Re-invent page aligning libraries in APK file.

build/android/gyp/finalize_apk.py

Index: build/android/gyp/finalize_apk.py
diff --git a/build/android/gyp/finalize_apk.py b/build/android/gyp/finalize_apk.py
index e66eac67e263baf4be4953f7e3b4702b13249102..5ba09e2ea48d82e069a491a80f313a8bc4d2e0a9 100755
--- a/build/android/gyp/finalize_apk.py
+++ b/build/android/gyp/finalize_apk.py
@@ -14,17 +14,33 @@ import tempfile
 
 from util import build_utils
 
-def RenameLibInApk(rezip_path, in_zip_file, out_zip_file):
-  rename_cmd = [
-      rezip_path,
-      'rename',
+def AddPageAlignment(prealign_path, in_zip_file, out_zip_file):
+  prealign_cmd = [
+      'java',
+      '-classpath',
+      prealign_path,
+      'PrealignApk',
+      'addalignment',
       in_zip_file,
       out_zip_file,
     ]
-  build_utils.CheckOutput(rename_cmd)
+  build_utils.CheckOutput(prealign_cmd)
+
+
+def ReorderApk(prealign_path, in_zip_file, out_zip_file):
+  prealign_cmd = [
+      'java',
+      '-classpath',
+      prealign_path,
+      'PrealignApk',
+      'reorder',
+      in_zip_file,
+      out_zip_file,
+    ]
+  build_utils.CheckOutput(prealign_cmd)
 
 
-def SignApk(key_path, key_name, key_passwd, unsigned_path, signed_path):
+def JarSigner(key_path, key_name, key_passwd, unsigned_path, signed_path):
   shutil.copy(unsigned_path, signed_path)
   sign_cmd = [
       'jarsigner',
@@ -48,20 +64,10 @@ def AlignApk(zipalign_path, unaligned_path, final_path):
   build_utils.CheckOutput(align_cmd)
 
 
-def UncompressLibAndPageAlignInApk(rezip_path, in_zip_file, out_zip_file):
+def RenameAndUncompressLibInApk(rezip_path, in_zip_file, out_zip_file):
   rename_cmd = [
       rezip_path,
-      'inflatealign',
-      in_zip_file,
-      out_zip_file,
-    ]
-  build_utils.CheckOutput(rename_cmd)
-
-
-def DropDataDescriptorsInApk(rezip_path, in_zip_file, out_zip_file):
-  rename_cmd = [
-      rezip_path,
-      'dropdescriptors',
+      'renameinflate',
       in_zip_file,
       out_zip_file,
     ]
@@ -72,6 +78,7 @@ def main():
   parser = optparse.OptionParser()
   build_utils.AddDepfileOption(parser)
 
+  parser.add_option('--prealign-path', help='Path to the prealign tool.')
   parser.add_option('--zipalign-path', help='Path to the zipalign tool.')
   parser.add_option('--rezip-path', help='Path to the rezip executable.')
   parser.add_option('--unsigned-apk-path', help='Path to input unsigned APK.')
@@ -90,41 +97,36 @@ def main():
 
   with tempfile.NamedTemporaryFile() as signed_apk_path_tmp, \
       tempfile.NamedTemporaryFile() as apk_to_sign_tmp, \
-      tempfile.NamedTemporaryFile() as apk_without_descriptors_tmp, \
-      tempfile.NamedTemporaryFile() as aligned_apk_tmp:
+      tempfile.NamedTemporaryFile() as uncompress_lib_apk_tmp:
 
     if options.load_library_from_zip_file:
       # We alter the name of the library so that the Android Package Manager
       # does not extract it into a separate file. This must be done before
-      # signing, as the filename is part of the signed manifest.
+      # signing, as the filename is part of the signed manifest. At the same
+      # time we uncompress the library, which is necessary so that it can be
+      # loaded directly from the APK.
+      uncompress_lib_apk_path = uncompress_lib_apk_tmp.name
+      RenameAndUncompressLibInApk(
+          options.rezip_path, options.unsigned_apk_path,
+          uncompress_lib_apk_path)
       apk_to_sign = apk_to_sign_tmp.name
-      RenameLibInApk(options.rezip_path, options.unsigned_apk_path, apk_to_sign)
+      # Move the library to a page boundary by adding a page alignment file.
+      AddPageAlignment(
+          options.prealign_path, uncompress_lib_apk_path, apk_to_sign)
     else:
       apk_to_sign = options.unsigned_apk_path
 
     signed_apk_path = signed_apk_path_tmp.name
-    SignApk(options.key_path, options.key_name, options.key_passwd,
-            apk_to_sign, signed_apk_path)
+    JarSigner(options.key_path, options.key_name, options.key_passwd,
+              apk_to_sign, signed_apk_path)
 
     if options.load_library_from_zip_file:
-      # Signing adds data descriptors to the APK. These are redundant
-      # information. We remove them as otherwise they can cause a
-      # miscalculation in the page alignment.
-      apk_to_align = apk_without_descriptors_tmp.name
-      DropDataDescriptorsInApk(
-          options.rezip_path, signed_apk_path, apk_to_align)
-      aligned_apk = aligned_apk_tmp.name
+      # Reorder the contents of the APK. This re-establishes the canonical
+      # order which means the library will be back at its page aligned location.
+      ReorderApk(options.prealign_path, signed_apk_path, options.final_apk_path)

[rmcilroy, 2014/09/29 11:38:32]

Given that ReorderApk also aligns the APK, could you mention that in the comment
above and name this function ReorderAndAlignApk, just so nobody is tempted to do
the AlignApk step on the output of this step.

[Anton, 2014/09/29 16:30:17]

Done.

     else:
-      apk_to_align = signed_apk_path
-      aligned_apk = options.final_apk_path
-
-    # Align uncompress items to 4 bytes
-    AlignApk(options.zipalign_path, apk_to_align, aligned_apk)
-
-    if options.load_library_from_zip_file:
-      # Uncompress the library and make sure that it is page aligned.
-      UncompressLibAndPageAlignInApk(
-          options.rezip_path, aligned_apk, options.final_apk_path)
+      # Align uncompress items to 4 bytes
+      AlignApk(options.zipalign_path, signed_apk_path, options.final_apk_path)
 
   if options.depfile:
     build_utils.WriteDepfile(