text: /*
   * This file is part of the MicroPython project, http://micropython.org/
   *
   * The MIT License (MIT)
   *
   * Copyright (c) 2013, 2014 Damien P. George
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #include <string.h>
  #include <stdarg.h>
  #include <assert.h>
  #include <stdio.h>
  
  #include "py/objlist.h"
  #include "py/objnamedtuple.h"
  #include "py/objstr.h"
  #include "py/objtuple.h"
  #include "py/objtype.h"
  #include "py/runtime.h"
  #include "py/gc.h"
  #include "py/mperrno.h"
  
  #include "supervisor/shared/translate.h"
  
  // Number of items per traceback entry (file, line, block)
  #define TRACEBACK_ENTRY_LEN (3)
  
  // Number of traceback entries to reserve in the emergency exception buffer
  #define EMG_TRACEBACK_ALLOC (2 * TRACEBACK_ENTRY_LEN)
  
  // Optionally allocated buffer for storing the first argument of an exception
  // allocated when the heap is locked.
  #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
  #   if MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE > 0
  #define mp_emergency_exception_buf_size MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE
  
  void mp_init_emergency_exception_buf(void) {
      // Nothing to do since the buffer was declared statically. We put this
      // definition here so that the calling code can call this function
      // regardless of how its configured (makes the calling code a bit cleaner).
  }
  
  #else
  #define mp_emergency_exception_buf_size MP_STATE_VM(mp_emergency_exception_buf_size)
  
  void mp_init_emergency_exception_buf(void) {
      mp_emergency_exception_buf_size = 0;
      MP_STATE_VM(mp_emergency_exception_buf) = NULL;
  }
  
  mp_obj_t mp_alloc_emergency_exception_buf(mp_obj_t size_in) {
      mp_int_t size = mp_obj_get_int(size_in);
      void *buf = NULL;
      if (size > 0) {
          buf = m_new(byte, size);
      }
  
      int old_size = mp_emergency_exception_buf_size;
      void *old_buf = MP_STATE_VM(mp_emergency_exception_buf);
  
      // Update the 2 variables atomically so that an interrupt can't occur
      // between the assignments.
      mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
      mp_emergency_exception_buf_size = size;
      MP_STATE_VM(mp_emergency_exception_buf) = buf;
      MICROPY_END_ATOMIC_SECTION(atomic_state);
  
      if (old_buf != NULL) {
          m_del(byte, old_buf, old_size);
      }
      return mp_const_none;
  }
  #endif
  #endif  // MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
  
  // Instance of GeneratorExit exception - needed by generator.close()
  // This would belong to objgenerator.c, but to keep mp_obj_exception_t
  // definition module-private so far, have it here.
  const mp_obj_exception_t mp_const_GeneratorExit_obj = {{&mp_type_GeneratorExit}, 0, 0, NULL, (mp_obj_tuple_t*)&mp_const_empty_tuple_obj};
  
  void mp_obj_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
      mp_obj_exception_t *o = MP_OBJ_TO_PTR(o_in);
      mp_print_kind_t k = kind & ~PRINT_EXC_SUBCLASS;
      bool is_subclass = kind & PRINT_EXC_SUBCLASS;
      if (!is_subclass && (k == PRINT_REPR || k == PRINT_EXC)) {
          mp_print_str(print, qstr_str(o->base.type->name));
      }
  
      if (k == PRINT_EXC) {
          mp_print_str(print, ": ");
      }
  
      if (k == PRINT_STR || k == PRINT_EXC) {
          if (o->args == NULL || o->args->len == 0) {
              mp_print_str(print, "");
              return;
          }
          if (MP_OBJ_IS_SMALL_INT(o->args->items[0]) &&
              mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(o->base.type), MP_OBJ_FROM_PTR(&mp_type_OSError)) &&
              o->args->len <= 2) {
              // try to provide a nice OSError error message
              char decompressed[50];
              const char *msg = mp_common_errno_to_str(o->args->items[0], decompressed, sizeof(decompressed));
              if (msg != NULL) {
                  mp_printf(print, "[Errno " INT_FMT "] %s", MP_OBJ_SMALL_INT_VALUE(o->args->items[0]), msg);
                  // if second arg exists, it is filename.
                  if (o->args->len == 2) {
                      mp_printf(print, ": '%s'", mp_obj_str_get_str(o->args->items[1]));
                  }
                  return;
              }
          }
          if (o->args->len == 1) {
              mp_obj_print_helper(print, o->args->items[0], PRINT_STR);
              return;
          }
      }
      mp_obj_tuple_print(print, MP_OBJ_FROM_PTR(o->args), kind);
  }
  
  mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type, size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
      mp_arg_check_num(n_args, kw_args, 0, MP_OBJ_FUN_ARGS_MAX, false);
  
      // Try to allocate memory for the exception, with fallback to emergency exception object
      mp_obj_exception_t *o_exc = m_new_obj_maybe(mp_obj_exception_t);
      if (o_exc == NULL) {
          o_exc = &MP_STATE_VM(mp_emergency_exception_obj);
      }
  
      // Populate the exception object
      o_exc->base.type = type;
      o_exc->traceback_data = NULL;
  
      mp_obj_tuple_t *o_tuple;
      if (n_args == 0) {
          // No args, can use the empty tuple straightaway
          o_tuple = (mp_obj_tuple_t*)&mp_const_empty_tuple_obj;
      } else {
          // Try to allocate memory for the tuple containing the args
          o_tuple = m_new_obj_var_maybe(mp_obj_tuple_t, mp_obj_t, n_args);
  
          #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
          // If we are called by mp_obj_new_exception_msg_varg then it will have
          // reserved room (after the traceback data) for a tuple with 1 element.
          // Otherwise we are free to use the whole buffer after the traceback data.
          if (o_tuple == NULL && mp_emergency_exception_buf_size >=
              EMG_TRACEBACK_ALLOC * sizeof(size_t) + sizeof(mp_obj_tuple_t) + n_args * sizeof(mp_obj_t)) {
              o_tuple = (mp_obj_tuple_t*)
                  ((uint8_t*)MP_STATE_VM(mp_emergency_exception_buf) + EMG_TRACEBACK_ALLOC * sizeof(size_t));
          }
          #endif
  
          if (o_tuple == NULL) {
              // No memory for a tuple, fallback to an empty tuple
              o_tuple = (mp_obj_tuple_t*)&mp_const_empty_tuple_obj;
          } else {
              // Have memory for a tuple so populate it
              o_tuple->base.type = &mp_type_tuple;
              o_tuple->len = n_args;
              memcpy(o_tuple->items, args, n_args * sizeof(mp_obj_t));
          }
      }
  
      // Store the tuple of args in the exception object
      o_exc->args = o_tuple;
  
      return MP_OBJ_FROM_PTR(o_exc);
  }
  
  // Get exception "value" - that is, first argument, or None
  mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in) {
      mp_obj_exception_t *self = MP_OBJ_TO_PTR(self_in);
      if (self->args->len == 0) {
          return mp_const_none;
      } else {
          return self->args->items[0];
      }
  }
  
  void mp_obj_exception_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
      mp_obj_exception_t *self = MP_OBJ_TO_PTR(self_in);
      if (dest[0] != MP_OBJ_NULL) {
          // store/delete attribute
          if (attr == MP_QSTR___traceback__ && dest[1] == mp_const_none) {
              // We allow 'exc.__traceback__ = None' assignment as low-level
              // optimization of pre-allocating exception instance and raising
              // it repeatedly - this avoids memory allocation during raise.
              // However, uPy will keep adding traceback entries to such
              // exception instance, so before throwing it, traceback should
              // be cleared like above.
              self->traceback_len = 0;
              dest[0] = MP_OBJ_NULL; // indicate success
          }
          return;
      }
      if (attr == MP_QSTR_args) {
          dest[0] = MP_OBJ_FROM_PTR(self->args);
      } else if (self->base.type == &mp_type_StopIteration && attr == MP_QSTR_value) {
          dest[0] = mp_obj_exception_get_value(self_in);
      #if MICROPY_CPYTHON_COMPAT
      } else if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(self->base.type), MP_OBJ_FROM_PTR(&mp_type_OSError))) {
          if (attr == MP_QSTR_errno) {
              dest[0] = mp_obj_exception_get_value(self_in);
          } else if (attr == MP_QSTR_strerror) {
              if (self->args->len > 1) {
                  dest[0] = self->args->items[1];
              } else if (self->args->len > 0) {
                  char decompressed[50];
                  const char *msg = mp_common_errno_to_str(self->args->items[0], decompressed, sizeof(decompressed));
                  if (msg != NULL) {
                      dest[0] = mp_obj_new_str(msg, strlen(msg));
                  } else {
                      dest[0] = mp_const_none;
                  }
              } else {
                  dest[0] = mp_const_none;
              }
          } else if (attr == MP_QSTR_filename) {
              dest[0] = self->args->len > 2 ? self->args->items[2] : mp_const_none;
          // skip winerror
          } else if (attr == MP_QSTR_filename2) {
              dest[0] = self->args->len > 4 ? self->args->items[4] : mp_const_none;
          }
      #endif
      }
  }
  
  const mp_obj_type_t mp_type_BaseException = {
      { &mp_type_type },
      .name = MP_QSTR_BaseException,
      .print = mp_obj_exception_print,
      .make_new = mp_obj_exception_make_new,
      .attr = mp_obj_exception_attr,
  };
  
  // List of all exceptions, arranged as in the table at:
  // http://docs.python.org/3/library/exceptions.html
  MP_DEFINE_EXCEPTION(SystemExit, BaseException)
  MP_DEFINE_EXCEPTION(KeyboardInterrupt, BaseException)
  MP_DEFINE_EXCEPTION(ReloadException, BaseException)
  MP_DEFINE_EXCEPTION(GeneratorExit, BaseException)
  MP_DEFINE_EXCEPTION(Exception, BaseException)
    #if MICROPY_PY_ASYNC_AWAIT
    MP_DEFINE_EXCEPTION(StopAsyncIteration, Exception)
    #endif
    MP_DEFINE_EXCEPTION(StopIteration, Exception)
    MP_DEFINE_EXCEPTION(ArithmeticError, Exception)
      //MP_DEFINE_EXCEPTION(FloatingPointError, ArithmeticError)
      MP_DEFINE_EXCEPTION(OverflowError, ArithmeticError)
      MP_DEFINE_EXCEPTION(ZeroDivisionError, ArithmeticError)
    MP_DEFINE_EXCEPTION(AssertionError, Exception)
    MP_DEFINE_EXCEPTION(AttributeError, Exception)
    //MP_DEFINE_EXCEPTION(BufferError, Exception)
    //MP_DEFINE_EXCEPTION(EnvironmentError, Exception) use OSError instead
    MP_DEFINE_EXCEPTION(EOFError, Exception)
    MP_DEFINE_EXCEPTION(ImportError, Exception)
    //MP_DEFINE_EXCEPTION(IOError, Exception) use OSError instead
    MP_DEFINE_EXCEPTION(LookupError, Exception)
      MP_DEFINE_EXCEPTION(IndexError, LookupError)
      MP_DEFINE_EXCEPTION(KeyError, LookupError)
    MP_DEFINE_EXCEPTION(MemoryError, Exception)
    MP_DEFINE_EXCEPTION(NameError, Exception)
      /*
      MP_DEFINE_EXCEPTION(UnboundLocalError, NameError)
      */
    MP_DEFINE_EXCEPTION(OSError, Exception)
    MP_DEFINE_EXCEPTION(TimeoutError, OSError)
      /*
      MP_DEFINE_EXCEPTION(BlockingIOError, OSError)
      MP_DEFINE_EXCEPTION(ChildProcessError, OSError)
      MP_DEFINE_EXCEPTION(ConnectionError, OSError)
        MP_DEFINE_EXCEPTION(BrokenPipeError, ConnectionError)
        MP_DEFINE_EXCEPTION(ConnectionAbortedError, ConnectionError)
        MP_DEFINE_EXCEPTION(ConnectionRefusedError, ConnectionError)
        MP_DEFINE_EXCEPTION(ConnectionResetError, ConnectionError)
      MP_DEFINE_EXCEPTION(InterruptedError, OSError)
      MP_DEFINE_EXCEPTION(IsADirectoryError, OSError)
      MP_DEFINE_EXCEPTION(NotADirectoryError, OSError)
      MP_DEFINE_EXCEPTION(PermissionError, OSError)
      MP_DEFINE_EXCEPTION(ProcessLookupError, OSError)
      MP_DEFINE_EXCEPTION(FileExistsError, OSError)
      MP_DEFINE_EXCEPTION(FileNotFoundError, OSError)
      MP_DEFINE_EXCEPTION(ReferenceError, Exception)
      */
    MP_DEFINE_EXCEPTION(RuntimeError, Exception)
      MP_DEFINE_EXCEPTION(NotImplementedError, RuntimeError)
    MP_DEFINE_EXCEPTION(SyntaxError, Exception)
      MP_DEFINE_EXCEPTION(IndentationError, SyntaxError)
      /*
        MP_DEFINE_EXCEPTION(TabError, IndentationError)
        */
    //MP_DEFINE_EXCEPTION(SystemError, Exception)
    MP_DEFINE_EXCEPTION(TypeError, Exception)
  #if MICROPY_EMIT_NATIVE
      MP_DEFINE_EXCEPTION(ViperTypeError, TypeError)
  #endif
    MP_DEFINE_EXCEPTION(ValueError, Exception)
  #if MICROPY_PY_BUILTINS_STR_UNICODE
      MP_DEFINE_EXCEPTION(UnicodeError, ValueError)
      //TODO: Implement more UnicodeError subclasses which take arguments
  #endif
      MP_DEFINE_EXCEPTION(MpyError, ValueError)
    /*
    MP_DEFINE_EXCEPTION(Warning, Exception)
      MP_DEFINE_EXCEPTION(DeprecationWarning, Warning)
      MP_DEFINE_EXCEPTION(PendingDeprecationWarning, Warning)
      MP_DEFINE_EXCEPTION(RuntimeWarning, Warning)
      MP_DEFINE_EXCEPTION(SyntaxWarning, Warning)
      MP_DEFINE_EXCEPTION(UserWarning, Warning)
      MP_DEFINE_EXCEPTION(FutureWarning, Warning)
      MP_DEFINE_EXCEPTION(ImportWarning, Warning)
      MP_DEFINE_EXCEPTION(UnicodeWarning, Warning)
      MP_DEFINE_EXCEPTION(BytesWarning, Warning)
      MP_DEFINE_EXCEPTION(ResourceWarning, Warning)
      */
  
  mp_obj_t mp_obj_new_exception(const mp_obj_type_t *exc_type) {
      return mp_obj_new_exception_args(exc_type, 0, NULL);
  }
  
  // "Optimized" version for common(?) case of having 1 exception arg
  mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg) {
      return mp_obj_new_exception_args(exc_type, 1, &arg);
  }
  
  mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, size_t n_args, const mp_obj_t *args) {
      assert(exc_type->make_new == mp_obj_exception_make_new);
      return exc_type->make_new(exc_type, n_args, args, NULL);
  }
  
  mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const compressed_string_t *msg) {
      return mp_obj_new_exception_msg_varg(exc_type, msg);
  }
  
  // The following struct and function implement a simple printer that conservatively
  // allocates memory and truncates the output data if no more memory can be obtained.
  // It leaves room for a null byte at the end of the buffer.
  
  struct _exc_printer_t {
      bool allow_realloc;
      size_t alloc;
      size_t len;
      byte *buf;
  };
  
  STATIC void exc_add_strn(void *data, const char *str, size_t len) {
      struct _exc_printer_t *pr = data;
      if (pr->len + len >= pr->alloc) {
          // Not enough room for data plus a null byte so try to grow the buffer
          if (pr->allow_realloc) {
              size_t new_alloc = pr->alloc + len + 16;
              byte *new_buf = m_renew_maybe(byte, pr->buf, pr->alloc, new_alloc, true);
              if (new_buf == NULL) {
                  pr->allow_realloc = false;
                  len = pr->alloc - pr->len - 1;
              } else {
                  pr->alloc = new_alloc;
                  pr->buf = new_buf;
              }
          } else {
              len = pr->alloc - pr->len - 1;
          }
      }
      memcpy(pr->buf + pr->len, str, len);
      pr->len += len;
  }
  
  
  mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const compressed_string_t *fmt, ...) {
      va_list ap;
      va_start(ap, fmt);
      mp_obj_t exception = mp_obj_new_exception_msg_vlist(exc_type, fmt, ap);
      va_end(ap);
      return exception;
  }
  
  mp_obj_t mp_obj_new_exception_msg_vlist(const mp_obj_type_t *exc_type, const compressed_string_t *fmt, va_list ap) {
      assert(fmt != NULL);
  
      // Check that the given type is an exception type
      assert(exc_type->make_new == mp_obj_exception_make_new);
  
      // Try to allocate memory for the message
      mp_obj_str_t *o_str = m_new_obj_maybe(mp_obj_str_t);
      size_t o_str_alloc = fmt->length + 1;
      byte *o_str_buf = m_new_maybe(byte, o_str_alloc);
  
      bool used_emg_buf = false;
      #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
      // If memory allocation failed and there is an emergency buffer then try to use
      // that buffer to store the string object and its data (at least 16 bytes for
      // the string data), reserving room at the start for the traceback and 1-tuple.
      if ((o_str == NULL || o_str_buf == NULL)
          && mp_emergency_exception_buf_size >= EMG_TRACEBACK_ALLOC * sizeof(size_t)
              + sizeof(mp_obj_tuple_t) + sizeof(mp_obj_t) + sizeof(mp_obj_str_t) + 16) {
          used_emg_buf = true;
          o_str = (mp_obj_str_t*)((uint8_t*)MP_STATE_VM(mp_emergency_exception_buf)
              + EMG_TRACEBACK_ALLOC * sizeof(size_t) + sizeof(mp_obj_tuple_t) + sizeof(mp_obj_t));
          o_str_buf = (byte*)&o_str[1];
          o_str_alloc = (uint8_t*)MP_STATE_VM(mp_emergency_exception_buf)
              + mp_emergency_exception_buf_size - o_str_buf;
      }
      #endif
  
      if (o_str == NULL) {
          // No memory for the string object so create the exception with no args
          return mp_obj_exception_make_new(exc_type, 0, 0, NULL);
      }
  
      if (o_str_buf == NULL) {
          // No memory for the string buffer: the string is compressed so don't add it.
          o_str->len = 0;
          o_str->data = NULL;
      } else {
          // We have some memory to format the string
          struct _exc_printer_t exc_pr = {!used_emg_buf, o_str_alloc, 0, o_str_buf};
          mp_print_t print = {&exc_pr, exc_add_strn};
          char fmt_decompressed[fmt->length];
          decompress(fmt, fmt_decompressed);
          mp_vprintf(&print, fmt_decompressed, ap);
          exc_pr.buf[exc_pr.len] = '\0';
          o_str->len = exc_pr.len;
          o_str->data = exc_pr.buf;
      }
  
      // Create the string object and call mp_obj_exception_make_new to create the exception
      o_str->base.type = &mp_type_str;
      o_str->hash = qstr_compute_hash(o_str->data, o_str->len);
      mp_obj_t arg = MP_OBJ_FROM_PTR(o_str);
      return mp_obj_exception_make_new(exc_type, 1, &arg, NULL);
  }
  
  // return true if the given object is an exception type
  bool mp_obj_is_exception_type(mp_obj_t self_in) {
      if (MP_OBJ_IS_TYPE(self_in, &mp_type_type)) {
          // optimisation when self_in is a builtin exception
          mp_obj_type_t *self = MP_OBJ_TO_PTR(self_in);
          if (self->make_new == mp_obj_exception_make_new) {
              return true;
          }
      }
      return mp_obj_is_subclass_fast(self_in, MP_OBJ_FROM_PTR(&mp_type_BaseException));
  }
  
  // return true if the given object is an instance of an exception type
  bool mp_obj_is_exception_instance(mp_obj_t self_in) {
      return mp_obj_is_exception_type(MP_OBJ_FROM_PTR(mp_obj_get_type(self_in)));
  }
  
  // Return true if exception (type or instance) is a subclass of given
  // exception type.  Assumes exc_type is a subclass of BaseException, as
  // defined by mp_obj_is_exception_type(exc_type).
  bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type) {
      // if exc is an instance of an exception, then extract and use its type
      if (mp_obj_is_exception_instance(exc)) {
          exc = MP_OBJ_FROM_PTR(mp_obj_get_type(exc));
      }
      return mp_obj_is_subclass_fast(exc, exc_type);
  }
  
  // traceback handling functions
  
  #define GET_NATIVE_EXCEPTION(self, self_in) \
      /* make sure self_in is an exception instance */ \
      assert(mp_obj_is_exception_instance(self_in)); \
      mp_obj_exception_t *self; \
      if (mp_obj_is_native_exception_instance(self_in)) { \
          self = MP_OBJ_TO_PTR(self_in); \
      } else { \
          self = MP_OBJ_TO_PTR(((mp_obj_instance_t*)MP_OBJ_TO_PTR(self_in))->subobj[0]); \
      }
  
  void mp_obj_exception_clear_traceback(mp_obj_t self_in) {
      GET_NATIVE_EXCEPTION(self, self_in);
      // just set the traceback to the null object
      // we don't want to call any memory management functions here
      self->traceback_data = NULL;
  }
  
  void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block) {
      GET_NATIVE_EXCEPTION(self, self_in);
  
      // append this traceback info to traceback data
      // if memory allocation fails (eg because gc is locked), just return
  
      if (self->traceback_data == NULL) {
          self->traceback_data = m_new_maybe(size_t, TRACEBACK_ENTRY_LEN);
          if (self->traceback_data == NULL) {
              #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
              if (mp_emergency_exception_buf_size >= EMG_TRACEBACK_ALLOC * sizeof(size_t)) {
                  // There is room in the emergency buffer for traceback data
                  size_t *tb = (size_t*)MP_STATE_VM(mp_emergency_exception_buf);
                  self->traceback_data = tb;
                  self->traceback_alloc = EMG_TRACEBACK_ALLOC;
              } else {
                  // Can't allocate and no room in emergency buffer
                  return;
              }
              #else
              // Can't allocate
              return;
              #endif
          } else {
              // Allocated the traceback data on the heap
              self->traceback_alloc = TRACEBACK_ENTRY_LEN;
          }
          self->traceback_len = 0;
      } else if (self->traceback_len + TRACEBACK_ENTRY_LEN > self->traceback_alloc) {
          #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
          if (self->traceback_data == (size_t*)MP_STATE_VM(mp_emergency_exception_buf)) {
              // Can't resize the emergency buffer
              return;
          }
          #endif
          // be conservative with growing traceback data
          size_t *tb_data = m_renew_maybe(size_t, self->traceback_data, self->traceback_alloc,
              self->traceback_alloc + TRACEBACK_ENTRY_LEN, true);
          if (tb_data == NULL) {
              return;
          }
          self->traceback_data = tb_data;
          self->traceback_alloc += TRACEBACK_ENTRY_LEN;
      }
  
      size_t *tb_data = &self->traceback_data[self->traceback_len];
      self->traceback_len += TRACEBACK_ENTRY_LEN;
      tb_data[0] = file;
      tb_data[1] = line;
      tb_data[2] = block;
  }
  
  void mp_obj_exception_get_traceback(mp_obj_t self_in, size_t *n, size_t **values) {
      GET_NATIVE_EXCEPTION(self, self_in);
  
      if (self->traceback_data == NULL) {
          *n = 0;
          *values = NULL;
      } else {
          *n = self->traceback_len;
          *values = self->traceback_data;
      }
  }
  
  #if MICROPY_PY_SYS_EXC_INFO
  STATIC const mp_obj_namedtuple_type_t code_type_obj = {
      .base = {
          .base = {
              .type = &mp_type_type
          },
          .name = MP_QSTR_code,
          .print = namedtuple_print,
          .make_new = namedtuple_make_new,
          .unary_op = mp_obj_tuple_unary_op,
          .binary_op = mp_obj_tuple_binary_op,
          .attr = namedtuple_attr,
          .subscr = mp_obj_tuple_subscr,
          .getiter = mp_obj_tuple_getiter,
          .parent = &mp_type_tuple,
      },
      .n_fields = 15,
      .fields = {
          MP_QSTR_co_argcount,
          MP_QSTR_co_kwonlyargcount,
          MP_QSTR_co_nlocals,
          MP_QSTR_co_stacksize,
          MP_QSTR_co_flags,
          MP_QSTR_co_code,
          MP_QSTR_co_consts,
          MP_QSTR_co_names,
          MP_QSTR_co_varnames,
          MP_QSTR_co_freevars,
          MP_QSTR_co_cellvars,
          MP_QSTR_co_filename,
          MP_QSTR_co_name,
          MP_QSTR_co_firstlineno,
          MP_QSTR_co_lnotab,
      },
  };
  
  STATIC mp_obj_t code_make_new(qstr file, qstr block) {
      mp_obj_t elems[15] = {
          mp_obj_new_int(0),             // co_argcount
          mp_obj_new_int(0),             // co_kwonlyargcount
          mp_obj_new_int(0),             // co_nlocals
          mp_obj_new_int(0),             // co_stacksize
          mp_obj_new_int(0),             // co_flags
          mp_obj_new_bytearray(0, NULL), // co_code
          mp_obj_new_tuple(0, NULL),     // co_consts
          mp_obj_new_tuple(0, NULL),     // co_names
          mp_obj_new_tuple(0, NULL),     // co_varnames
          mp_obj_new_tuple(0, NULL),     // co_freevars
          mp_obj_new_tuple(0, NULL),     // co_cellvars
          MP_OBJ_NEW_QSTR(file),         // co_filename
          MP_OBJ_NEW_QSTR(block),        // co_name
          mp_obj_new_int(1),             // co_firstlineno
          mp_obj_new_bytearray(0, NULL), // co_lnotab
      };
  
      return namedtuple_make_new((const mp_obj_type_t*)&code_type_obj, 15, elems, NULL);
  }
  
  STATIC const mp_obj_namedtuple_type_t frame_type_obj = {
      .base = {
          .base = {
              .type = &mp_type_type
          },
          .name = MP_QSTR_frame,
          .print = namedtuple_print,
          .make_new = namedtuple_make_new,
          .unary_op = mp_obj_tuple_unary_op,
          .binary_op = mp_obj_tuple_binary_op,
          .attr = namedtuple_attr,
          .subscr = mp_obj_tuple_subscr,
          .getiter = mp_obj_tuple_getiter,
          .parent = &mp_type_tuple,
      },
      .n_fields = 8,
      .fields = {
          MP_QSTR_f_back,
          MP_QSTR_f_builtins,
          MP_QSTR_f_code,
          MP_QSTR_f_globals,
          MP_QSTR_f_lasti,
          MP_QSTR_f_lineno,
          MP_QSTR_f_locals,
          MP_QSTR_f_trace,
      },
  };
  
  STATIC mp_obj_t frame_make_new(mp_obj_t f_code, int f_lineno) {
      mp_obj_t elems[8] = {
          mp_const_none,             // f_back
          mp_obj_new_dict(0),        // f_builtins
          f_code,                    // f_code
          mp_obj_new_dict(0),        // f_globals
          mp_obj_new_int(0),         // f_lasti
          mp_obj_new_int(f_lineno),  // f_lineno
          mp_obj_new_dict(0),        // f_locals
          mp_const_none,             // f_trace
      };
  
      return namedtuple_make_new((const mp_obj_type_t*)&frame_type_obj, 8, elems, NULL);
  }
  
  STATIC const mp_obj_namedtuple_type_t traceback_type_obj = {
      .base = {
          .base = {
              .type = &mp_type_type
          },
          .name = MP_QSTR_traceback,
          .print = namedtuple_print,
          .make_new = namedtuple_make_new,
          .unary_op = mp_obj_tuple_unary_op,
          .binary_op = mp_obj_tuple_binary_op,
          .attr = namedtuple_attr,
          .subscr = mp_obj_tuple_subscr,
          .getiter = mp_obj_tuple_getiter,
          .parent = &mp_type_tuple,
      },
      .n_fields = 4,
      .fields = {
          MP_QSTR_tb_frame,
          MP_QSTR_tb_lasti,
          MP_QSTR_tb_lineno,
          MP_QSTR_tb_next,
      },
  };
  
  STATIC mp_obj_t traceback_from_values(size_t *values, mp_obj_t tb_next) {
      int lineno = values[1];
  
      mp_obj_t elems[4] = {
          frame_make_new(code_make_new(values[0], values[2]), lineno),
          mp_obj_new_int(0),
          mp_obj_new_int(lineno),
          tb_next,
      };
  
      return namedtuple_make_new((const mp_obj_type_t*)&traceback_type_obj, 4, elems, NULL);
  };
  
  mp_obj_t mp_obj_exception_get_traceback_obj(mp_obj_t self_in) {
      mp_obj_exception_t *self = MP_OBJ_TO_PTR(self_in);
  
      if (!mp_obj_is_exception_instance(self)) {
          return mp_const_none;
      }
  
      size_t n, *values;
      mp_obj_exception_get_traceback(self, &n, &values);
      if (n == 0) {
          return mp_const_none;
      }
  
      mp_obj_t tb_next = mp_const_none;
  
      for (size_t i = 0; i < n; i += 3) {
          tb_next = traceback_from_values(&values[i], tb_next);
      }
  
      return tb_next;
  }
  #endif
  