Added CVFSFile, a simple wrapper around vfs_load to allow slightly cleaner code elsewhere

This was SVN commit r841.

source/lib/res/CVFSFile.cpp

@@ -0,0 +1,60 @@
+#include "precompiled.h"
+
+#include "lib/res/CVFSFile.h"
+
+#include "lib/res/mem.h"
+#include "lib/res/vfs.h"
+#include "ps/CLogger.h"
+
+CVFSFile::CVFSFile() : m_Handle(0) {}
+
+CVFSFile::~CVFSFile()
+{
+	// I hope this is the right way to delete the handle returned by
+	// vfs_load... C++ destructors would be far less ambiguous ;-)
+	if (m_Handle)
+		mem_free_h(m_Handle);
+}
+
+PSRETURN CVFSFile::Load(const char* filename)
+{
+	assert(!m_Handle && "Mustn't open files twice");
+	if (m_Handle)
+		throw PSERROR_CVFSFile_AlreadyLoaded();
+
+	m_Handle = vfs_load(filename, m_Buffer, m_BufferSize);
+	if (m_Handle <= 0)
+	{
+		LOG(ERROR, "CVFSFile: file %s couldn't be opened (vfs_load: %lld)", filename, m_Handle);
+		return PSRETURN_CVFSFile_LoadFailed;
+	}
+
+	return PSRETURN_OK;
+}
+
+const void* CVFSFile::GetBuffer() const
+{
+	// Die in a very obvious way, to avoid problems caused by
+	// accidentally forgetting to check that the open succeeded
+	assert(m_Handle && "GetBuffer() called with no file loaded");
+	if (!m_Handle)
+		throw PSERROR_CVFSFile_InvalidBufferAccess();
+
+	return m_Buffer;
+}
+
+const size_t CVFSFile::GetBufferSize() const
+{
+	return m_BufferSize;
+}
+
+CStr CVFSFile::GetAsString() const
+{
+	// Die in a very obvious way, to avoid subtle problems caused by
+	// accidentally forgetting to check that the open succeeded
+	assert(m_Handle && "GetBuffer() called with no file loaded");
+	if (!m_Handle)
+		throw PSERROR_CVFSFile_InvalidBufferAccess();
+
+	return std::string((char*)m_Buffer, m_BufferSize);
+}

source/lib/res/CVFSFile.h

@@ -0,0 +1,31 @@
+// OO wrapper around VFS file Handles, to simplify common usages
+
+#include "lib/res/h_mgr.h"
+#include "ps/CStr.h"
+
+ERROR_GROUP(CVFSFile);
+ERROR_TYPE(CVFSFile, LoadFailed);
+ERROR_TYPE(CVFSFile, AlreadyLoaded);
+ERROR_TYPE(CVFSFile, InvalidBufferAccess);
+
+// Reads a file, then gives read-only access to the contents
+class CVFSFile
+{
+public:
+	CVFSFile();
+	~CVFSFile();
+
+	// Returns either PSRETURN_OK or PSRETURN_CVFSFile_LoadFailed.
+	// Dies if a file has already been successfully loaded.
+	PSRETURN Load(const char* filename);
+
+	// These die if called when no file has been successfully loaded.
+	const void* GetBuffer() const;
+	const size_t GetBufferSize() const;
+	CStr GetAsString() const;
+
+private:
+	Handle m_Handle;
+	void* m_Buffer;
+	size_t m_BufferSize;
+};