[Libguestfs] [hivex] python: Check type of variable passed into set_value.

[Peter Wu]

On Tuesday 05 August 2014 22:35:23 Hilko Bengen wrote:
> The following code, reported by Peter Wu <peter at lekensteyn.nl>, broke
> on x86_64 with different symptoms on Python2 and Python3 (malloc()
> failure and segmentation fault, respectively):
> 
> r = h.node_set_value(h.root(), {
>     'key': 'broken',
>     't': 4,
>     'value': 1234
> })
> ---
>  generator/generator.ml | 25 ++++++++++++++++++++-----
>  1 file changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/generator/generator.ml b/generator/generator.ml
> index bcf1966..0fa5c04 100755
> --- a/generator/generator.ml
> +++ b/generator/generator.ml
> @@ -2799,6 +2799,7 @@ typedef int Py_ssize_t;
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <assert.h>
> +#include <inttypes.h>
> 
>  #include \"hivex.h\"
> 
> @@ -2868,14 +2869,28 @@ get_value (PyObject *v, hive_set_value *ret)
>      PyErr_SetString (PyExc_RuntimeError, \"no 'value' element in
> dictionary\"); return -1;
>    }
> +  if (PyInt_Check (obj)) {

Triggers -Wimplicit-function-declaration for me (Python 3.4.1).

> +    uint32_t* v = malloc (sizeof (uint32_t));
> +    *v = PyInt_AsLong (obj);

This also triggers implicit function warning.

> +    ret->value = (char*) v;
> +    ret->len = sizeof (uint32_t);
>  #ifdef HAVE_PYSTRING_ASSTRING
> -  ret->value = PyString_AsString (obj);
> -  ret->len = PyString_Size (obj);
> +  } else if (PyString_Check (obj)) {
> +    ret->value = PyString_AsString (obj);
> +    ret->len = PyString_Size (obj);
>  #else
> -  bytes = PyUnicode_AsUTF8String (obj);
> -  ret->value = PyBytes_AS_STRING (bytes);
> -  ret->len = PyBytes_GET_SIZE (bytes);
> +  } else if (PyUnicode_Check (obj)) {
> +    bytes = PyUnicode_AsUTF8String (obj);
> +    if (!bytes) {
> +      return -1;
> +    }
> +    ret->value = PyBytes_AS_STRING (bytes);
> +    ret->len = PyBytes_GET_SIZE (bytes);
>  #endif
> +  } else {
> +    PyErr_SetString (PyExc_RuntimeError, \"Cannot use 'value' element in
> dictionary\"); +    return -1;
> +  }
> 
>    return 0;
>  }

Reproduced with this one-liner:

PYTHONPATH=python/.libs python -c \
"import hivex;h=hivex.Hivex('images/minimal',write=True); 
h.node_set_value(h.root(), {'key':'x', 't':5, 'value':123})"

I'll give a shot at fixing this, the key handling is equally broken:

python -c 'import hivex; 
h=hivex.Hivex("images/minimal");h.node_set_values(h.root(), [{"key":1}])'

Kind regards,
Peter
https://lekensteyn.nl