directory.h

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#include "copyright.h"

#ifndef DIRECTORY_H
#define DIRECTORY_H

#include "openfile.h"

#define FileNameMaxLen        15    // for simplicity, we assume file names are <= 9 characters long


class DirectoryEntry {
public:
    bool inUse;                // Is this directory entry in use?
    int sector;                // Location on disk to find the FileHeader for this file
    char name[FileNameMaxLen + 1]; // Text name for file, with +1 for the trailing '\0'
};

// The following class defines a UNIX-like "directory".  Each entry in
// the directory describes a file, and where to find it on disk.
//
// The directory data structure can be stored in memory, or on disk.
// When it is on disk, it is stored as a regular Nachos file.
//
// The constructor initializes a directory structure in memory; the
// FetchFrom/WriteBack operations shuffle the directory information
// from/to disk. 

class Directory {
public:
    Directory(int size);        // Initialize an empty directory
    // with space for "size" files
    ~Directory();            // De-allocate the directory

    void FetchFrom(OpenFile *file);    // Init directory contents from disk
    void WriteBack(OpenFile *file);    // Write modifications to
    // directory contents back to disk

    int Find(const char *name);        // Find the sector number of the FileHeader for file: "name"

    bool Add(const char *name, int newSector);  // Add a file name into the directory

    bool Remove(const char *name);    // Remove a file from the directory

    void List();            // Print the names of all the files in the directory
    void Print();            // Verbose print of the contents of the directory -- all the file names and their contents.
    bool isEmpty();         // check if the folder is empty
private:
    int tableSize;            // Number of directory entries
    DirectoryEntry *table;        // Table of pairs: <file name, file header location>

    int FindIndex(const char *name);    // Find the index into the directory table corresponding to "name"
};

#endif // DIRECTORY_H