Restore JNIEnv in advance for clean env to modules

native/src/zygisk/hook.cpp

@@ -28,6 +28,7 @@ using xstring = jni_hook::string;
 static void hook_unloader();
 static void unhook_functions();
 static void hook_jni_env();
+static bool unhook_jni(JNIEnv *env);
 
 namespace {
 
@@ -94,7 +95,11 @@ struct HookContext {
 
     HookContext(JNIEnv *env, void *args) :
     env(env), args{args}, process(nullptr), pid(-1), info_flags(0),
-    hook_info_lock(PTHREAD_MUTEX_INITIALIZER) { g_ctx = this; }
+    hook_info_lock(PTHREAD_MUTEX_INITIALIZER) {
+        static bool unloaded = unhook_jni(env);
+        should_unmap_zygisk = unloaded;
+        g_ctx = this;
+    }
 
     ~HookContext();
 
@@ -405,6 +410,7 @@ void HookContext::fork_pre() {
     // First block SIGCHLD, unblock after original fork is done
     sigmask(SIG_BLOCK, SIGCHLD);
     pid = old_fork();
+
     if (pid != 0 || flags[SKIP_FD_SANITIZATION])
         return;
 
@@ -601,28 +607,6 @@ HookContext::~HookContext() {
     if (!is_child())
         return;
 
-    should_unmap_zygisk = true;
-
-    // Restore JNIEnv
-    env->functions = old_functions;
-    delete new_functions;
-
-    // Unhook JNI methods
-    for (const auto &[clz, methods] : *jni_hook_list) {
-        if (!methods.empty() && env->RegisterNatives(
-                env->FindClass(clz.data()), methods.data(),
-                static_cast<int>(methods.size())) != 0) {
-            ZLOGE("Failed to restore JNI hook of class [%s]\n", clz.data());
-            should_unmap_zygisk = false;
-        }
-    }
-    delete jni_hook_list;
-
-    // Do NOT call the destructor
-    operator delete(jni_method_map);
-    // Directly unmap the whole memory block
-    jni_hook::memory_block::release();
-
     // Strip out all API function pointers
     for (auto &m : modules) {
         m.clearApi();
@@ -786,6 +770,31 @@ static void unhook_functions() {
     }
 }
 
+static bool unhook_jni(JNIEnv *env) {
+    // Restore JNIEnv
+    env->functions = old_functions;
+    delete new_functions;
+
+    bool success = true;
+
+    // Unhook JNI methods
+    for (const auto &[clz, methods] : *jni_hook_list) {
+        if (!methods.empty() && env->RegisterNatives(
+                env->FindClass(clz.data()), methods.data(),
+                static_cast<int>(methods.size())) != 0) {
+            ZLOGE("Failed to restore JNI hook of class [%s]\n", clz.data());
+            success = false;
+        }
+    }
+    delete jni_hook_list;
+
+    // Do NOT call the destructor
+    operator delete(jni_method_map);
+    // Directly unmap the whole memory block
+    jni_hook::memory_block::release();
+    return success;
+}
+
 // -----------------------------------------------------------------
 
 static JNINativeMethod *hookAndSaveJNIMethods(const char *, const JNINativeMethod *, int);