RE: MemoryView missing from Python 2.4 and 2.6

["Wiederhake, Tim" <tim.wiederhake@intel.com>]

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Hi,

thank you for your patience.
I revisited option (2) and found that I could actually do without big code refactoring. See attached patch how this could look like. "memoryview" offers some functions and data members that "buffer" does not have, like information about the stride size, the number of dimensions and explicit conversion functions to "bytes" and "list". Since we always return a one-dimensional array of bytes, this information is not too useful and is probably bearable to miss in Python 2. Besides these differences, the behavior is the same in regard to indexing and iterating over the object.

Jose, can you confirm that this patch un-breaks GDB linked with Python 2.6?

Regards,
Tim
Intel Deutschland GmbH
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From 1e3c5400b84af756f6bc596b626d773be7bebdeb Mon Sep 17 00:00:00 2001
From: Tim Wiederhake <tim.wiederhake@intel.com>
Date: Tue, 28 Feb 2017 09:10:58 +0100
Subject: [PATCH] Fix break on Python 2

This changes the return type of "gdb.BtraceInstruction.data ()" from
"memoryview" to "buffer" on Python 2.7 and below, similar to what
"gdb.Inferior.read_memory ()" does.

gdb/ChangeLog:

	* python/py-record-btrace.c (btpy_insn_data): Change return type
	for Python 2.

gdb/doc/ChangeLog:

	* python.texi (Recordings In Python): Document return type of
	gdb.BtraceInstruction.data.

---
 gdb/doc/python.texi           | 3 ++-
 gdb/python/py-record-btrace.c | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index c3ea203..b4a52bd 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -3181,7 +3181,8 @@ if the instruction is a gap or the debug symbols could not be read.
 
 @defvar BtraceInstruction.data
 A buffer with the raw instruction data.  May be @code{None} if the
-instruction is a gap.
+instruction is a gap.  In Python 3, the return value is a @code{memoryview}
+object.
 @end defvar
 
 @defvar BtraceInstruction.decoded
diff --git a/gdb/python/py-record-btrace.c b/gdb/python/py-record-btrace.c
index 6158f31..c816332 100644
--- a/gdb/python/py-record-btrace.c
+++ b/gdb/python/py-record-btrace.c
@@ -330,7 +330,12 @@ btpy_insn_data (PyObject *self, void *closure)
   if (object == NULL)
     return NULL;
 
+#ifdef IS_PY3K
   return PyMemoryView_FromObject (object);
+#else
+  return PyBuffer_FromObject (object, 0, Py_END_OF_BUFFER);
+#endif
+
 }
 
 /* Implementation of BtraceInstruction.decode [str].  Returns
-- 
2.7.4