Checking for device errors on TTYAvailable

POSIX/tty.c

@@ -190,18 +190,29 @@ void ttyread(int fd, int *ch, int *fdo)
 	debug("ttyread done");
 }
 
-void ttyavailable(int fd, int *r, int *fdo)
+void ttyavailable(int fd, int *r, int *e, int *fdo)
 {
 //	debug("ttyavailable");
-	fd_set fds;
+	fd_set rfds, efds;
 	struct timeval tv;
 	tv.tv_sec = 0;
 	tv.tv_usec = 0;
 
-	FD_ZERO(&fds);
-	FD_SET(fd, &fds);
+	FD_ZERO(&rfds);
+	FD_SET(fd, &rfds);
+
+	FD_ZERO(&efds);
+	FD_SET(fd, &efds);
+
+	*e = 0;
+	*r = select(fd+1, &rfds, NULL, &efds, &tv);
+
+	if (FD_ISSET(fd, &efds)){
+		*e = 1;
+		*fdo = fd;
+		return;
+	}
 
-	*r = select(fd+1, &fds, NULL, NULL, &tv);
 	if(*r == -1)
 		die("select");
 	*fdo = fd;

TTY.dcl

@@ -29,5 +29,12 @@ TTYerror :: !*env -> (!String, !*env)
 TTYopen :: !TTYSettings !*env -> (!Bool,!*TTY,!*env)
 TTYread :: !*TTY -> (!Int, !*TTY)
 TTYreadline :: !*TTY -> (!String, !*TTY)
-TTYavailable :: !*TTY -> (!Bool, !*TTY)
+/**
+* Checks if the TTY device is available for reading
+*
+* @param The TTY Device
+* @return A 3-tuple containing whether there is data available,
+*         whether there was an error and the TTY device
+*/
+TTYavailable :: !*TTY -> (!Bool, !Bool, !*TTY)
 TTYwrite :: !String !*TTY -> *TTY

TTY.icl

@@ -90,9 +90,9 @@ TTYwrite _ _ = code {
 		ccall ttywrite "SI:I"
 	}
 
-TTYavailable :: !*TTY -> (!Bool, !*TTY)
+TTYavailable :: !*TTY -> (!Bool, !Bool, !*TTY)
 TTYavailable _ = code {
-		ccall ttyavailable "I:VII"
+		ccall ttyavailable "I:VIII"
 	}
 
 TTYerror :: !*env -> (!String, !*env)

iTasksTTY.icl

@@ -72,9 +72,10 @@ where
 					, {iworld & resources=[TTYd dp tty:resources]})
 				(r,s,ss)
 					# tty = foldr TTYwrite tty $ reverse $ map enc s
-					# (newdata, tty) = readWhileAvailable tty
+					# (merr, tty) = readWhileAvailable tty
+					| isError merr = (exc (fromError merr), iworld)
 					# iworld = {iworld & resources=[TTYd dp tty:iworld.resources]}
-					= case dec (acc +++ toString newdata) of
+					= case dec (acc +++ toString (fromOk merr)) of
 						(Left err, newacc) = (exc "Error while parsing", iworld)
 						(Right msgs, newacc)
 							# (merr, iworld) = if (msgs =: [] && s =: [])
@@ -104,10 +105,12 @@ where
 	getResource = iworldResource (\t=:(TTYd p _)->(p == opts.devicePath, t))
 	exc = ExceptionResult o exception
 
-readWhileAvailable :: !*TTY -> ([Char], !*TTY)
+readWhileAvailable :: !*TTY -> (MaybeError String [Char], !*TTY)
 readWhileAvailable tty
-# (available, tty) = TTYavailable tty
-| not available = ([], tty)
+# (available, error, tty) = TTYavailable tty
+| error = (Error "TTY device disconnected", tty)
+| not available = (Ok [], tty)
 # (c, tty) = TTYread tty
-# (cs, tty) = readWhileAvailable tty
-= ([toChar c:cs], tty)
+# (merr, tty) = readWhileAvailable tty
+| isError merr = (merr, tty)
+= (Ok [toChar c:fromOk merr], tty)

test.icl

@@ -17,7 +17,7 @@ Start w
 # (ok, tty, w) = TTYopen {zero & devicePath="/dev/ttyUSB0"} w
 | not ok = TTYerrorclose io w
 #! tty = TTYwrite "echo123\n" tty
-#! (av, tty) = TTYavailable tty
+#! (av, e, tty) = TTYavailable tty
 # io = io <<< ("Bytes available: " +++ toString av +++ "\n")
 #! (l, tty) = TTYreadline tty
 # io = io <<< ("Line read: " +++ l)