Create SFFS library out of HGFS

This Shared Folders File System library (libsffs) now contains all the
file system logic originally in HGFS. The actual HGFS server code is
now a stub that passes on all the work to libsffs. The libhgfs library
is changed accordingly.

lib/libsffs/util.c

@@ -0,0 +1,63 @@
+/* This file contains various utility functions.
+ *
+ * The entry points into this file are:
+ *   get_name		retrieve a path component string from VFS
+ *   do_noop		handle file system calls that do nothing and succeed
+ *   no_sys		handle file system calls that are not implemented
+ *
+ * Created:
+ *   April 2009 (D.C. van Moolenbroek)
+ */
+
+#include "inc.h"
+
+/*===========================================================================*
+ *				get_name				     *
+ *===========================================================================*/
+int get_name(grant, len, name)
+cp_grant_id_t grant;		/* memory grant for the path component */
+size_t len;			/* length of the name, including '\0' */
+char name[NAME_MAX+1];		/* buffer in which store the result */
+{
+/* Retrieve a path component from the caller, using a given grant.
+ */
+  int r;
+
+  /* Copy in the name of the directory entry. */
+  if (len <= 1) return EINVAL;
+  if (len > NAME_MAX+1) return ENAMETOOLONG;
+
+  r = sys_safecopyfrom(m_in.m_source, grant, 0, (vir_bytes) name, len, D);
+
+  if (r != OK) return r;
+
+  if (name[len-1] != 0) {
+	printf("%s: VFS did not zero-terminate path component!\n", sffs_name);
+
+	return EINVAL;
+  }
+
+  return OK;
+}
+
+/*===========================================================================*
+ *				do_noop					     *
+ *===========================================================================*/
+int do_noop()
+{
+/* Generic handler for no-op system calls.
+ */
+
+  return OK;
+}
+
+/*===========================================================================*
+ *				no_sys					     *
+ *===========================================================================*/
+int no_sys()
+{
+/* Generic handler for unimplemented system calls.
+ */
+
+  return ENOSYS;
+}