Add a DynamicLib loading class

src/common/CMakeLists.txt

@@ -19,6 +19,8 @@ list(APPEND COMMON_SOURCES
     ${COMMON_DIR}/Assert.h
     ${COMMON_DIR}/BitSetIterator.h
     ${COMMON_DIR}/Compiler.h
+    ${COMMON_DIR}/DynamicLib.cpp
+    ${COMMON_DIR}/DynamicLib.h
     ${COMMON_DIR}/Math.cpp
     ${COMMON_DIR}/Math.h
     ${COMMON_DIR}/Platform.h

src/common/DynamicLib.cpp

@@ -0,0 +1,100 @@
+// Copyright 2017 The NXT Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "common/DynamicLib.h"
+
+#include "common/Platform.h"
+
+#if NXT_PLATFORM_WINDOWS
+    #include <windows.h>
+#elif NXT_PLATFORM_POSIX
+    #include <dlfcn.h>
+#else
+    #error "Unsupported platform for DynamicLib"
+#endif
+
+DynamicLib::~DynamicLib() {
+    Close();
+}
+
+DynamicLib::DynamicLib(DynamicLib&& other) {
+    std::swap(this->handle, other.handle);
+}
+
+DynamicLib& DynamicLib::operator=(DynamicLib&& other) {
+    std::swap(this->handle, other.handle);
+    return *this;
+}
+
+bool DynamicLib::Valid() const {
+    return handle != nullptr;
+}
+
+bool DynamicLib::Open(const std::string& filename, std::string* error) {
+    #if NXT_PLATFORM_WINDOWS
+        handle = LoadLibraryA(filename.c_str());
+
+        if (handle == nullptr && error != nullptr) {
+            *error = "Windows Error: " + std::to_string(GetLastError());
+        }
+    #elif NXT_PLATFORM_POSIX
+        handle = dlopen(filename.c_str(), RTLD_NOW);
+
+        if (handle == nullptr && error != nullptr) {
+            *error = dlerror();
+        }
+    #else
+        #error "Unsupported platform for DynamicLib"
+    #endif
+
+    return handle != nullptr;
+}
+
+void DynamicLib::Close() {
+    if (handle == nullptr) {
+        return;
+    }
+
+    #if NXT_PLATFORM_WINDOWS
+        FreeLibrary(static_cast<HMODULE>(handle));
+    #elif NXT_PLATFORM_POSIX
+        dlclose(handle);
+    #else
+        #error "Unsupported platform for DynamicLib"
+    #endif
+
+    handle = nullptr;
+}
+
+void* DynamicLib::GetProc(const std::string& procName, std::string* error) const {
+    void* proc = nullptr;
+
+    #if NXT_PLATFORM_WINDOWS
+        proc = reinterpret_cast<void*>(GetProcAddress(static_cast<HMODULE>(handle), procName.c_str()));
+
+        if (proc == nullptr && error != nullptr) {
+            *error = "Windows Error: " + std::to_string(GetLastError());
+        }
+    #elif NXT_PLATFORM_POSIX
+        proc = reinterpret_cast<void*>(dlsym(handle, procName.c_str()));
+
+        if (proc == nullptr && error != nullptr) {
+            *error = dlerror();
+        }
+    #else
+        #error "Unsupported platform for DynamicLib"
+    #endif
+
+    return proc;
+}

src/common/DynamicLib.h

@@ -0,0 +1,54 @@
+// Copyright 2017 The NXT Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef COMMON_DYNAMICLIB_H_
+#define COMMON_DYNAMICLIB_H_
+
+#include "common/Assert.h"
+
+#include <string>
+#include <type_traits>
+
+class DynamicLib {
+    public:
+        DynamicLib() = default;
+        ~DynamicLib();
+
+        DynamicLib(const DynamicLib&) = delete;
+        DynamicLib& operator=(const DynamicLib&) = delete;
+
+        DynamicLib(DynamicLib&& other);
+        DynamicLib& operator=(DynamicLib&& other);
+
+        bool Valid() const;
+
+        bool Open(const std::string& filename, std::string* error = nullptr);
+        void Close();
+
+        void* GetProc(const std::string& procName, std::string* error = nullptr) const;
+
+        template<typename T>
+        bool GetProc(T** proc, const std::string& procName, std::string* error = nullptr) const {
+            ASSERT(proc != nullptr);
+            static_assert(std::is_function<T>::value, "");
+
+            *proc = reinterpret_cast<T*>(GetProc(procName, error));
+            return *proc != nullptr;
+        }
+
+    private:
+        void* handle = nullptr;
+};
+
+#endif // COMMON_DYNAMICLIB_H_