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Simplify tkagg C extension. #10936

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Merged
merged 1 commit into from
Jul 15, 2018
Merged

Simplify tkagg C extension. #10936

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116 changes: 38 additions & 78 deletions src/_tkagg.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ static int PyAggImagePhoto(ClientData clientdata, Tcl_Interp *interp, int
}
/* get buffer from str which is "height width ptr" */
if (sscanf(argv[2], IMG_FORMAT, &hdata, &wdata, &pdata) != 3) {
TCL_APPEND_RESULT(interp,
TCL_APPEND_RESULT(interp,
"error reading data, expected height width ptr",
(char *)NULL);
return TCL_ERROR;
Expand Down Expand Up @@ -291,8 +291,7 @@ int get_tcl(HMODULE hMod)
if (TCL_CREATE_COMMAND == NULL) { // Maybe not TCL module
return 0;
}
TCL_APPEND_RESULT = (Tcl_AppendResult_t) _dfunc(hMod,
"Tcl_AppendResult");
TCL_APPEND_RESULT = (Tcl_AppendResult_t) _dfunc(hMod, "Tcl_AppendResult");
return (TCL_APPEND_RESULT == NULL) ? -1 : 1;
}

Expand All @@ -306,20 +305,20 @@ int get_tk(HMODULE hMod)
if (TK_MAIN_WINDOW == NULL) { // Maybe not Tk module
return 0;
}
return ( // -1 if any remaining symbols are NULL
return // -1 if any remaining symbols are NULL
((TK_FIND_PHOTO = (Tk_FindPhoto_t)
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I think it would be clearer if these were a bunch of separate ifs instead of this long chained thing (if every assignment fit on one line, that would also be clearer.)

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That'll be much simpler to do after #10680 is merged and we later get to remove the old version of the API. Then the only functions we'll have to load are Tk_FindPhoto and Tk_PhotoPutBlock_NoComposite, which also means that the Windows and non-Windows versions will only need to differ by how they call _dfunc.
Not convinced it's worth changing for now.

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Just to be clear, the endgame is to just do (e.g.)

void *_dfunc(void *lib_handle, const char *func_name);

int _func_loader(void *lib)
{
    // Fill global function pointers from dynamic lib.
    // Return number of successfully loaded functions.
    #define LOAD_TK(name) tk::name = Tk_##name##_t(_dfunc(lib, "Tk_" #name))
    return bool(LOAD_TK(FindPhoto)) + bool(LOAD_TK(PhotoPutBlock_NoComposite));
    #undef LOAD_TK
}

followed by OS-specific versions of _dfunc.

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#10680 is merged now.

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But the old API is still around (the simplification will only come after matplotlib.backends.tkagg is completely removed).

_dfunc(hMod, "Tk_FindPhoto")) == NULL) ||
((TK_PHOTO_PUT_BLOCK_NO_COMPOSITE = (Tk_PhotoPutBlock_NoComposite_t)
_dfunc(hMod, "Tk_PhotoPutBlock_NoComposite")) == NULL) ||
((TK_PHOTO_BLANK = (Tk_PhotoBlank_t)
_dfunc(hMod, "Tk_PhotoBlank")) == NULL))
_dfunc(hMod, "Tk_PhotoBlank")) == NULL)
? -1 : 1;
}

int load_tkinter_funcs(void)
void load_tkinter_funcs(void)
{
// Load TCL and Tk functions by searching all modules in current process.
// Return 0 for success, non-zero for failure.
// Sets an error on failure.

HMODULE hMods[1024];
HANDLE hProcess;
Expand All @@ -337,17 +336,17 @@ int load_tkinter_funcs(void)
if (!found_tcl) {
found_tcl = get_tcl(hMods[i]);
if (found_tcl == -1) {
return 1;
return;
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What error is set here instead?

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good catch... fixed.

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Actually no, there is indeed an error being set by _dfunc()

void *_dfunc(void *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.

    void* func;
    // Reset errors.
    dlerror();
    func = dlsym(lib_handle, func_name);
    if (func == NULL) {
        PyErr_SetString(PyExc_RuntimeError, dlerror());  // here
    }
    return func;
}

(and similarly on Windows).

Left the original version as is.

}
}
if (!found_tk) {
found_tk = get_tk(hMods[i]);
if (found_tk == -1) {
return 1;
return;
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Or here?

}
}
if (found_tcl && found_tk) {
return 0;
return;
}
}
}
Expand All @@ -357,7 +356,7 @@ int load_tkinter_funcs(void)
} else {
PyErr_SetString(PyExc_RuntimeError, "Could not find Tk routines");
}
return 1;
return;
}

#else // not Windows
Expand All @@ -367,16 +366,6 @@ int load_tkinter_funcs(void)
* tkinter uses these symbols, and the symbols are therefore visible in the
* tkinter dynamic library (module).
*/
// From module __file__ attribute to char *string for dlopen.
char *fname2char(PyObject *fname)
{
PyObject* bytes;
bytes = PyUnicode_EncodeFSDefault(fname);
if (bytes == NULL) {
return NULL;
}
return PyBytes_AsString(bytes);
}

#include <dlfcn.h>

Expand All @@ -391,8 +380,7 @@ void *_dfunc(void *lib_handle, const char *func_name)
dlerror();
func = dlsym(lib_handle, func_name);
if (func == NULL) {
const char *error = dlerror();
PyErr_SetString(PyExc_RuntimeError, error);
PyErr_SetString(PyExc_RuntimeError, dlerror());
}
return func;
}
Expand All @@ -401,7 +389,7 @@ int _func_loader(void *lib)
{
// Fill global function pointers from dynamic lib.
// Return 1 if any pointer is NULL, 0 otherwise.
return (
return
((TCL_CREATE_COMMAND = (Tcl_CreateCommand_t)
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Same split up here, probably.

_dfunc(lib, "Tcl_CreateCommand")) == NULL) ||
((TCL_APPEND_RESULT = (Tcl_AppendResult_t)
Expand All @@ -413,75 +401,50 @@ int _func_loader(void *lib)
((TK_PHOTO_PUT_BLOCK_NO_COMPOSITE = (Tk_PhotoPutBlock_NoComposite_t)
_dfunc(lib, "Tk_PhotoPutBlock_NoComposite")) == NULL) ||
((TK_PHOTO_BLANK = (Tk_PhotoBlank_t)
_dfunc(lib, "Tk_PhotoBlank")) == NULL));
_dfunc(lib, "Tk_PhotoBlank")) == NULL);
}

int load_tkinter_funcs(void)
void load_tkinter_funcs(void)
{
// Load tkinter global funcs from tkinter compiled module.
// Return 0 for success, non-zero for failure.
int ret = -1;
// Sets an error on failure.
void *main_program, *tkinter_lib;
char *tkinter_libname;
PyObject *pModule = NULL, *pSubmodule = NULL, *pString = NULL;
PyObject *module = NULL, *py_path = NULL, *py_path_b = NULL;
char *path;

// Try loading from the main program namespace first
// Try loading from the main program namespace first.
main_program = dlopen(NULL, RTLD_LAZY);
if (_func_loader(main_program) == 0) {
return 0;
goto exit;
}
// Clear exception triggered when we didn't find symbols above.
PyErr_Clear();

// Now try finding the tkinter compiled module
pModule = PyImport_ImportModule("tkinter");
if (pModule == NULL) {
goto exit;
}
pSubmodule = PyObject_GetAttrString(pModule, "_tkinter");
if (pSubmodule == NULL) {
goto exit;
// Handle PyPy first, as that import will correctly fail on CPython.
module = PyImport_ImportModule("_tkinter.tklib_cffi"); // PyPy
if (!module) {
PyErr_Clear();
module = PyImport_ImportModule("_tkinter"); // CPython
}
pString = PyObject_GetAttrString(pSubmodule, "__file__");
if (pString == NULL) {
if (!(module &&
(py_path = PyObject_GetAttrString(module, "__file__")) &&
(py_path_b = PyUnicode_EncodeFSDefault(py_path)) &&
(path = PyBytes_AsString(py_path_b)))) {
goto exit;
}
tkinter_libname = fname2char(pString);
if (tkinter_libname == NULL) {
tkinter_lib = dlopen(path, RTLD_LAZY);
if (!tkinter_lib) {
PyErr_SetString(PyExc_RuntimeError, dlerror());
goto exit;
}
tkinter_lib = dlopen(tkinter_libname, RTLD_LAZY);
if (tkinter_lib == NULL) {
/* Perhaps it is a cffi module, like in PyPy? */
pString = PyObject_GetAttrString(pSubmodule, "tklib_cffi");
if (pString == NULL) {
goto fail;
}
pString = PyObject_GetAttrString(pString, "__file__");
if (pString == NULL) {
goto fail;
}
tkinter_libname = fname2char(pString);
if (tkinter_libname == NULL) {
goto fail;
}
tkinter_lib = dlopen(tkinter_libname, RTLD_LAZY);
}
if (tkinter_lib == NULL) {
goto fail;
}
ret = _func_loader(tkinter_lib);
// dlclose probably safe because tkinter has been imported.
_func_loader(tkinter_lib);
// dlclose is safe because tkinter has been imported.
dlclose(tkinter_lib);
goto exit;
fail:
PyErr_SetString(PyExc_RuntimeError,
"Cannot dlopen tkinter module file");
exit:
Py_XDECREF(pModule);
Py_XDECREF(pSubmodule);
Py_XDECREF(pString);
return ret;
Py_XDECREF(module);
Py_XDECREF(py_path);
Py_XDECREF(py_path_b);
}
#endif // end not Windows

Expand All @@ -491,9 +454,6 @@ static PyModuleDef _tkagg_module = {

PyMODINIT_FUNC PyInit__tkagg(void)
{
PyObject *m;

m = PyModule_Create(&_tkagg_module);

return (load_tkinter_funcs() == 0) ? m : NULL;
load_tkinter_funcs();
return PyErr_Occurred() ? NULL : PyModule_Create(&_tkagg_module);
}