Took a step back on cmd exec, just getting EOF/hangup on client/server ends working

demo/client/client.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sync"
 
 	hkex "blitter.com/herradurakex"
 )
@@ -22,6 +23,8 @@ import (
 // connection (app-specific, passed through to the server to use or
 // ignore at its discretion).
 func main() {
+	var wg sync.WaitGroup
+
 	var cAlg string
 	var hAlg string
 	var server string
@@ -36,8 +39,48 @@ func main() {
 		fmt.Println("Err!")
 		panic(err)
 	}
-	_, err = io.Copy(conn, os.Stdin)
-	if err != nil && err.Error() != "EOF" {
-		fmt.Println(err)
+	defer conn.Close()
+
+	wg.Add(1)
+	go func() {
+		// This will guarantee the side that closes first
+		// marks its direction's goroutine as finished.
+		// Whichever direction's goroutine finishes first
+		// will call wg.Done() once more explicitly to
+		// hang up on the other side so the client
+		// exits immediately on an EOF from either side.
+		defer wg.Done()
+
+		// io.Copy() expects EOF so this will
+		// exit with inerr == nil
+		_, inerr := io.Copy(os.Stdout, conn)
+		if inerr != nil {
+			if inerr.Error() != "EOF" {
+				fmt.Println(inerr)
+				os.Exit(1)
 			}
+		}
+		fmt.Println("[Got Write EOF]")
+		wg.Done() // client hanging up, close server read goroutine
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		// io.Copy() expects EOF so this will
+		// exit with outerr == nil
+		_, outerr := io.Copy(conn, os.Stdin)
+		if outerr != nil {
+			if outerr.Error() != "EOF" {
+				fmt.Println(outerr)
+				os.Exit(2)
+			}
+		}
+		fmt.Println("[Got Read EOF]")
+		wg.Done() // server hung up, close client write goroutine
+	}()
+
+	// Wait until both stdin and stdout goroutines finish
+	wg.Wait()
 }

demo/server/server.go

@@ -33,16 +33,9 @@ type cmdRunner struct {
 	who        string
 	arg        string
 	authCookie string
-	CloseHandler func(*cmdRunner)
 	status     int
 }
 
-func testCloseHandler(r *cmdRunner) {
-	fmt.Println("[testCloseHandler()]")
-	r.arg = "/usr/bin/touch " + r.arg
-	cmd(r)
-}
-
 func cmd(r *cmdRunner) {
 	switch r.op {
 	case OpR:
@@ -134,7 +127,7 @@ func main() {
 			}(ch, eCh)
 
 			ticker := time.Tick(time.Second / 100)
-			var r cmdRunner
+			//var r cmdRunner
 			var connOp *byte = nil
 		Term:
 			// continuously read from the connection
@@ -157,12 +150,20 @@ func main() {
 						fmt.Printf("[* connOp '%c']\n", *connOp)
 						// The CloseHandler typically handles the
 						// accumulated command data
-						r = cmdRunner{op: Op(*connOp),
-							who: "larissa", arg: string(data),
-							authCookie:   "c00ki3",
-							CloseHandler: testCloseHandler,
-							status:       0}
-						conn.Write([]byte("SERVER OUTPUT"))
+						//r = cmdRunner{op: Op(*connOp),
+						//	who: "larissa", arg: string(data),
+						//	authCookie:   "c00ki3",
+						//	status:       0}
+					}
+					
+					// From here, one could pass all subsequent data
+					// between client/server attached to an exec.Cmd,
+					// as data to/from a file, etc.
+					conn.Write([]byte("SERVER RESPONSE to '"))
+					conn.Write(data)
+					conn.Write([]byte("'\n"))
+					if strings.Trim(string(data), "\r\n") == "exit" {
+						conn.Close()
 					}
 
 					//fmt.Printf("Client sent %s\n", string(data))
@@ -171,7 +172,6 @@ func main() {
 					// handle our error then exit for loop
 					if err.Error() == "EOF" {
 						fmt.Printf("[Client disconnected]\n")
-						r.CloseHandler(&r)
 					} else {
 						fmt.Printf("Error reading client data! (%+v)\n", err)
 					}