echoerr() { printf "%s\n" "$*" >&2; }

dump_string_char()
{
  local string len_str idx this_char this_int
  string="$1"
  echoerr "string: \"\"\"$string\"\"\"" 
  len_str="${#string}"
  idx=0
  while [ $idx -lt ${len_str} ]; do
    this_char="${string:$idx:1}"
    this_int="$(LC_CTYPE=C printf "%d" "'$this_char")"
    echoerr "idx: $idx"
    if [ $this_int -lt 32 ]; then
      echoerr "$idx: ${this_int}" 
    else
      echoerr "$idx: \"${this_char}\"" 
    fi
    ((idx++))
  done
}

second_function()
{
  local second_ini_buffer result2_buffer
  second_ini_buffer="$1"

  # Some magical awk/sed that did not match any pattern
  # So let us use 'echo' to re-save the same string

  IFS= read -rd '' result2_buffer < <(echo "$second_ini_buffer")
  echoerr "result2_buffer len: ${#result2_buffer}"
  echoerr "\"\"\"$result2_buffer\"\"\""
  # so pass back the full ini_buffer as-is.
  # hopefully with ONE chr(1) at end-of-line.
  # but it doesn't.

  echo "$result2_buffer"
}


first_function()
{
  local first_buffer result1_buffer
  # takes a string with a single chr(10)
  first_buffer="$1"

  # calls a function, which does nothing.
  IFS= read -rd '' result1_buffer < <(second_function "$first_buffer")
  # IFS= read -rd '' result1_buffer < <(echo "$first_buffer")
  # yet it got prepended by another chr(10) for a total of two chr(10)

echoerr "result1_buffer len: ${#result1_buffer}"
echoerr "\"\"\"$result1_buffer\"\"\""
  # Suuposedly only one way to return a multi-line string neatly, 
  # and that is via STDOUT (fd=1)
  # echo "first_buffer len: ${#first_buffer}"
  echo "$result1_buffer"
}


# there is exactly one chr(10) at the end of ini_buffer
ini_buffer="1.2.3.4
"
echoerr "initial ini_buffer \"\"\"$ini_buffer\"\"\""
echoerr "initial ini_buffer len: ${#ini_buffer}"
echoerr
dump_string_char "$ini_buffer"


IFS= read -rd '' result < <(first_function "$ini_buffer")
# got a SECOND chr(10) prepended to the final output 
# for a total of 3 prepended chr(10)s

echoerr "result len: ${#result}"
echoerr "\"\"\"$result\"\"\""
echoerr