1 files changed, 62 insertions, 0 deletions
diff --git a/kernel/include/fs/file.h b/kernel/include/fs/file.h
new file mode 100644
index 0000000..72caee4
--- /dev/null
+++ b/kernel/include/fs/file.h
@@ -0,0 +1,62 @@
+#pragma once
+
+#include "types.h"
+
+#define FMODE_READ 1
+#define FMODE_WRITE 2
+#define FMODE_APPEND 4
+#define FMODE_MAX_VALUE (FMODE_READ | FMODE_WRITE | FMODE_APPEND)
+
+struct vnode;
+
+typedef struct file
+{
+    /*
+     * The current position in the file. Can be modified by system calls
+     * like lseek(2), read(2), and write(2) (and possibly others) as
+     * described in the man pages of those calls.
+     */
+    size_t f_pos;
+
+    /*
+     * The mode in which this file was opened. This is a mask of the flags
+     * FMODE_READ, FMODE_WRITE, and FMODE_APPEND. It is set when the file
+     * is first opened, and use to restrict the operations that can be
+     * performed on the underlying vnode.
+     */
+    unsigned int f_mode;
+
+    /*
+     * The number of references to this struct. 
+     */
+    size_t f_refcount;
+
+    /*
+     * The vnode which corresponds to this file.
+     */
+    struct vnode *f_vnode;
+} file_t;
+
+struct file *fcreate(int fd, struct vnode *vnode, unsigned int mode);
+
+/*
+ * Returns the file_t assiciated with the given file descriptor for the
+ * current process. If there is no associated file_t, returns NULL.
+ */
+struct file *fget(int fd);
+
+/*
+ * fref() increments the reference count on the given file.
+ */
+void fref(file_t *file);
+
+/*
+ * fput() decrements the reference count on the given file.
+ *
+ * If the refcount reaches 0, the storage for the given file_t will be
+ * released (f won't point to a valid memory address anymore), and the
+ * refcount on the associated vnode (if any) will be decremented.
+ * 
+ * The vnode release operation will also be called if it exists.
+ */
+void fput(file_t **filep);