# HG changeset patch
# Parent  8160786d029509a7563a1321068fc330ec2ff0c6
Issue #24291: Avoid WSGIRequestHandler doing partial writes

If the underlying send() method indicates a partial write, such as when the
call is interrupted to handle a signal, the server would silently drop the
remaining data.

diff -r 8160786d0295 Doc/library/wsgiref.rst
--- a/Doc/library/wsgiref.rst	Sat Apr 09 11:33:53 2016 +0200
+++ b/Doc/library/wsgiref.rst	Tue May 31 10:52:53 2016 +0000
@@ -515,6 +515,9 @@
    streams are stored in the :attr:`stdin`, :attr:`stdout`, :attr:`stderr`, and
    :attr:`environ` attributes.
 
+   The :meth:`~io.BufferedIOBase.write` method of *stdout* should write
+   each chunk in full, like :class:`io.BufferedIOBase`.
+
 
 .. class:: BaseHandler()
 
diff -r 8160786d0295 Lib/test/test_wsgiref.py
--- a/Lib/test/test_wsgiref.py	Sat Apr 09 11:33:53 2016 +0200
+++ b/Lib/test/test_wsgiref.py	Tue May 31 10:52:53 2016 +0000
@@ -1,3 +1,5 @@
+from test import support
+from test.test_httpservers import NoLogRequestHandler
 from unittest import TestCase
 from wsgiref.util import setup_testing_defaults
 from wsgiref.headers import Headers
@@ -6,12 +8,14 @@
 from wsgiref.validate import validator
 from wsgiref.simple_server import WSGIServer, WSGIRequestHandler
 from wsgiref.simple_server import make_server
+from http.client import HTTPConnection
 from io import StringIO, BytesIO, BufferedReader
 from socketserver import BaseServer
 from platform import python_implementation
 
 import os
 import re
+import signal
 import sys
 import unittest
 
@@ -221,6 +225,56 @@
                 b"data",
                 out)
 
+    def test_interrupted_write(self):
+        # BaseHandler._write() and _flush() have to write all data, even if
+        # it takes multiple send() calls.  Test this by interrupting a send()
+        # call with a Unix signal.
+        threading = support.import_module("threading")
+        pthread_kill = support.get_attribute(signal, "pthread_kill")
+
+        def app(environ, start_response):
+            start_response("200 OK", [])
+            return [bytes(support.SOCK_MAX_SIZE)]
+
+        class WsgiHandler(NoLogRequestHandler, WSGIRequestHandler):
+            pass
+
+        server = make_server(support.HOST, 0, app, handler_class=WsgiHandler)
+        self.addCleanup(server.server_close)
+        interrupted = threading.Event()
+
+        def signal_handler(signum, frame):
+            interrupted.set()
+
+        original = signal.signal(signal.SIGUSR1, signal_handler)
+        self.addCleanup(signal.signal, signal.SIGUSR1, original)
+        received = None
+        main_thread = threading.get_ident()
+
+        def run_client():
+            http = HTTPConnection(*server.server_address)
+            http.request("GET", "/")
+            with http.getresponse() as response:
+                response.read(100)
+                # The main thread should now be blocking in a send() system
+                # call.  But in theory, it could be interrupted by other
+                # signals, and then retried.  So keep sending the signal in a
+                # loop, in case an earlier signal happens to be delivered
+                # at an inconvenient moment.
+                while True:
+                    pthread_kill(main_thread, signal.SIGUSR1)
+                    if interrupted.wait(timeout=float(1)):
+                        break
+                nonlocal received
+                received = len(response.read())
+            http.close()
+
+        background = threading.Thread(target=run_client)
+        background.start()
+        server.handle_request()
+        background.join()
+        self.assertEqual(received, support.SOCK_MAX_SIZE - 100)
+
 
 class UtilityTests(TestCase):
 
diff -r 8160786d0295 Lib/wsgiref/simple_server.py
--- a/Lib/wsgiref/simple_server.py	Sat Apr 09 11:33:53 2016 +0200
+++ b/Lib/wsgiref/simple_server.py	Tue May 31 10:52:53 2016 +0000
@@ -11,6 +11,7 @@
 """
 
 from http.server import BaseHTTPRequestHandler, HTTPServer
+from io import BufferedWriter
 import sys
 import urllib.parse
 from wsgiref.handlers import SimpleHandler
@@ -126,11 +127,17 @@
         if not self.parse_request(): # An error code has been sent, just exit
             return
 
-        handler = ServerHandler(
-            self.rfile, self.wfile, self.get_stderr(), self.get_environ()
-        )
-        handler.request_handler = self      # backpointer for logging
-        handler.run(self.server.get_app())
+        # Avoid passing the raw file object wfile, which can do partial
+        # writes (Issue 24291)
+        stdout = BufferedWriter(self.wfile)
+        try:
+            handler = ServerHandler(
+                self.rfile, stdout, self.get_stderr(), self.get_environ()
+            )
+            handler.request_handler = self      # backpointer for logging
+            handler.run(self.server.get_app())
+        finally:
+            stdout.detach()
 
 
 
diff -r 8160786d0295 Misc/NEWS
--- a/Misc/NEWS	Sat Apr 09 11:33:53 2016 +0200
+++ b/Misc/NEWS	Tue May 31 10:52:53 2016 +0000
@@ -237,6 +237,10 @@
 Library
 -------
 
+- Issue #24291: Fix wsgiref.simple_server.WSGIRequestHandler to completely
+  write data to the client.  Previously it could do partial writes and
+  truncate data.
+
 - Issue #16329: Add .webm to mimetypes.types_map.  Patch by Giampaolo Rodola'.
 
 - Issue #13952: Add .csv to mimetypes.types_map.  Patch by Geoff Wilson.