(define copy-string
  ;; NOTE: returning a c-string leads to segfaults
  (foreign-lambda* (c-pointer char) ((scheme-object string))
    "char *src = C_c_string(string);"
    "size_t size = C_SIZEOF_STRING(string);"
    "char *dest = malloc(size + 1);"
    "strncpy(dest, src, size);"
    "dest[size] = '\\0';"
    "C_return(dest);"))