Issue #13374: The Windows bytes API has been deprecated in the os module. Use
Unicode filenames instead of bytes filenames to not depend on the ANSI code
page anymore and to support any filename.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 26fc25f..9012e39 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -546,6 +546,34 @@
 
     return TRUE;
 }
+
+static int
+win32_warn_bytes_api()
+{
+    return PyErr_WarnEx(PyExc_DeprecationWarning,
+        "The Windows bytes API has been deprecated, "
+        "use Unicode filenames instead",
+        1);
+}
+
+static PyObject*
+win32_decode_filename(PyObject *obj)
+{
+    PyObject *unicode;
+    if (PyUnicode_Check(obj)) {
+        if (PyUnicode_READY(obj))
+            return NULL;
+        Py_INCREF(obj);
+        return obj;
+    }
+    if (!PyUnicode_FSDecoder(obj, &unicode))
+        return NULL;
+    if (win32_warn_bytes_api()) {
+        Py_DECREF(unicode);
+        return NULL;
+    }
+    return unicode;
+}
 #endif /* MS_WINDOWS */
 
 /* Return a dictionary corresponding to the POSIX environment table */
@@ -725,22 +753,6 @@
         return PyErr_SetFromWindowsErr(errno);
 }
 
-static int
-convert_to_unicode(PyObject **param)
-{
-    if (PyUnicode_CheckExact(*param))
-        Py_INCREF(*param);
-    else if (PyUnicode_Check(*param))
-        /* For a Unicode subtype that's not a Unicode object,
-           return a true Unicode object with the same data. */
-        *param = PyUnicode_Copy(*param);
-    else
-        *param = PyUnicode_FromEncodedObject(*param,
-                                             Py_FileSystemDefaultEncoding,
-                                             "strict");
-    return (*param) != NULL;
-}
-
 #endif /* MS_WINDOWS */
 
 #if defined(PYOS_OS2)
@@ -895,7 +907,7 @@
            char* wformat, BOOL (__stdcall *funcW)(LPWSTR))
 {
     PyObject *uni;
-    char *ansi;
+    const char *ansi;
     BOOL result;
 
     if (PyArg_ParseTuple(args, wformat, &uni))
@@ -915,6 +927,8 @@
 
     if (!PyArg_ParseTuple(args, format, &ansi))
         return NULL;
+    if (win32_warn_bytes_api())
+        return NULL;
     Py_BEGIN_ALLOW_THREADS
     result = funcA(ansi);
     Py_END_ALLOW_THREADS
@@ -1129,14 +1143,15 @@
 
 /* Grab GetFinalPathNameByHandle dynamically from kernel32 */
 static int has_GetFinalPathNameByHandle = 0;
-static DWORD (CALLBACK *Py_GetFinalPathNameByHandleA)(HANDLE, LPSTR, DWORD,
-                                                      DWORD);
 static DWORD (CALLBACK *Py_GetFinalPathNameByHandleW)(HANDLE, LPWSTR, DWORD,
                                                       DWORD);
 static int
 check_GetFinalPathNameByHandle()
 {
     HINSTANCE hKernel32;
+    DWORD (CALLBACK *Py_GetFinalPathNameByHandleA)(HANDLE, LPSTR, DWORD,
+                                                   DWORD);
+
     /* only recheck */
     if (!has_GetFinalPathNameByHandle)
     {
@@ -1853,6 +1868,12 @@
     if (!PyArg_ParseTuple(args, format,
                           PyUnicode_FSConverter, &opath))
         return NULL;
+#ifdef MS_WINDOWS
+    if (win32_warn_bytes_api()) {
+        Py_DECREF(opath);
+        return NULL;
+    }
+#endif
     path = PyBytes_AsString(opath);
     Py_BEGIN_ALLOW_THREADS
     res = (*statfunc)(path, &st);
@@ -1885,8 +1906,7 @@
 static PyObject *
 posix_access(PyObject *self, PyObject *args)
 {
-    PyObject *opath;
-    char *path;
+    const char *path;
     int mode;
 
 #ifdef MS_WINDOWS
@@ -1904,14 +1924,13 @@
     /* Drop the argument parsing error as narrow strings
        are also valid. */
     PyErr_Clear();
-    if (!PyArg_ParseTuple(args, "O&i:access",
-                          PyUnicode_FSConverter, &opath, &mode))
+    if (!PyArg_ParseTuple(args, "yi:access", &path, &mode))
         return NULL;
-    path = PyBytes_AsString(opath);
+    if (win32_warn_bytes_api())
+        return NULL;
     Py_BEGIN_ALLOW_THREADS
     attr = GetFileAttributesA(path);
     Py_END_ALLOW_THREADS
-    Py_DECREF(opath);
 finish:
     if (attr == 0xFFFFFFFF)
         /* File does not exist, or cannot read attributes */
@@ -1923,6 +1942,7 @@
                            || !(attr & FILE_ATTRIBUTE_READONLY)
                            || (attr & FILE_ATTRIBUTE_DIRECTORY));
 #else
+    PyObject *opath;
     int res;
     if (!PyArg_ParseTuple(args, "O&i:access",
                           PyUnicode_FSConverter, &opath, &mode))
@@ -2042,7 +2062,7 @@
 posix_chmod(PyObject *self, PyObject *args)
 {
     PyObject *opath = NULL;
-    char *path = NULL;
+    const char *path = NULL;
     int i;
     int res;
 #ifdef MS_WINDOWS
@@ -2073,10 +2093,10 @@
        are also valid. */
     PyErr_Clear();
 
-    if (!PyArg_ParseTuple(args, "O&i:chmod", PyUnicode_FSConverter,
-                          &opath, &i))
+    if (!PyArg_ParseTuple(args, "yi:chmod", &path, &i))
         return NULL;
-    path = PyBytes_AsString(opath);
+    if (win32_warn_bytes_api())
+        return NULL;
     Py_BEGIN_ALLOW_THREADS
     attr = GetFileAttributesA(path);
     if (attr != 0xFFFFFFFF) {
@@ -2091,10 +2111,8 @@
     Py_END_ALLOW_THREADS
     if (!res) {
         win32_error("chmod", path);
-        Py_DECREF(opath);
         return NULL;
     }
-    Py_DECREF(opath);
     Py_INCREF(Py_None);
     return Py_None;
 #else /* MS_WINDOWS */
@@ -2450,51 +2468,56 @@
 static PyObject *
 win32_link(PyObject *self, PyObject *args)
 {
-    PyObject *osrc, *odst;
-    char *src, *dst;
-    BOOL rslt;
-    PyObject *usrc, *udst;
+    PyObject *src, *dst;
+    BOOL ok;
 
-    if (PyArg_ParseTuple(args, "UU:link", &usrc, &udst))
+    if (PyArg_ParseTuple(args, "UU:link", &src, &dst))
     {
         wchar_t *wsrc, *wdst;
-        wsrc = PyUnicode_AsUnicode(usrc);
+
+        wsrc = PyUnicode_AsUnicode(src);
         if (wsrc == NULL)
-            return NULL;
-        wdst = PyUnicode_AsUnicode(udst);
+            goto error;
+        wdst = PyUnicode_AsUnicode(dst);
         if (wdst == NULL)
-            return NULL;
+            goto error;
 
         Py_BEGIN_ALLOW_THREADS
-        rslt = CreateHardLinkW(wdst, wsrc, NULL);
+        ok = CreateHardLinkW(wdst, wsrc, NULL);
         Py_END_ALLOW_THREADS
 
-        if (rslt == 0)
+        if (!ok)
             return win32_error("link", NULL);
-
         Py_RETURN_NONE;
     }
+    else {
+        PyErr_Clear();
+        if (!PyArg_ParseTuple(args, "O&O&:link",
+                              PyUnicode_FSConverter, &src,
+                              PyUnicode_FSConverter, &dst))
+            return NULL;
 
-    /* Narrow strings also valid. */
-    PyErr_Clear();
+        if (win32_warn_bytes_api())
+            goto error;
 
-    if (!PyArg_ParseTuple(args, "O&O&:link", PyUnicode_FSConverter, &osrc,
-                          PyUnicode_FSConverter, &odst))
+        Py_BEGIN_ALLOW_THREADS
+        ok = CreateHardLinkA(PyBytes_AS_STRING(dst),
+                             PyBytes_AS_STRING(src),
+                             NULL);
+        Py_END_ALLOW_THREADS
+
+        Py_XDECREF(src);
+        Py_XDECREF(dst);
+
+        if (!ok)
+            return win32_error("link", NULL);
+        Py_RETURN_NONE;
+
+    error:
+        Py_XDECREF(src);
+        Py_XDECREF(dst);
         return NULL;
-
-    src = PyBytes_AsString(osrc);
-    dst = PyBytes_AsString(odst);
-
-    Py_BEGIN_ALLOW_THREADS
-    rslt = CreateHardLinkA(dst, src, NULL);
-    Py_END_ALLOW_THREADS
-
-    Py_DECREF(osrc);
-    Py_DECREF(odst);
-    if (rslt == 0)
-        return win32_error("link", NULL);
-
-    Py_RETURN_NONE;
+    }
 }
 #endif /* MS_WINDOWS */
 
@@ -2519,7 +2542,8 @@
     HANDLE hFindFile;
     BOOL result;
     WIN32_FIND_DATA FileData;
-    PyObject *opath;
+    const char *path;
+    Py_ssize_t pathlen;
     char namebuf[MAX_PATH+5]; /* Overallocate for \\*.*\0 */
     char *bufptr = namebuf;
     Py_ssize_t len = sizeof(namebuf)-5; /* only claim to have space for MAX_PATH */
@@ -2613,17 +2637,16 @@
        are also valid. */
     PyErr_Clear();
 
-    if (!PyArg_ParseTuple(args, "O&:listdir",
-                          PyUnicode_FSConverter, &opath))
+    if (!PyArg_ParseTuple(args, "y#:listdir", &path, &pathlen))
         return NULL;
-    if (PyBytes_GET_SIZE(opath)+1 > MAX_PATH) {
+    if (win32_warn_bytes_api())
+        return NULL;
+    if (pathlen+1 > MAX_PATH) {
         PyErr_SetString(PyExc_ValueError, "path too long");
-        Py_DECREF(opath);
         return NULL;
     }
-    strcpy(namebuf, PyBytes_AsString(opath));
-    len = PyObject_Size(opath);
-    Py_DECREF(opath);
+    strcpy(namebuf, path);
+    len = pathlen;
     if (len > 0) {
         char ch = namebuf[len-1];
         if (ch != SEP && ch != ALTSEP && ch != ':')
@@ -2915,11 +2938,9 @@
 static PyObject *
 posix__getfullpathname(PyObject *self, PyObject *args)
 {
-    PyObject *opath;
-    char *path;
+    const char *path;
     char outbuf[MAX_PATH*2];
     char *temp;
-#ifdef MS_WINDOWS
     PyObject *po;
 
     if (PyArg_ParseTuple(args, "U|:_getfullpathname", &po))
@@ -2953,19 +2974,17 @@
     /* Drop the argument parsing error as narrow strings
        are also valid. */
     PyErr_Clear();
-#endif
 
-    if (!PyArg_ParseTuple (args, "O&:_getfullpathname",
-                           PyUnicode_FSConverter, &opath))
+    if (!PyArg_ParseTuple (args, "y:_getfullpathname",
+                           &path))
         return NULL;
-    path = PyBytes_AsString(opath);
+    if (win32_warn_bytes_api())
+        return NULL;
     if (!GetFullPathName(path, Py_ARRAY_LENGTH(outbuf),
                          outbuf, &temp)) {
         win32_error("GetFullPathName", path);
-        Py_DECREF(opath);
         return NULL;
     }
-    Py_DECREF(opath);
     if (PyUnicode_Check(PyTuple_GetItem(args, 0))) {
         return PyUnicode_Decode(outbuf, strlen(outbuf),
                                 Py_FileSystemDefaultEncoding, NULL);
@@ -3069,8 +3088,7 @@
 static PyObject *
 posix__isdir(PyObject *self, PyObject *args)
 {
-    PyObject *opath;
-    char *path;
+    const char *path;
     PyObject *po;
     DWORD attributes;
 
@@ -3088,11 +3106,10 @@
        are also valid. */
     PyErr_Clear();
 
-    if (!PyArg_ParseTuple(args, "O&:_isdir",
-                          PyUnicode_FSConverter, &opath))
+    if (!PyArg_ParseTuple(args, "y:_isdir", &path))
         return NULL;
-
-    path = PyBytes_AsString(opath);
+    if (win32_warn_bytes_api())
+        return NULL;
     attributes = GetFileAttributesA(path);
     if (attributes == INVALID_FILE_ATTRIBUTES)
         Py_RETURN_FALSE;
@@ -3113,8 +3130,7 @@
 posix_mkdir(PyObject *self, PyObject *args)
 {
     int res;
-    PyObject *opath;
-    char *path;
+    const char *path;
     int mode = 0777;
 
 #ifdef MS_WINDOWS
@@ -3136,22 +3152,21 @@
     /* Drop the argument parsing error as narrow strings
        are also valid. */
     PyErr_Clear();
-    if (!PyArg_ParseTuple(args, "O&|i:mkdir",
-                          PyUnicode_FSConverter, &opath, &mode))
+    if (!PyArg_ParseTuple(args, "y|i:mkdir", &path, &mode))
         return NULL;
-    path = PyBytes_AsString(opath);
+    if (win32_warn_bytes_api())
+        return NULL;
     Py_BEGIN_ALLOW_THREADS
     res = CreateDirectoryA(path, NULL);
     Py_END_ALLOW_THREADS
     if (!res) {
         win32_error("mkdir", path);
-        Py_DECREF(opath);
         return NULL;
     }
-    Py_DECREF(opath);
     Py_INCREF(Py_None);
     return Py_None;
 #else
+    PyObject *opath;
 
     if (!PyArg_ParseTuple(args, "O&|i:mkdir",
                           PyUnicode_FSConverter, &opath, &mode))
@@ -3265,44 +3280,54 @@
 posix_rename(PyObject *self, PyObject *args)
 {
 #ifdef MS_WINDOWS
-    PyObject *o1, *o2;
-    wchar_t *w1, *w2;
-    char *p1, *p2;
+    PyObject *src, *dst;
     BOOL result;
-    if (!PyArg_ParseTuple(args, "OO:rename", &o1, &o2))
-        goto error;
-    if (!convert_to_unicode(&o1))
-        goto error;
-    if (!convert_to_unicode(&o2)) {
-        Py_DECREF(o1);
-        goto error;
+    if (PyArg_ParseTuple(args, "UU:rename", &src, &dst))
+    {
+        wchar_t *wsrc, *wdst;
+
+        wsrc = PyUnicode_AsUnicode(src);
+        if (wsrc == NULL)
+            return NULL;
+        wdst = PyUnicode_AsUnicode(dst);
+        if (wdst == NULL)
+            return NULL;
+        Py_BEGIN_ALLOW_THREADS
+        result = MoveFileW(wsrc, wdst);
+        Py_END_ALLOW_THREADS
+        if (!result)
+            return win32_error("rename", NULL);
+        Py_INCREF(Py_None);
+        return Py_None;
     }
-    w1 = PyUnicode_AsUnicode(o1);
-    if (w1 == NULL)
-        goto error;
-    w2 = PyUnicode_AsUnicode(o2);
-    if (w2 == NULL)
-        goto error;
-    Py_BEGIN_ALLOW_THREADS
-    result = MoveFileW(w1, w2);
-    Py_END_ALLOW_THREADS
-    Py_DECREF(o1);
-    Py_DECREF(o2);
-    if (!result)
-        return win32_error("rename", NULL);
-    Py_INCREF(Py_None);
-    return Py_None;
+    else {
+        PyErr_Clear();
+        if (!PyArg_ParseTuple(args, "O&O&:rename",
+                              PyUnicode_FSConverter, &src,
+                              PyUnicode_FSConverter, &dst))
+            return NULL;
+
+        if (win32_warn_bytes_api())
+            goto error;
+
+        Py_BEGIN_ALLOW_THREADS
+        result = MoveFileA(PyBytes_AS_STRING(src),
+                           PyBytes_AS_STRING(dst));
+        Py_END_ALLOW_THREADS
+
+        Py_XDECREF(src);
+        Py_XDECREF(dst);
+
+        if (!result)
+            return win32_error("rename", NULL);
+        Py_INCREF(Py_None);
+        return Py_None;
+
 error:
-    PyErr_Clear();
-    if (!PyArg_ParseTuple(args, "ss:rename", &p1, &p2))
+        Py_XDECREF(src);
+        Py_XDECREF(dst);
         return NULL;
-    Py_BEGIN_ALLOW_THREADS
-    result = MoveFileA(p1, p2);
-    Py_END_ALLOW_THREADS
-    if (!result)
-        return win32_error("rename", NULL);
-    Py_INCREF(Py_None);
-    return Py_None;
+    }
 #else
     return posix_2str(args, "O&O&:rename", rename);
 #endif
@@ -3546,8 +3571,7 @@
     PyObject *arg = Py_None;
     PyObject *obwpath;
     wchar_t *wpath = NULL;
-    PyObject *oapath;
-    char *apath;
+    const char *apath;
     HANDLE hFile;
     time_t atimesec, mtimesec;
     long ausec, musec;
@@ -3571,11 +3595,11 @@
            are also valid. */
         PyErr_Clear();
 
-        if (!PyArg_ParseTuple(args, "O&|O:utime",
-                        PyUnicode_FSConverter, &oapath, &arg))
+        if (!PyArg_ParseTuple(args, "y|O:utime", &apath, &arg))
+            return NULL;
+        if (win32_warn_bytes_api())
             return NULL;
 
-        apath = PyBytes_AsString(oapath);
         Py_BEGIN_ALLOW_THREADS
         hFile = CreateFileA(apath, FILE_WRITE_ATTRIBUTES, 0,
                             NULL, OPEN_EXISTING,
@@ -3583,10 +3607,8 @@
         Py_END_ALLOW_THREADS
         if (hFile == INVALID_HANDLE_VALUE) {
             win32_error("utime", apath);
-            Py_DECREF(oapath);
             return NULL;
         }
-        Py_DECREF(oapath);
     }
 
     if (arg == Py_None) {
@@ -6516,7 +6538,8 @@
 win_symlink(PyObject *self, PyObject *args, PyObject *kwargs)
 {
     static char *kwlist[] = {"src", "dest", "target_is_directory", NULL};
-    PyObject *src, *dest;
+    PyObject *osrc, *odest;
+    PyObject *usrc = NULL, *udest = NULL;
     wchar_t *wsrc, *wdest;
     int target_is_directory = 0;
     DWORD res;
@@ -6528,24 +6551,25 @@
         return PyErr_Format(PyExc_NotImplementedError,
             "CreateSymbolicLinkW not found");
     }
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "OO|i:symlink",
-        kwlist, &src, &dest, &target_is_directory))
+    if (!PyArg_ParseTupleAndKeywords(
+            args, kwargs, "OO|i:symlink", kwlist,
+            &osrc, &odest, &target_is_directory))
         return NULL;
 
+    usrc = win32_decode_filename(osrc);
+    if (!usrc)
+        return NULL;
+    udest = win32_decode_filename(odest);
+    if (!udest)
+        goto error;
+
     if (win32_can_symlink == 0)
         return PyErr_Format(PyExc_OSError, "symbolic link privilege not held");
 
-    if (!convert_to_unicode(&src))
-        return NULL;
-    if (!convert_to_unicode(&dest)) {
-        Py_DECREF(src);
-        return NULL;
-    }
-
-    wsrc = PyUnicode_AsUnicode(src);
+    wsrc = PyUnicode_AsUnicode(usrc);
     if (wsrc == NULL)
         goto error;
-    wdest = PyUnicode_AsUnicode(dest);
+    wdest = PyUnicode_AsUnicode(udest);
     if (wsrc == NULL)
         goto error;
 
@@ -6563,17 +6587,17 @@
     res = Py_CreateSymbolicLinkW(wdest, wsrc, target_is_directory);
     Py_END_ALLOW_THREADS
 
-    Py_DECREF(src);
-    Py_DECREF(dest);
+    Py_DECREF(usrc);
+    Py_DECREF(udest);
     if (!res)
-        return win32_error_object("symlink", src);
+        return win32_error_object("symlink", osrc);
 
     Py_INCREF(Py_None);
     return Py_None;
 
 error:
-    Py_DECREF(src);
-    Py_DECREF(dest);
+    Py_XDECREF(usrc);
+    Py_XDECREF(udest);
     return NULL;
 }
 #endif /* defined(HAVE_SYMLINK) && defined(MS_WINDOWS) */
@@ -6791,6 +6815,12 @@
                           PyUnicode_FSConverter, &ofile,
                           &flag, &mode))
         return NULL;
+#ifdef MS_WINDOWS
+    if (win32_warn_bytes_api()) {
+        Py_DECREF(ofile);
+        return NULL;
+    }
+#endif
     file = PyBytes_AsString(ofile);
     Py_BEGIN_ALLOW_THREADS
     fd = open(file, flag, mode);
@@ -9290,6 +9320,10 @@
                           PyUnicode_FSConverter, &ofilepath,
                           &operation))
         return NULL;
+    if (win32_warn_bytes_api()) {
+        Py_DECREF(ofilepath);
+        return NULL;
+    }
     filepath = PyBytes_AsString(ofilepath);
     Py_BEGIN_ALLOW_THREADS
     rc = ShellExecute((HWND)0, operation, filepath,