# HG changeset patch
# Parent  5d8042ab3361978b7fd9493867277c286a46cec9
Issue #26720: Release temporary memory views at the end of their life

diff -r 5d8042ab3361 Doc/library/codecs.rst
--- a/Doc/library/codecs.rst	Mon Apr 18 07:16:17 2016 +0000
+++ b/Doc/library/codecs.rst	Mon Apr 18 13:23:55 2016 +0000
@@ -469,7 +469,7 @@
    character set encoding to a string object.
 
    For text encodings and bytes-to-bytes codecs,
-   *input* must be a bytes object or one which provides the read-only
+   *input* must be a bytes object or an object which provides the read-only
    buffer interface -- for example, buffer objects and memory mapped files.
 
    The *errors* argument defines the error handling to apply.
diff -r 5d8042ab3361 Doc/library/io.rst
--- a/Doc/library/io.rst	Mon Apr 18 07:16:17 2016 +0000
+++ b/Doc/library/io.rst	Mon Apr 18 13:23:55 2016 +0000
@@ -406,6 +406,9 @@
       returned if the raw stream is set not to block and no single byte could
       be readily written to it.
 
+      The caller may mutate *b* after this method returns, so the
+      implementation should only access *b* during the method call.
+
 
 .. class:: BufferedIOBase
 
diff -r 5d8042ab3361 Lib/test/test_codecs.py
--- a/Lib/test/test_codecs.py	Mon Apr 18 07:16:17 2016 +0000
+++ b/Lib/test/test_codecs.py	Mon Apr 18 13:23:55 2016 +0000
@@ -1821,6 +1821,18 @@
             self.assertRaises(UnicodeError,
                 codecs.decode, b'abc', 'undefined', errors)
 
+    def test_decode_buffer_lifetime(self):
+        class Codec(codecs.Codec):
+            def decode(self, input, errors=None):
+                self.view = input
+                return ('decoded', 0)
+        codec = Codec()
+        info = codecs.CodecInfo(codec.encode, codec.decode)
+        with support.swap_item(_TEST_CODECS, 'test', info):
+            b'abc'.decode('test')
+            with self.assertRaisesRegex(ValueError, 'released memoryview'):
+                codec.view.tobytes()
+
 
 class StreamReaderTest(unittest.TestCase):
 
diff -r 5d8042ab3361 Lib/test/test_io.py
--- a/Lib/test/test_io.py	Mon Apr 18 07:16:17 2016 +0000
+++ b/Lib/test/test_io.py	Mon Apr 18 13:23:55 2016 +0000
@@ -1298,6 +1298,18 @@
         self.assertRaises(ValueError, b.peek)
         self.assertRaises(ValueError, b.read1, 1)
 
+    def test_read_buffer_lifetime(self):
+        class Raw(self.MockRawIOWithoutRead):
+            def readinto(self, b):
+                self.view = b
+                b[:7] = b"abcdefg"
+                return 7
+        reader = self.tp(Raw())
+        self.assertEqual(reader.read(7), b"abcdefg")
+        if isinstance(reader.raw.view, memoryview):
+            with self.assertRaisesRegex(ValueError, "released memoryview"):
+                reader.raw.view.tobytes()
+
 
 class CBufferedReaderTest(BufferedReaderTest, SizeofTest):
     tp = io.BufferedReader
@@ -1606,6 +1618,18 @@
         self.assertRaises(OSError, b.close) # exception not swallowed
         self.assertTrue(b.closed)
 
+    def test_write_buffer_lifetime(self):
+        class Raw(self.MockRawIO):
+            def write(self, b):
+                self.view = b
+                return len(b)
+        writer = self.tp(Raw())
+        writer.write(b"abc")
+        writer.flush()
+        if isinstance(writer.raw.view, memoryview):
+            with self.assertRaisesRegex(ValueError, "released memoryview"):
+                writer.raw.view.tobytes()
+
 
 class CBufferedWriterTest(BufferedWriterTest, SizeofTest):
     tp = io.BufferedWriter
diff -r 5d8042ab3361 Misc/NEWS
--- a/Misc/NEWS	Mon Apr 18 07:16:17 2016 +0000
+++ b/Misc/NEWS	Mon Apr 18 13:23:55 2016 +0000
@@ -10,6 +10,11 @@
 Core and Builtins
 -----------------
 
+- Issue #15994: When the interpreter passes a temporary memoryview object to
+  a Python method, it now releases the memoryview when the method returns.
+  This affects calls to RawIOBase.readinto() by BufferedReader,
+  RawIOBase.write() by BufferedWriter, and Codec.decode() by bytes.decode().
+
 - Issue #26659: Make the builtin slice type support cycle collection.
 
 - Issue #26718: super.__init__ no longer leaks memory if called multiple times.
diff -r 5d8042ab3361 Modules/_io/bufferedio.c
--- a/Modules/_io/bufferedio.c	Mon Apr 18 07:16:17 2016 +0000
+++ b/Modules/_io/bufferedio.c	Mon Apr 18 13:23:55 2016 +0000
@@ -1474,7 +1474,8 @@
     Py_buffer buf;
     PyObject *memobj, *res;
     Py_ssize_t n;
-    /* NOTE: the buffer needn't be released as its object is NULL. */
+    PyObject *exc, *val, *tb, *release_res;
+    /* The buffer will be released when raw.readinto() returns. */
     if (PyBuffer_FillInfo(&buf, NULL, start, len, 0, PyBUF_CONTIG) == -1)
         return -1;
     memobj = PyMemoryView_FromBuffer(&buf);
@@ -1488,7 +1489,15 @@
     do {
         res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_readinto, memobj, NULL);
     } while (res == NULL && _PyIO_trap_eintr());
+    PyErr_Fetch(&exc, &val, &tb);
+    release_res = PyObject_CallMethod(memobj, "release", NULL);
+    _PyErr_ChainExceptions(exc, val, tb);
     Py_DECREF(memobj);
+    if (release_res == NULL) {
+        Py_XDECREF(res);
+        return -1;
+    }
+    Py_DECREF(release_res);
     if (res == NULL)
         return -1;
     if (res == Py_None) {
@@ -1828,7 +1837,8 @@
     PyObject *memobj, *res;
     Py_ssize_t n;
     int errnum;
-    /* NOTE: the buffer needn't be released as its object is NULL. */
+    PyObject *exc, *val, *tb, *release_res;
+    /* The buffer will be released when raw.write() returns. */
     if (PyBuffer_FillInfo(&buf, NULL, start, len, 1, PyBUF_CONTIG_RO) == -1)
         return -1;
     memobj = PyMemoryView_FromBuffer(&buf);
@@ -1844,7 +1854,15 @@
         res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_write, memobj, NULL);
         errnum = errno;
     } while (res == NULL && _PyIO_trap_eintr());
+    PyErr_Fetch(&exc, &val, &tb);
+    release_res = PyObject_CallMethod(memobj, "release", NULL);
+    _PyErr_ChainExceptions(exc, val, tb);
     Py_DECREF(memobj);
+    if (release_res == NULL) {
+        Py_XDECREF(res);
+        return -1;
+    }
+    Py_DECREF(release_res);
     if (res == NULL)
         return -1;
     if (res == Py_None) {
diff -r 5d8042ab3361 Objects/unicodeobject.c
--- a/Objects/unicodeobject.c	Mon Apr 18 07:16:17 2016 +0000
+++ b/Objects/unicodeobject.c	Mon Apr 18 13:23:55 2016 +0000
@@ -3142,6 +3142,7 @@
     PyObject *buffer = NULL, *unicode;
     Py_buffer info;
     char lower[11];  /* Enough for any encoding shortcut */
+    PyObject *exc, *val, *tb, *res;
 
     /* Shortcuts for common default encodings */
     if (_Py_normalize_encoding(encoding, lower, sizeof(lower))) {
@@ -3173,6 +3174,14 @@
     if (buffer == NULL)
         goto onError;
     unicode = _PyCodec_DecodeText(buffer, encoding, errors);
+    PyErr_Fetch(&exc, &val, &tb);
+    res = PyObject_CallMethod(buffer, "release", NULL);
+    _PyErr_ChainExceptions(exc, val, tb);
+    if (res == NULL) {
+        Py_XDECREF(unicode);
+        goto onError;
+    }
+    Py_DECREF(res);
     if (unicode == NULL)
         goto onError;
     if (!PyUnicode_Check(unicode)) {