openfile.h

来自「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」· C头文件 代码 · 共 70 行

/////////////////////////////////////////////////////////////
//FileName		: openfile.h
//
//Creator		: Fang Wenbin(0410706)
//CreateTime	: 2006-12-26
//
//File Desc:
//	the highest level for file writing and reading.
//	
/////////////////////////////////////////////////////////////
#ifndef OPENFILE_H
#define OPENFILE_H

#include "copyright.h"
#include "utility.h"
#include "directory.h"

#ifdef FILESYS_STUB		
class OpenFile {
  public:
    OpenFile(char* f) { file = 0; currentOffset = 0; }
    ~OpenFile() { Close(file); }			

    int ReadAt(char *into, int numBytes, int position) { 
    		Lseek(file, position, 0); 
		return ReadPartial(file, into, numBytes); 
		}	
    int WriteAt(char *from, int numBytes, int position) { 
    		Lseek(file, position, 0); 
		WriteFile(file, from, numBytes); 
		return numBytes;
		}	
    int Read(char *into, int numBytes) {
		int numRead = ReadAt(into, numBytes, currentOffset); 
		currentOffset += numRead;
		return numRead;
    		}
    int Write(char *from, int numBytes) {
		int numWritten = WriteAt(from, numBytes, currentOffset); 
		currentOffset += numWritten;
		return numWritten;
		}

    int Length() { Lseek(file, 0, 2); return Tell(file); }
    
  private:
    int file;
    int currentOffset;
};
#else // FILESYS
class FileHeader;

class OpenFile {
  public:
    OpenFile(char* fileName);
    ~OpenFile();		

    int Read(char *into, int numBytes);
    int Write(char *from, int numBytes);
	int ReadAt(char *into, int numBytes, int pos);
	int WriteAt(char *into, int numBytes, int pos);

  private:
	Directory *dir;			//the basis of file operation!
};

#endif // FILESYS

#endif // OPENFILE_H