Implement ffi.dlclose() for the in-line case

3 files changed, 63 insertions, 1 deletions

diff --git a/c/_cffi_backend.c b/c/_cffi_backend.c
index 19070b1..b812600 100644
--- a/c/_cffi_backend.c
+++ b/c/_cffi_backend.c
@@ -3982,7 +3982,8 @@ typedef struct {
 
 static void dl_dealloc(DynLibObject *dlobj)
 {
-    dlclose(dlobj->dl_handle);
+    if (dlobj->dl_handle != NULL)
+        dlclose(dlobj->dl_handle);
     free(dlobj->dl_name);
     PyObject_Del(dlobj);
 }
@@ -3992,6 +3993,17 @@ static PyObject *dl_repr(DynLibObject *dlobj)
     return PyText_FromFormat("<clibrary %s>", dlobj->dl_name);
 }
 
+static int dl_check_closed(DynLibObject *dlobj)
+{
+    if (dlobj->dl_handle == NULL)
+    {
+        PyErr_Format(PyExc_ValueError, "library '%s' has already been closed",
+                     dlobj->dl_name);
+        return -1;
+    }
+    return 0;
+}
+
 static PyObject *dl_load_function(DynLibObject *dlobj, PyObject *args)
 {
     CTypeDescrObject *ct;
@@ -4002,6 +4014,9 @@ static PyObject *dl_load_function(DynLibObject *dlobj, PyObject *args)
                           &CTypeDescr_Type, &ct, &funcname))
         return NULL;
 
+    if (dl_check_closed(dlobj) < 0)
+        return NULL;
+
     if (!(ct->ct_flags & (CT_FUNCTIONPTR | CT_POINTER | CT_ARRAY))) {
         PyErr_Format(PyExc_TypeError,
                      "function or pointer or array cdata expected, got '%s'",
@@ -4034,6 +4049,9 @@ static PyObject *dl_read_variable(DynLibObject *dlobj, PyObject *args)
                           &CTypeDescr_Type, &ct, &varname))
         return NULL;
 
+    if (dl_check_closed(dlobj) < 0)
+        return NULL;
+
     dlerror();   /* clear error condition */
     data = dlsym(dlobj->dl_handle, varname);
     if (data == NULL) {
@@ -4059,6 +4077,9 @@ static PyObject *dl_write_variable(DynLibObject *dlobj, PyObject *args)
                           &CTypeDescr_Type, &ct, &varname, &value))
         return NULL;
 
+    if (dl_check_closed(dlobj) < 0)
+        return NULL;
+
     dlerror();   /* clear error condition */
     data = dlsym(dlobj->dl_handle, varname);
     if (data == NULL) {
@@ -4074,10 +4095,21 @@ static PyObject *dl_write_variable(DynLibObject *dlobj, PyObject *args)
     return Py_None;
 }
 
+static PyObject *dl_close_lib(DynLibObject *dlobj, PyObject *no_args)
+{
+    if (dl_check_closed(dlobj) < 0)
+        return NULL;
+    dlclose(dlobj->dl_handle);
+    dlobj->dl_handle = NULL;
+    Py_INCREF(Py_None);
+    return Py_None;
+}
+
 static PyMethodDef dl_methods[] = {
     {"load_function",   (PyCFunction)dl_load_function,  METH_VARARGS},
     {"read_variable",   (PyCFunction)dl_read_variable,  METH_VARARGS},
     {"write_variable",  (PyCFunction)dl_write_variable, METH_VARARGS},
+    {"close_lib",       (PyCFunction)dl_close_lib,      METH_NOARGS},
     {NULL,              NULL}           /* sentinel */
 };
 
diff --git a/cffi/api.py b/cffi/api.py
index 446e554..7b63ca7 100644
--- a/cffi/api.py
+++ b/cffi/api.py
@@ -143,6 +143,13 @@ class FFI(object):
             self._libraries.append(lib)
         return lib
 
+    def dlclose(self, lib):
+        """Close a library obtained with ffi.dlopen().  After this call,
+        access to functions or variables from the library will fail
+        (possibly with a segmentation fault).
+        """
+        type(lib).__cffi_close__(lib)
+
     def _typeof_locked(self, cdecl):
         # call me with the lock!
         key = cdecl
@@ -898,6 +905,9 @@ def _make_ffi_library(ffi, libname, flags):
                 return addressof_var(name)
             raise AttributeError("cffi library has no function or "
                                  "global variable named '%s'" % (name,))
+        def __cffi_close__(self):
+            backendlib.close_lib()
+            self.__dict__.clear()
     #
     if libname is not None:
         try:
diff --git a/testing/cffi0/test_function.py b/testing/cffi0/test_function.py
index 61be656..077f806 100644
--- a/testing/cffi0/test_function.py
+++ b/testing/cffi0/test_function.py
@@ -499,3 +499,23 @@ class TestFunction(object):
         """)
         m = ffi.dlopen(lib_m)
         assert dir(m) == ['MYE1', 'MYE2', 'MYFOO', 'myconst', 'myfunc', 'myvar']
+
+    def test_dlclose(self):
+        if self.Backend is CTypesBackend:
+            py.test.skip("not with the ctypes backend")
+        ffi = FFI(backend=self.Backend())
+        ffi.cdef("int foobar(void); int foobaz;")
+        lib = ffi.dlopen(lib_m)
+        ffi.dlclose(lib)
+        e = py.test.raises(ValueError, ffi.dlclose, lib)
+        assert str(e.value).startswith("library '")
+        assert str(e.value).endswith("' has already been closed")
+        e = py.test.raises(ValueError, getattr, lib, 'foobar')
+        assert str(e.value).startswith("library '")
+        assert str(e.value).endswith("' has already been closed")
+        e = py.test.raises(ValueError, getattr, lib, 'foobaz')
+        assert str(e.value).startswith("library '")
+        assert str(e.value).endswith("' has already been closed")
+        e = py.test.raises(ValueError, setattr, lib, 'foobaz', 42)
+        assert str(e.value).startswith("library '")
+        assert str(e.value).endswith("' has already been closed")