Issue #15841: The readable(), writable() and seekable() methods of io.BytesIO

and io.StringIO objects now raise ValueError when the object has been closed.
Patch by Alessandro Moura.

2 files changed, 31 insertions, 8 deletions

diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index ae8c1c1..6498320 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -106,7 +106,7 @@ resize_buffer(bytesio *self, size_t size)
 }
 
 /* Internal routine for writing a string of bytes to the buffer of a BytesIO
-   object. Returns the number of bytes wrote, or -1 on error. */
+   object. Returns the number of bytes written, or -1 on error. */
 static Py_ssize_t
 write_bytes(bytesio *self, const char *bytes, Py_ssize_t len)
 {
@@ -156,10 +156,20 @@ bytesio_get_closed(bytesio *self)
     }
 }
 
+PyDoc_STRVAR(readable_doc,
+"readable() -> bool. Returns True if the IO object can be read.");
+
+PyDoc_STRVAR(writable_doc,
+"writable() -> bool. Returns True if the IO object can be written.");
+
+PyDoc_STRVAR(seekable_doc,
+"seekable() -> bool. Returns True if the IO object can be seeked.");
+
 /* Generic getter for the writable, readable and seekable properties */
 static PyObject *
-return_true(bytesio *self)
+return_not_closed(bytesio *self)
 {
+    CHECK_CLOSED(self);
     Py_RETURN_TRUE;
 }
 
@@ -827,9 +837,9 @@ static PyGetSetDef bytesio_getsetlist[] = {
 };
 
 static struct PyMethodDef bytesio_methods[] = {
-    {"readable",   (PyCFunction)return_true,        METH_NOARGS, NULL},
-    {"seekable",   (PyCFunction)return_true,        METH_NOARGS, NULL},
-    {"writable",   (PyCFunction)return_true,        METH_NOARGS, NULL},
+    {"readable",   (PyCFunction)return_not_closed,  METH_NOARGS, readable_doc},
+    {"seekable",   (PyCFunction)return_not_closed,  METH_NOARGS, seekable_doc},
+    {"writable",   (PyCFunction)return_not_closed,  METH_NOARGS, writable_doc},
     {"close",      (PyCFunction)bytesio_close,      METH_NOARGS, close_doc},
     {"flush",      (PyCFunction)bytesio_flush,      METH_NOARGS, flush_doc},
     {"isatty",     (PyCFunction)bytesio_isatty,     METH_NOARGS, isatty_doc},
diff --git a/Modules/_io/stringio.c b/Modules/_io/stringio.c
index e3de751..59a3905 100644
--- a/Modules/_io/stringio.c
+++ b/Modules/_io/stringio.c
@@ -632,10 +632,21 @@ stringio_init(stringio *self, PyObject *args, PyObject *kwds)
 }
 
 /* Properties and pseudo-properties */
+
+PyDoc_STRVAR(stringio_readable_doc,
+"readable() -> bool. Returns True if the IO object can be read.");
+
+PyDoc_STRVAR(stringio_writable_doc,
+"writable() -> bool. Returns True if the IO object can be written.");
+
+PyDoc_STRVAR(stringio_seekable_doc,
+"seekable() -> bool. Returns True if the IO object can be seeked.");
+
 static PyObject *
 stringio_seekable(stringio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
     Py_RETURN_TRUE;
 }
 
@@ -643,6 +654,7 @@ static PyObject *
 stringio_readable(stringio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
     Py_RETURN_TRUE;
 }
 
@@ -650,6 +662,7 @@ static PyObject *
 stringio_writable(stringio *self, PyObject *args)
 {
     CHECK_INITIALIZED(self);
+    CHECK_CLOSED(self);
     Py_RETURN_TRUE;
 }
 
@@ -817,9 +830,9 @@ static struct PyMethodDef stringio_methods[] = {
     {"seek",     (PyCFunction)stringio_seek,     METH_VARARGS, stringio_seek_doc},
     {"write",    (PyCFunction)stringio_write,    METH_O,       stringio_write_doc},
 
-    {"seekable", (PyCFunction)stringio_seekable, METH_NOARGS},
-    {"readable", (PyCFunction)stringio_readable, METH_NOARGS},
-    {"writable", (PyCFunction)stringio_writable, METH_NOARGS},
+    {"seekable", (PyCFunction)stringio_seekable, METH_NOARGS, stringio_seekable_doc},
+    {"readable", (PyCFunction)stringio_readable, METH_NOARGS, stringio_readable_doc},
+    {"writable", (PyCFunction)stringio_writable, METH_NOARGS, stringio_writable_doc},
 
     {"__getstate__", (PyCFunction)stringio_getstate, METH_NOARGS},
     {"__setstate__", (PyCFunction)stringio_setstate, METH_O},