Use new to_xfer_partial interface in ctf and tfile target

This patch adjust both ctf and tfile target implementation of to_xfer_partial,
to return TARGET_XFER_E_UNAVAILABLE and set *XFERED_LEN if data is
unavailable.  Note that some code on xfer in exec.c can be shared, but
we can do it in a separate pass later.

gdb:

2014-02-23  Yao Qi  <yao@codesourcery.com>

	* exec.c (section_table_read_available_memory): New function.
	* exec.h (section_table_read_available_memory): Declare.
	* ctf.c (ctf_xfer_partial): Call
	section_table_read_available_memory.
	* tracefile-tfile.c (tfile_xfer_partial): Likewise.

1 files changed, 7 insertions, 2 deletions

diff --git a/gdb/ctf.c b/gdb/ctf.c
index 9c8f4d7..95fd31f 100644
--- a/gdb/ctf.c
+++ b/gdb/ctf.c
@@ -1465,9 +1465,14 @@ ctf_xfer_partial (struct target_ops *ops, enum target_object object,
 
       /* Restore the position.  */
       bt_iter_set_pos (bt_ctf_get_iter (ctf_iter), pos);
-    }
 
-  return exec_read_partial_read_only (readbuf, offset, len, xfered_len);
+      return exec_read_partial_read_only (readbuf, offset, len, xfered_len);
+    }
+  else
+    {
+      /* Fallback to reading from read-only sections.  */
+      return section_table_read_available_memory (readbuf, offset, len, xfered_len);
+    }
 }
 
 /* This is the implementation of target_ops method