src/python-importer.cpp

   1 /***************************************
   2 ** Tsunagari Tile Engine              **
   3 ** python-importer.cpp                **
   4 ** Copyright 2011-2013 PariahSoft LLC **
   5 ***************************************/
   6
   7 // **********
   8 // Permission is hereby granted, free of charge, to any person obtaining a copy
   9 // of this software and associated documentation files (the "Software"), to
  10 // deal in the Software without restriction, including without limitation the
  11 // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  12 // sell copies of the Software, and to permit persons to whom the Software is
  13 // furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in
  16 // all copies or substantial portions of the Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  24 // IN THE SOFTWARE.
  25 // **********
  26
  27
  28 #include <Python.h>
  29
  30 #include "formatter.h"
  31 #include "log.h"
  32 #include "reader.h"
  33 #include "python-importer.h"
  34
  35
  36 //! List of known safe Python modules allowed for importing.
  37 static const char* module_whitelist[] = {
  38         "__builtin__",
  39         "__main__",
  40         "math",
  41         "traceback",
  42         NULL
  43 };
  44
  45 static bool wi_in_whitelist(const char* name)
  46 {
  47         for (int i = 0; module_whitelist[i]; i++)
  48                 if (!strcmp(name, module_whitelist[i]))
  49                         return true;
  50         return false;
  51 }
  52
  53 static PyObject* wi_find_module(PyObject* /*self*/, PyObject* args)
  54 {
  55         PyObject* fullname = NULL;
  56         PyObject* path = NULL; // dummy
  57
  58         if (!PyArg_UnpackTuple(args, "find_module", 1, 2, &fullname, &path)) {
  59                 // exc already set
  60                 return NULL;
  61         }
  62         if (!PyString_Check(fullname)) {
  63                 PyErr_Format(PyExc_TypeError, "expected string, got %.200s",
  64                                 fullname->ob_type->tp_name);
  65                 return NULL;
  66         }
  67
  68         const char* dotname = PyString_AsString(fullname); // "foo.bar"
  69         std::string slashname(dotname); // "foo/bar.py"
  70         std::replace(slashname.begin(), slashname.end(), '.', '/');
  71
  72         Log::info("PyWorldImporter", Formatter("%: requested") % dotname);
  73
  74         // Returning Py_None allows the import to continue. NULL stops it.
  75         if (wi_in_whitelist(dotname)) {
  76                 Py_INCREF(Py_None);
  77                 return Py_None;
  78         }
  79         else if (Reader::directoryExists(slashname) && Reader::fileExists(slashname + "/__init__.py")) {
  80                 Py_INCREF(Py_None);
  81                 return Py_None;
  82         }
  83         else if (Reader::resourceExists(slashname + ".py")) {
  84                 Py_INCREF(Py_None);
  85                 return Py_None;
  86         }
  87         else {
  88                 PyErr_Format(PyExc_ImportError, "No module name %.200s", dotname);
  89                 return NULL;
  90         }
  91 }
  92
  93 typedef struct {
  94         PyObject_HEAD
  95 } worldimporterobject;
  96
  97 static PyMethodDef pyworldimporter_methods[] = {
  98         {"find_module", (PyCFunction)wi_find_module, METH_VARARGS, NULL},
  99         {NULL, NULL, 0, NULL},
 100 };
 101
 102 static bool initted = false;
 103 static PyTypeObject worldimporter_type = {
 104         PyObject_HEAD_INIT(&PyType_Type)
 105 };
 106
 107 static bool wi_init_type()
 108 {
 109         if (!initted) {
 110                 initted = false;
 111
 112                 worldimporter_type.tp_name = "worldimporter";
 113                 worldimporter_type.tp_basicsize = sizeof(worldimporterobject);
 114                 worldimporter_type.tp_getattro = PyObject_GenericGetAttr;
 115                 worldimporter_type.tp_flags = Py_TPFLAGS_DEFAULT;
 116                 worldimporter_type.tp_methods = pyworldimporter_methods;
 117
 118                 if (PyType_Ready(&worldimporter_type) < 0) {
 119                         Py_FatalError("Can't initialize worldimporter type");
 120                         return false;
 121                 }
 122         }
 123         return true;
 124 }
 125
 126 static PyObject* wi_worldimporter_new()
 127 {
 128         wi_init_type();
 129         return (PyObject*)PyObject_New(worldimporterobject, &worldimporter_type);
 130 }
 131
 132
 133 /** Public functions **/
 134
 135 bool pythonImporterInstall()
 136 {
 137         PyObject* meta_path = NULL;
 138         PyObject* importer = NULL;
 139         int idx = -1;
 140
 141         /* meta_path is a borrowed reference; no decref */
 142         meta_path = PySys_GetObject((char*)"meta_path");
 143         if (meta_path == NULL || !PyList_Check(meta_path)) {
 144                 Log::fatal("Python Importer",
 145                         "sys.meta_path must be a list of import hooks");
 146                 goto err;
 147         }
 148
 149         importer = wi_worldimporter_new();
 150         if (importer == NULL) {
 151                 Log::fatal("Python Importer",
 152                         "failed to create PyWorldImporter object");
 153                 goto err;
 154         }
 155
 156         idx = PyList_Append(meta_path, importer);
 157         if (idx == -1) {
 158                 Log::fatal("Python Importer", "failed to append to sys.meta_path");
 159                 goto err;
 160         }
 161
 162         Py_DECREF(importer);
 163         return true;
 164
 165 err:
 166         Py_XDECREF(importer);
 167         return false;
 168 }
 169