openfile.cc

操作系统课程设计。在UNIX平台下实现Solary操作系统的一些功能

// openfile.cc 
//	Routines to manage an open Nachos file.  As in UNIX, a
//	file must be open before we can read or write to it.
//	Once we're all done, we can close it (in Nachos, by deleting
//	the OpenFile data structure).
//
//	Also as in UNIX, for convenience, we keep the file header in
//	memory while the file is open.
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "filehdr.h"
#include "openfile.h"
#include "system.h"
#ifdef HOST_SPARC
#include <strings.h>
#endif

//----------------------------------------------------------------------
// OpenFile::OpenFile
// 	Open a Nachos file for reading and writing.  Bring the file header
//	into memory while the file is open.
//
//	"sector" -- the location on disk of the file header for this file
//----------------------------------------------------------------------

OpenFile::OpenFile(char* fileName)
{ 
	dir = new Directory((char*)fileName);
}

//----------------------------------------------------------------------
// OpenFile::~OpenFile
// 	Close a Nachos file, de-allocating any in-memory data structures.
//----------------------------------------------------------------------

OpenFile::~OpenFile()
{
	delete dir;
}

int
OpenFile::Read(char *into, int numBytes)
{
	dir->s_ReadFile(numBytes, into);	
}

int
OpenFile::Write(char *into, int numBytes)
{
	dir->s_WriteFile(numBytes, into);	
}

int
OpenFile::ReadAt(char *into, int numBytes, int pos)
{
	int len = dir->dirHdr->numBytes;
	char *data = new char[len];
	dir->s_ReadFile(len, data);
	data += pos;
	memcpy(into, data, numBytes);
	data -= pos;
	delete data;
}

int
OpenFile::WriteAt(char *into, int numBytes, int pos)
{
}