Segfault on Hash#has_key?

io.cpp

#include <ruby.h>

#define RB_HASH_HAS_SYMBOL_KEY(hash, str)   (rb_funcall((hash), rb_intern("has_key?"), 1, rb_intern((str))) == Qtrue)

typedef VALUE (*METHOD)(...);

/*
 * Take a string of bytes which represent MATLAB data type values and repack them into a string
 * of bytes representing values of an NMatrix dtype (or itype).
 *
 * Returns what appears to be a Ruby String.
 *
 * Arguments:
 * * str        :: the data
 * * from       :: symbol representing MATLAB data type (e.g., :miINT8)
 * * options    :: hash, give either :itype => some_itype or :dtype => some_dtype, tells function
 *                 what to give as output.
 */
static VALUE nm_rbstring_matlab_repack(VALUE self, VALUE str, VALUE from, VALUE options) {
  NM_MATLAB_DTYPE_TEMPLATE_TABLE(ttable, nm::io::matlab_cstring_to_dtype_string, std::string, const char* str, size_t bytes);

  nm::io::matlab_dtype_t from_type = matlab_dtype_from_rbsymbol(from);
  uint8_t to_type;

  if (TYPE(options) != T_HASH) {
    rb_raise(rb_eArgError, "third argument to repack must be hash");
  } else if (!rb_respond_to(options, rb_intern("has_key?"))) {
    rb_raise(rb_eArgError, "hash does not respond to has_key?!");
  }

  if (RB_HASH_HAS_SYMBOL_KEY(options, "dtype")) { // Hash#has_key?(:dtype)
    dtype_t to_dtype = nm_dtype_from_rbsymbol(rb_hash_aref(options, rb_intern("dtype")));
    to_type  = static_cast<int8_t>(to_dtype);
  } else if (RB_HASH_HAS_SYMBOL_KEY(options, "itype")) {
    itype_t to_itype = nm_itype_from_rbsymbol(rb_hash_aref(options, rb_intern("itype")));

    // we're going to cheat and use the DTYPE template table. To do this, we just act like uint8_t
    // is a dtype (both are 0, itype and dtype), or we add 1 to the other itypes and treat them as
    // signed.
    to_type = static_cast<uint8_t>(to_itype);
    if (to_itype != UINT8) to_type += 1;
  } else {
    rb_raise(rb_eArgError, "third argument must have either :itype or :dtype as a key");
  }

  // For next few lines, see explanation above NM_MATLAB_DTYPE_TEMPLATE_TABLE definition in io.h.
  if (to_type >= static_cast<uint8_t>(COMPLEX64)) {
    rb_raise(rb_eArgError, "can only repack into a simple dtype, no complex/rational/VALUE");
  }

  std::string repacked_data = ttable[to_type][from_type](RSTRING_PTR(str), RSTRING_LEN(str));

  return rb_str_new2(repacked_data.c_str());
}


void nm_init_io() {
  cNMatrix_IO = rb_define_module_under(cNMatrix, "IO");
  cNMatrix_IO_Matlab = rb_define_module_under(cNMatrix_IO, "Matlab");

  rb_define_singleton_method(cNMatrix_IO_Matlab, "repack", (METHOD)nm_rbstring_matlab_repack, 3);
}