From 11b2ddbad8fe3f1c365e6f29b65a4c24e69319f2 Mon Sep 17 00:00:00 2001
From: LoveSy <shana@zju.edu.cn>
Date: Wed, 23 Nov 2022 03:49:31 +0800
Subject: [PATCH] Fix zygisk v4 ApiTable abi

Also refactor some code to let the compiler check the abi

Co-authored-by: topjohnwu <topjohnwu@gmail.com>
---
 native/src/zygisk/hook.cpp   | 34 ++++++++++++++--------------------
 native/src/zygisk/module.hpp | 19 ++++++++++++-------
 2 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/native/src/zygisk/hook.cpp b/native/src/zygisk/hook.cpp
index 257a09b68..d33677af2 100644
--- a/native/src/zygisk/hook.cpp
+++ b/native/src/zygisk/hook.cpp
@@ -311,47 +311,41 @@ ZygiskModule::ZygiskModule(int id, void *handle, void *entry)
     api.base.registerModule = &ZygiskModule::RegisterModuleImpl;
 }
 
-bool ZygiskModule::RegisterModuleImpl(api_abi_base *api, long *module) {
+bool ZygiskModule::RegisterModuleImpl(ApiTable *api, long *module) {
     long api_version = *module;
     // Unsupported version
     if (api_version > ZYGISK_API_VERSION)
         return false;
 
     // Set the actual module_abi*
-    api->impl->mod = { module };
+    api->base.impl->mod = { module };
 
     // Fill in API accordingly with module API version
     switch (api_version) {
-    case 4: {
-        auto v4 = static_cast<api_abi_v4 *>(api);
-        v4->exemptFd = [](int fd) { return g_ctx != nullptr && g_ctx->exempt_fd(fd); };
-    }
+    case 4:
+        api->v4.exemptFd = [](int fd) { return g_ctx != nullptr && g_ctx->exempt_fd(fd); };
         // fallthrough
     case 3:
-    case 2: {
-        auto v2 = static_cast<api_abi_v2 *>(api);
-        v2->getModuleDir = [](ZygiskModule *m) { return m->getModuleDir(); };
-        v2->getFlags = [](auto) { return ZygiskModule::getFlags(); };
-    }
+    case 2:
+        api->v2.getModuleDir = [](ZygiskModule *m) { return m->getModuleDir(); };
+        api->v2.getFlags = [](auto) { return ZygiskModule::getFlags(); };
         // fallthrough
-    case 1: {
-        auto v1 = static_cast<api_abi_v1 *>(api);
-        v1->hookJniNativeMethods = &hookJniNativeMethods;
-        v1->pltHookRegister = [](const char *p, const char *s, void *n, void **o) {
+    case 1:
+        api->v1.hookJniNativeMethods = &hookJniNativeMethods;
+        api->v1.pltHookRegister = [](const char *p, const char *s, void *n, void **o) {
             xhook_register(p, s, n, o);
         };
-        v1->pltHookExclude = [](const char *p, const char *s) {
+        api->v1.pltHookExclude = [](const char *p, const char *s) {
             xhook_ignore(p, s);
         };
-        v1->pltHookCommit = [] {
+        api->v1.pltHookCommit = [] {
             bool r = xhook_refresh(0) == 0;
             xhook_clear();
             return r;
         };
-        v1->connectCompanion = [](ZygiskModule *m) { return m->connectCompanion(); };
-        v1->setOption = [](ZygiskModule *m, auto opt) { m->setOption(opt); };
+        api->v1.connectCompanion = [](ZygiskModule *m) { return m->connectCompanion(); };
+        api->v1.setOption = [](ZygiskModule *m, auto opt) { m->setOption(opt); };
         break;
-    }
     default:
         // Unknown version number
         return false;
diff --git a/native/src/zygisk/module.hpp b/native/src/zygisk/module.hpp
index e892b1ed1..39144b78a 100644
--- a/native/src/zygisk/module.hpp
+++ b/native/src/zygisk/module.hpp
@@ -22,6 +22,8 @@ struct api_abi_v2;
 using  api_abi_v3 = api_abi_v2;
 struct api_abi_v4;
 
+union ApiTable;
+
 struct AppSpecializeArgs_v3 {
     jint &uid;
     jint &gid;
@@ -118,7 +120,7 @@ enum : uint32_t {
 
 struct api_abi_base {
     ZygiskModule *impl;
-    bool (*registerModule)(api_abi_base *, long *);
+    bool (*registerModule)(ApiTable *, long *);
 };
 
 struct api_abi_v1 : public api_abi_base {
@@ -140,6 +142,13 @@ struct api_abi_v4 : public api_abi_v2 {
     bool (*exemptFd)(int);
 };
 
+union ApiTable {
+    api_abi_base base;
+    api_abi_v1 v1;
+    api_abi_v2 v2;
+    api_abi_v4 v4;
+};
+
 #define call_app(method)               \
 switch (*mod.api_version) {            \
 case 1:                                \
@@ -182,7 +191,7 @@ struct ZygiskModule {
 
     ZygiskModule(int id, void *handle, void *entry);
 
-    static bool RegisterModuleImpl(api_abi_base *api, long *module);
+    static bool RegisterModuleImpl(ApiTable *api, long *module);
 
 private:
     const int id;
@@ -194,11 +203,7 @@ private:
         void (* const fn)(void *, void *);
     } entry;
 
-    union {
-        api_abi_base base;
-        api_abi_v1 v1;
-        api_abi_v2 v2;
-    } api;
+    ApiTable api;
 
     union {
         long *api_version;