X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Ffilesys%2Ffile.c;h=27e907feabe36b689d40bf85ae0d865cdc5deef9;hb=59bbbf9d74b6c6b430c51def30a9e1437f5e14a1;hp=b2a4942f56561a6ee3317d06295e98e3ded8001b;hpb=8256dc4ff8f7c0a1f76c2d3a601b92d67aa8acfe;p=pintos-anon

diff --git a/src/filesys/file.c b/src/filesys/file.c
index b2a4942..27e907f 100644
--- a/src/filesys/file.c
+++ b/src/filesys/file.c
@@ -1,51 +1,196 @@
-#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 */