filesys : open & create

src/filesys/filesys.rs

@@ -1,11 +1,11 @@
-use crate::simulator::disk;
-
+use crate::{simulator::disk, utility::bitmap, kernel::mgerror::ErrorCode};
 
+const ERROR : i32 = -1;
 const FREE_MAP_SECTOR : i32 = 0;
 const DIRECTORY_SECTOR : i32 = 1;
 
 pub struct Filesys {
-    pub free_map_file : Open_File, //Bit map of free disk blocks, represented as a file
+    pub free_map_file : Open_file, //Bit map of free disk blocks, represented as a file
     pub directory_file : Open_file //"Root" directory -- list of file names, represented as a file
 }
 
@@ -56,17 +56,17 @@ impl Filesys {
         }
     }
 
-    /// create a file in the Nachos file system (similar to UNIX create).
+    /// Create a file in the BurritOS file system (similar to UNIX create).
     /// Since we can't increase the size of files dynamically, we have
     /// to give Create the initial size of the file.
     //
     /// The steps to create a file are:
-    /// Make sure the file doesn't already exist
-    /// Allocate a sector for the file header
-    /// Allocate space on disk for the data blocks for the file
-    /// Add the name to the directory
-    /// Store the new file header on disk 
-    /// Flush the changes to the bitmap and the directory back to disk
+    ///     Make sure the file doesn't already exist
+    ///     Allocate a sector for the file header
+    ///     Allocate space on disk for the data blocks for the file
+    ///     Add the name to the directory
+    ///     Store the new file header on disk 
+    ///     Flush the changes to the bitmap and the directory back to disk
     ///
     ///	Create fails if:
     /// 	file is already in directory
@@ -81,9 +81,97 @@ impl Filesys {
     ///
     ///	-**name** is the name of file to be created (NOT MODIFIED)
     ///	-**initialSize** is the size of file to be created
-    ///	\return NO_ERROR if everything goes ok, otherwise, return an error
-    //              code as define in msgerror.h
-    pub fn create(name : String, initial_size : i32) -> i32 {
+    pub fn create(&mut self, name : String, initial_size : i32) -> Result<(), ErrorCode> {
+        
+        lock.acquire();
 
+        let dir_sector = find_dir(name);
+        if dir_sector == ERROR {
+            lock.release();
+            return Err(ErrorCode::InexistFileError);
+        }
+
+        let dir_file = openfile::init_open_file(dir_sector);
+        let directory = directory::init_directory(num_dir_entries);
+        directory.fetch_from(&dir_file);
+
+        if directory.find(name) != ERROR {
+            lock.release();
+            return Err(ErrorCode::AlreadyInDirectory);
+        }
+
+        // Get the freemap from the disk
+        let free_map = bitmap::init_bitmap(disk::NUM_SECTORS);
+        free_map.fetch_from(self.free_map_file);
+
+        // Find a sector to hold the file header
+        let sector = free_map.find();
+        if sector == ERROR {
+            lock.release();
+            return Err(ErrorCode::OutOfDisk);
+        }
+
+        // Add the file in the directory
+        let add_result = directory.add(name, sector);
+        match add_result {
+            Err(e) => {
+                lock.release();
+                return Err(e);
+            }
+            _ => {}
+        }
+
+        // Indicate that this is a file, not a directory
+        let hdr = file_header::init_file_header();
+        hdr.set_file();
+
+        if !hdr.allocate(&free_map, initial_size) {
+            lock.release();
+            return Err(ErrorCode::OutOfDisk);
+        }
+
+        // everthing worked, flush all changes back to disk
+        hdr.write_back(sector);
+        directory.write_back(&dir_file);
+        free_map.write_back(self.free_map_file);
+
+        lock.release();
+
+        Ok(())
     }
+
+    /// Open a file for reading and writing.  
+    ///	To open a file:
+    ///	  Find the location of the file's header, using the directory 
+    ///	  Bring the header into memory
+    ///
+    /// ### parameters
+    /// 
+    ///	-**name** the text name of the file to be opened (NOT MODIFIED)
+    pub fn open(name : String) -> Option<Open_file> {
+        let open_file : Open_file;
+        // Find the directory containing the file
+        let dir_sector = find_dir(name);
+        if dir_sector == ERROR {
+            return None;
+        }
+
+        // Read the directory from disk
+        let dir_file = open_file::init_open_file(dir_sector);
+        let directory = directory::init_directory(num_dir_entries);
+        directory.fetch_from(&directory);
+
+        // Find the file in the directory
+        let sector = directory.find(name);
+        if sector >= 0 {
+            open_file = openfile::init_open_file(sector);
+            open_file.set_name(name);
+            if open_file.is_dir() {
+                return None;
+            }
+        }
+
+        Some(open_file)
+    }
+
 }