Initial work

external/android-emugl/shared/emugl/common/shared_library.h

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+// Copyright (C) 2014 The Android Open Source Project
+//
+// 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 EMUGL_COMMON_SHARED_LIBRARY_H
+#define EMUGL_COMMON_SHARED_LIBRARY_H
+
+#include <stddef.h>
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+namespace emugl {
+
+// A class used to open a platform-specific shared library, and probe
+// it for symbols. Usage is the following:
+//
+//    // Open the library.
+//    SharedLibrary* library = SharedLibrary::open("libFoo");
+//    if (!library) {
+//        ... could not find / open library!
+//    }
+//
+//    //Probe for function symbol.
+//    FunctionPtr my_func = library->findSymbol("my_func");
+//
+//    // Closes library/
+//    delete library;
+//
+class SharedLibrary {
+public:
+    // Open a given library.  If |libraryName| has no extension, a
+    // platform-appropriate extension is added and that path is opened.
+    // If the |libraryName| has an extension, that form is opened.
+    //
+    // On OSX, some libraries don't include an extension (notably OpenGL)
+    // On OSX we try to open |libraryName| first.  If that doesn't exist,
+    // we try |libraryName|.dylib
+    //
+    // On success, returns a new SharedLibrary instance that must be
+    // deleted by the caller.
+    static SharedLibrary* open(const char* libraryName);
+
+    // A variant of open() that can report a human-readable error if loading
+    // the library fails. |error| is a caller-provided buffer of |errorSize|
+    // bytes that will be filled with snprintf() and always zero terminated.
+    //
+    // On success, return a new SharedLibrary instance, and do not touch
+    // the content of |error|. On failure, return NULL, and sets the content
+    // of |error|.
+    static SharedLibrary* open(const char* libraryName,
+                               char* error,
+                               size_t errorSize);
+
+    // Closes an existing SharedLibrary instance.
+    ~SharedLibrary();
+
+    // Generic function pointer type, for values returned by the
+    // findSymbol() method.
+    typedef void (*FunctionPtr)(void);
+
+    // Probe a given SharedLibrary instance to find a symbol named
+    // |symbolName| in it. Return its address as a FunctionPtr, or
+    // NULL if the symbol is not found.
+    FunctionPtr findSymbol(const char* symbolName) const;
+
+private:
+#ifdef _WIN32
+    typedef HMODULE HandleType;
+#else
+    typedef void* HandleType;
+#endif
+
+    // Constructor intentionally hidden.
+    SharedLibrary(HandleType);
+
+    HandleType mLib;
+};
+
+// Macro to compose emugl shared library name under various OS and bitness
+// eg.
+//     on x86_64, EMUGL_LIBNAME("foo") --> "lib64foo"
+
+#if defined(__x86_64__)
+#  define EMUGL_LIBNAME(name) "lib64" name
+#elif defined(__i386__)
+#  define EMUGL_LIBNAME(name) "lib" name
+#else
+/* This header is included by target w/o using EMUGL_LIBNAME().  Don't #error, leave it undefined */
+#  define EMUGL_LIBNAME(name) "lib" name
+#endif
+
+}  // namespace emugl
+
+#endif  // EMUGL_COMMON_SHARED_LIBRARY_H