Let a patched app use Google sign-in and push through MicroG RE

[kuomartin]

Problem

A patched app is signed with LSPatch's key, so Google Play services refuses it wherever it checks the caller's certificate; Google sign-in fails with UNREGISTERED_ON_API_CONSOLE. MicroG RE (ReVanced GmsCore) can stand in for it, but only if the app's traffic reaches it and it knows the app's original certificate.

This supersedes #84, which no longer applies to master and cannot be edited by maintainers. The redirect is ported from NPatch's current version of that work; its authors are credited as co-authors.

Solution

An opt-in MicroG RE support option (--microg-re, also in the manager), recorded in the patch config so a re-patch keeps it.

Patch time — the manifest gets:

• app.revanced.android.gms.SPOOFED_PACKAGE_SIGNATURE: the original certificate's SHA-1, which MicroG RE reports to Google instead of the caller's.
• Every com.google.android.c2dm.* string renamed to app.revanced.android.c2dm.*. MicroG RE finds the push receiver by its own RECEIVE action, and the receiver only accepts senders holding com.google.android.c2dm.permission.SEND, a signature permission MicroG RE cannot hold. The manifest editor never descends into intent filters, so the rename is a separate pass over the AXML.

Run time — GmsRedirector rewrites the package, component, action and provider authority of GMS-bound intents and provider calls to MicroG RE, and maps C2DM actions both ways. CHOOSE_ACCOUNT goes to the system account picker; the chimera authority is left to Google Play services.

Differences from #84 and NPatch:

• An intent the app addresses to itself keeps its action, including through readFromParcel: the sign-in library opens its own SignInHubActivity with GOOGLE_SIGN_IN, and that activity finishes on any other action.
• No ContentResolver.call retry. It rewrote arguments after the call had returned and swallowed the SecurityException, so callers got null instead of an error.
• No getPackageInfo hook. It reported the app's own certificate as MicroG's, which matches no check a GMS client makes.

Scope:

• MicroG RE only. Upstream microG installs as Google Play services, needs no redirect, and would lose pushes to the rename. For it, --fake-signature declares fake-signature with FAKE_PACKAGE_SIGNATURE for a ROM with signature spoofing, as a separate option, also recorded in the patch config.
• The loader redirects only if it can see MicroG RE, which the app's <queries> don't cover. Local mode already holds QUERY_ALL_PACKAGES; integrated mode needs it added through the added permissions. The option's description and the loader's log say so.

Validation

On a Pixel 10 (Android 17), ReVanced GmsCore installed beside Google Play services, local mode:

• Google sign-in completes through MicroG RE, which reports the original certificate.
• Push reaches the app's FCM service, and the app acknowledges it.
• Rewrite rules (action redirect and restore, self-addressed intents, C2DM mapping) pass a JVM check outside the repo, which has no JUnit setup.
• The patched manifest for --microg-re, --fake-signature and neither, in both modes, carries exactly the entries above.

Not covered: --fake-signature (no ROM with signature spoofing at hand).