-#include "file.h"
+#include "filesys/file.h"
+#include <debug.h>
+#include "filesys/inode.h"
+#include "threads/malloc.h"
-#ifdef FILESYS_STUB
-off_t
-file_read (struct file *file, void *buffer, off_t size)
+/* An open file. */
+struct file
+ {
+ struct inode *inode; /* File's inode. */
+ off_t pos; /* Current position. */
+ bool deny_write; /* Has file_deny_write() been called? */
+ };
+
+/* Opens a file for the given INODE, of which it takes ownership,
+ and returns the new file. Returns a null pointer if an
+ allocation fails or if INODE is null. */
+struct file *
+file_open (struct inode *inode)
+{
+ struct file *file = calloc (1, sizeof *file);
+ if (inode != NULL && file != NULL)
+ {
+ file->inode = inode;
+ file->pos = 0;
+ file->deny_write = false;
+ return file;
+ }
+ else
+ {
+ inode_close (inode);
+ free (file);
+ return NULL;
+ }
+}
+
+/* Opens and returns a new file for the same inode as FILE.
+ Returns a null pointer if unsuccessful. */
+struct file *
+file_reopen (struct file *file)
{
- int32_t retval = -1;
- filesys_stub_send ("s'read' i i", (int32_t) file, (int32_t) size);
- filesys_stub_receive ("s'read' i", &retval);
- if (retval > 0)
+ return file_open (inode_reopen (file->inode));
+}
+
+/* Closes FILE. */
+void
+file_close (struct file *file)
+{
+ if (file != NULL)
{
- if (!filesys_stub_receive ("B", buffer, (size_t) retval))
- retval = -1;
+ file_allow_write (file);
+ inode_close (file->inode);
+ free (file);
}
- return retval;
}
+/* Reads SIZE bytes from FILE into BUFFER,
+ starting at the file's current position.
+ Returns the number of bytes actually read,
+ which may be less than SIZE if end of file is reached.
+ Advances FILE's position by the number of bytes read. */
+off_t
+file_read (struct file *file, void *buffer, off_t size)
+{
+ off_t bytes_read = inode_read_at (file->inode, buffer, size, file->pos);
+ file->pos += bytes_read;
+ return bytes_read;
+}
+
+/* Reads SIZE bytes from FILE into BUFFER,
+ starting at offset FILE_OFS in the file.
+ Returns the number of bytes actually read,
+ which may be less than SIZE if end of file is reached.
+ The file's current position is unaffected. */
+off_t
+file_read_at (struct file *file, void *buffer, off_t size, off_t file_ofs)
+{
+ return inode_read_at (file->inode, buffer, size, file_ofs);
+}
+
+/* Writes SIZE bytes from BUFFER into FILE,
+ starting at the file's current position.
+ Returns the number of bytes actually written,
+ which may be less than SIZE if end of file is reached.
+ (Normally we'd grow the file in that case, but file growth is
+ not yet implemented.)
+ Advances FILE's position by the number of bytes read. */
off_t
file_write (struct file *file, const void *buffer, off_t size)
{
- int32_t retval = -1;
- filesys_stub_send ("s'write' i B", (int32_t) file, buffer, (size_t) size);
- filesys_stub_receive ("s'write' i", &retval);
- return retval;
+ off_t bytes_written = inode_write_at (file->inode, buffer, size, file->pos);
+ file->pos += bytes_written;
+ return bytes_written;
+}
+
+/* Writes SIZE bytes from BUFFER into FILE,
+ starting at offset FILE_OFS in the file.
+ Returns the number of bytes actually written,
+ which may be less than SIZE if end of file is reached.
+ (Normally we'd grow the file in that case, but file growth is
+ not yet implemented.)
+ The file's current position is unaffected. */
+off_t
+file_write_at (struct file *file, const void *buffer, off_t size,
+ off_t file_ofs)
+{
+ return inode_write_at (file->inode, buffer, size, file_ofs);
+}
+
+/* Prevents write operations on FILE's underlying inode
+ until file_allow_write() is called or FILE is closed. */
+void
+file_deny_write (struct file *file)
+{
+ ASSERT (file != NULL);
+ if (!file->deny_write)
+ {
+ file->deny_write = true;
+ inode_deny_write (file->inode);
+ }
+}
+
+/* Re-enables write operations on FILE's underlying inode.
+ (Writes might still be denied by some other file that has the
+ same inode open.) */
+void
+file_allow_write (struct file *file)
+{
+ ASSERT (file != NULL);
+ if (file->deny_write)
+ {
+ file->deny_write = false;
+ inode_allow_write (file->inode);
+ }
}
+/* Returns the size of FILE in bytes. */
off_t
file_length (struct file *file)
{
- int32_t length = -1;
- filesys_stub_send ("s'length' i", (int32_t) file);
- filesys_stub_receive ("s'length' i", &length);
- return length;
+ ASSERT (file != NULL);
+ return inode_length (file->inode);
}
+/* Sets the current position in FILE to NEW_POS bytes from the
+ start of the file. */
void
-file_seek (struct file *file, off_t pos)
+file_seek (struct file *file, off_t new_pos)
{
- filesys_stub_send ("s'seek' i i", (int32_t) file, (int32_t) pos);
- filesys_stub_receive ("s'seek'");
+ ASSERT (file != NULL);
+ ASSERT (new_pos >= 0);
+ file->pos = new_pos;
}
+/* Returns the current position in FILE as a byte offset from the
+ start of the file. */
off_t
file_tell (struct file *file)
{
- int32_t pos = -1;
- filesys_stub_send ("s'tell' i", (int32_t) file);
- filesys_stub_receive ("s'tell'", &pos);
- return pos;
+ ASSERT (file != NULL);
+ return file->pos;
}
-#endif /* FILESYS_STUB */
projects / pintos-anon / blobdiff