X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Ffilesys%2Ffilesys.c;h=77284ad26c9b56584526eb2d9cf66166cc301762;hb=f6580e9ad405b519dbe85027691bf3c66074b0a4;hp=f8348ed2a2eaf4f17182507a9aebce1c47564966;hpb=3fc16f6e9abc98a3bd5427eb210669860609a224;p=pintos-anon

diff --git a/src/filesys/filesys.c b/src/filesys/filesys.c
index f8348ed..77284ad 100644
--- a/src/filesys/filesys.c
+++ b/src/filesys/filesys.c
@@ -1,90 +1,388 @@
+/* This file is derived from source code for the Nachos
+   instructional operating system.  The Nachos copyright notice
+   is reproduced in full below. */
+
+/* Copyright (c) 1992-1996 The Regents of the University of California.
+   All rights reserved.
+
+   Permission to use, copy, modify, and distribute this software
+   and its documentation for any purpose, without fee, and
+   without written agreement is hereby granted, provided that the
+   above copyright notice and the following two paragraphs appear
+   in all copies of this software.
+
+   IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO
+   ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
+   CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE
+   AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA
+   HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+   THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY
+   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+   PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
+   BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
+   PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
+   MODIFICATIONS.
+*/
+
 #include "filesys.h"
+#include "file.h"
+#include "filehdr.h"
+#include "directory.h"
+#include "devices/disk.h"
+#include "lib/bitmap.h"
+#include "lib/debug.h"
+#include "lib/lib.h"
+
+/* Filesystem.
+
+   The filesystem consists of a set of files.  Each file has a
+   header, represented by struct filehdr, that is stored by
+   itself in a single sector (see filehdr.h).  The header
+   contains the file's length in bytes and an array that lists
+   the sector numbers for the file's contents.
+
+   Two files are special.  The first special file is the free
+   map, whose header is always stored in sector 0
+   (FREE_MAP_SECTOR).  The free map stores a bitmap (see
+   lib/bitmap.h) that contains one bit for each sector on the
+   disk.  Each bit that corresponds to a sector within a file is
+   set to true, and the other bits, which are not part of any
+   file, are set to false.
+
+   The second special file is the root directory, whose header is
+   always stored in sector 1 (ROOT_DIR_SECTOR).  The root
+   directory file stores an array of `struct dir_entry' (see
+   directory.h), each of which, if it is in use, associates a
+   filename with the sector of the file's header.
+
+   The filesystem implemented here has the following limitations:
+
+     - No synchronization.  Concurrent accesses will interfere
+       with one another.
+
+     - File size is fixed at creation time.  Because the root
+       directory is represented as a file, the number of files
+       that may be created is also limited.
+
+     - No indirect blocks.  This limits maximum file size to the
+       number of sector pointers that fit in a single sector
+       times the size of a sector, or 126 * 512 == 63 kB given
+       32-bit sizes and 512-byte sectors.
+
+     - No nested subdirectories.
+
+     - Filenames limited to 14 characters.
+
+     - A system crash mid-operation may corrupt the disk in a way
+       that cannot be repaired automatically.  No `fsck' tool is
+       provided in any case.
 
+   Note: for the purposes of the "user processes" assignment
+   (project 2), please treat all the code in the filesys
+   directory as a black box.  No changes should be needed.  For
+   that project, a single lock external to the filesystem code
+   suffices. */
 
-#ifdef FILESYS_STUB
-#include <stdint.h>
-#include "debug.h"
-#include "filesys-stub.h"
-#include "lib.h"
+/* File header sectors for system files. */
+#define FREE_MAP_SECTOR 0       /* Free map file header sector. */
+#define ROOT_DIR_SECTOR 1       /* Root directory file header sector. */
 
+/* Root directory. */
+#define NUM_DIR_ENTRIES 10      /* Maximum number of directory entries. */
+#define ROOT_DIR_FILE_SIZE      /* Root directory file size in bytes. */ \
+         (sizeof (struct dir_entry) * NUM_DIR_ENTRIES)
+
+/* The disk that contains the filesystem. */
+struct disk *filesys_disk;
+
+/* The free map and root directory files.
+   These files are opened by filesys_init() and never closed. */
+static struct file free_map_file, root_dir_file;
+
+static void do_format (void);
+
+/* Initializes the filesystem module.
+   If FORMAT is true, reformats the filesystem. */
 void
-filesys_init (bool reformat) 
+filesys_init (bool format) 
 {
-  if (reformat)
-    printk ("filesystem stubs don't support formatting\n");
-  filesys_stub_init ();
+  filesys_disk = disk_get (0, 1);
+  if (filesys_disk == NULL)
+    PANIC ("hd0:1 (hdb) not present, filesystem initialization failed");
+
+  if (format) 
+    do_format ();
+  
+  if (!file_open (&free_map_file, FREE_MAP_SECTOR))
+    PANIC ("can't open free map file");
+  if (!file_open (&root_dir_file, ROOT_DIR_SECTOR))
+    PANIC ("can't open root dir file");
 }
 
+/* Creates a file named NAME with the given INITIAL_SIZE.
+   Returns true if successful, false otherwise.
+   Fails if a file named NAME already exists,
+   or if internal memory allocation fails. */
 bool
-filesys_create (const char *name) 
+filesys_create (const char *name, off_t initial_size) 
 {
-  bool success;
+  struct dir dir;
+  struct bitmap free_map;
+  disk_sector_t hdr_sector;
+  struct filehdr *filehdr;
+  bool success = false;
+
+  /* Read the root directory. */
+  if (!dir_init (&dir, NUM_DIR_ENTRIES))
+    return false;
+  dir_read (&dir, &root_dir_file);
+  if (dir_lookup (&dir, name, NULL)) 
+    goto exit1;
+
+  /* Allocate a block for the file header. */
+  if (!bitmap_init (&free_map, disk_size (filesys_disk)))
+    goto exit1;
+  bitmap_read (&free_map, &free_map_file);
+  hdr_sector = bitmap_find_and_set (&free_map);
+  if (hdr_sector == BITMAP_ERROR)
+    goto exit2;
+
+  /* Add the file to the directory. */
+  if (!dir_add (&dir, name, hdr_sector))
+    goto exit2;
 
-  filesys_stub_lock ();
-  filesys_stub_put_string ("create");
-  filesys_stub_put_string (name);
-  filesys_stub_match_string ("create");
-  success = filesys_stub_get_bool ();
-  filesys_stub_unlock ();
+  /* Allocate space for the file. */
+  filehdr = filehdr_allocate (&free_map, initial_size);
+  if (filehdr == NULL)
+    goto exit2;
+
+  /* Write everything back. */
+  filehdr_write (filehdr, hdr_sector);
+  dir_write (&dir, &root_dir_file);
+  bitmap_write (&free_map, &free_map_file);
+
+  success = true;
+
+  /* Clean up. */
+  filehdr_destroy (filehdr);
+ exit2:
+  bitmap_destroy (&free_map);
+ exit1:
+  dir_destroy (&dir);
 
   return success;
 }
 
-struct file *
-filesys_open (const char *name) 
+/* Opens a file named NAME and initializes FILE for usage with
+   the file_*() functions declared in file.h.
+   Returns true if successful, false on failure.
+   Fails if no file named NAME exists,
+   or if an internal memory allocation fails. */
+bool
+filesys_open (const char *name, struct file *file)
 {
-  struct file *file;
-
-  filesys_stub_lock ();
-  filesys_stub_put_string ("open");
-  filesys_stub_put_string (name);
-  filesys_stub_match_string ("open");
-  file = filesys_stub_get_file ();
-  filesys_stub_unlock ();
+  struct dir dir;
+  disk_sector_t hdr_sector;
+  bool success = false;
+
+  if (!dir_init (&dir, NUM_DIR_ENTRIES))
+    return false;
+  dir_read (&dir, &root_dir_file);
+  if (dir_lookup (&dir, name, &hdr_sector))
+    success = file_open (file, hdr_sector);
   
-  return file;
+  dir_destroy (&dir);
+  return success;
 }
 
+/* Deletes the file named NAME.
+   Returns true if successful, false on failure.
+   Fails if no file named NAME exists,
+   or if an internal memory allocation fails. */
 bool
 filesys_remove (const char *name) 
 {
-  bool success;
+  struct dir dir;
+  disk_sector_t hdr_sector;
+  struct filehdr *filehdr;
+  struct bitmap free_map;
+  bool success = false;
+
+  /* Read the root directory. */
+  if (!dir_init (&dir, NUM_DIR_ENTRIES))
+    return false;
+  dir_read (&dir, &root_dir_file);
+  if (!dir_lookup (&dir, name, &hdr_sector))
+    goto exit1;
+
+  /* Read the file header. */
+  filehdr = filehdr_read (hdr_sector);
+  if (filehdr == NULL)
+    goto exit1;
 
-  filesys_stub_lock ();
-  filesys_stub_put_string ("remove");
-  filesys_stub_put_string (name);
-  filesys_stub_match_string ("remove");
-  success = filesys_stub_get_bool ();
-  filesys_stub_unlock ();
+  /* Allocate a block for the file header. */
+  if (!bitmap_init (&free_map, disk_size (filesys_disk)))
+    goto exit2;
+  bitmap_read (&free_map, &free_map_file);
+
+  /* Deallocate. */
+  filehdr_deallocate (filehdr, &free_map);
+  bitmap_reset (&free_map, hdr_sector);
+  dir_remove (&dir, name);
+
+  /* Write everything back. */
+  bitmap_write (&free_map, &free_map_file);
+  dir_write (&dir, &root_dir_file);
+
+  success = true;
+
+  /* Clean up. */
+  bitmap_destroy (&free_map);
+ exit2:
+  filehdr_destroy (filehdr);
+ exit1:
+  dir_destroy (&dir);
 
   return success;
 }
-#endif /* FILESYS_STUB */
 
-#undef NDEBUG
-#include "debug.h"
-#include "file.h"
+/* Prints a list of files in the filesystem to the system
+   console.
+   Returns true if successful, false on failure,
+   which occurs only if an internal memory allocation fails. */
+bool
+filesys_list (void) 
+{
+  struct dir dir;
+
+  if (!dir_init (&dir, NUM_DIR_ENTRIES))
+    return false;
+  dir_read (&dir, &root_dir_file);
+  dir_list (&dir);
+  dir_destroy (&dir);
+
+  return true;
+}
+
+/* Dumps the filesystem state to the system console,
+   including the free map, the list of files, and file contents.
+   Returns true if successful, false on failure,
+   which occurs only if an internal memory allocation fails. */
+bool
+filesys_dump (void) 
+{
+  struct bitmap free_map;
+  struct dir dir;  
+
+  printk ("Free map:\n");
+  if (!bitmap_init (&free_map, disk_size (filesys_disk)))
+    return false;
+  bitmap_read (&free_map, &free_map_file);
+  bitmap_dump (&free_map);
+  bitmap_destroy (&free_map);
+  printk ("\n");
+  
+  if (!dir_init (&dir, NUM_DIR_ENTRIES))
+    return false;
+  dir_read (&dir, &root_dir_file);
+  dir_dump (&dir);
+  dir_destroy (&dir);
+
+  return true;
+}
 
+static void must_succeed_function (int, bool) NO_INLINE;
+#define MUST_SUCCEED(EXPR) must_succeed_function (__LINE__, EXPR)
+
+/* Performs basic sanity checks on the filesystem.
+   The filesystem should not contain a file named `foo' when
+   called. */
 void
 filesys_self_test (void)
 {
   static const char s[] = "This is a test string.";
-  struct file *file;
+  struct file file;
   char s2[sizeof s];
 
-  ASSERT (filesys_create ("foo"));
-  ASSERT ((file = filesys_open ("foo")) != NULL);
-  ASSERT (file_write (file, s, sizeof s) == sizeof s);
-  ASSERT (file_tell (file) == sizeof s);
-  ASSERT (file_length (file) == sizeof s);
-  file_close (file);
-
-  ASSERT ((file = filesys_open ("foo")) != NULL);
-  ASSERT (file_read (file, s2, sizeof s2) == sizeof s2);
-  ASSERT (memcmp (s, s2, sizeof s) == 0);
-  ASSERT (file_tell (file) == sizeof s2);
-  ASSERT (file_length (file) == sizeof s2);
-  file_close (file);
-
-  ASSERT (filesys_remove ("foo"));
+  MUST_SUCCEED (filesys_create ("foo", sizeof s));
+  MUST_SUCCEED (filesys_open ("foo", &file));
+  MUST_SUCCEED (file_write (&file, s, sizeof s) == sizeof s);
+  MUST_SUCCEED (file_tell (&file) == sizeof s);
+  MUST_SUCCEED (file_length (&file) == sizeof s);
+  file_close (&file);
+
+  MUST_SUCCEED (filesys_open ("foo", &file));
+  MUST_SUCCEED (file_read (&file, s2, sizeof s2) == sizeof s2);
+  MUST_SUCCEED (memcmp (s, s2, sizeof s) == 0);
+  MUST_SUCCEED (file_tell (&file) == sizeof s2);
+  MUST_SUCCEED (file_length (&file) == sizeof s2);
+  file_close (&file);
+
+  MUST_SUCCEED (filesys_remove ("foo"));
+
+  printk ("filesys: self test ok\n");
+}
+
+/* Formats the filesystem. */
+static void
+do_format (void)
+{
+  struct bitmap free_map;
+  struct filehdr *map_hdr, *dir_hdr;
+  struct dir dir;
+
+  printk ("Formatting filesystem...");
+
+  /* Create the initial bitmap and reserve sectors for the
+     free map and root directory file headers. */
+  if (!bitmap_init (&free_map, disk_size (filesys_disk)))
+    PANIC ("bitmap creation failed--disk is too large");
+  bitmap_mark (&free_map, FREE_MAP_SECTOR);
+  bitmap_mark (&free_map, ROOT_DIR_SECTOR);
+
+  /* Allocate data sector(s) for the free map file
+     and write its file header to disk. */
+  map_hdr = filehdr_allocate (&free_map, bitmap_file_size (&free_map));
+  if (map_hdr == NULL)
+    PANIC ("free map creation failed--disk is too large");
+  filehdr_write (map_hdr, FREE_MAP_SECTOR);
+  filehdr_destroy (map_hdr);
+
+  /* Allocate data sector(s) for the root directory file
+     and write its file header to disk. */
+  dir_hdr = filehdr_allocate (&free_map, ROOT_DIR_FILE_SIZE);
+  if (dir_hdr == NULL)
+    PANIC ("root directory creation failed");
+  filehdr_write (dir_hdr, ROOT_DIR_SECTOR);
+  filehdr_destroy (dir_hdr);
+
+  /* Write out the free map now that we have space reserved
+     for it. */
+  if (!file_open (&free_map_file, FREE_MAP_SECTOR))
+    PANIC ("can't open free map file");
+  bitmap_write (&free_map, &free_map_file);
+  bitmap_destroy (&free_map);
+  file_close (&free_map_file);
+
+  /* Write out the root directory in the same way. */
+  if (!file_open (&root_dir_file, ROOT_DIR_SECTOR))
+    PANIC ("can't open root directory");
+  if (!dir_init (&dir, NUM_DIR_ENTRIES))
+    PANIC ("can't initialize root directory");
+  dir_write (&dir, &root_dir_file);
+  dir_destroy (&dir);
+  file_close (&free_map_file);
+
+  printk ("done.\n");
+}
+
+/* If SUCCESS is false, panics with an error complaining about
+   LINE_NO. */
+static void 
+must_succeed_function (int line_no, bool success) 
+{
+  if (!success)
+    PANIC ("filesys_self_test: operation failed on line %d", line_no);
 }