Improve payload magic header handling
Currently, we use central directory's extra fields and filenames to
determine starting position of a zipentry's file data. However, central
directory's extra field might differ from extra field in local file
header. For example, the Extended-Timestamp field has different formats
depending on whether it's in local file header or central directory. We
should use local file header for computing offsets.
Test: Serve an OTA by update_device.py
Change-Id: I00d150d874b9c874bb713569ea14938e036f854e
diff --git a/scripts/update_device.py b/scripts/update_device.py
index 7be3edb..1cd4b6a 100755
--- a/scripts/update_device.py
+++ b/scripts/update_device.py
@@ -20,12 +20,14 @@
from __future__ import absolute_import
import argparse
+import binascii
import hashlib
import logging
import os
import socket
import subprocess
import sys
+import struct
import threading
import xml.etree.ElementTree
import zipfile
@@ -89,6 +91,7 @@
OTA_PAYLOAD_PROPERTIES_TXT = 'payload_properties.txt'
SECONDARY_OTA_PAYLOAD_BIN = 'secondary/payload.bin'
SECONDARY_OTA_PAYLOAD_PROPERTIES_TXT = 'secondary/payload_properties.txt'
+ PAYLOAD_MAGIC_HEADER = b'CrAU'
def __init__(self, otafilename, secondary_payload=False):
self.otafilename = otafilename
@@ -97,10 +100,34 @@
payload_entry = (self.SECONDARY_OTA_PAYLOAD_BIN if secondary_payload else
self.OTA_PAYLOAD_BIN)
payload_info = otazip.getinfo(payload_entry)
- self.offset = payload_info.header_offset
- self.offset += zipfile.sizeFileHeader
- self.offset += len(payload_info.extra) + len(payload_info.filename)
- self.size = payload_info.file_size
+
+ if payload_info.compress_type != 0:
+ logging.error(
+ "Expected layload to be uncompressed, got compression method %d",
+ payload_info.compress_type)
+ # Don't use len(payload_info.extra). Because that returns size of extra
+ # fields in central directory. We need to look at local file directory,
+ # as these two might have different sizes.
+ with open(otafilename, "rb") as fp:
+ fp.seek(payload_info.header_offset)
+ data = fp.read(zipfile.sizeFileHeader)
+ fheader = struct.unpack(zipfile.structFileHeader, data)
+ # Last two fields of local file header are filename length and
+ # extra length
+ filename_len = fheader[-2]
+ extra_len = fheader[-1]
+ self.offset = payload_info.header_offset
+ self.offset += zipfile.sizeFileHeader
+ self.offset += filename_len + extra_len
+ self.size = payload_info.file_size
+ fp.seek(self.offset)
+ payload_header = fp.read(4)
+ if payload_header != self.PAYLOAD_MAGIC_HEADER:
+ logging.warning(
+ "Invalid header, expeted %s, got %s."
+ "Either the offset is not correct, or payload is corrupted",
+ binascii.hexlify(self.PAYLOAD_MAGIC_HEADER),
+ payload_header)
property_entry = (self.SECONDARY_OTA_PAYLOAD_PROPERTIES_TXT if
secondary_payload else self.OTA_PAYLOAD_PROPERTIES_TXT)