Initial version

code/filesys/directory.h

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+// directory.h 
+//	Data structures to manage a UNIX-like directory of file names.
+// 
+//      A directory is a table of pairs: <file name, sector #>,
+//	giving the name of each file in the directory, and 
+//	where to find its file header (the data structure describing
+//	where to find the file's data blocks) on disk.
+//
+//      We assume mutual exclusion is provided by the caller.
+//
+// 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"
+
+#ifndef DIRECTORY_H
+#define DIRECTORY_H
+
+#include "openfile.h"
+
+#define FileNameMaxLen 		9	// for simplicity, we assume 
+					// file names are <= 9 characters long
+
+// The following class defines a "directory entry", representing a file
+// in the directory.  Each entry gives the name of the file, and where
+// the file's header is to be found on disk.
+//
+// Internal data structures kept public so that Directory operations can
+// access them directly.
+
+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 dontcopythis {
+  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.
+
+  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