Add command line argument to ignore all unix based exceptions

src/app/gandalf_args.ml

@@ -8,6 +8,12 @@ let be_verbose =
   in
   Arg.(value & flag & info ["v"; "verbose"] ~doc)
 
+let ignore_all_unix_errors =
+  let doc = "Ignore all Unix exceptions, most likely raised by Usbmuxd. \
+             Warning: this may hide errors"
+  in
+  Arg.(value & flag & info ["ignore_all_unix_exceptions"] ~doc)
+
 let forward_connection_file =
   let doc =
     "A JSON based mapping from udid to local ports to forward, \

src/app/main.ml

@@ -102,7 +102,8 @@ let begin_program
     log_async_exn
     log_plugged_inout
     log_everything_else
-    stats_server =
+    stats_server
+    ignore_unix_exn_ =
   let starting_place = Sys.getcwd () in
   if do_daemonize then begin
     (* This order matters, must get this done before anything Lwt
@@ -148,7 +149,11 @@ let begin_program
         in
         Usbmux.Logging.(
           let relay_with =
-            R.make_tunnels ?stats_server ?tunnel_timeout ~device_map
+            R.make_tunnels
+              ~ignore_unix_exn:ignore_unix_exn_
+              ?stats_server
+              ?tunnel_timeout
+              ~device_map
           in
           if very_loud
           then relay_with
@@ -175,7 +180,7 @@ let begin_program
          | e ->
            Printexc.to_string e
            |> Lwt_io.printlf "Error: Please report: Unknown exception: %s" >>
-           exit 9
+           exit 10
        ))
 
 let entry_point = let open Gandalf_args in
@@ -192,7 +197,8 @@ let entry_point = let open Gandalf_args in
         $ log_async_exceptions
         $ log_plugged_action
         $ log_everything_else
-        $ status_server_port)
+        $ status_server_port
+        $ ignore_all_unix_errors)
 
 let top_level_info =
   let doc = "Control TCP forwarding for iDevices" in
@@ -243,7 +249,9 @@ let top_level_info =
              `P "6 -> Check if $(b,$(tname)) is even running";
              `P "7 -> Check if usbmuxd is running";
              `P "8 -> Error in mapping file, check your json";
-             `P "9 -> Unknown reason, please report";
+             `P "9 -> Some kind of Unix error, most likely caused by usbmuxd, \
+                 check misc section logs";
+             `P "10 -> Unknown reason, please report";
              `S "AUTHOR";
              `P "Edgar Aroutiounian <edgar.factorial@gmail.com>"]
   in

src/lib/usbmux.ml

@@ -184,8 +184,9 @@ module Relay = struct
        relay_timeout,
        lazy_exceptions,
        tunnels_created,
-       tunnel_timeouts) =
-    Hashtbl.create 24, ref "", ref None, ref 0, ref 0, ref 0
+       tunnel_timeouts,
+       unix_exn_exit_program) =
+    Hashtbl.create 24, ref "", ref None, ref 0, ref 0, ref 0, ref false
 
   let status_server port =
     P.sprintf "http://127.0.0.1:%d" port
@@ -215,8 +216,8 @@ module Relay = struct
     (fun () ->
        Lwt.pick
          (* Either get data off the stream or timeout after a period
-             of time, we don't want to keep relays open that have no
-             activity on them *)
+            of time, we don't want to keep relays open that have no
+            activity on them *)
          [Lwt_stream.get stream; timeout_task ~after_timeout read_timeout])
     |> Lwt_stream.from
 
@@ -352,6 +353,9 @@ module Relay = struct
             lazy_exceptions := !lazy_exceptions + 1;
             "(Safe to ignore) OCaml lazy value exception from TCP tunneling"
             |> log `misc
+          | Unix_error(e, _, _) ->
+            error_message e |> P.sprintf "Unix based error: %s" |> log `misc;
+            if !unix_exn_exit_program then exit 9
           | exn ->
             "Please report, this is an unhandled async exception (A bug)"
             |> log (`exn exn);
@@ -455,6 +459,7 @@ module Relay = struct
     |> Lwt.async
 
   let rec make_tunnels
+      ?(ignore_unix_exn=false)
       ?(log_opts=(!Logging.logging_opts))
       ?stats_server
       ?tunnel_timeout
@@ -467,6 +472,9 @@ module Relay = struct
        else Lwt.return_unit)
     |> Lwt_main.at_exit;
 
+    (* Should Unix exceptions exit the program? *)
+    unix_exn_exit_program := ignore_unix_exn;
+
     (* Set the logging options *)
     Logging.logging_opts := log_opts;
     (* Ask for larger internal buffers for Lwt_io function rather than
@@ -531,6 +539,7 @@ module Relay = struct
       (* Spin it up again *)
       make_tunnels
         (* Use existing status server *)
+        ~ignore_unix_exn:!unix_exn_exit_program
         ~log_opts:!Logging.logging_opts
         ?stats_server:None
         ?tunnel_timeout:None

src/lib/usbmux.mli

@@ -85,6 +85,7 @@ module Relay : sig
       creates the tunnels requested for in the {b device_map} and creates a
       HTTP status server that is accessible at localport 5000. *)
   val make_tunnels :
+    ?ignore_unix_exn:bool ->
     ?log_opts:Logging.log_opts ->
     ?stats_server:int ->
     ?tunnel_timeout:int ->