Libguestfs - Apr 2011 - [PATCH] hivex/python fix for i386 integer size issue

Hi,

While working on Debian packages of hivex 1.2.5, I came across a test
failure for the Python bindings with Python 2.7 on the i386
architecture. (The tests ran fine on amd64.)

,----
| $ make -C python check
| make[1]: Entering directory `/home/bengen/src/deb/hivex/hivex.git/python'
| 010-import.py
| 020-open.py
| 021-close.py
| 200-write.py
| python: hivex-py.c:52: get_handle: Assertion `obj' failed.
`----

I narrowed this down to hivex-py.c:py_hivex_node_add_child():

The call

,----
| PyArg_ParseTuple (args, (char *) "OLs:hivex_node_add_child", 
|                         &py_h, &parent, &name)
`----

results in `py_h' set to NULL, though Python's documentation claims that
this cannot happen. I think this happens because `parent' is declared a
`long int', but "L" in the format string corresponds to a `long
long'.
On amd64, they have the same size, but on i386 they don't, so the
PyObject pointer is written to the wrong address.

Please consider applying the patch below which just changes the format
string. After regenerating hivex-py.c, I have successfully tested the
1.2.5 code base on both architectures.

Cheers,
-Hilko

diff --git a/generator/generator.ml b/generator/generator.ml
index 7e706d1..9722312 100755
--- a/generator/generator.ml
+++ b/generator/generator.ml
@@ -2875,7 +2875,7 @@ put_val_type (char *val, size_t len, hive_type t)
 	    pr "O"
 	| ANode n
 	| AValue n ->
-	    pr "L"
+	    pr "l"
 	| AString n ->
 	    pr "s"
         | AStringNullable n ->

On Thu, Apr 28, 2011 at 12:20:08AM +0200, Hilko Bengen
wrote:
> Hi,
> 
> While working on Debian packages of hivex 1.2.5, I came across a test
> failure for the Python bindings with Python 2.7 on the i386
> architecture. (The tests ran fine on amd64.)
> 
> ,----
> | $ make -C python check
> | make[1]: Entering directory
`/home/bengen/src/deb/hivex/hivex.git/python'
> | 010-import.py
> | 020-open.py
> | 021-close.py
> | 200-write.py
> | python: hivex-py.c:52: get_handle: Assertion `obj' failed.
> `----
> 
> I narrowed this down to hivex-py.c:py_hivex_node_add_child():
> 
> The call
> 
> ,----
> | PyArg_ParseTuple (args, (char *) "OLs:hivex_node_add_child", 
> |                         &py_h, &parent, &name)
> `----
> 
> results in `py_h' set to NULL, though Python's documentation claims
that
> this cannot happen. I think this happens because `parent' is declared a
> `long int', but "L" in the format string corresponds to a
`long long'.
> On amd64, they have the same size, but on i386 they don't, so the
> PyObject pointer is written to the wrong address.
> 
> Please consider applying the patch below which just changes the format
> string. After regenerating hivex-py.c, I have successfully tested the
> 1.2.5 code base on both architectures.
> 
> Cheers,
> -Hilko
> 
> diff --git a/generator/generator.ml b/generator/generator.ml
> index 7e706d1..9722312 100755
> --- a/generator/generator.ml
> +++ b/generator/generator.ml
> @@ -2875,7 +2875,7 @@ put_val_type (char *val, size_t len, hive_type t)
>  	    pr "O"
>  	| ANode n
>  	| AValue n ->
> -	    pr "L"
> +	    pr "l"
>  	| AString n ->
>  	    pr "s"
>          | AStringNullable n ->
Elizabeth, can you try this to see if it fixes your problem too?

Rich.

-- 
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On Thu, Apr 28, 2011 at 12:20:08AM +0200, Hilko Bengen
wrote:
> Hi,
> 
> While working on Debian packages of hivex 1.2.5, I came across a test
> failure for the Python bindings with Python 2.7 on the i386
> architecture. (The tests ran fine on amd64.)
> 
> ,----
> | $ make -C python check
> | make[1]: Entering directory
`/home/bengen/src/deb/hivex/hivex.git/python'
> | 010-import.py
> | 020-open.py
> | 021-close.py
> | 200-write.py
> | python: hivex-py.c:52: get_handle: Assertion `obj' failed.
> `----
> 
> I narrowed this down to hivex-py.c:py_hivex_node_add_child():
> 
> The call
> 
> ,----
> | PyArg_ParseTuple (args, (char *) "OLs:hivex_node_add_child", 
> |                         &py_h, &parent, &name)
> `----
> 
> results in `py_h' set to NULL, though Python's documentation claims
that
> this cannot happen. I think this happens because `parent' is declared a
> `long int', but "L" in the format string corresponds to a
`long long'.
> On amd64, they have the same size, but on i386 they don't, so the
> PyObject pointer is written to the wrong address.
> 
> Please consider applying the patch below which just changes the format
> string. After regenerating hivex-py.c, I have successfully tested the
> 1.2.5 code base on both architectures.
> 
> Cheers,
> -Hilko
> 
> diff --git a/generator/generator.ml b/generator/generator.ml
> index 7e706d1..9722312 100755
> --- a/generator/generator.ml
> +++ b/generator/generator.ml
> @@ -2875,7 +2875,7 @@ put_val_type (char *val, size_t len, hive_type t)
>  	    pr "O"
>  	| ANode n
>  	| AValue n ->
> -	    pr "L"
> +	    pr "l"
>  	| AString n ->
>  	    pr "s"
>          | AStringNullable n ->
Looking at the code, I think this was clearly a mistake and I've
pushed your fix.

Thanks for your contribution!

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
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