Protect GAP_ValueGlobalVariable calls by GAP_Enter/GAP_Leave and use …

…char_to_str earlier

src/sage/libs/gap/element.pxd

@@ -29,9 +29,9 @@ cdef GapElement_Boolean make_GapElement_Boolean(parent, Obj obj)
 cdef GapElement_Function make_GapElement_Function(parent, Obj obj)
 cdef GapElement_Permutation make_GapElement_Permutation(parent, Obj obj)
 
-cdef char *capture_stdout(Obj, Obj)
-cdef char *gap_element_str(Obj)
-cdef char *gap_element_repr(Obj)
+cdef str capture_stdout(Obj, Obj)
+cdef str gap_element_str(Obj)
+cdef str gap_element_repr(Obj)
 
 
 cdef class GapElement(RingElement):

src/sage/libs/gap/element.pyx

@@ -120,7 +120,7 @@ cdef Obj make_gap_matrix(sage_list, gap_ring) except NULL:
     return l.value
 
 
-cdef char *capture_stdout(Obj func, Obj obj):
+cdef str capture_stdout(Obj func, Obj obj):
     """
     Call a single-argument GAP function ``func`` with the argument ``obj``
     and return the stdout from that function call.
@@ -152,24 +152,28 @@ cdef char *capture_stdout(Obj func, Obj obj):
 
         CALL_1ARGS(func, obj)
         CloseOutput(&output)
-        return CSTR_STRING(s)
+        return char_to_str(CSTR_STRING(s))
     finally:
         GAP_Leave()
 
 
-cdef char *gap_element_repr(Obj obj):
+cdef str gap_element_repr(Obj obj):
     """
     Implement ``repr()`` of ``GapElement``s using the ``ViewObj()`` function,
     which is by default closest to what you get when displaying an object in
     GAP on the command-line (i.e. when evaluating an expression that returns
     that object.
     """
-
-    cdef Obj func = GAP_ValueGlobalVariable("ViewObj")
-    return capture_stdout(func, obj)
+    cdef Obj func
+    try:
+        GAP_Enter()
+        func = GAP_ValueGlobalVariable("ViewObj")
+        return capture_stdout(func, obj)
+    finally:
+        GAP_Leave()
 
 
-cdef char *gap_element_str(Obj obj):
+cdef str gap_element_str(Obj obj):
     """
     Implement ``str()`` of ``GapElement``s using the ``Print()`` function.
 
@@ -179,8 +183,13 @@ cdef char *gap_element_str(Obj obj):
     slightly different approach more closely mirroring Python's str/repr
     difference (though this does not map perfectly onto GAP).
     """
-    cdef Obj func = GAP_ValueGlobalVariable("Print")
-    return capture_stdout(func, obj)
+    cdef Obj func
+    try:
+        GAP_Enter()
+        func = GAP_ValueGlobalVariable("Print")
+        return capture_stdout(func, obj)
+    finally:
+        GAP_Leave()
 
 
 cdef Obj make_gap_record(sage_dict) except NULL:
@@ -761,7 +770,7 @@ cdef class GapElement(RingElement):
         if  self.value == NULL:
             return 'NULL'
 
-        s = char_to_str(gap_element_str(self.value))
+        s = gap_element_str(self.value)
         return s.strip()
 
     def _repr_(self):
@@ -783,7 +792,7 @@ cdef class GapElement(RingElement):
         if  self.value == NULL:
             return 'NULL'
 
-        s = char_to_str(gap_element_repr(self.value))
+        s = gap_element_repr(self.value)
         return s.strip()
 
     cpdef _set_compare_by_id(self):