[pypy-commit] cffi default: ffi.addressof(lib, "name") now also works in in-line mode

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r2886:4174b2bf46e0
Date: 2017-02-07 16:28 +0100
http://bitbucket.org/cffi/cffi/changeset/4174b2bf46e0/

Log:	ffi.addressof(lib, "name") now also works in in-line mode

diff --git a/c/_cffi_backend.c b/c/_cffi_backend.c
--- a/c/_cffi_backend.c
+++ b/c/_cffi_backend.c
@@ -3691,19 +3691,14 @@
     CTypeDescrObject *ct;
     char *funcname;
     void *funcptr;
-    int ok;
 
     if (!PyArg_ParseTuple(args, "O!s:load_function",
                           &CTypeDescr_Type, &ct, &funcname))
         return NULL;
 
-    ok = 0;
-    if (ct->ct_flags & CT_FUNCTIONPTR)
-        ok = 1;
-    if ((ct->ct_flags & CT_POINTER) && (ct->ct_itemdescr->ct_flags & CT_VOID))
-        ok = 1;
-    if (!ok) {
-        PyErr_Format(PyExc_TypeError, "function cdata expected, got '%s'",
+    if (!(ct->ct_flags & (CT_FUNCTIONPTR | CT_POINTER | CT_ARRAY))) {
+        PyErr_Format(PyExc_TypeError,
+                     "function or pointer or array cdata expected, got '%s'",
                      ct->ct_name);
         return NULL;
     }
@@ -3711,12 +3706,15 @@
     funcptr = dlsym(dlobj->dl_handle, funcname);
     if (funcptr == NULL) {
         const char *error = dlerror();
-        PyErr_Format(PyExc_KeyError,
-                     "function '%s' not found in library '%s': %s",
+        PyErr_Format(PyExc_AttributeError,
+                     "function/symbol '%s' not found in library '%s': %s",
                      funcname, dlobj->dl_name, error);
         return NULL;
     }
 
+    if ((ct->ct_flags & CT_ARRAY) && ct->ct_length < 0) {
+        ct = (CTypeDescrObject *)ct->ct_stuff;
+    }
     return new_simple_cdata(funcptr, ct);
 }
 
diff --git a/cffi/api.py b/cffi/api.py
--- a/cffi/api.py
+++ b/cffi/api.py
@@ -462,7 +462,12 @@
         field or array item in the structure or array, recursively in
         case of nested structures.
         """
-        ctype = self._backend.typeof(cdata)
+        try:
+            ctype = self._backend.typeof(cdata)
+        except TypeError:
+            if '__addressof__' in type(cdata).__dict__:
+                return type(cdata).__addressof__(cdata, *fields_or_indexes)
+            raise
         if fields_or_indexes:
             ctype, offset = self._typeoffsetof(ctype, *fields_or_indexes)
         else:
@@ -775,10 +780,7 @@
         key = 'function ' + name
         tp, _ = ffi._parser._declarations[key]
         BType = ffi._get_cached_btype(tp)
-        try:
-            value = backendlib.load_function(BType, name)
-        except KeyError as e:
-            raise AttributeError('%s: %s' % (name, e))
+        value = backendlib.load_function(BType, name)
         library.__dict__[name] = value
     #
     def accessor_variable(name):
@@ -791,6 +793,21 @@
             lambda self: read_variable(BType, name),
             lambda self, value: write_variable(BType, name, value)))
     #
+    def addressof_var(name):
+        try:
+            return addr_variables[name]
+        except KeyError:
+            with ffi._lock:
+                if name not in addr_variables:
+                    key = 'variable ' + name
+                    tp, _ = ffi._parser._declarations[key]
+                    BType = ffi._get_cached_btype(tp)
+                    if BType.kind != 'array':
+                        BType = model.pointer_cache(ffi, BType)
+                    p = backendlib.load_function(BType, name)
+                    addr_variables[name] = p
+            return addr_variables[name]
+    #
     def accessor_constant(name):
         raise NotImplementedError("non-integer constant '%s' cannot be "
                                   "accessed from a dlopen() library" % (name,))
@@ -800,6 +817,7 @@
     #
     accessors = {}
     accessors_version = [False]
+    addr_variables = {}
     #
     def update_accessors():
         if accessors_version[0] is ffi._cdef_version:
@@ -850,6 +868,18 @@
             with ffi._lock:
                 update_accessors()
                 return accessors.keys()
+        def __addressof__(self, name):
+            if name in library.__dict__:
+                return library.__dict__[name]
+            if name in FFILibrary.__dict__:
+                return addressof_var(name)
+            make_accessor(name)
+            if name in library.__dict__:
+                return library.__dict__[name]
+            if name in FFILibrary.__dict__:
+                return addressof_var(name)
+            raise AttributeError("cffi library has no function or "
+                                 "global variable named '%s'" % (name,))
     #
     if libname is not None:
         try:
diff --git a/doc/source/whatsnew.rst b/doc/source/whatsnew.rst
--- a/doc/source/whatsnew.rst
+++ b/doc/source/whatsnew.rst
@@ -46,6 +46,10 @@
 * ``ffi.buffer`` is now the name of cffi's buffer type, and
   ``ffi.buffer()`` works like before but is the constructor of that type.
 
+* ``ffi.addressof(lib, "name")``  now works also in in-line mode, not
+  only in out-of-line mode.  This is useful for taking the address of
+  global variables.
+
 
 v1.9
 ====
diff --git a/testing/cffi0/test_ownlib.py b/testing/cffi0/test_ownlib.py
--- a/testing/cffi0/test_ownlib.py
+++ b/testing/cffi0/test_ownlib.py
@@ -282,3 +282,21 @@
             assert ret.right == ownlib.right
             assert ret.top == ownlib.top
             assert ret.bottom == ownlib.bottom
+
+    def test_addressof_lib(self):
+        if self.module is None:
+            py.test.skip("fix the auto-generation of the tiny test lib")
+        if self.Backend is CTypesBackend:
+            py.test.skip("not implemented with the ctypes backend")
+        ffi = FFI(backend=self.Backend())
+        ffi.cdef("long left; int test_getting_errno(void);")
+        lib = ffi.dlopen(self.module)
+        lib.left = 123456
+        p = ffi.addressof(lib, "left")
+        assert ffi.typeof(p) == ffi.typeof("long *")
+        assert p[0] == 123456
+        p[0] += 1
+        assert lib.left == 123457
+        pfn = ffi.addressof(lib, "test_getting_errno")
+        assert ffi.typeof(pfn) == ffi.typeof("int(*)(void)")
+        assert pfn == lib.test_getting_errno