Add port support to io_lib.erl

Add support for io_lib (and io, etc...) to format ports.
Adds port_to_list/1 to erlang module exports to keep dialyzer happy.
Add test/erlang_tests/test_port_to_list.erl to test result of port_to_list/1 using the "echo" port.

Signed-off-by: Winford <winford@object.stream>

libs/estdlib/src/erlang.erl

@@ -74,6 +74,7 @@
     integer_to_list/2,
     fun_to_list/1,
     pid_to_list/1,
+    port_to_list/1,
     ref_to_list/1,
     register/2,
     unregister/1,
@@ -848,6 +849,16 @@ fun_to_list(_Fun) ->
 pid_to_list(_Pid) ->
     erlang:nif_error(undefined).
 
+%%-----------------------------------------------------------------------------
+%% @param   Port     port to convert to a string
+%% @returns a string representation of the port
+%% @doc     Create a string representing a port.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec port_to_list(Port :: port()) -> string().
+port_to_list(_Port) ->
+    erlang:nif_error(undefined).
+
 %%-----------------------------------------------------------------------------
 %% @param   Ref     reference to convert to a string
 %% @returns a string representation of the reference

libs/estdlib/src/io_lib.erl

@@ -292,6 +292,8 @@ format_spw(_Format, T) when is_float(T) ->
     erlang:float_to_list(T);
 format_spw(_Format, T) when is_pid(T) ->
     erlang:pid_to_list(T);
+format_spw(_Format, T) when is_port(T) ->
+    erlang:port_to_list(T);
 format_spw(_Format, T) when is_reference(T) ->
     erlang:ref_to_list(T);
 format_spw(_Format, T) when is_function(T) ->

tests/erlang_tests/CMakeLists.txt

@@ -162,6 +162,7 @@ compile_erlang(test_concat_badarg)
 compile_erlang(register_and_whereis_badarg)
 compile_erlang(test_send)
 compile_erlang(test_open_port_badargs)
+compile_erlang(test_port_to_list)
 compile_erlang(echo)
 compile_erlang(pingpong)
 compile_erlang(prime_ext)
@@ -641,6 +642,7 @@ add_custom_target(erlang_test_modules DEPENDS
     register_and_whereis_badarg.beam
     test_send.beam
     test_open_port_badargs.beam
+    test_port_to_list.beam
     echo.beam
     pingpong.beam
     prime_ext.beam

tests/erlang_tests/test_port_to_list.erl

@@ -0,0 +1,61 @@
+%%
+%% This file is part of AtomVM.
+%%
+%% Copyright (c) 2025 <winford@object.stream>
+%% All rights reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%%
+%% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%%
+-module(test_port_to_list).
+
+-export([start/0, test_echo_port_to_list/0]).
+
+-define(PortBegin, "#Port<0.").
+-define(PortEnd, ">").
+
+start() ->
+    test_echo_port_to_list().
+
+test_echo_port_to_list() ->
+    Port = open_port({spawn, "echo"}, []),
+    validate_port_fmt(Port).
+
+%% internal
+validate_port_fmt(Port) ->
+    case get_valid_portchars(Port) of
+        {ok, PortChars} ->
+            Res = port_to_list(Port) =:= lists:flatten([?PortBegin, PortChars, ?PortEnd]),
+            case Res of
+                true -> 0;
+                _ -> 1
+            end;
+        {invalid_format, Port} ->
+            1
+    end.
+
+get_valid_portchars(Port) ->
+    PList = port_to_list(Port),
+    [_H, T] = string:split(PList, ?PortBegin),
+    [PortNum, _] = string:split(T, ?PortEnd),
+    try list_to_integer(PortNum) of
+        Num when is_integer(Num) ->
+            {ok, PortNum};
+        _ ->
+            {invalid_format, Port}
+    catch
+        _:_ ->
+            {invalid_format, Port}
+    end.

tests/test.c

@@ -208,6 +208,7 @@ struct Test tests[] = {
     TEST_CASE_EXPECTED(register_and_whereis_badarg, 333),
     TEST_CASE(test_send),
     TEST_CASE_EXPECTED(test_open_port_badargs, -21),
+    TEST_CASE(test_port_to_list),
     TEST_CASE_EXPECTED(prime_ext, 1999),
     TEST_CASE_EXPECTED(test_try_case_end, 256),
     TEST_CASE(test_exception_classes),