RF: find TCL / Tk symbols correctly on Windows

matthew-brett · matthew-brett · commit 830d7a36894c · 2016-05-19T15:46:23.000-04:00
As Christoph G found, we can't use the tkinter extension module to find the TCL / Tk symbols on Windows, because Windows DLLs do not return the addresses of symbols they import from GetProcAddress. Instead, iterate through the modules loaded in the current process to find the TCL and Tk symbols. See: * https://msdn.microsoft.com/en-us/library/windows/desktop/ms682621(v=vs.85).aspx * https://msdn.microsoft.com/en-us/library/windows/desktop/ms683179(v=vs.85).aspx
diff --git a/setupext.py b/setupext.py
@@ -1732,6 +1732,8 @@ def add_flags(self, ext):
                     ext.include_dirs.extend(['win32_static/include/tcl85'])
                 else:
                     ext.include_dirs.extend(['win32_static/include/tcl86'])
+            # PSAPI library needed for finding TCL / Tk at run time
+            ext.libraries.extend(['psapi'])
 
         elif sys.platform == 'darwin':
             # this config section lifted directly from Imaging - thanks to
diff --git a/src/_tkagg.cpp b/src/_tkagg.cpp
@@ -252,8 +252,119 @@ static PyMethodDef functions[] = {
     { NULL, NULL } /* sentinel */
 };
 
-// Functions to fill global TCL / Tk function pointers from tkinter module.
+// Functions to fill global TCL / Tk function pointers by dynamic loading
+#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
 
+/*
+ * On Windows, we can't load the tkinter module to get the TCL or Tk symbols,
+ * because Windows does not load symbols into the library name-space of
+ * importing modules. So, knowing that tkinter has already been imported by
+ * Python, we scan all modules in the running process for the TCL and Tk
+ * function names.
+ */
+#include <windows.h>
+#define PSAPI_VERSION 1
+#include <psapi.h>
+// Must be linked with 'psapi' library
+
+FARPROC _dfunc(HMODULE lib_handle, const char *func_name)
+{
+    // Load function `func_name` from `lib_handle`.
+    // Set Python exception if we can't find `func_name` in `lib_handle`.
+    // Returns function pointer or NULL if not present.
+
+    char message[100];
+
+    FARPROC func = GetProcAddress(lib_handle, func_name);
+    if (func == NULL) {
+        sprintf(message, "Cannot load function %s", func_name);
+        PyErr_SetString(PyExc_RuntimeError, message);
+    }
+    return func;
+}
+
+int get_tcl(HMODULE hMod)
+{
+    // Try to fill TCL global vars with function pointers. Return 0 for no
+    // functions found, 1 for all functions found, -1 for some but not all
+    // functions found.
+    TCL_CREATE_COMMAND = (tcl_cc) GetProcAddress(hMod, "Tcl_CreateCommand");
+    if (TCL_CREATE_COMMAND == NULL) {  // Maybe not TCL module
+        return 0;
+    }
+    TCL_APPEND_RESULT = (tcl_app_res) _dfunc(hMod, "Tcl_AppendResult");
+    return (TCL_APPEND_RESULT == NULL) ? -1 : 1;
+}
+
+int get_tk(HMODULE hMod)
+{
+    // Try to fill Tk global vars with function pointers. Return 0 for no
+    // functions found, 1 for all functions found, -1 for some but not all
+    // functions found.
+    TK_MAIN_WINDOW = (tk_mw) GetProcAddress(hMod, "Tk_MainWindow");
+    if (TK_MAIN_WINDOW == NULL) {  // Maybe not Tk module
+        return 0;
+    }
+    TK_FIND_PHOTO = (tk_fp) _dfunc(hMod, "Tk_FindPhoto");
+    TK_PHOTO_PUTBLOCK = (tk_ppb_nc) _dfunc(hMod,
+            "Tk_PhotoPutBlock_NoComposite");
+    TK_PHOTO_BLANK = (tk_pb) _dfunc(hMod, "Tk_PhotoBlank");
+    return ((TK_FIND_PHOTO == NULL) ||
+            (TK_PHOTO_PUTBLOCK == NULL) ||
+            (TK_PHOTO_BLANK == NULL)) ? -1 : 1;
+}
+
+int load_tkinter_funcs(void)
+{
+    // Load TCL and Tk functions by searching all modules in current process.
+    // Return 0 for success, non-zero for failure.
+
+    HMODULE hMods[1024];
+    HANDLE hProcess;
+    DWORD cbNeeded;
+    unsigned int i;
+    int found_tcl = 0;
+    int found_tk = 0;
+
+    // Returns pseudo-handle that does not need to be closed
+    hProcess = GetCurrentProcess();
+
+    // Iterate through modules in this process looking for TCL / Tk names
+    if (EnumProcessModules(hProcess, hMods, sizeof(hMods), &cbNeeded)) {
+        for (i = 0; i < (cbNeeded / sizeof(HMODULE)); i++) {
+            if (!found_tcl) {
+                found_tcl = get_tcl(hMods[i]);
+                if (found_tcl == -1) {
+                    return 1;
+                }
+            }
+            if (!found_tk) {
+                found_tk = get_tk(hMods[i]);
+                if (found_tk == -1) {
+                    return 1;
+                }
+            }
+            if (found_tcl && found_tk) {
+                return 0;
+            }
+        }
+    }
+
+    if (found_tcl == 0) {
+        PyErr_SetString(PyExc_RuntimeError, "Could not find TCL routines");
+    } else {
+        PyErr_SetString(PyExc_RuntimeError, "Could not find Tk routines");
+    }
+    return 1;
+}
+
+#else  // not Windows
+
+/*
+ * On Unix, we can get the TCL and Tk synbols from the tkinter module, because
+ * tkinter uses these symbols, and the symbols are therefore visible in the
+ * tkinter dynamic library (module).
+ */
 #if PY3K
 #define TKINTER_PKG "tkinter"
 #define TKINTER_MOD "_tkinter"
@@ -273,31 +384,8 @@ char *fname2char(PyObject *fname)
 #define fname2char(s) (PyString_AsString(s))
 #endif
 
-#if defined(_MSC_VER)
-#include <windows.h>
-#define LIB_PTR_TYPE HMODULE
-#define LOAD_LIB(name) LoadLibrary(name)
-#define CLOSE_LIB(name) FreeLibrary(name)
-FARPROC _dfunc(LIB_PTR_TYPE lib_handle, const char *func_name)
-{
-    // Load function `func_name` from `lib_handle`.
-    // Set Python exception if we can't find `func_name` in `lib_handle`.
-    // Returns function pointer or NULL if not present.
-
-    char message[100];
-
-    FARPROC func = GetProcAddress(lib_handle, func_name);
-    if (func == NULL) {
-        sprintf(message, "Cannot load function %s", func_name);
-        PyErr_SetString(PyExc_RuntimeError, message);
-    }
-    return func;
-}
-#else
 #include <dlfcn.h>
-#define LIB_PTR_TYPE void*
-#define LOAD_LIB(name) dlopen(name, RTLD_LAZY)
-#define CLOSE_LIB(name) dlclose(name)
+
 void *_dfunc(void *lib_handle, const char *func_name)
 {
     // Load function `func_name` from `lib_handle`.
@@ -313,9 +401,8 @@ void *_dfunc(void *lib_handle, const char *func_name)
     }
     return func;
 }
-#endif
 
-int _func_loader(LIB_PTR_TYPE lib)
+int _func_loader(void *lib)
 {
     // Fill global function pointers from dynamic lib.
     // Return 1 if any pointer is NULL, 0 otherwise.
@@ -339,7 +426,7 @@ int load_tkinter_funcs(void)
     // Load tkinter global funcs from tkinter compiled module.
     // Return 0 for success, non-zero for failure.
     int ret = -1;
-    LIB_PTR_TYPE tkinter_lib;
+    void *tkinter_lib;
     char *tkinter_libname;
     PyObject *pModule = NULL, *pSubmodule = NULL, *pString = NULL;
 
@@ -359,21 +446,22 @@ int load_tkinter_funcs(void)
     if (tkinter_libname == NULL) {
         goto exit;
     }
-    tkinter_lib = LOAD_LIB(tkinter_libname);
+    tkinter_lib = dlopen(tkinter_libname, RTLD_LAZY);
     if (tkinter_lib == NULL) {
         PyErr_SetString(PyExc_RuntimeError,
                 "Cannot dlopen tkinter module file");
         goto exit;
     }
     ret = _func_loader(tkinter_lib);
     // dlclose probably safe because tkinter has been imported.
-    CLOSE_LIB(tkinter_lib);
+    dlclose(tkinter_lib);
 exit:
     Py_XDECREF(pModule);
     Py_XDECREF(pSubmodule);
     Py_XDECREF(pString);
     return ret;
 }
+#endif // end not Windows
 
 #if PY3K
 static PyModuleDef _tkagg_module = { PyModuleDef_HEAD_INIT, "_tkagg", "",   -1,  functions,
