From: Ben Pfaff <blp@cs.stanford.edu>
Date: Mon, 30 Aug 2004 22:55:39 +0000 (+0000)
Subject: Working filesystem.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?p=pintos-anon;a=commitdiff_plain;h=621963e2a383d53b2c5eca627102625421b46545

Working filesystem.
---

diff --git a/src/filesys/directory.c b/src/filesys/directory.c
new file mode 100644
index 0000000..43f87f0
--- /dev/null
+++ b/src/filesys/directory.c
@@ -0,0 +1,120 @@
+#include "directory.h"
+#include "file.h"
+#include "lib.h"
+#include "malloc.h"
+
+bool
+dir_init (struct dir *d, size_t entry_cnt) 
+{
+  d->entry_cnt = entry_cnt;
+  d->entries = calloc (1, sizeof *d->entries * entry_cnt);
+  return d->entries != NULL;
+}
+
+void
+dir_destroy (struct dir *d) 
+{
+  free (d->entries);
+}
+
+static off_t
+dir_size (struct dir *d) 
+{
+  return d->entry_cnt * sizeof *d->entries;
+}
+
+void
+dir_read (struct dir *d, struct file *file) 
+{
+  file_read_at (file, d->entries, dir_size (d), 0);
+}
+
+void
+dir_write (struct dir *d, struct file *file) 
+{
+  file_write_at (file, d->entries, dir_size (d), 0);
+}
+
+static struct dir_entry *
+lookup (const struct dir *d, const char *name) 
+{
+  size_t i;
+  
+  ASSERT (d != NULL);
+  ASSERT (name != NULL);
+
+  if (strlen (name) > FILENAME_LEN_MAX)
+    return NULL;
+
+  for (i = 0; i < d->entry_cnt; i++) 
+    {
+      struct dir_entry *e = &d->entries[i];
+      if (e->in_use && !strcmp (name, e->name))
+        return e;
+    }
+  return NULL;
+}
+
+bool
+dir_lookup (const struct dir *d, const char *name,
+            disk_sector_no *filehdr_sector) 
+{
+  const struct dir_entry *e;
+
+  ASSERT (d != NULL);
+  ASSERT (name != NULL);
+  
+  e = lookup (d, name);
+  if (e != NULL) 
+    {
+      if (filehdr_sector != NULL)
+        *filehdr_sector = e->filehdr_sector;
+      return true;
+    }
+  else
+    return false;
+}
+
+bool
+dir_add (struct dir *d, const char *name, disk_sector_no filehdr_sector) 
+{
+  size_t i;
+  
+  ASSERT (d != NULL);
+  ASSERT (name != NULL);
+  ASSERT (lookup (d, name) == NULL);
+
+  for (i = 0; i < d->entry_cnt; i++)
+    {
+      struct dir_entry *e = &d->entries[i];
+      if (!e->in_use) 
+        {
+          e->in_use = true;
+          strlcpy (e->name, name, sizeof e->name);
+          e->filehdr_sector = filehdr_sector;
+          return true;
+        }
+    }
+  return false;
+}
+
+bool
+dir_remove (struct dir *d, const char *name) 
+{
+  struct dir_entry *e;
+
+  ASSERT (d != NULL);
+  ASSERT (name != NULL);
+
+  e = lookup (d, name);
+  if (e != NULL) 
+    {
+      e->in_use = false;
+      return true;
+    }
+  else
+    return false;
+}
+
+void dir_list (const struct dir *);
+void dir_print (const struct dir *);
diff --git a/src/filesys/directory.h b/src/filesys/directory.h
new file mode 100644
index 0000000..fe7f333
--- /dev/null
+++ b/src/filesys/directory.h
@@ -0,0 +1,36 @@
+#ifndef HEADER_DIRECTORY_H
+#define HEADER_DIRECTORY_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+#include "disk.h"
+
+/* Maximum length of a filename.
+   This is the traditional UNIX maximum. */
+#define FILENAME_LEN_MAX 14
+
+struct dir_entry 
+  {
+    bool in_use;
+    char name[FILENAME_LEN_MAX + 1];
+    disk_sector_no filehdr_sector;
+  };
+
+struct dir 
+  {
+    size_t entry_cnt;
+    struct dir_entry *entries;
+  };
+
+struct file;
+bool dir_init (struct dir *, size_t entry_cnt);
+void dir_destroy (struct dir *);
+void dir_read (struct dir *, struct file *);
+void dir_write (struct dir *, struct file *);
+bool dir_lookup (const struct dir *, const char *name, disk_sector_no *);
+bool dir_add (struct dir *, const char *name, disk_sector_no);
+bool dir_remove (struct dir *, const char *name);
+void dir_list (const struct dir *);
+void dir_print (const struct dir *);
+
+#endif /* directory.h */
diff --git a/src/filesys/file.c b/src/filesys/file.c
index e6f282f..e16ff5f 100644
--- a/src/filesys/file.c
+++ b/src/filesys/file.c
@@ -1,82 +1,74 @@
 #include "file.h"
-
-#ifdef FILESYS_STUB
 #include "debug.h"
-#include "filesys-stub.h"
 #include "lib.h"
 #include "malloc.h"
+#include "directory.h"
+#include "filehdr.h"
+#include "filesys.h"
 
 bool
-file_open (struct file *file, const char *name) 
-{
-  struct dir dir;
-  disk_sector_no hdr_sector;
-  bool success = false;
-
-  dir_init (&dir, NUM_DIR_ENTRIES);
-  dir_read (&dir, &root_dir_file);
-  if (dir_lookup (&dir, name, &hdr_sector))
-    success = file_open_sector (file, hdr_sector);
-
-  dir_destroy (&dir);
-  return success;
-}
-
-bool
-file_open_sector (struct file *file, disk_sector_no hdr_sector) 
+file_open (struct file *file, disk_sector_no hdr_sector) 
 {
+  file->hdr = filehdr_read (hdr_sector);
+  file->bounce = malloc (DISK_SECTOR_SIZE);
   file->pos = 0;
-  return filehdr_read (&file->hdr, hdr_sector);
+  if (file->hdr != NULL && file->bounce != NULL)
+    return true;
+  else
+    {
+      filehdr_destroy (file->hdr);
+      free (file->bounce);
+      return false;
+    }
 }
 
 void
 file_close (struct file *file) 
 {
-  filehdr_destroy (file);
+  filehdr_destroy (file->hdr);
 }
 
 off_t
 file_read (struct file *file, void *buffer, off_t size) 
 {
-  off_t retval = file_read_at (file, buffer, size, file->pos);
-  file->pos += retval;
-  return retval;
+  off_t bytes_read = file_read_at (file, buffer, size, file->pos);
+  file->pos += bytes_read;
+  return bytes_read;
 }
 
 off_t
-file_read_at (struct file *file, void *buffer_, off_t size, off_t start) 
+file_read_at (struct file *file, void *buffer_, off_t size,
+              off_t file_ofs) 
 {
   uint8_t *buffer = buffer_;
   off_t bytes_read = 0;
-  uint8_t *bounce;
 
-  bounce = malloc (DISK_SECTOR_SIZE);
   while (size > 0) 
     {
       /* Disk sector to read, starting byte offset within sector. */
-      off_t sector_idx = filehdr_byte_to_sector (file->hdr);
-      int sector_ofs = start % DISK_SECTOR_SIZE;
+      off_t sector_idx = filehdr_byte_to_sector (file->hdr, file_ofs);
+      int sector_ofs = file_ofs % DISK_SECTOR_SIZE;
 
-      /* Bytes left in file, bytes left in sector. */
-      off_t file_left = filehdr_size (file->hdr) - start;
-      off_t sector_left = DISK_SECTOR_SIZE - sector_ofs;
+      /* Bytes left in file, bytes left in sector, lesser of the two. */
+      off_t file_left = filehdr_length (file->hdr) - file_ofs;
+      int sector_left = DISK_SECTOR_SIZE - sector_ofs;
+      int min_left = file_left < sector_left ? file_left : sector_left;
 
       /* Number of bytes to actually copy out of this sector. */
-      int chunk_size = file_left < sector_left ? file_left : sector_left;
+      int chunk_size = size < min_left ? size : min_left;
       if (chunk_size == 0)
         break;
 
       /* Read sector into bounce buffer, then copy into caller's
          buffer. */
-      disk_read (disk, sector_idx, bounce);
-      memcpy (buffer + bytes_read, bounce + sector_ofs, chunk_size);
+      disk_read (filesys_disk, sector_idx, file->bounce);
+      memcpy (buffer + bytes_read, file->bounce + sector_ofs, chunk_size);
 
       /* Advance. */
       size -= chunk_size;
-      start += chunk_size;
+      file_ofs += chunk_size;
       bytes_read += chunk_size;
     }
-  free (bounce);
 
   return bytes_read;
 }
@@ -84,88 +76,72 @@ file_read_at (struct file *file, void *buffer_, off_t size, off_t start)
 off_t
 file_write (struct file *file, const void *buffer, off_t size) 
 {
-  off_t retval = file_write_at (file, buffer, size, file->pos);
-  file->pos += retval;
-  return retval;
+  off_t bytes_written = file_write_at (file, buffer, size, file->pos);
+  file->pos += bytes_written;
+  return bytes_written;
 }
 
 off_t
 file_write_at (struct file *file, const void *buffer_, off_t size,
-               off_t start) 
+               off_t file_ofs) 
 {
-  uint8_t *buffer = buffer_;
-  off_t bytes_read = 0;
-  uint8_t *bounce;
+  const uint8_t *buffer = buffer_;
+  off_t bytes_written = 0;
 
-  bounce = malloc (DISK_SECTOR_SIZE);
   while (size > 0) 
     {
-      /* Disk sector to read, starting byte offset within sector. */
-      off_t sector_idx = filehdr_byte_to_sector (file->hdr);
-      int sector_ofs = start % DISK_SECTOR_SIZE;
+      /* Starting byte offset within sector to read. */
+      off_t sector_idx = filehdr_byte_to_sector (file->hdr, file_ofs);
+      int sector_ofs = file_ofs % DISK_SECTOR_SIZE;
 
-      /* Bytes left in file, bytes left in sector. */
-      off_t file_left = filehdr_size (file->hdr) - start;
-      off_t sector_left = DISK_SECTOR_SIZE - sector_ofs;
+      /* Bytes left in file, bytes left in sector, lesser of the two. */
+      off_t file_left = filehdr_length (file->hdr) - file_ofs;
+      int sector_left = DISK_SECTOR_SIZE - sector_ofs;
+      int min_left = file_left < sector_left ? file_left : sector_left;
 
-      /* Number of bytes to actually copy out of this sector. */
-      int chunk_size = file_left < sector_left ? file_left : sector_left;
+      /* Number of bytes to actually writen into this sector. */
+      int chunk_size = size < min_left ? size : min_left;
       if (chunk_size == 0)
         break;
 
-      /* Read sector into bounce buffer, then copy into caller's
-         buffer. */
-      disk_read (disk, sector_idx, bounce);
-      memcpy (buffer + bytes_read, bounce + sector_ofs, chunk_size);
+      /* If the sector contains data before or after the chunk
+         we're writing, then we need to read in the sector
+         first.  Otherwise we start with a sector of all zeros. */
+      if (sector_ofs > 0 || chunk_size < sector_ofs)
+        disk_read (filesys_disk, sector_idx, file->bounce);
+      else
+        memset (file->bounce, 0, DISK_SECTOR_SIZE);
+      memcpy (file->bounce + sector_ofs, buffer + bytes_written, chunk_size);
+      disk_write (filesys_disk, sector_idx, file->bounce);
 
       /* Advance. */
       size -= chunk_size;
-      start += chunk_size;
-      bytes_read += chunk_size;
+      file_ofs += chunk_size;
+      bytes_written += chunk_size;
     }
-  free (bounce);
+  free (file->bounce);
 
-  return bytes_read;
+  return bytes_written;
 }
 
 off_t
 file_length (struct file *file) 
 {
-  int32_t length;
-
-  filesys_stub_lock ();
-  filesys_stub_put_string ("length");
-  filesys_stub_put_file (file);
-  filesys_stub_match_string ("length");
-  length = filesys_stub_get_int32 ();
-  filesys_stub_unlock ();
-
-  return length;
+  ASSERT (file != NULL);
+  return filehdr_length (file->hdr);
 }
 
 void
-file_seek (struct file *file, off_t pos) 
+file_seek (struct file *file, off_t file_ofs) 
 {
-  filesys_stub_lock ();
-  filesys_stub_put_string ("seek");
-  filesys_stub_put_file (file);
-  filesys_stub_put_uint32 (pos);
-  filesys_stub_match_string ("seek");
-  filesys_stub_unlock ();
+  ASSERT (file != NULL);
+  ASSERT (file_ofs >= 0);
+  file->pos = file_ofs;
 }
 
 off_t
 file_tell (struct file *file) 
 {
-  int32_t pos;
-
-  filesys_stub_lock ();
-  filesys_stub_put_string ("tell");
-  filesys_stub_put_file (file);
-  filesys_stub_match_string ("tell");
-  pos = filesys_stub_get_int32 ();
-  filesys_stub_unlock ();
-
-  return pos;
+  ASSERT (file != NULL);
+  return file->pos;
 }
-#endif /* FILESYS_STUB */
diff --git a/src/filesys/file.h b/src/filesys/file.h
index d165e80..b29ce33 100644
--- a/src/filesys/file.h
+++ b/src/filesys/file.h
@@ -1,22 +1,20 @@
 #ifndef HEADER_FILE_H
 #define HEADER_FILE_H 1
 
+#include <stdbool.h>
 #include <stdint.h>
 #include <stddef.h>
-
-#ifndef OFF_T
-#define OFF_T
-typedef int32_t off_t;
-#endif
+#include "disk.h"
+#include "off_t.h"
 
 struct file 
   {
     struct filehdr *hdr;
+    void *bounce;
     off_t pos;
   };
 
-bool file_open (struct file *, const char *name);
-bool file_open_sector (struct file *, disk_sector_no);
+bool file_open (struct file *, disk_sector_no);
 void file_close (struct file *);
 off_t file_read (struct file *, void *, off_t);
 off_t file_read_at (struct file *, void *, off_t size, off_t start);
diff --git a/src/filesys/filehdr.c b/src/filesys/filehdr.c
new file mode 100644
index 0000000..aad11e5
--- /dev/null
+++ b/src/filesys/filehdr.c
@@ -0,0 +1,94 @@
+#include "filehdr.h"
+#include "bitmap.h"
+#include "debug.h"
+#include "malloc.h"
+#include "filesys.h"
+#include "lib.h"
+
+struct filehdr *
+filehdr_allocate (struct bitmap *b, off_t length) 
+{
+  struct filehdr *h;
+  size_t sector_cnt;
+
+  ASSERT (b != NULL);
+  ASSERT (length >= 0);
+
+  h = calloc (1, sizeof *h);
+  if (h == NULL)
+    return NULL;
+
+  h->length = length;
+  sector_cnt = (length / DISK_SECTOR_SIZE) + (length % DISK_SECTOR_SIZE > 0);
+  while (h->sector_cnt < sector_cnt)
+    {
+      size_t sector = bitmap_find_and_set (b);
+      if (sector == BITMAP_ERROR)
+        {
+          filehdr_deallocate (h, b);
+          return NULL;
+        }
+      h->sectors[h->sector_cnt++] = sector;
+    }
+
+  return h;
+}
+
+void
+filehdr_deallocate (struct filehdr *h, struct bitmap *b) 
+{
+  size_t i;
+  
+  ASSERT (h != NULL);
+  ASSERT (b != NULL);
+
+  for (i = 0; i < h->sector_cnt; i++)
+    bitmap_reset (b, h->sectors[i]);
+}
+
+struct filehdr *
+filehdr_read (disk_sector_no filehdr_sector) 
+{
+  struct filehdr *h = calloc (1, sizeof *h);
+  if (h == NULL)
+    return NULL;
+
+  ASSERT (sizeof *h == DISK_SECTOR_SIZE);
+  disk_read (filesys_disk, filehdr_sector, h);
+
+  return h;
+}
+
+void
+filehdr_write (const struct filehdr *h, disk_sector_no filehdr_sector) 
+{
+  ASSERT (h != NULL);
+  ASSERT (sizeof *h == DISK_SECTOR_SIZE);
+  disk_write (filesys_disk, filehdr_sector, h);
+}
+
+void
+filehdr_destroy (struct filehdr *h) 
+{
+  free (h);
+}
+
+disk_sector_no
+filehdr_byte_to_sector (const struct filehdr *h, off_t pos) 
+{
+  size_t idx;
+
+  ASSERT (h != NULL);
+
+  idx = pos / DISK_SECTOR_SIZE;
+  return idx < h->sector_cnt ? h->sectors[idx] : (disk_sector_no) -1;
+}
+
+off_t
+filehdr_length (const struct filehdr *h)
+{
+  ASSERT (h != NULL);
+  return h->length;
+}
+
+void filehdr_print (const struct filehdr *);
diff --git a/src/filesys/filehdr.h b/src/filesys/filehdr.h
new file mode 100644
index 0000000..7b0ecc2
--- /dev/null
+++ b/src/filesys/filehdr.h
@@ -0,0 +1,29 @@
+#ifndef HEADER_FILEHDR_H
+#define HEADER_FILEHDR_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+#include "disk.h"
+#include "off_t.h"
+
+#define DIRECT_CNT ((DISK_SECTOR_SIZE - sizeof (off_t) * 2)     \
+                    / sizeof (disk_sector_no))
+
+struct filehdr 
+  {
+    off_t length;
+    size_t sector_cnt;
+    disk_sector_no sectors[DIRECT_CNT];
+  };
+
+struct bitmap;
+struct filehdr *filehdr_allocate (struct bitmap *, off_t length);
+void filehdr_deallocate (struct filehdr *, struct bitmap *);
+struct filehdr *filehdr_read (disk_sector_no);
+void filehdr_write (const struct filehdr *, disk_sector_no);
+void filehdr_destroy (struct filehdr *);
+disk_sector_no filehdr_byte_to_sector (const struct filehdr *, off_t);
+off_t filehdr_length (const struct filehdr *);
+void filehdr_print (const struct filehdr *);
+
+#endif /* filehdr.h */
diff --git a/src/filesys/filesys.c b/src/filesys/filesys.c
index d0e5c49..2cc0721 100644
--- a/src/filesys/filesys.c
+++ b/src/filesys/filesys.c
@@ -1,10 +1,11 @@
 #include "filesys.h"
-#include "disk.h"
+#include "bitmap.h"
+#include "debug.h"
 #include "directory.h"
-
-static struct disk *disk;
-
-static struct file free_map_file, root_dir_file;
+#include "disk.h"
+#include "file.h"
+#include "filehdr.h"
+#include "lib.h"
 
 #define FREE_MAP_SECTOR 0
 #define ROOT_DIR_SECTOR 1
@@ -12,46 +13,53 @@ static struct file free_map_file, root_dir_file;
 #define NUM_DIR_ENTRIES 10
 #define ROOT_DIR_FILE_SIZE (sizeof (struct dir_entry) * NUM_DIR_ENTRIES)
 
+struct disk *filesys_disk;
+
+static struct file free_map_file, root_dir_file;
+
 static void
 do_format (void)
 {
   struct bitmap free_map;
-  struct filehdr map_hdr, dir_hdr;
+  struct filehdr *map_hdr, *dir_hdr;
   struct dir dir;
 
   /* Create the initial bitmap and reserve sectors for the
      free map and root directory file headers. */
-  if (!bitmap_init (&free_map, disk_size (disk)))
-    panic ("bitmap creation failed");
+  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. */
-  if (!filehdr_allocate (&map_hdr, bitmap_storage_size (&free_map)))
-    panic ("free map creation failed");
-  filehdr_write (&map_hdr, FREE_MAP_SECTOR);
-  filehdr_destroy (&map_hdr);
+  map_hdr = filehdr_allocate (&free_map, bitmap_storage_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. */
-  if (!filehdr_allocate (&dir_hdr, ROOT_DIR_FILE_SIZE))
+  dir_hdr = filehdr_allocate (&free_map, ROOT_DIR_FILE_SIZE);
+  if (dir_hdr == NULL)
     panic ("root directory creation failed");
-  filehdr_write (&dir_hdr, FREE_MAP_SECTOR);
-  filehdr_destroy (&dir_hdr);
+  filehdr_write (dir_hdr, ROOT_DIR_SECTOR);
+  filehdr_destroy (dir_hdr);
 
   /* Write out the free map now that we have space reserved
      for it. */
   file_open (&free_map_file, FREE_MAP_SECTOR);
-  bitmapio_write (&free_map, 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. */
-  file_open (&root_dir_file, ROOT_DIR_SECTOR);
+  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 (root_dir_file);
+  dir_write (&dir, &root_dir_file);
   dir_destroy (&dir);
   file_close (&free_map_file);
 }
@@ -59,8 +67,8 @@ do_format (void)
 void
 filesys_init (bool format) 
 {
-  disk = disk_get (1);
-  if (disk == NULL)
+  filesys_disk = disk_get (1);
+  if (filesys_disk == NULL)
     panic ("ide1:1 not present, filesystem initialization failed");
 
   if (format) 
@@ -76,7 +84,7 @@ filesys_create (const char *name, off_t initial_size)
   struct dir dir;
   struct bitmap free_map;
   disk_sector_no hdr_sector;
-  struct filehdr filehdr;
+  struct filehdr *filehdr;
   bool success = false;
 
   /* Read the root directory. */
@@ -86,9 +94,9 @@ filesys_create (const char *name, off_t initial_size)
     goto exit1;
 
   /* Allocate a block for the file header. */
-  if (!bitmap_init (&free_map, disk_size (disk)))
+  if (!bitmap_init (&free_map, disk_size (filesys_disk)))
     goto exit1;
-  bitmapio_read (&free_map, &free_map_file);
+  bitmap_read (&free_map, &free_map_file);
   hdr_sector = bitmap_find_and_set (&free_map);
   if (hdr_sector == BITMAP_ERROR)
     goto exit2;
@@ -98,18 +106,19 @@ filesys_create (const char *name, off_t initial_size)
     goto exit2;
 
   /* Allocate space for the file. */
-  if (!filehdr_allocate (&filehdr, initial_size))
+  filehdr = filehdr_allocate (&free_map, initial_size);
+  if (filehdr == NULL)
     goto exit2;
 
   /* Write everything back. */
-  filehdr_write (&filehdr, hdr_sector);
+  filehdr_write (filehdr, hdr_sector);
   dir_write (&dir, &root_dir_file);
-  bitmapio_write (&free_map, &free_map_file);
+  bitmap_write (&free_map, &free_map_file);
 
   success = true;
 
   /* Clean up. */
-  filehdr_destroy (&filehdr);
+  filehdr_destroy (filehdr);
  exit2:
   bitmap_destroy (&free_map);
  exit1:
@@ -118,12 +127,28 @@ filesys_create (const char *name, off_t initial_size)
   return success;
 }
 
+bool
+filesys_open (const char *name, struct file *file)
+{
+  struct dir dir;
+  disk_sector_no hdr_sector;
+  bool success = false;
+
+  dir_init (&dir, NUM_DIR_ENTRIES);
+  dir_read (&dir, &root_dir_file);
+  if (dir_lookup (&dir, name, &hdr_sector))
+    success = file_open (file, hdr_sector);
+  
+  dir_destroy (&dir);
+  return success;
+}
+
 bool
 filesys_remove (const char *name) 
 {
   struct dir dir;
   disk_sector_no hdr_sector;
-  struct filehdr filehdr;
+  struct filehdr *filehdr;
   struct bitmap free_map;
   bool success = false;
 
@@ -134,21 +159,22 @@ filesys_remove (const char *name)
     goto exit1;
 
   /* Read the file header. */
-  if (!filehdr_read (&filehdr, hdr_sector))
+  filehdr = filehdr_read (hdr_sector);
+  if (filehdr == NULL)
     goto exit1;
 
   /* Allocate a block for the file header. */
-  if (!bitmap_init (&free_map, disk_size (disk)))
+  if (!bitmap_init (&free_map, disk_size (filesys_disk)))
     goto exit2;
-  bitmapio_read (&free_map, &free_map_file);
+  bitmap_read (&free_map, &free_map_file);
 
   /* Deallocate. */
-  filehdr_deallocate (&filehdr, &free_map);
+  filehdr_deallocate (filehdr, &free_map);
   bitmap_reset (&free_map, hdr_sector);
   dir_remove (&dir, name);
 
   /* Write everything back. */
-  bitmapio_write (&free_map, &free_map_file);
+  bitmap_write (&free_map, &free_map_file);
   dir_write (&dir, &root_dir_file);
 
   success = true;
@@ -156,37 +182,46 @@ filesys_remove (const char *name)
   /* Clean up. */
   bitmap_destroy (&free_map);
  exit2:
-  filehdr_destroy (&filehdr);
+  filehdr_destroy (filehdr);
  exit1:
   dir_destroy (&dir);
 
   return success;
 }
 
-#undef NDEBUG
-#include "debug.h"
-#include "file.h"
+static void must_succeed_function (int, int) ATTRIBUTE((noinline));
+
+static void 
+must_succeed_function (int line_no, int success) 
+{
+  if (!success)
+    panic ("filesys_self_test: operation failed on line %d", line_no);
+}
+
+#define MUST_SUCCEED(EXPR) must_succeed_function (__LINE__, EXPR)
 
 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");
 }
diff --git a/src/filesys/filesys.h b/src/filesys/filesys.h
index 3de5f85..73aff31 100644
--- a/src/filesys/filesys.h
+++ b/src/filesys/filesys.h
@@ -3,17 +3,17 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include "off_t.h"
 
-#ifndef OFF_T
-#define OFF_T
-typedef int32_t off_t;
-#endif
+struct disk *filesys_disk;
 
 struct file;
 void filesys_init (bool format);
 bool filesys_create (const char *name, off_t initial_size);
+bool filesys_open (const char *name, struct file *);
 bool filesys_remove (const char *name);
 void filesys_list (void);
+void filesys_print (void);
 
 void filesys_self_test (void);
 
diff --git a/src/filesys/off_t.h b/src/filesys/off_t.h
new file mode 100644
index 0000000..2b97bca
--- /dev/null
+++ b/src/filesys/off_t.h
@@ -0,0 +1,7 @@
+#ifndef HEADER_OFF_T_H
+#define HEADER_OFF_T_H 1
+
+#include <stdint.h>
+typedef int32_t off_t;
+
+#endif /* off_t.h */