Issue #22896: Avoid to use PyObject_AsCharBuffer(), PyObject_AsReadBuffer()

and PyObject_AsWriteBuffer().

Author: serhiy-storchaka

Diff for: Include/bytes_methods.h

@@ -22,7 +22,7 @@ extern void _Py_bytes_capitalize(char *result, char *s, Py_ssize_t len);
 extern void _Py_bytes_swapcase(char *result, char *s, Py_ssize_t len);
 
 /* The maketrans() static method. */
-extern PyObject* _Py_bytes_maketrans(PyObject *frm, PyObject *to);
+extern PyObject* _Py_bytes_maketrans(Py_buffer *frm, Py_buffer *to);
 
 /* Shared __doc__ strings. */
 extern const char _Py_isspace__doc__[];

Diff for: Lib/ctypes/test/test_frombuffer.py

@@ -10,7 +10,7 @@ def __init__(self):
         self._init_called = True
 
 class Test(unittest.TestCase):
-    def test_fom_buffer(self):
+    def test_from_buffer(self):
         a = array.array("i", range(16))
         x = (c_int * 16).from_buffer(a)
 
@@ -23,25 +23,37 @@ def test_fom_buffer(self):
         a[0], a[-1] = 200, -200
         self.assertEqual(x[:], a.tolist())
 
-        self.assertIn(a, x._objects.values())
+        self.assertRaises(BufferError, a.append, 100)
+        self.assertRaises(BufferError, a.pop)
 
-        self.assertRaises(ValueError,
-                          c_int.from_buffer, a, -1)
+        del x; del y; gc.collect(); gc.collect(); gc.collect()
+        a.append(100)
+        a.pop()
+        x = (c_int * 16).from_buffer(a)
+
+        self.assertIn(a, [obj.obj if isinstance(obj, memoryview) else obj
+                          for obj in x._objects.values()])
 
         expected = x[:]
         del a; gc.collect(); gc.collect(); gc.collect()
         self.assertEqual(x[:], expected)
 
-        self.assertRaises(TypeError,
-                          (c_char * 16).from_buffer, "a" * 16)
+        with self.assertRaises(TypeError):
+            (c_char * 16).from_buffer(b"a" * 16)
+        with self.assertRaises(TypeError):
+            (c_char * 16).from_buffer("a" * 16)
 
-    def test_fom_buffer_with_offset(self):
+    def test_from_buffer_with_offset(self):
         a = array.array("i", range(16))
         x = (c_int * 15).from_buffer(a, sizeof(c_int))
 
         self.assertEqual(x[:], a.tolist()[1:])
-        self.assertRaises(ValueError, lambda: (c_int * 16).from_buffer(a, sizeof(c_int)))
-        self.assertRaises(ValueError, lambda: (c_int * 1).from_buffer(a, 16 * sizeof(c_int)))
+        with self.assertRaises(ValueError):
+            c_int.from_buffer(a, -1)
+        with self.assertRaises(ValueError):
+            (c_int * 16).from_buffer(a, sizeof(c_int))
+        with self.assertRaises(ValueError):
+            (c_int * 1).from_buffer(a, 16 * sizeof(c_int))
 
     def test_from_buffer_copy(self):
         a = array.array("i", range(16))
@@ -56,26 +68,30 @@ def test_from_buffer_copy(self):
         a[0], a[-1] = 200, -200
         self.assertEqual(x[:], list(range(16)))
 
-        self.assertEqual(x._objects, None)
+        a.append(100)
+        self.assertEqual(x[:], list(range(16)))
 
-        self.assertRaises(ValueError,
-                          c_int.from_buffer, a, -1)
+        self.assertEqual(x._objects, None)
 
         del a; gc.collect(); gc.collect(); gc.collect()
         self.assertEqual(x[:], list(range(16)))
 
         x = (c_char * 16).from_buffer_copy(b"a" * 16)
         self.assertEqual(x[:], b"a" * 16)
+        with self.assertRaises(TypeError):
+            (c_char * 16).from_buffer_copy("a" * 16)
 
-    def test_fom_buffer_copy_with_offset(self):
+    def test_from_buffer_copy_with_offset(self):
         a = array.array("i", range(16))
         x = (c_int * 15).from_buffer_copy(a, sizeof(c_int))
 
         self.assertEqual(x[:], a.tolist()[1:])
-        self.assertRaises(ValueError,
-                          (c_int * 16).from_buffer_copy, a, sizeof(c_int))
-        self.assertRaises(ValueError,
-                          (c_int * 1).from_buffer_copy, a, 16 * sizeof(c_int))
+        with self.assertRaises(ValueError):
+            c_int.from_buffer_copy(a, -1)
+        with self.assertRaises(ValueError):
+            (c_int * 16).from_buffer_copy(a, sizeof(c_int))
+        with self.assertRaises(ValueError):
+            (c_int * 1).from_buffer_copy(a, 16 * sizeof(c_int))
 
 if __name__ == '__main__':
     unittest.main()

Diff for: Misc/NEWS

@@ -10,6 +10,9 @@ Release date: TBA
 Core and Builtins
 -----------------
 
+- Issue #22896: Avoid using PyObject_AsCharBuffer(), PyObject_AsReadBuffer()
+  and PyObject_AsWriteBuffer().
+
 - Issue #21295: Revert some changes (issue #16795) to AST line numbers and
   column offsets that constituted a regression.
 

Diff for: Modules/_codecsmodule.c

@@ -288,8 +288,6 @@ unicode_internal_decode(PyObject *self,
 {
     PyObject *obj;
     const char *errors = NULL;
-    const char *data;
-    Py_ssize_t size;
 
     if (!PyArg_ParseTuple(args, "O|z:unicode_internal_decode",
                           &obj, &errors))
@@ -302,11 +300,16 @@ unicode_internal_decode(PyObject *self,
         return codec_tuple(obj, PyUnicode_GET_LENGTH(obj));
     }
     else {
-        if (PyObject_AsReadBuffer(obj, (const void **)&data, &size))
+        Py_buffer view;
+        PyObject *result;
+        if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) != 0)
             return NULL;
 
-        return codec_tuple(_PyUnicode_DecodeUnicodeInternal(data, size, errors),
-                           size);
+        result = codec_tuple(
+                _PyUnicode_DecodeUnicodeInternal(view.buf, view.len, errors),
+                view.len);
+        PyBuffer_Release(&view);
+        return result;
     }
 }
 
@@ -731,8 +734,6 @@ unicode_internal_encode(PyObject *self,
 {
     PyObject *obj;
     const char *errors = NULL;
-    const char *data;
-    Py_ssize_t len, size;
 
     if (PyErr_WarnEx(PyExc_DeprecationWarning,
                      "unicode_internal codec has been deprecated",
@@ -745,6 +746,7 @@ unicode_internal_encode(PyObject *self,
 
     if (PyUnicode_Check(obj)) {
         Py_UNICODE *u;
+        Py_ssize_t len, size;
 
         if (PyUnicode_READY(obj) < 0)
             return NULL;
@@ -759,9 +761,13 @@ unicode_internal_encode(PyObject *self,
                            PyUnicode_GET_LENGTH(obj));
     }
     else {
-        if (PyObject_AsReadBuffer(obj, (const void **)&data, &size))
+        Py_buffer view;
+        PyObject *result;
+        if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) != 0)
             return NULL;
-        return codec_tuple(PyBytes_FromStringAndSize(data, size), size);
+        result = codec_tuple(PyBytes_FromStringAndSize(view.buf, view.len), view.len);
+        PyBuffer_Release(&view);
+        return result;
     }
 }
 

Diff for: Modules/_ctypes/_ctypes.c

@@ -463,39 +463,45 @@ KeepRef(CDataObject *target, Py_ssize_t index, PyObject *keep);
 static PyObject *
 CDataType_from_buffer(PyObject *type, PyObject *args)
 {
-    void *buffer;
-    Py_ssize_t buffer_len;
+    Py_buffer buffer;
     Py_ssize_t offset = 0;
-    PyObject *obj, *result;
+    PyObject *result, *mv;
     StgDictObject *dict = PyType_stgdict(type);
     assert (dict);
 
-    if (!PyArg_ParseTuple(args, "O|n:from_buffer", &obj, &offset))
-        return NULL;
-
-    if (-1 == PyObject_AsWriteBuffer(obj, &buffer, &buffer_len))
+    if (!PyArg_ParseTuple(args, "w*|n:from_buffer", &buffer, &offset))
         return NULL;
 
     if (offset < 0) {
         PyErr_SetString(PyExc_ValueError,
                         "offset cannot be negative");
+        PyBuffer_Release(&buffer);
         return NULL;
     }
-    if (dict->size > buffer_len - offset) {
+    if (dict->size > buffer.len - offset) {
         PyErr_Format(PyExc_ValueError,
                      "Buffer size too small (%zd instead of at least %zd bytes)",
-                     buffer_len, dict->size + offset);
+                     buffer.len, dict->size + offset);
+        PyBuffer_Release(&buffer);
         return NULL;
     }
 
-    result = PyCData_AtAddress(type, (char *)buffer + offset);
-    if (result == NULL)
+    result = PyCData_AtAddress(type, (char *)buffer.buf + offset);
+    if (result == NULL) {
+        PyBuffer_Release(&buffer);
         return NULL;
+    }
 
-    Py_INCREF(obj);
-    if (-1 == KeepRef((CDataObject *)result, -1, obj)) {
+    mv = PyMemoryView_FromBuffer(&buffer);
+    if (mv == NULL) {
+        PyBuffer_Release(&buffer);
         return NULL;
     }
+    /* Hack the memoryview so that it will release the buffer. */
+    ((PyMemoryViewObject *)mv)->mbuf->master.obj = buffer.obj;
+    ((PyMemoryViewObject *)mv)->view.obj = buffer.obj;
+    if (-1 == KeepRef((CDataObject *)result, -1, mv))
+        result = NULL;
     return result;
 }
 
@@ -508,37 +514,36 @@ GenericPyCData_new(PyTypeObject *type, PyObject *args, PyObject *kwds);
 static PyObject *
 CDataType_from_buffer_copy(PyObject *type, PyObject *args)
 {
-    const void *buffer;
-    Py_ssize_t buffer_len;
+    Py_buffer buffer;
     Py_ssize_t offset = 0;
-    PyObject *obj, *result;
+    PyObject *result;
     StgDictObject *dict = PyType_stgdict(type);
     assert (dict);
 
-    if (!PyArg_ParseTuple(args, "O|n:from_buffer", &obj, &offset))
-        return NULL;
-
-    if (-1 == PyObject_AsReadBuffer(obj, (const void**)&buffer, &buffer_len))
+    if (!PyArg_ParseTuple(args, "y*|n:from_buffer", &buffer, &offset))
         return NULL;
 
     if (offset < 0) {
         PyErr_SetString(PyExc_ValueError,
                         "offset cannot be negative");
+        PyBuffer_Release(&buffer);
         return NULL;
     }
 
-    if (dict->size > buffer_len - offset) {
+    if (dict->size > buffer.len - offset) {
         PyErr_Format(PyExc_ValueError,
                      "Buffer size too small (%zd instead of at least %zd bytes)",
-                     buffer_len, dict->size + offset);
+                     buffer.len, dict->size + offset);
+        PyBuffer_Release(&buffer);
         return NULL;
     }
 
     result = GenericPyCData_new((PyTypeObject *)type, NULL, NULL);
-    if (result == NULL)
-        return NULL;
-    memcpy(((CDataObject *)result)->b_ptr,
-           (char *)buffer+offset, dict->size);
+    if (result != NULL) {
+        memcpy(((CDataObject *)result)->b_ptr,
+               (char *)buffer.buf + offset, dict->size);
+    }
+    PyBuffer_Release(&buffer);
     return result;
 }
 

Diff for: Modules/_io/bytesio.c

@@ -553,28 +553,30 @@ PyDoc_STRVAR(readinto_doc,
 "is set not to block as has no data to read.");
 
 static PyObject *
-bytesio_readinto(bytesio *self, PyObject *buffer)
+bytesio_readinto(bytesio *self, PyObject *arg)
 {
-    void *raw_buffer;
+    Py_buffer buffer;
     Py_ssize_t len, n;
 
     CHECK_CLOSED(self, NULL);
 
-    if (PyObject_AsWriteBuffer(buffer, &raw_buffer, &len) == -1)
+    if (!PyArg_Parse(arg, "w*", &buffer))
         return NULL;
 
     /* adjust invalid sizes */
+    len = buffer.len;
     n = self->string_size - self->pos;
     if (len > n) {
         len = n;
         if (len < 0)
             len = 0;
     }
 
-    memcpy(raw_buffer, self->buf + self->pos, len);
+    memcpy(buffer.buf, self->buf + self->pos, len);
     assert(self->pos + len < PY_SSIZE_T_MAX);
     assert(len >= 0);
     self->pos += len;
+    PyBuffer_Release(&buffer);
 
     return PyLong_FromSsize_t(len);
 }

Diff for: Modules/_sqlite/connection.c

@@ -522,19 +522,20 @@ _pysqlite_set_result(sqlite3_context* context, PyObject* py_val)
             return -1;
         sqlite3_result_text(context, str, -1, SQLITE_TRANSIENT);
     } else if (PyObject_CheckBuffer(py_val)) {
-        const char* buffer;
-        Py_ssize_t buflen;
-        if (PyObject_AsCharBuffer(py_val, &buffer, &buflen) != 0) {
+        Py_buffer view;
+        if (PyObject_GetBuffer(py_val, &view, PyBUF_SIMPLE) != 0) {
             PyErr_SetString(PyExc_ValueError,
                             "could not convert BLOB to buffer");
             return -1;
         }
-        if (buflen > INT_MAX) {
+        if (view.len > INT_MAX) {
             PyErr_SetString(PyExc_OverflowError,
                             "BLOB longer than INT_MAX bytes");
+            PyBuffer_Release(&view);
             return -1;
         }
-        sqlite3_result_blob(context, buffer, (int)buflen, SQLITE_TRANSIENT);
+        sqlite3_result_blob(context, view.buf, (int)view.len, SQLITE_TRANSIENT);
+        PyBuffer_Release(&view);
     } else {
         return -1;
     }

Diff for: Modules/_sqlite/statement.c

@@ -94,7 +94,6 @@ int pysqlite_statement_create(pysqlite_Statement* self, pysqlite_Connection* con
 int pysqlite_statement_bind_parameter(pysqlite_Statement* self, int pos, PyObject* parameter)
 {
     int rc = SQLITE_OK;
-    const char* buffer;
     char* string;
     Py_ssize_t buflen;
     parameter_type paramtype;
@@ -145,18 +144,22 @@ int pysqlite_statement_bind_parameter(pysqlite_Statement* self, int pos, PyObjec
             }
             rc = sqlite3_bind_text(self->st, pos, string, (int)buflen, SQLITE_TRANSIENT);
             break;
-        case TYPE_BUFFER:
-            if (PyObject_AsCharBuffer(parameter, &buffer, &buflen) != 0) {
+        case TYPE_BUFFER: {
+            Py_buffer view;
+            if (PyObject_GetBuffer(parameter, &view, PyBUF_SIMPLE) != 0) {
                 PyErr_SetString(PyExc_ValueError, "could not convert BLOB to buffer");
                 return -1;
             }
-            if (buflen > INT_MAX) {
+            if (view.len > INT_MAX) {
                 PyErr_SetString(PyExc_OverflowError,
                                 "BLOB longer than INT_MAX bytes");
+                PyBuffer_Release(&view);
                 return -1;
             }
-            rc = sqlite3_bind_blob(self->st, pos, buffer, buflen, SQLITE_TRANSIENT);
+            rc = sqlite3_bind_blob(self->st, pos, view.buf, (int)view.len, SQLITE_TRANSIENT);
+            PyBuffer_Release(&view);
             break;
+        }
         case TYPE_UNKNOWN:
             rc = -1;
     }