83 lines
2.9 KiB
C++
83 lines
2.9 KiB
C++
// directory.h
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// Data structures to manage a UNIX-like directory of file names.
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//
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// A directory is a table of pairs: <file name, sector #>,
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// giving the name of each file in the directory, and
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// where to find its file header (the data structure describing
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// where to find the file's data blocks) on disk.
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//
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// We assume mutual exclusion is provided by the caller.
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//
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// Copyright (c) 1992-1993 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#include "copyright.h"
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#ifndef DIRECTORY_H
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#define DIRECTORY_H
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#include "openfile.h"
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#define FileNameMaxLen 9 // for simplicity, we assume
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// file names are <= 9 characters long
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// The following class defines a "directory entry", representing a file
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// in the directory. Each entry gives the name of the file, and where
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// the file's header is to be found on disk.
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//
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// Internal data structures kept public so that Directory operations can
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// access them directly.
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class DirectoryEntry {
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public:
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bool inUse; // Is this directory entry in use?
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int sector; // Location on disk to find the
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// FileHeader for this file
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char name[FileNameMaxLen + 1]; // Text name for file, with +1 for
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// the trailing '\0'
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};
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// The following class defines a UNIX-like "directory". Each entry in
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// the directory describes a file, and where to find it on disk.
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//
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// The directory data structure can be stored in memory, or on disk.
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// When it is on disk, it is stored as a regular Nachos file.
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//
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// The constructor initializes a directory structure in memory; the
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// FetchFrom/WriteBack operations shuffle the directory information
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// from/to disk.
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class Directory:public dontcopythis {
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public:
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Directory(int size); // Initialize an empty directory
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// with space for "size" files
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~Directory(); // De-allocate the directory
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void FetchFrom(OpenFile *file); // Init directory contents from disk
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void WriteBack(OpenFile *file); // Write modifications to
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// directory contents back to disk
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int Find(const char *name); // Find the sector number of the
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// FileHeader for file: "name"
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bool Add(const char *name, int newSector); // Add a file name into the directory
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bool Remove(const char *name); // Remove a file from the directory
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void List(); // Print the names of all the files
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// in the directory
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void Print(); // Verbose print of the contents
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// of the directory -- all the file
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// names and their contents.
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private:
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int tableSize; // Number of directory entries
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DirectoryEntry *table; // Table of pairs:
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// <file name, file header location>
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int FindIndex(const char *name); // Find the index into the directory
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// table corresponding to "name"
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};
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#endif // DIRECTORY_H
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