Created patch-vbmeta.py

Completed script

patch-vbmeta.py

@@ -0,0 +1,44 @@
+import os
+import sys
+
+# Magic for the vbmeta image header
+AVB_MAGIC = b"AVB0"
+AVB_MAGIC_LEN = 4
+
+# Information about the verification flags
+FLAGS_OFFSET = 123
+FLAGS_TO_SET = b'\x03'
+
+
+### main program
+
+# if an argument is not provided
+if len(sys.argv) != 2:
+    sys.exit("Usage: python ./" + os.path.basename(__file__) + " <vbmeta-image>")
+
+# try reading the file with read/write to make sure it exists
+FILE = sys.argv[1]
+
+try:
+    fd = os.open(FILE, os.O_RDWR)
+except OSError:
+    sys.exit("Error reading file: " + FILE + ". File not modified. Exiting...")
+
+# making sure it's a vbmeta image by reading the magic bytes at the start of the file
+magic = os.read(fd, AVB_MAGIC_LEN)
+
+if (magic != AVB_MAGIC):
+    fd.close()
+    sys.exit("Error: The provided image is not a valid vbmeta image. File not modified. Exiting...")
+
+# set the disable-verity and disable-verification flags at offset 123
+try:
+    os.lseek(fd, FLAGS_OFFSET, os.SEEK_SET)
+    os.write(fd, FLAGS_TO_SET)
+except OSError:
+    fd.close()
+    sys.exit("Error: Failed when patching the vbmeta image. Exiting...")
+
+# end of program
+os.close(fd)
+print("Patching successful.")