=== modified file 'ChangeLog'
--- ChangeLog	2011-01-15 00:03:32 +0000
+++ ChangeLog	2011-01-15 00:08:24 +0000
@@ -1,5 +1,12 @@
 2011-01-15  Szymon Janc  <address@hidden>
 
+	* grub-core/io/xzio.c (test_footer): Return true for not seekable file.
+	(grub_xzio_open): FIXME comment removed.
+	(grub_xzio_read): Set real size for unknown size file when it is known.
+	Handle NULL buffer pointer.
+
+2011-01-15  Szymon Janc  <address@hidden>
+
 	* grub-core/io/gzio.c (test_header): For not seekable files: don't
 	check footer and set size to unknown.
 	(inflate_window): Set real size for unknown size file when it is

=== modified file 'grub-core/io/xzio.c'
--- grub-core/io/xzio.c	2010-12-26 20:15:31 +0000
+++ grub-core/io/xzio.c	2011-01-15 00:08:24 +0000
@@ -129,6 +129,10 @@ test_footer (grub_file_t file)
   grub_uint64_t uncompressed_size;
   grub_uint64_t records;
 
+  /* Don't test footer on not easily seekable files.  */
+  if (! grub_file_seekable(xzio->file))
+    return 1;
+
   grub_file_seek (xzio->file, xzio->file->size - FOOTER_MAGIC_SIZE);
   if (grub_file_read (xzio->file, footer, FOOTER_MAGIC_SIZE) !=
       FOOTER_MAGIC_SIZE
@@ -222,7 +226,6 @@ grub_xzio_open (grub_file_t io)
   xzio->buf.out_pos = 0;
   xzio->buf.out_size = XZBUFSIZ;
 
-  /* FIXME: don't test footer on not easily seekable files.  */
   if (!test_header (file) || !test_footer (file))
     {
       grub_errno = GRUB_ERR_NONE;
@@ -297,10 +300,14 @@ grub_xzio_read (grub_file_t file, char *
 	  /* Store first chunk of data in buffer.  */
 	  {
 	    grub_size_t delta = new_offset - (file->offset + ret);
-	    grub_memmove (buf, xzio->buf.out + (xzio->buf.out_pos - delta),
+
+	    if (buf)
+	      {
+		grub_memmove (buf, xzio->buf.out + (xzio->buf.out_pos - delta),
 			  delta);
+		buf += delta;
+	      }
 	    len -= delta;
-	    buf += delta;
 	    ret += delta;
 	  }
 	current_offset = new_offset;
@@ -308,7 +315,11 @@ grub_xzio_read (grub_file_t file, char *
       xzio->buf.out_pos = 0;
 
       if (xzret == XZ_STREAM_END)	/* Stream end, EOF.  */
-	break;
+	{
+	  if(file->size == GRUB_FILE_SIZE_UNKNOWN)
+	    file->size = file->offset + ret;
+	  break;
+	}
     }
 
   if (ret >= 0)