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

[Hilko Bengen]

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)) {
+    uint32_t* v = malloc (sizeof (uint32_t));
+    *v = PyInt_AsLong (obj);
+    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;
 }
-- 
2.0.1