SERVER-17519: Add support for multi-platform shared library loading

1 files changed, 98 insertions, 0 deletions

diff --git a/src/mongo/platform/shared_library.h b/src/mongo/platform/shared_library.h
new file mode 100644
index 00000000000..c77f8290f85
--- /dev/null
+++ b/src/mongo/platform/shared_library.h
@@ -0,0 +1,98 @@
+/**
+ *    Copyright (C) 2015 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+#pragma once
+
+#include <boost/filesystem.hpp>
+#include <memory>
+
+#include "mongo/base/status_with.h"
+
+namespace mongo {
+
+    /**
+     * Loads shared library or DLL at runtime
+     * Provides functionality to resolve symols and functions at runtime.
+     * Note: shared library is released by destructor
+     */
+    class SharedLibrary {
+    public:
+        /**
+         * Releases reference to shared library on destruction.
+         *
+         * May unload the shared library.
+         * May invalidate all symbol pointers, depends on OS implementation.
+         */
+        ~SharedLibrary();
+
+        /*
+         * Loads the shared library
+         *
+         * Returns a handle to a SharedLibrary on success otherwise StatusWith contains the
+         * appropriate error.
+         */
+        static StatusWith<std::unique_ptr<SharedLibrary>> create(
+                const boost::filesystem::path& full_path);
+
+        /**
+         * Retrieves the public symbol of a shared library specified in the name parameter.
+         *
+         * Returns a pointer to the symbol if it exists with Status::OK,
+         * returns NULL if the symbol does not exist with Status::OK,
+         * otherwise returns an error if the underlying OS infrastructure returns an error.
+         */
+        StatusWith<void*> getSymbol(StringData name);
+
+        /**
+         * A generic function version of getSymbol, see notes in getSymbol for more information
+         * Callers should use getFunctionAs.
+         */
+        StatusWith<void (*)()> getFunction(StringData name);
+
+        /**
+         * A type-safe version of getFunction, see notes in getSymbol for more information
+         */
+        template<typename FuncT>
+        StatusWith<FuncT> getFunctionAs(StringData name) {
+
+            StatusWith<void (*) ()> s = getFunction(name);
+
+            if (!s.isOK()) {
+                return StatusWith<FuncT>(s.getStatus());
+            }
+
+            return StatusWith<FuncT>(reinterpret_cast<FuncT>(s.getValue()));
+        }
+
+    private:
+        SharedLibrary(void* handle);
+
+    private:
+        void* const _handle;
+    };
+
+} // namespace mongo