-#include "file.h"
+#include "filesys/file.h"
+#include <debug.h>
+#include <string.h>
+#include "filesys/directory.h"
+#include "filesys/inode.h"
+#include "filesys/filesys.h"
+#include "threads/malloc.h"
-#ifdef FILESYS_STUB
+/* An open file. */
+struct file
+ {
+ struct inode *inode; /* File's inode. */
+ uint8_t *bounce; /* Bounce buffer for reads and writes. */
+ off_t pos; /* Current position. */
+ };
+
+/* Opens and returns the file whose inode is in sector
+ INODE_SECTOR. Returns a null pointer if unsuccessful. */
+struct file *
+file_open (disk_sector_t inode_sector)
+{
+ struct file *file = calloc (1, sizeof *file);
+ if (file == NULL)
+ return NULL;
+
+ file->inode = inode_open (inode_sector);
+ file->bounce = malloc (DISK_SECTOR_SIZE);
+ file->pos = 0;
+ if (file->inode == NULL || file->bounce == NULL)
+ {
+ inode_close (file->inode);
+ free (file->bounce);
+ return NULL;
+ }
+
+ return file;
+}
+
+/* Closes FILE. */
+void
+file_close (struct file *file)
+{
+ if (file == NULL)
+ return;
+
+ inode_close (file->inode);
+ free (file->bounce);
+}
+
+/* Reads SIZE bytes from FILE into BUFFER,
+ starting at the file's current position,
+ and advances the current position.
+ Returns the number of bytes actually read,
+ which may be less than SIZE if end of file is reached. */
off_t
file_read (struct file *file, void *buffer, off_t size)
{
- 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)
+ off_t bytes_read = file_read_at (file, 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.
+ The file's current position is unaffected
+ Returns the number of bytes actually read,
+ which may be less than SIZE if end of file is reached. */
+off_t
+file_read_at (struct file *file, void *buffer_, off_t size,
+ off_t file_ofs)
+{
+ uint8_t *buffer = buffer_;
+ off_t bytes_read = 0;
+
+ while (size > 0)
{
- if (!filesys_stub_receive ("B", buffer, (size_t) retval))
- retval = -1;
+ /* Disk sector to read, starting byte offset within sector. */
+ disk_sector_t sector_idx;
+ int sector_ofs = file_ofs % DISK_SECTOR_SIZE;
+
+ /* Bytes left in file, bytes left in sector, lesser of the two. */
+ off_t file_left = inode_length (file->inode) - 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 = size < min_left ? size : min_left;
+ if (chunk_size <= 0)
+ break;
+
+ /* Read sector into bounce buffer, then copy into caller's
+ buffer. */
+ sector_idx = inode_byte_to_sector (file->inode, file_ofs);
+ disk_read (filesys_disk, sector_idx, file->bounce);
+ memcpy (buffer + bytes_read, file->bounce + sector_ofs, chunk_size);
+
+ /* Advance. */
+ size -= chunk_size;
+ file_ofs += chunk_size;
+ bytes_read += chunk_size;
}
- return retval;
+
+ return bytes_read;
}
+/* Writes SIZE bytes from BUFFER into FILE,
+ starting at the file's current position,
+ and advances the 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.) */
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 = file_write_at (file, 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.
+ The file's current position is unaffected
+ 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.) */
+off_t
+file_write_at (struct file *file, const void *buffer_, off_t size,
+ off_t file_ofs)
+{
+ const uint8_t *buffer = buffer_;
+ off_t bytes_written = 0;
+
+ while (size > 0)
+ {
+ /* Sector to write, starting byte offset within sector. */
+ off_t sector_idx;
+ int sector_ofs = file_ofs % DISK_SECTOR_SIZE;
+
+ /* Bytes left in file, bytes left in sector, lesser of the two. */
+ off_t file_left = inode_length (file->inode) - 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 write into this sector. */
+ int chunk_size = size < min_left ? size : min_left;
+ if (chunk_size <= 0)
+ break;
+
+ /* 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. */
+ sector_idx = inode_byte_to_sector (file->inode, file_ofs);
+ if (sector_ofs > 0 || chunk_size < sector_left)
+ 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;
+ file_ofs += chunk_size;
+ bytes_written += chunk_size;
+ }
+
+ return bytes_written;
}
+/* 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 an offset of FILE_OFS
+ bytes from the start of the file. */
void
-file_seek (struct file *file, off_t pos)
+file_seek (struct file *file, off_t file_ofs)
{
- filesys_stub_send ("s'seek' i i", (int32_t) file, (int32_t) pos);
- filesys_stub_receive ("s'seek'");
+ ASSERT (file != NULL);
+ ASSERT (file_ofs >= 0);
+ file->pos = file_ofs;
}
+/* 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