[python] Fix two memory leaks

[python] Fix two memory leaks

[Phil Muldoon]

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I'm submitting the first fix here for continuity, even though the 
unicode_decref.patch case was submitted in this message:

http://sources.redhat.com/ml/archer/2009-q1/msg00240.html

And reviewed in this one:

http://sources.redhat.com/ml/archer/2009-q1/msg00248.html

The unicode_decref patch changes the: 
"python-utils.c/python_string_to_unicode" function to always return a 
new reference.  Previously it would return either a new or borrowed 
reference, which created ambiguity to the callers about clean-up.  This 
resulted in a memory leak in some unicode string handling operations in 
GDB Python.

The second patch is a straightforward addition of a variable dereference 
inside the function:  "python.c/apply_val_pretty_printer". This value 
object was never being dereferenced.

Hopefully I'll have the two other areas that I am investigating 
submitted soon. These fixes are not inter-dependent, so I decided to 
submit them as soon as possible.

Regards

Phil

ChangeLog

2009-02-25  Phil Muldoon  <pmuldoon@redhat.com>

    * python/python.c (apply_val_pretty_printer): Clean-up value
    instance after search.
    * python/python-utils.c (python_string_to_unicode): Always return
    a new reference.
    (python_string_to_target_string): Decrement transient python
    instance.
    (python_string_to_host_string): Likewise.


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diff --git a/gdb/python/python-utils.c b/gdb/python/python-utils.c
index c6c305f..f9c9486 100644
--- a/gdb/python/python-utils.c
+++ b/gdb/python/python-utils.c
@@ -82,7 +82,11 @@ python_string_to_unicode (PyObject *obj)
   /* If obj is already a unicode string, just return it.
      I wish life was always that simple...  */
   if (PyUnicode_Check (obj))
-    unicode_str = obj;
+    {
+      unicode_str = obj;
+      Py_INCREF (obj);
+    }
+  
   else if (PyString_Check (obj))
     unicode_str = PyUnicode_FromEncodedObject (obj, host_charset (), NULL);
   else
@@ -137,12 +141,15 @@ char *
 python_string_to_target_string (PyObject *obj)
 {
   PyObject *str;
+  char *result;
 
   str = python_string_to_unicode (obj);
   if (str == NULL)
     return NULL;
 
-  return unicode_to_target_string (str);
+  result = unicode_to_target_string (str);
+  Py_DECREF (str);
+  return result;
 }
 
 /* Converts a python string (8-bit or unicode) to a target string in
@@ -153,12 +160,15 @@ char *
 python_string_to_host_string (PyObject *obj)
 {
   PyObject *str;
+  char *result;
 
   str = python_string_to_unicode (obj);
   if (str == NULL)
     return NULL;
 
-  return unicode_to_encoded_string (str, host_charset ());
+  result = unicode_to_encoded_string (str, host_charset ()); 
+  Py_DECREF (str);
+  return result;
 }
 
 /* Converts a target string of LENGTH bytes in the target's charset to a

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diff --git a/gdb/python/python.c b/gdb/python/python.c
index 4d104c2..11b0aeb 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1527,6 +1527,7 @@ apply_val_pretty_printer (struct type *type, const gdb_byte *valaddr,
   
   /* Find the constructor.  */
   printer = find_pretty_printer (val_obj);
+  Py_DECREF (val_obj);
   make_cleanup_py_decref (printer);
   if (! printer || printer == Py_None)
     goto done;

Re: [python] Fix two memory leaks

[Tom Tromey]

>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:

Phil> The unicode_decref patch changes the:
Phil> "python-utils.c/python_string_to_unicode" function to always return a
Phil> new reference.

Could you submit this to gdb-patches?  This utility code is already
there, so the fix needs to be as well.  Thanks.

Phil> The second patch is a straightforward addition of a variable
Phil> dereference inside the function:
Phil> "python.c/apply_val_pretty_printer". This value object was never being
Phil> dereferenced.

This is ok, thanks.

Tom

Re: [python] Fix two memory leaks

[Phil Muldoon]

Tom Tromey wrote:
>>>>>> "Phil" == Phil Muldoon <pmuldoon@redhat.com> writes:
>>>>>>             
>
> Phil> The unicode_decref patch changes the:
> Phil> "python-utils.c/python_string_to_unicode" function to always return a
> Phil> new reference.
>
> Could you submit this to gdb-patches?  This utility code is already
> there, so the fix needs to be as well.  Thanks.
>   


Done. I also committed this to the archer-tromey-python branch. The 
commit is:

b5235efef9aa1d619d8a5defc5aa1219dff76d3d

We should revert it should we merge master -> archer-tromey-python after 
this particular fix has been accepted and committed upstream.

> Phil> The second patch is a straightforward addition of a variable
> Phil> dereference inside the function:
> Phil> "python.c/apply_val_pretty_printer". This value object was never being
> Phil> dereferenced.
>
> This is ok, thanks

Committed.

Regards

Phil