gh-85524: Raise "UnsupportedOperation" on FileIO.readall (#141214)

io.UnsupportedOperation is a subclass of OSError and recommended by
io.IOBase for this case; matches other read methods on io.FileIO.

diff --git a/Lib/test/test_io/test_general.py b/Lib/test/test_io/test_general.py
index a1cdd6876c28924f7b605284e67fcfe8bc021256..f0677b01ea5ce1172318b725e8df475a6420de5c 100644 (file)
--- a/Lib/test/test_io/test_general.py
+++ b/Lib/test/test_io/test_general.py
@@ -125,6 +125,7 @@ class IOTest:
             self.assertRaises(exc, fp.readline)
         with self.open(os_helper.TESTFN, "wb", buffering=0) as fp:
             self.assertRaises(exc, fp.read)
+            self.assertRaises(exc, fp.readall)
             self.assertRaises(exc, fp.readline)
         with self.open(os_helper.TESTFN, "rb", buffering=0) as fp:
             self.assertRaises(exc, fp.write, b"blah")

diff --git a/Misc/NEWS.d/next/Library/2025-11-07-12-25-46.gh-issue-85524.9SWFIC.rst b/Misc/NEWS.d/next/Library/2025-11-07-12-25-46.gh-issue-85524.9SWFIC.rst
new file mode 100644 (file)
index 0000000..3e4fd1a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-11-07-12-25-46.gh-issue-85524.9SWFIC.rst
@@ -0,0 +1,3 @@
+Update ``io.FileIO.readall``, an implementation of :meth:`io.RawIOBase.readall`,
+to follow :class:`io.IOBase` guidelines and raise :exc:`io.UnsupportedOperation`
+when a file is in "w" mode rather than :exc:`OSError`

diff --git a/Modules/_io/clinic/fileio.c.h b/Modules/_io/clinic/fileio.c.h
index 04870b1c890361949e3fc0b55d287dbe51bace81..96c31ce8d6f415a1f5b9e0c6ac5e968d69b8402e 100644 (file)
--- a/Modules/_io/clinic/fileio.c.h
+++ b/Modules/_io/clinic/fileio.c.h
@@ -277,15 +277,19 @@ PyDoc_STRVAR(_io_FileIO_readall__doc__,
 "data is available (EAGAIN is returned before bytes are read) returns None.");
 
 #define _IO_FILEIO_READALL_METHODDEF    \
-    {"readall", (PyCFunction)_io_FileIO_readall, METH_NOARGS, _io_FileIO_readall__doc__},
+    {"readall", _PyCFunction_CAST(_io_FileIO_readall), METH_METHOD|METH_FASTCALL|METH_KEYWORDS, _io_FileIO_readall__doc__},
 
 static PyObject *
-_io_FileIO_readall_impl(fileio *self);
+_io_FileIO_readall_impl(fileio *self, PyTypeObject *cls);
 
 static PyObject *
-_io_FileIO_readall(PyObject *self, PyObject *Py_UNUSED(ignored))
+_io_FileIO_readall(PyObject *self, PyTypeObject *cls, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
-    return _io_FileIO_readall_impl((fileio *)self);
+    if (nargs || (kwnames && PyTuple_GET_SIZE(kwnames))) {
+        PyErr_SetString(PyExc_TypeError, "readall() takes no arguments");
+        return NULL;
+    }
+    return _io_FileIO_readall_impl((fileio *)self, cls);
 }
 
 PyDoc_STRVAR(_io_FileIO_read__doc__,
@@ -543,4 +547,4 @@ _io_FileIO_isatty(PyObject *self, PyObject *Py_UNUSED(ignored))
 #ifndef _IO_FILEIO_TRUNCATE_METHODDEF
     #define _IO_FILEIO_TRUNCATE_METHODDEF
 #endif /* !defined(_IO_FILEIO_TRUNCATE_METHODDEF) */
-/*[clinic end generated code: output=1902fac9e39358aa input=a9049054013a1b77]*/
+/*[clinic end generated code: output=2e48f3df2f189170 input=a9049054013a1b77]*/

diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 2544ff4ea91ec87ed68abfe6768c2c77eeea525f..5d7741fdd830a53fe4738f97f5bc6c7687081678 100644 (file)
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -728,6 +728,9 @@ new_buffersize(fileio *self, size_t currentsize)
 @permit_long_docstring_body
 _io.FileIO.readall
 
+    cls: defining_class
+    /
+
 Read all data from the file, returned as bytes.
 
 Reads until either there is an error or read() returns size 0 (indicates EOF).
@@ -738,8 +741,8 @@ data is available (EAGAIN is returned before bytes are read) returns None.
 [clinic start generated code]*/
 
 static PyObject *
-_io_FileIO_readall_impl(fileio *self)
-/*[clinic end generated code: output=faa0292b213b4022 input=10d8b2ec403302dc]*/
+_io_FileIO_readall_impl(fileio *self, PyTypeObject *cls)
+/*[clinic end generated code: output=d546737ec895c462 input=cecda40bf9961299]*/
 {
     Py_off_t pos, end;
     PyBytesWriter *writer;
@@ -750,6 +753,10 @@ _io_FileIO_readall_impl(fileio *self)
     if (self->fd < 0) {
         return err_closed();
     }
+    if (!self->readable) {
+        _PyIO_State *state = get_io_state_by_cls(cls);
+        return err_mode(state, "reading");
+    }
 
     if (self->stat_atopen != NULL && self->stat_atopen->st_size < _PY_READ_MAX) {
         end = (Py_off_t)self->stat_atopen->st_size;
@@ -873,7 +880,7 @@ _io_FileIO_read_impl(fileio *self, PyTypeObject *cls, Py_ssize_t size)
     }
 
     if (size < 0)
-        return _io_FileIO_readall_impl(self);
+        return _io_FileIO_readall_impl(self, cls);
 
     if (size > _PY_READ_MAX) {
         size = _PY_READ_MAX;