diff --git a/Lib/codecs.py b/Lib/codecs.py index 590238ec502..e120d636bcb 100644 --- a/Lib/codecs.py +++ b/Lib/codecs.py @@ -472,15 +472,17 @@ class StreamReader(Codec): self.charbuffer = "".join(self.linebuffer) self.linebuffer = None + if chars < 0: + # For compatibility with other read() methods that take a + # single argument + chars = size + # read until we get the required number of characters (if available) while True: # can the request be satisfied from the character buffer? if chars >= 0: if len(self.charbuffer) >= chars: break - elif size >= 0: - if len(self.charbuffer) >= size: - break # we need more data if size < 0: newdata = self.stream.read() diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py index efc40cf2c23..0ec8bf5a4b4 100644 --- a/Lib/test/test_codecs.py +++ b/Lib/test/test_codecs.py @@ -149,19 +149,33 @@ class ReadTest(unittest.TestCase): self.assertEqual(f.read(), ''.join(lines[1:])) self.assertEqual(f.read(), '') + # Issue #32110: Test readline() followed by read(n) + f = getreader() + self.assertEqual(f.readline(), lines[0]) + self.assertEqual(f.read(1), lines[1][0]) + self.assertEqual(f.read(0), '') + self.assertEqual(f.read(100), data[len(lines[0]) + 1:][:100]) + # Issue #16636: Test readline() followed by readlines() f = getreader() self.assertEqual(f.readline(), lines[0]) self.assertEqual(f.readlines(), lines[1:]) self.assertEqual(f.read(), '') - # Test read() followed by read() + # Test read(n) followed by read() f = getreader() self.assertEqual(f.read(size=40, chars=5), data[:5]) self.assertEqual(f.read(), data[5:]) self.assertEqual(f.read(), '') - # Issue #12446: Test read() followed by readlines() + # Issue #32110: Test read(n) followed by read(n) + f = getreader() + self.assertEqual(f.read(size=40, chars=5), data[:5]) + self.assertEqual(f.read(1), data[5]) + self.assertEqual(f.read(0), '') + self.assertEqual(f.read(100), data[6:106]) + + # Issue #12446: Test read(n) followed by readlines() f = getreader() self.assertEqual(f.read(size=40, chars=5), data[:5]) self.assertEqual(f.readlines(), [lines[0][5:]] + lines[1:]) diff --git a/Misc/NEWS.d/next/Library/2017-11-22-09-44-15.bpo-32110.VJa9bo.rst b/Misc/NEWS.d/next/Library/2017-11-22-09-44-15.bpo-32110.VJa9bo.rst new file mode 100644 index 00000000000..b57ff1acaff --- /dev/null +++ b/Misc/NEWS.d/next/Library/2017-11-22-09-44-15.bpo-32110.VJa9bo.rst @@ -0,0 +1,3 @@ +``codecs.StreamReader.read(n)`` now returns not more than *n* +characters/bytes for non-negative *n*. This makes it compatible with +``read()`` methods of other file-like objects.