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gh-150836: Mount embedded Tk ZIP in _tkinter on Windows #151562

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Merged
zooba merged 3 commits into from
Jun 19, 2026
+61 −3
Merged

gh-150836: Mount embedded Tk ZIP in _tkinter on Windows #151562

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6b57a35
gh-150836: Mount embedded Tk ZIP in _tkinter on Windows
jjhelmus Jun 16, 2026
baaa534
Support long paths when mounting the embedded Tk ZIP
jjhelmus Jun 18, 2026
0c268a6
Clarify expected Tk ZIP mount failures
jjhelmus Jun 18, 2026
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Windows/2026-06-04-18-53-18.gh-issue-150836.Wci7bZ.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Make installed tkinter work with Tcl/Tk 9 builds that embed the Tk script library in the Tk DLL on Windows.
59 changes: 57 additions & 2 deletions Modules/_tkinter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,10 @@ Copyright (C) 1994 Steen Lumholt.
# include <tk.h>
#endif

#if defined(MS_WINDOWS) && TK_MAJOR_VERSION >= 9
# include <tkPlatDecls.h>
#endif

#include "tkinter.h"

#if TK_HEX_VERSION < 0x0805020c
Expand Down Expand Up @@ -175,6 +179,57 @@ _get_tcl_lib_path(void)
}
#endif /* MS_WINDOWS */

#if defined(MS_WINDOWS) && TK_MAJOR_VERSION >= 9
static void
mount_tk_dll_zip(void)
{
HINSTANCE tk_module = Tk_GetHINSTANCE();
wchar_t *tk_path = NULL;
DWORD path_len = 0;
for (DWORD buffer_len = 256;
tk_path == NULL && buffer_len < (1024 * 1024);
buffer_len *= 2)
{
tk_path = (wchar_t *)PyMem_RawMalloc(
buffer_len * sizeof(*tk_path));
if (tk_path != NULL) {
path_len = GetModuleFileNameW(tk_module, tk_path, buffer_len);
if (path_len == buffer_len) {
PyMem_RawFree(tk_path);
tk_path = NULL;
}
}
}

if (tk_path == NULL || path_len == 0) {
PyMem_RawFree(tk_path);
return;
}

Tcl_DString utf8_path;

Tcl_DStringInit(&utf8_path);
Tcl_WCharToUtfDString(tk_path, path_len, &utf8_path);
/* Failure is harmless if the DLL has no embedded ZIP or if another
interpreter has already mounted it. */
(void) TclZipfs_Mount(NULL, Tcl_DStringValue(&utf8_path),
"//zipfs:/lib/tk", NULL);

@zooba zooba Jun 17, 2026

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I assume this handles re-mounting without an issue? It seems like it could be called multiple times by someone's code.

@jjhelmus jjhelmus Jun 18, 2026

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Calling TclZipfs_Mount on an existing mount leaves the original untouched but does raise an error. Since this call passes a null interpreter this error is discarded. Trying to mount a DLL without an embedded Zip also results in a discarded error.
I added a comment about the failures here being harmless.

Tcl_DStringFree(&utf8_path);
PyMem_RawFree(tk_path);
}
#endif

int
Tkinter_TkInit(Tcl_Interp *interp)
{
#if defined(MS_WINDOWS) && TK_MAJOR_VERSION >= 9
/* Tcl/Tk 9 may embed the tk_library in the Tk DLL which tcl_findLibrary
does not search. Mount the DLL using Zipfs if possible. */
mount_tk_dll_zip();
#endif
return Tk_Init(interp);
}

/* The threading situation is complicated. Tcl is not thread-safe, except
when configured with --enable-threads.

Expand Down Expand Up @@ -544,7 +599,7 @@ Tcl_AppInit(Tcl_Interp *interp)
return TCL_OK;
}

if (Tk_Init(interp) == TCL_ERROR) {
if (Tkinter_TkInit(interp) == TCL_ERROR) {
PySys_WriteStderr("Tk_Init error: %s\n", Tcl_GetStringResult(interp));
return TCL_ERROR;
}
Expand Down Expand Up @@ -2988,7 +3043,7 @@ _tkinter_tkapp_loadtk_impl(TkappObject *self)
return NULL;
}
if (_tk_exists == NULL || strcmp(_tk_exists, "1") != 0) {
if (Tk_Init(interp) == TCL_ERROR) {
if (Tkinter_TkInit(interp) == TCL_ERROR) {
Tkinter_Error(self);
return NULL;
}
Expand Down
2 changes: 1 addition & 1 deletion Modules/tkappinit.c
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Expand Up @@ -37,7 +37,7 @@ Tcl_AppInit(Tcl_Interp *interp)
return TCL_OK;
}

if (Tk_Init(interp) == TCL_ERROR) {
if (Tkinter_TkInit(interp) == TCL_ERROR) {
return TCL_ERROR;
}

Expand Down
2 changes: 2 additions & 0 deletions Modules/tkinter.h
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Expand Up @@ -16,4 +16,6 @@
(TK_RELEASE_LEVEL << 8) | \
(TK_RELEASE_SERIAL << 0))

int Tkinter_TkInit(Tcl_Interp *interp);

#endif /* !TKINTER_H */
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