)
+    print('HdrSz:     0x%04x' % hdrsz)
+    print('Flags:     0x%04x' % flags)
+    print('PayloadSz: 0x%04x' % imgsz)
+    return 0
+
+parser = argparse.ArgumentParser(description='Add capsule header on firmware')
+parser.add_argument('--guid', help='GUID of the device', required=True)
+parser.add_argument('--bin', help='Path to the .bin file', required=True)
+parser.add_argument('--cap', help='Output capsule file path', required=True)
+parser.add_argument('--flags', help='Flags, e.g. 0x40000')
+args = parser.parse_args()
+
+sys.exit(main(args))