1HEADmaster

1 files changed, 148 insertions, 0 deletions

diff --git a/tier0/dynfunction.cpp b/tier0/dynfunction.cpp
new file mode 100644
index 0000000..e05dcb3
--- /dev/null
+++ b/tier0/dynfunction.cpp
@@ -0,0 +1,148 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: Shared library loading and symbol lookup.
+//
+// $NoKeywords: $
+//=============================================================================//
+
+#include "pch_tier0.h"
+#include "tier0/dynfunction.h"
+
+#if defined(WIN32)
+typedef HMODULE LibraryHandle;
+#define LoadLibraryHandle(libname) LoadLibrary(libname)
+#define CloseLibraryHandle(handle) FreeLibrary(handle)
+#define LookupInLibraryHandle(handle, fn) GetProcAddress(handle, fn)
+#elif defined(POSIX)
+#include <dlfcn.h>
+typedef void *LibraryHandle;
+#define LoadLibraryHandle(libname) dlopen(libname, RTLD_NOW)
+#define CloseLibraryHandle(handle) dlclose(handle)
+#define LookupInLibraryHandle(handle, fn) dlsym(handle, fn)
+#else
+#error Please define your platform.
+#endif
+
+#if 1
+static inline void dbgdynfn(const char *fmt, ...) {}
+#else
+#define dbgdynfn printf
+#endif
+
+// NOTE: This has to be the last file included!
+#include "tier0/memdbgon.h"
+
+class CSharedLibraryCache
+{
+public:
+	static CSharedLibraryCache &GetCache()
+	{
+		static CSharedLibraryCache Singleton;
+		return Singleton;
+	}
+
+	struct CSharedLibraryItem
+	{
+		CSharedLibraryItem(LibraryHandle handle, const char *name)
+		{
+			m_handle = handle;
+			m_name = new char[strlen(name) + 1];
+			m_next = NULL;
+			strcpy(m_name, name);
+		}
+
+		~CSharedLibraryItem()
+		{
+			dbgdynfn("CDynamicFunction: Closing library '%s' (%p)\n", m_name, (void *) m_handle);
+			CloseLibraryHandle(m_handle);
+			delete[] m_name;
+			delete m_next;
+		}
+
+		char *m_name;
+		CSharedLibraryItem *m_next;
+		LibraryHandle m_handle;
+	};
+
+	CSharedLibraryCache() : m_pList(NULL) {}
+	~CSharedLibraryCache() { CloseAllLibraries(); }
+
+	LibraryHandle GetHandle(const char *name)
+	{
+		CSharedLibraryItem *item = GetCacheItem(name);
+		if (item == NULL)
+		{
+			LibraryHandle lib = LoadLibraryHandle(name);
+			dbgdynfn("CDynamicFunction: Loading library '%s' (%p)\n", name, (void *) lib);
+			if (lib == NULL)
+				return NULL;
+
+			item = new CSharedLibraryItem(lib, name);
+			item->m_next = m_pList;
+			m_pList = item;
+		}
+		return item->m_handle;
+	}
+
+	void CloseLibrary(const char *name)
+	{
+		CSharedLibraryItem *item = GetCacheItem(name);
+		if (item)
+		{
+			assert(item == m_pList);
+			m_pList = item->m_next;
+			item->m_next = NULL;
+			delete item;
+		}
+	}
+
+	void CloseAllLibraries()
+	{
+		delete m_pList;
+	}
+
+private:
+	CSharedLibraryItem *GetCacheItem(const char *name)
+	{
+		CSharedLibraryItem *prev = NULL;
+		CSharedLibraryItem *item = m_pList;
+		while (item)
+		{
+			if (strcmp(item->m_name, name) == 0)
+			{
+				// move this item to the front of the list, since there will
+				//  probably be a big pile of these lookups in a row
+				//  and then none ever again.
+				if (prev != NULL)
+				{
+					prev->m_next = item->m_next;
+					item->m_next = m_pList;
+					m_pList = item;
+				}
+				return item;
+			}
+
+			prev = item;
+			item = item->m_next;
+		}
+		return NULL;  // not found.
+	}
+
+	CSharedLibraryItem *m_pList;
+};
+
+void *VoidFnPtrLookup_Tier0(const char *libname, const char *fn, void *fallback)
+{
+	LibraryHandle lib = CSharedLibraryCache::GetCache().GetHandle(libname);
+	void *retval = NULL;
+	if (lib != NULL)
+	{
+		retval = LookupInLibraryHandle(lib, fn);
+		dbgdynfn("CDynamicFunction: Lookup of '%s' in '%s': %p\n", fn, libname, retval);
+	}
+
+	if (retval == NULL)
+		retval = fallback;
+	return retval;
+}
+