Issue #5179: Fixed subprocess handle leak on failure on windows.

Lib/subprocess.py

@@ -642,21 +642,13 @@ class Popen(object):
                             c2pread, c2pwrite,
                             errread, errwrite)
 
-        # On Windows, you cannot just redirect one or two handles: You
-        # either have to redirect all three or none. If the subprocess
-        # user has only redirected one or two handles, we are
-        # automatically creating PIPEs for the rest. We should close
-        # these after the process is started. See bug #1124861.
         if mswindows:
-            if stdin is None and p2cwrite is not None:
+            if p2cwrite is not None:
-                os.close(p2cwrite)
+                p2cwrite = msvcrt.open_osfhandle(p2cwrite.Detach(), 0)
-                p2cwrite = None
+            if c2pread is not None:
-            if stdout is None and c2pread is not None:
+                c2pread = msvcrt.open_osfhandle(c2pread.Detach(), 0)
-                os.close(c2pread)
+            if errread is not None:
-                c2pread = None
+                errread = msvcrt.open_osfhandle(errread.Detach(), 0)
-            if stderr is None and errread is not None:
-                os.close(errread)
-                errread = None
 
         if p2cwrite is not None:
             self.stdin = os.fdopen(p2cwrite, 'wb', bufsize)
@@ -740,13 +732,10 @@ class Popen(object):
 
             if stdin is None:
                 p2cread = GetStdHandle(STD_INPUT_HANDLE)
-            if p2cread is not None:
+                if p2cread is None:
-                pass
+                    p2cread, _ = CreatePipe(None, 0)
-            elif stdin is None or stdin == PIPE:
+            elif stdin == PIPE:
                 p2cread, p2cwrite = CreatePipe(None, 0)
-                # Detach and turn into fd
-                p2cwrite = p2cwrite.Detach()
-                p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0)
             elif isinstance(stdin, int):
                 p2cread = msvcrt.get_osfhandle(stdin)
             else:
@@ -756,13 +745,10 @@ class Popen(object):
 
             if stdout is None:
                 c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE)
-            if c2pwrite is not None:
+                if c2pwrite is None:
-                pass
+                    _, c2pwrite = CreatePipe(None, 0)
-            elif stdout is None or stdout == PIPE:
+            elif stdout == PIPE:
                 c2pread, c2pwrite = CreatePipe(None, 0)
-                # Detach and turn into fd
-                c2pread = c2pread.Detach()
-                c2pread = msvcrt.open_osfhandle(c2pread, 0)
             elif isinstance(stdout, int):
                 c2pwrite = msvcrt.get_osfhandle(stdout)
             else:
@@ -772,13 +758,10 @@ class Popen(object):
 
             if stderr is None:
                 errwrite = GetStdHandle(STD_ERROR_HANDLE)
-            if errwrite is not None:
+                if errwrite is None:
-                pass
+                    _, errwrite = CreatePipe(None, 0)
-            elif stderr is None or stderr == PIPE:
+            elif stderr == PIPE:
                 errread, errwrite = CreatePipe(None, 0)
-                # Detach and turn into fd
-                errread = errread.Detach()
-                errread = msvcrt.open_osfhandle(errread, 0)
             elif stderr == STDOUT:
                 errwrite = c2pwrite
             elif isinstance(stderr, int):

Misc/NEWS

@@ -168,6 +168,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #5179: Fixed subprocess handle leak on failure on windows.
+
 - PEP 372:  Added collections.OrderedDict().
 
 - The _asdict() for method for namedtuples now returns an OrderedDict().

PC/_subprocess.c

@@ -87,7 +87,7 @@ sp_handle_detach(sp_handle_object* self, PyObject* args)
 
 	handle = self->handle;
 
-	self->handle = NULL;
+	self->handle = INVALID_HANDLE_VALUE;
 
 	/* note: return the current handle, as an integer */
 	return HANDLE_TO_PYNUM(handle);