Fix GL resource access thread safety

src/OpenGL/libGLESv2/Context.h

@@ -699,6 +699,7 @@ public:
 	Device *getDevice();
 
 	const GLubyte *getExtensions(GLuint index, GLuint *numExt = nullptr) const;
+	sw::MutexLock *getResourceLock() { return mResourceManager->getLock(); }
 
 private:
 	~Context() override;
@@ -769,6 +770,26 @@ private:
 	Device *device;
 	ResourceManager *mResourceManager;
 };
+
+// ptr to a context, which also holds the context's resource manager's lock.
+class ContextPtr {
+public:
+	explicit ContextPtr(Context *context) : ptr(context)
+	{
+		if (ptr) ptr->getResourceLock()->lock();
+    }
+
+	~ContextPtr() {
+		if (ptr) ptr->getResourceLock()->unlock();
+	}
+
+	Context *operator ->() { return ptr; }
+	operator bool() const { return ptr != nullptr; }
+
+private:
+	Context *ptr;
+};
+
 }
 
 #endif   // INCLUDE_CONTEXT_H_

src/OpenGL/libGLESv2/Framebuffer.cpp

@@ -65,7 +65,7 @@ Framebuffer::~Framebuffer()
 
 Renderbuffer *Framebuffer::lookupRenderbuffer(GLenum type, GLuint handle, GLint level) const
 {
-	Context *context = getContext();
+	Context *context = getContextLocked();
 	Renderbuffer *buffer = nullptr;
 
 	if(type == GL_NONE)

src/OpenGL/libGLESv2/ResourceManager.h

@@ -19,6 +19,7 @@
 #define LIBGLESV2_RESOURCEMANAGER_H_
 
 #include "common/NameSpace.hpp"
+#include "Common/MutexLock.hpp"
 
 #include <GLES2/gl2.h>
 
@@ -86,9 +87,11 @@ public:
 	void checkSamplerAllocation(GLuint sampler);
 
 	bool isSampler(GLuint sampler);
+	sw::MutexLock *getLock() { return &mMutex; }
 
 private:
 	std::size_t mRefCount;
+	sw::MutexLock mMutex;
 
 	gl::NameSpace<Buffer> mBufferNameSpace;
 	gl::NameSpace<Program> mProgramNameSpace;

src/OpenGL/libGLESv2/main.cpp

@@ -75,7 +75,7 @@ extern "C" BOOL WINAPI DllMain(HINSTANCE instance, DWORD reason, LPVOID reserved
 
 namespace es2
 {
-es2::Context *getContext()
+Context *getContextLocked()
 {
 	egl::Context *context = libEGL->clientGetCurrentContext();
 
@@ -88,17 +88,23 @@ es2::Context *getContext()
 	return nullptr;
 }
 
+ContextPtr getContext()
+{
+	return ContextPtr{getContextLocked()};
+}
+
 Device *getDevice()
 {
-	Context *context = getContext();
+	Context *context = getContextLocked();
 
 	return context ? context->getDevice() : nullptr;
 }
 
 // Records an error code
+// Assumed to already hold the context lock for the current context
 void error(GLenum errorCode)
 {
-	es2::Context *context = es2::getContext();
+	es2::Context *context = es2::getContextLocked();
 
 	if(context)
 	{

src/OpenGL/libGLESv2/main.h

@@ -30,7 +30,8 @@
 
 namespace es2
 {
-	Context *getContext();
+	Context *getContextLocked();
+	ContextPtr getContext();
 	Device *getDevice();
 
 	void error(GLenum errorCode);