correct logic when pos is after the string #10467
diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index dcf6d51..13d7e17 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -452,6 +452,11 @@
self.assertEqual(a.tobytes(), b"1234567890d")
memio.close()
self.assertRaises(ValueError, memio.readinto, b)
+ memio = self.ioclass(b"123")
+ b = bytearray()
+ memio.seek(42)
+ memio.readinto(b)
+ self.assertEqual(b, b"")
def test_relative_seek(self):
buf = self.buftype("1234567890")
diff --git a/Misc/NEWS b/Misc/NEWS
index 76bf481..7094504 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -24,6 +24,9 @@
Library
-------
+- Issue #10467: Fix BytesIO.readinto() after seeking into a position after the
+ end of the file.
+
- Issue #1682942: configparser supports alternative option/value delimiters.
- Issue #5412: configparser supports mapping protocol access.
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index c565404..b40513f 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -430,15 +430,20 @@
bytesio_readinto(bytesio *self, PyObject *buffer)
{
void *raw_buffer;
- Py_ssize_t len;
+ Py_ssize_t len, n;
CHECK_CLOSED(self);
if (PyObject_AsWriteBuffer(buffer, &raw_buffer, &len) == -1)
return NULL;
- if (self->pos + len > self->string_size)
- len = self->string_size - self->pos;
+ /* adjust invalid sizes */
+ n = self->string_size - self->pos;
+ if (len > n) {
+ len = n;
+ if (len < 0)
+ len = 0;
+ }
memcpy(raw_buffer, self->buf + self->pos, len);
assert(self->pos + len < PY_SSIZE_T_MAX);