From 58cb1b8b0ef200b7f7d4aba82642a63ce7532545 Mon Sep 17 00:00:00 2001
From: Christian Heimes <christian@cheimes.de>
Date: Tue, 13 Nov 2007 02:19:40 +0000
Subject: Fix for #1415 pythonw.exe fails because std streams a missing

After a long discussion about the problem with Windows GUI apps Guido decided that sys.stdin, stdout and stderr should be None when the C runtime library returns invalid file descriptors for the standard streams.

So far the only known cases are Windows GUI apps and scripts started with pythonw on Windows. The OS restrictions are tight enough to catch the problem on other OSes.
---
 Doc/library/sys.rst  |  8 +++++++
 Misc/NEWS            |  5 +++++
 Objects/fileobject.c |  2 +-
 Python/pythonrun.c   | 61 +++++++++++++++++++++++++++++++++++++++++-----------
 4 files changed, 63 insertions(+), 13 deletions(-)

diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 6f1aaff..94e4eb9 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -513,6 +513,13 @@ always available.
    could be useful to restore the actual files to known working file objects in
    case they have been overwritten with a broken object.
 
+  .. note::
+
+    Under some conditions ``stdin``, ``stdout`` and ``stderr`` as well as the
+    original values ``__stdin__``, ``__stdout__`` and ``__stderr__`` can be
+    None. It is usually the case for Windows GUI apps that aren't connected to
+    a console and Python apps started with :program:`pythonw`.
+
 
 .. data:: tracebacklimit
 
@@ -571,3 +578,4 @@ always available.
    Module :mod:`site`
       This describes how to use .pth files to extend ``sys.path``.
 
+
diff --git a/Misc/NEWS b/Misc/NEWS
index c79b531..f68ac90 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -34,6 +34,11 @@ Core and Builtins
 - Added a new option -b to issues warnings (-bb for errors) about certain
   operations between bytes/buffer and str like str(b'') and comparsion.
 
+- The standards streams sys.stdin, stdout and stderr may be None when the
+  when the C runtime library returns an invalid file descriptor for the
+  streams (fileno(stdin) < 0). For now this happens only for Windows GUI
+  apps and scripts started with `pythonw.exe`.
+
 Extension Modules
 -----------------
 
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 6d6022e..5d69911 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -363,7 +363,7 @@ PyFile_NewStdPrinter(int fd)
 {
 	PyStdPrinter_Object *self;
 
-	if ((fd != fileno(stdout) && fd != fileno(stderr)) || fd < 0) {
+	if (fd != fileno(stdout) && fd != fileno(stderr)) {
 		/* not enough infrastructure for PyErr_BadInternalCall() */
 		return NULL;
 	}
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 0b3935a..82f8e37 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -717,7 +717,7 @@ initstdio(void)
 	PyObject *bimod = NULL;
 	PyObject *m;
 	PyObject *std = NULL;
-	int status = 0;
+	int status = 0, fd;
 
 	/* Hack to avoid a nasty recursion issue when Python is invoked
 	   in verbose mode: pre-import the Latin-1 and UTF-8 codecs */
@@ -748,35 +748,72 @@ initstdio(void)
 	}
 
 	/* Set sys.stdin */
-	if (!(std = PyFile_FromFd(fileno(stdin), "<stdin>", "r", -1,
-				  NULL, "\n", 0))) {
+	fd = fileno(stdin);
+	/* Under some conditions stdin, stdout and stderr may not be connected
+	 * and fileno() may point to an invalid file descriptor. For example
+	 * GUI apps don't have valid standard streams by default.
+	 */
+	if (fd < 0) {
+#ifdef MS_WINDOWS
+		std = Py_None;
+		Py_INCREF(std);
+#else
 		goto error;
+#endif
 	}
+	else {
+		if (!(std = PyFile_FromFd(fd, "<stdin>", "r", -1, NULL, 
+					  "\n", 0))) {
+			goto error;
+		}
+	} /* if (fd < 0) */
 	PySys_SetObject("__stdin__", std);
 	PySys_SetObject("stdin", std);
 	Py_DECREF(std);
 
 	/* Set sys.stdout */
-	if (!(std = PyFile_FromFd(fileno(stdout), "<stdout>", "w", -1,
-				  NULL, "\n", 0))) {
-            goto error;
-        }
+	fd = fileno(stdout);
+	if (fd < 0) {
+#ifdef MS_WINDOWS
+		std = Py_None;
+		Py_INCREF(std);
+#else
+		goto error;
+#endif
+	}
+	else {
+		if (!(std = PyFile_FromFd(fd, "<stdout>", "w", -1, NULL, 
+					  "\n", 0))) {
+			goto error;
+		}
+	} /* if (fd < 0) */
 	PySys_SetObject("__stdout__", std);
 	PySys_SetObject("stdout", std);
 	Py_DECREF(std);
 
 #if 1 /* Disable this if you have trouble debugging bootstrap stuff */
 	/* Set sys.stderr, replaces the preliminary stderr */
-	if (!(std = PyFile_FromFd(fileno(stderr), "<stderr>", "w", -1,
-				  NULL, "\n", 0))) {
-            goto error;
-        }
+	fd = fileno(stderr);
+	if (fd < 0) {
+#ifdef MS_WINDOWS
+		std = Py_None;
+		Py_INCREF(std);
+#else
+		goto error;
+#endif
+	}
+	else {
+		if (!(std = PyFile_FromFd(fd, "<stderr>", "w", -1, NULL, 
+					  "\n", 0))) {
+			goto error;
+		}
+	} /* if (fd < 0) */
         PySys_SetObject("__stderr__", std);
 	PySys_SetObject("stderr", std);
 	Py_DECREF(std);
 #endif
 
-        if (0) {
+	if (0) {
   error:
                 status = -1;
         }
-- 
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