A custom APEX signing tool with --signing_args

apex_utils.SignApex() has `signing_args` argument which is supposed to
be passed to avbtool to set `--signing_helper` or
`--signing_helper_with_files`.

A custom APEX signing tool which relies on avbtool's signing should pass
the same arguments when signing_args is set.

This change passes signing_args verbatim to the custom APEX signing tool
via --signing_args argument.

Bug: 216971834
Test: tbd
Change-Id: I8aaec9440c4536e11e1e4a1dd4ae5f4fe32d4f23

tools/releasetools/apex_utils.py

@@ -102,14 +102,14 @@ class ApexApkSigner(object):
                        ' %s', entry)
 
     payload_dir, has_signed_content = self.ExtractApexPayloadAndSignContents(
-        apk_entries, apk_keys, payload_key)
+        apk_entries, apk_keys, payload_key, signing_args)
     if not has_signed_content:
       logger.info('No contents has been signed in %s', self.apex_path)
       return self.apex_path
 
     return self.RepackApexPayload(payload_dir, payload_key, signing_args)
 
-  def ExtractApexPayloadAndSignContents(self, apk_entries, apk_keys, payload_key):
+  def ExtractApexPayloadAndSignContents(self, apk_entries, apk_keys, payload_key, signing_args):
     """Extracts the payload image and signs the containing apk files."""
     if not os.path.exists(self.debugfs_path):
       raise ApexSigningError(
@@ -143,7 +143,12 @@ class ApexApkSigner(object):
 
     if self.sign_tool:
       logger.info('Signing payload contents in apex %s with %s', self.apex_path, self.sign_tool)
-      cmd = [self.sign_tool, '--avbtool', self.avbtool, payload_key, payload_dir]
+      # Pass avbtool to the custom signing tool
+      cmd = [self.sign_tool, '--avbtool', self.avbtool]
+      # Pass signing_args verbatim which will be forwarded to avbtool (e.g. --signing_helper=...)
+      if signing_args:
+        cmd.extend(['--signing_args', '"{}"'.format(signing_args)])
+      cmd.extend([payload_key, payload_dir])
       common.RunAndCheckOutput(cmd)
       has_signed_content = True