Issue #7640: In the new `io` module, fix relative seek() for buffered
readable streams when the internal buffer isn't empty. Patch by Pascal
Chambon.
diff --git a/Lib/io.py b/Lib/io.py
index 54de504..1458b47 100644
--- a/Lib/io.py
+++ b/Lib/io.py
@@ -1199,6 +1199,10 @@
self.flush()
# First do the raw seek, then empty the read buffer, so that
# if the raw seek fails, we don't lose buffered data forever.
+ if self._read_buf and whence == 1:
+ # Undo read ahead.
+ with self._read_lock:
+ self.raw.seek(self._read_pos - len(self._read_buf), 1)
pos = self.raw.seek(pos, whence)
with self._read_lock:
self._reset_read_buf()
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index c732b1f..aebe67b 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -107,6 +107,10 @@
self.assertEqual(f.truncate(12), 12)
self.assertEqual(f.tell(), 13)
+ self.assertEqual(f.write(b"hij"), 3)
+ self.assertEqual(f.seek(0,1), 16)
+ self.assertEqual(f.tell(), 16)
+ self.assertEqual(f.truncate(12), 12)
self.assertRaises(TypeError, f.seek, 0.0)
def read_ops(self, f, buffered=False):
@@ -129,6 +133,10 @@
self.assertEqual(f.seek(-6, 1), 5)
self.assertEqual(f.read(5), b" worl")
self.assertEqual(f.tell(), 10)
+ f.seek(0)
+ f.read(2)
+ f.seek(0, 1)
+ self.assertEqual(f.tell(), 2)
self.assertRaises(TypeError, f.seek, 0.0)
if buffered:
f.seek(0)
@@ -182,6 +190,13 @@
self.assertEqual(f.writable(), False)
self.assertEqual(f.seekable(), True)
self.read_ops(f, True)
+ f = io.open(test_support.TESTFN, "r+b")
+ self.assertEqual(f.readable(), True)
+ self.assertEqual(f.writable(), True)
+ self.assertEqual(f.seekable(), True)
+ self.write_ops(f)
+ f.seek(0)
+ self.read_ops(f, True)
f.close()
def test_readline(self):
@@ -513,7 +528,7 @@
self.assertEquals(b"abcdefghijkl", writer._write_stack[0])
def testWriteNonBlocking(self):
- raw = MockNonBlockWriterIO((9, 2, 22, -6, 10, 12, 12))
+ raw = MockNonBlockWriterIO((9, 2, 10, -6, 10, 8, 12))
bufio = io.BufferedWriter(raw, 8, 16)
bufio.write(b"asdf")