releasetools: Fix the use of StringIO.
Based on the actual semantics, it actually wants an in-memory _bytes_
buffer (io.BytesIO), especially when running with Python 3. This CL
fixes the issue and adds a unittest.
Bug: 131631303
Test: python -m unittest test_sign_target_files_apks
Test: python3 -m unittest test_sign_target_files_apks
Change-Id: I3fb067acc26713f1842e831225607779fd0d1b7e
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index 4cb3a37..2f3642b 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -111,6 +111,7 @@
import copy
import errno
import gzip
+import io
import itertools
import logging
import os
@@ -746,12 +747,7 @@
filename: The archive name in the output zip.
keys: A list of public keys to use during OTA package verification.
"""
-
- try:
- from StringIO import StringIO
- except ImportError:
- from io import StringIO
- temp_file = StringIO()
+ temp_file = io.BytesIO()
certs_zip = zipfile.ZipFile(temp_file, "w")
for k in keys:
common.ZipWrite(certs_zip, k)