X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Ffilesys%2Ffile.c;h=d5fc10de15004e98d4f8490aa8a7ec8a4c7efcff;hb=735ac4b8d255f4d1cf8cebaeb3a6a724ea3df008;hp=b2a4942f56561a6ee3317d06295e98e3ded8001b;hpb=8256dc4ff8f7c0a1f76c2d3a601b92d67aa8acfe;p=pintos-anon

diff --git a/src/filesys/file.c b/src/filesys/file.c
index b2a4942..d5fc10d 100644
--- a/src/filesys/file.c
+++ b/src/filesys/file.c
@@ -1,51 +1,168 @@
-#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) 
 {
-  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) 
+  struct file *file = calloc (1, sizeof *file);
+  if (inode != NULL && file != NULL)
     {
-      if (!filesys_stub_receive ("B", buffer, (size_t) retval))
-        retval = -1;
+      file->inode = inode;
+      file->pos = 0;
+      file->deny_write = false;
+      return file;
     }
-  return retval;
+  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) 
+{
+  return file_open (inode_reopen (file->inode));
+}
+
+/* Closes FILE. */
+void
+file_close (struct file *file) 
+{
+  if (file != NULL)
+    {
+      file_allow_write (file);
+      inode_close (file->inode);
+      free (file); 
+    }
+}
+
+/* Returns the inode encapsulated by FILE. */
+struct inode *
+file_get_inode (struct file *file) 
+{
+  return file->inode;
+}
+
+/* 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 */