Start work on filesystem code.

[pintos-anon] / src / filesys / file.c

diff --git a/src/filesys/file.c b/src/filesys/file.c
index 0c18ab093dab78aea95471da9f4bd14a1f3b3c92..e6f282f8062dc2c383f3a540c08b73d0a9628ce7 100644 (file)
--- a/src/filesys/file.c
+++ b/src/filesys/file.c
@@ -6,53 +6,126 @@
 #include "lib.h"
 #include "malloc.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->pos = 0;
+  return filehdr_read (&file->hdr, hdr_sector);
+}
+
 void
 file_close (struct file *file) 
 {
-  filesys_stub_lock ();
-  filesys_stub_put_string ("close");
-  filesys_stub_put_file (file);
-  filesys_stub_match_string ("close");
-  filesys_stub_unlock ();
+  filehdr_destroy (file);
 }
 
 off_t
 file_read (struct file *file, void *buffer, off_t size) 
 {
-  int32_t retval;
+  off_t retval = file_read_at (file, buffer, size, file->pos);
+  file->pos += retval;
+  return retval;
+}
 
-  filesys_stub_lock ();
-  filesys_stub_put_string ("read");
-  filesys_stub_put_file (file);
-  filesys_stub_put_uint32 (size);
-  filesys_stub_match_string ("read");
-  retval = filesys_stub_get_int32 ();
-  if (retval > 0) 
+off_t
+file_read_at (struct file *file, void *buffer_, off_t size, off_t start) 
+{
+  uint8_t *buffer = buffer_;
+  off_t bytes_read = 0;
+  uint8_t *bounce;
+
+  bounce = malloc (DISK_SECTOR_SIZE);
+  while (size > 0) 
     {
-      ASSERT (retval <= size);
-      filesys_stub_get_bytes (buffer, retval);
+      /* 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;
+
+      /* 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;
+
+      /* Number of bytes to actually copy out of this sector. */
+      int chunk_size = file_left < sector_left ? file_left : sector_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);
+
+      /* Advance. */
+      size -= chunk_size;
+      start += chunk_size;
+      bytes_read += chunk_size;
     }
-  filesys_stub_unlock ();
-  
-  return retval;
+  free (bounce);
+
+  return bytes_read;
 }
 
 off_t
 file_write (struct file *file, const void *buffer, off_t size) 
 {
-  int32_t retval;
+  off_t retval = file_write_at (file, buffer, size, file->pos);
+  file->pos += retval;
+  return retval;
+}
 
-  filesys_stub_lock ();
-  filesys_stub_put_string ("write");
-  filesys_stub_put_file (file);
-  filesys_stub_put_uint32 (size);
-  filesys_stub_put_bytes (buffer, size);
-  filesys_stub_match_string ("write");
-  retval = filesys_stub_get_int32 ();
-  ASSERT (retval <= size);
-  filesys_stub_unlock ();
+off_t
+file_write_at (struct file *file, const void *buffer_, off_t size,
+               off_t start) 
+{
+  uint8_t *buffer = buffer_;
+  off_t bytes_read = 0;
+  uint8_t *bounce;
 
-  return retval;
+  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;
+
+      /* 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;
+
+      /* Number of bytes to actually copy out of this sector. */
+      int chunk_size = file_left < sector_left ? file_left : sector_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);
+
+      /* Advance. */
+      size -= chunk_size;
+      start += chunk_size;
+      bytes_read += chunk_size;
+    }
+  free (bounce);
+
+  return bytes_read;
 }
 
 off_t