Backport trunk revision 53527:

SF patch #1630975: Fix crash when replacing sys.stdout in sitecustomize

When running the interpreter in an environment that would cause it to set
stdout/stderr/stdin's encoding, having a sitecustomize that would replace
them with something other than PyFile objects would crash the interpreter.
Fix it by simply ignoring the encoding-setting for non-files.

This could do with a test, but I can think of no maintainable and portable
way to test this bug, short of adding a sitecustomize.py to the buildsystem
and have it always run with it (hmmm....)

4 files changed, 13 insertions, 6 deletions

diff --git a/Misc/NEWS b/Misc/NEWS
index 9876af9..f30f50b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@ What's New in Python 2.5.1c1?
 Core and builtins
 -----------------
 
+- patch #1630975: Fix crash when replacing sys.stdout in sitecustomize.py
+
 - Bug #1637022: Prefix AST symbols with _Py_.
 
 - Prevent seg fault on shutdown which could occur if an object
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index ced0768..869ded9 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -354,6 +354,8 @@ PyFile_SetEncoding(PyObject *f, const char *enc)
 {
 	PyFileObject *file = (PyFileObject*)f;
 	PyObject *str = PyString_FromString(enc);
+
+	assert(PyFile_Check(f));
 	if (!str)
 		return 0;
 	Py_DECREF(file->f_encoding);
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index e8f4fa2..e83c4cb 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -275,7 +275,8 @@ Py_InitializeEx(int install_sigs)
 		sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
 		if (!sys_isatty)
 			PyErr_Clear();
-		if(sys_isatty && PyObject_IsTrue(sys_isatty)) {
+		if(sys_isatty && PyObject_IsTrue(sys_isatty) &&
+		   PyFile_Check(sys_stream)) {
 			if (!PyFile_SetEncoding(sys_stream, codeset))
 				Py_FatalError("Cannot set codeset of stdin");
 		}
@@ -285,7 +286,8 @@ Py_InitializeEx(int install_sigs)
 		sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
 		if (!sys_isatty)
 			PyErr_Clear();
-		if(sys_isatty && PyObject_IsTrue(sys_isatty)) {
+		if(sys_isatty && PyObject_IsTrue(sys_isatty) &&
+		   PyFile_Check(sys_stream)) {
 			if (!PyFile_SetEncoding(sys_stream, codeset))
 				Py_FatalError("Cannot set codeset of stdout");
 		}
@@ -295,7 +297,8 @@ Py_InitializeEx(int install_sigs)
 		sys_isatty = PyObject_CallMethod(sys_stream, "isatty", "");
 		if (!sys_isatty)
 			PyErr_Clear();
-		if(sys_isatty && PyObject_IsTrue(sys_isatty)) {
+		if(sys_isatty && PyObject_IsTrue(sys_isatty) &&
+		   PyFile_Check(sys_stream)) {
 			if (!PyFile_SetEncoding(sys_stream, codeset))
 				Py_FatalError("Cannot set codeset of stderr");
 		}
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 4970adf..59f6cfc 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1087,17 +1087,17 @@ _PySys_Init(void)
 	if (PyErr_Occurred())
 		return NULL;
 #ifdef MS_WINDOWS
-	if(isatty(_fileno(stdin))){
+	if(isatty(_fileno(stdin)) && PyFile_Check(sysin)) {
 		sprintf(buf, "cp%d", GetConsoleCP());
 		if (!PyFile_SetEncoding(sysin, buf))
 			return NULL;
 	}
-	if(isatty(_fileno(stdout))) {
+	if(isatty(_fileno(stdout)) && PyFile_Check(sysout)) {
 		sprintf(buf, "cp%d", GetConsoleOutputCP());
 		if (!PyFile_SetEncoding(sysout, buf))
 			return NULL;
 	}
-	if(isatty(_fileno(stderr))) {
+	if(isatty(_fileno(stderr)) && PyFile_Check(syserr)) {
 		sprintf(buf, "cp%d", GetConsoleOutputCP());
 		if (!PyFile_SetEncoding(syserr, buf))
 			return NULL;