Fix concurrency issues and error handling in ESP32 UART driver

Fixes possible concurrency problems by using a mutex for access to `reader_process_pid` and
`reader_ref_ticks` in `uart_data`.

Avoid possible overflow of the queue by handling all mesages in the interrupt callback.

Now cleans up and returns errors, with improved log messages when initalization fails with a badarg
in the configuration parameters, rather than aborting.

Fixes incorrect pin integers being cast to terms.

Pin numbers are validated for the chip the VM is compiled for before use to mitigate VM crashes from
bad input parameters.

Signed-off-by: Winford <[email protected]>

CHANGELOG.md

@@ -52,6 +52,11 @@ bug when handling errors from BIFs used as NIFs (when called with `CALL_EXT` and
 - Fixed potential crashes or memory leaks caused by a mistake in calculation of reference counts
 and a race condition in otp_socket code
 - Fixed an out of memory issue by forcing GC to copy data from message fragments
+- Fixed possible concurrency problems in ESP32 UART driver
+
+### Changed
+
+- ESP32 UART driver no longer aborts because of badargs in configuration, instead raising an error
 
 ## [0.6.5] - 2024-10-15
 

libs/eavmlib/src/uart.erl

@@ -19,7 +19,7 @@
 %
 
 -module(uart).
--export([open/1, open/2, close/1, read/1, write/2]).
+-export([open/1, open/2, close/1, read/1, read/2, write/2]).
 
 -type peripheral() :: string() | binary().
 % The peripheral `Name' may be one of: `"UART0"' | `"UART1"' | `"UART2"' | `<<"UART0">>' | `<<"UART1">>' | `<<"UART2">>'.
@@ -104,6 +104,42 @@ close(Pid) when is_pid(Pid) ->
 read(Pid) when is_pid(Pid) ->
     port:call(Pid, read).
 
+%%-----------------------------------------------------------------------------
+%% @param   Pid of the uart port to be read
+%% @param   Timeout millisecond to wait for data to become available
+%% @returns `{ok, Data}', or `{error, Reason}'
+%% @doc     Read data from a UART port
+%%
+%%          This function will return any data that is available within the
+%%          timeout period to the process. After the timeout has expired a new
+%%          read command may be used regardless of whether the last read was
+%%          sent a payload.
+%%          Example:
+%%          ```
+%%          Data = case uart:read(Uart, 3000) of
+%%              {ok, Bin} -> Bin;
+%%              {error, timeout} -> <<"">>;
+%%              Error -> error_handler_fun(Uart, Error)
+%%          end,
+%%          '''
+%%          Any data sent to the esp32 over uart between reads with a timeout will
+%%          be lost, so be sure this is what you want. Most applications will want
+%%          a single process to read from UART and continue to listen until a payload
+%%          is received, and likely pass the payload off for processing and
+%%          immediately begin another read.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec read(Pid :: pid(), Timeout :: pos_integer()) ->
+    {ok, Data :: iodata()} | {error, _Reason :: term()}.
+read(Pid, Timeout) when is_pid(Pid) ->
+    case port:call(Pid, read, Timeout) of
+        {error, timeout} ->
+            port:call(Pid, cancel_read),
+            {error, timeout};
+        Result ->
+            Result
+    end.
+
 %%-----------------------------------------------------------------------------
 %% @param   Pid of the uart port to be written to
 %% @param   Data to be written to the given uart port