From 3132a66692b70495680b63a262847849eea59780 Mon Sep 17 00:00:00 2001
From: LoveSy <shana@zju.edu.cn>
Date: Fri, 18 Feb 2022 10:01:40 +0800
Subject: [PATCH] Allow customize generated class

---
 library/jni/include/lsplant.hpp | 16 +++++++++++++-
 library/jni/lsplant.cc          | 39 ++++++++++++++++++++++++++-------
 2 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/library/jni/include/lsplant.hpp b/library/jni/include/lsplant.hpp
index 0ef7474..a000063 100644
--- a/library/jni/include/lsplant.hpp
+++ b/library/jni/include/lsplant.hpp
@@ -35,9 +35,20 @@ struct InitInfo {
     InlineUnhookFunType inline_unhooker;
     /// \brief The symbol resolver to \p libart.so. Must not be null.
     ArtSymbolResolver art_symbol_resolver;
+
+    /// \brief The generated class name. Must not be empty. It contains a field and a method
+    /// and they could be set by \p generated_field_name and \p generated_method_name respectively.
+    std::string_view generated_class_name = "LSPHooker_";
+    /// \brief The generated source name. Could be empty.
+    std::string_view generated_source_name = "LSP";
+    /// \brief The generated field name. Must not be empty.
+    std::string_view generated_field_name = "hooker";
+    /// \brief The generated class name. Must not be emtpy. If {target} is set,
+    /// it will follows the name of the target.
+    std::string_view generated_method_name = "{target}";
 };
 
-/// \brief Initialize LSPlant for procceding hook.
+/// \brief Initialize LSPlant for the proceeding hook.
 /// It mainly prefetch needed symbols and hook some functions.
 /// \param[in] env The Java environment. Must not be null.
 /// \param[in] info The information for initialized. \ref InitInfo.
@@ -71,6 +82,9 @@ bool Init(JNIEnv *env, const InitInfo &info);
 /// This method must be a method to \p hooker_object.
 /// \return The backup method. You can invoke it by reflection to invoke the original method. null
 /// if fails.
+/// \note This function will automatically generate a stub class for hook. To help debug, you
+/// can set the generated class name, its field name, its source name and its method name
+/// by setting generated_* in \p InitInfo.
 /// \note This function thread safe (you can call it simultaneously from multiple thread)
 /// but it's not atomic to the same \b target_method. That means \p UnHook or \p IsUnhook does
 /// not guarantee to work properly on the same \p target_method before it returns. Also,
diff --git a/library/jni/lsplant.cc b/library/jni/lsplant.cc
index 32e88a6..3934798 100644
--- a/library/jni/lsplant.cc
+++ b/library/jni/lsplant.cc
@@ -76,6 +76,31 @@ jclass in_memory_class_loader = nullptr;
 jmethodID in_memory_class_loader_init = nullptr;
 jmethodID load_class = nullptr;
 
+std::string generated_class_name;
+std::string generated_source_name;
+std::string generated_field_name;
+std::string generated_method_name;
+
+bool InitConfig(const InitInfo &info) {
+    if (info.generated_class_name.empty()) {
+        LOGE("generated class name cannot be empty");
+        return false;
+    }
+    generated_class_name = info.generated_class_name;
+    if (info.generated_field_name.empty()) {
+        LOGE("generated field name cannot be empty");
+        return false;
+    }
+    generated_field_name = info.generated_field_name;
+    if (info.generated_method_name.empty()) {
+        LOGE("generated method name cannot be empty");
+        return false;
+    }
+    generated_method_name = info.generated_method_name;
+    generated_source_name = info.generated_source_name;
+    return true;
+}
+
 bool InitJNI(JNIEnv *env) {
     auto executable = JNI_FindClass(env, "java/lang/reflect/Executable");
     if (!executable) {
@@ -204,20 +229,18 @@ BuildDex(JNIEnv *env, jobject class_loader,
                         static_cast<char>(param)));
     }
 
-    // TODO(yujincheng08): customize it
-    ClassBuilder cbuilder{ dex_file.MakeClass("LspHooker_") };
-    // TODO(yujincheng08): customize it
-    cbuilder.set_source_file("LSP");
+    ClassBuilder cbuilder{ dex_file.MakeClass(generated_class_name) };
+    if (!generated_source_name.empty()) cbuilder.set_source_file(generated_source_name);
 
     auto hooker_type = TypeDescriptor::FromClassname(hooker_class.data());
 
-    // TODO(yujincheng08): customize it
-    auto *hooker_field = cbuilder.CreateField("hooker", hooker_type)
+    auto *hooker_field = cbuilder.CreateField(generated_field_name, hooker_type)
             .access_flags(dex::kAccStatic)
             .Encode();
 
     auto hook_builder{ cbuilder.CreateMethod(
-            method_name.data(), Prototype{ return_type, parameter_types }) };
+            generated_method_name == "{target}" ? method_name.data() : generated_method_name,
+            Prototype{ return_type, parameter_types }) };
     // allocate tmp first because of wide
     auto tmp{ hook_builder.AllocRegister() };
     hook_builder.BuildConst(tmp, static_cast<int>(parameter_types.size()));
@@ -420,7 +443,7 @@ using ::lsplant::IsHooked;
 
 [[maybe_unused]]
 bool Init(JNIEnv *env, const InitInfo &info) {
-    bool static kInit = InitJNI(env) && InitNative(env, info);
+    bool static kInit = InitConfig(info) && InitJNI(env) && InitNative(env, info);
     return kInit;
 }