third-party/folly/src/folly/python/error.cpp

   1 /*
   2  * Copyright (c) Meta Platforms, Inc. and affiliates.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <folly/python/error.h>
  18
  19 #include <stdexcept>
  20 #include <string>
  21
  22 #include <Python.h>
  23
  24 #include <folly/Conv.h>
  25 #include <folly/ScopeGuard.h>
  26
  27 namespace folly {
  28 namespace python {
  29 namespace {
  30 // Best effort c-api implementation of repr(obj)
  31 std::string pyObjectToString(PyObject* obj) {
  32   constexpr StringPiece kConversionFail = "Error conversion failed";
  33   PyObject *pyStr, *pyBytes;
  34   SCOPE_EXIT {
  35     Py_XDECREF(pyStr);
  36     Py_XDECREF(pyBytes);
  37     // Swallow any errors that arise in this function
  38     PyErr_Clear();
  39   };
  40
  41   pyStr = PyObject_Repr(obj);
  42   if (pyStr == nullptr) {
  43     return std::string(kConversionFail);
  44   }
  45
  46   char* cStr = nullptr;
  47 #if PY_VERSION_HEX < 0x0300000
  48   cStr = PyString_AsString(pyStr);
  49 #else
  50   pyBytes = PyUnicode_AsEncodedString(pyStr, "utf-8", "strict");
  51   if (pyBytes == nullptr) {
  52     return std::string(kConversionFail);
  53   }
  54
  55   cStr = PyBytes_AsString(pyBytes);
  56 #endif
  57
  58   if (cStr == nullptr) {
  59     return std::string(kConversionFail);
  60   }
  61
  62   return std::string(cStr);
  63 }
  64
  65 } // namespace
  66
  67 void handlePythonError(StringPiece errPrefix) {
  68   PyObject *ptype, *pvalue, *ptraceback;
  69   SCOPE_EXIT {
  70     Py_XDECREF(ptype);
  71     Py_XDECREF(pvalue);
  72     Py_XDECREF(ptraceback);
  73   };
  74   /**
  75    * PyErr_Fetch will clear the error indicator (which *should* be set here, but
  76    * let's not assume it is)
  77    */
  78   PyErr_Fetch(&ptype, &pvalue, &ptraceback);
  79
  80   if (ptype == nullptr) {
  81     throw std::runtime_error(
  82         to<std::string>(errPrefix, "No error indicator set"));
  83   }
  84
  85   if (pvalue == nullptr) {
  86     throw std::runtime_error(to<std::string>(
  87         errPrefix, "Exception of type: ", pyObjectToString(ptype)));
  88   }
  89
  90   throw std::runtime_error(
  91       to<std::string>(errPrefix, pyObjectToString(pvalue)));
  92 }
  93 } // namespace python
  94 } // namespace folly