correct stdin handling. stderr might still be broken

Signed-off-by: Jeff Carr <jcarr@wit.com>

example1/Makefile

@@ -0,0 +1,3 @@
+all:
+	go build
+	./example1

example1/main.go

@@ -0,0 +1,27 @@
+package main
+
+/*
+import "log"
+import "reflect"
+import "os"
+*/
+
+// import "github.com/davecgh/go-spew/spew"
+
+import "git.wit.com/jcarr/shell"
+
+func main() {
+	shell.SpewOn()
+
+	shell.Run("ls /tmp")
+
+	shell.Run("ping -c 4 localhost")
+
+	// slow down the polling to every 2 seconds
+	shell.SetDelayInMsec(2000)
+	shell.Run("ping -c 4 localhost")
+
+	// TODO: this might not be working
+	// check error handling
+	shell.Run("ls /tmpthisisnothere")
+}

shell.go

@@ -16,6 +16,7 @@ var shellStdout *os.File
 var shellStderr *os.File
 
 var spewOn bool = false
+var msecDelay int = 20	// number of milliseconds to delay between reads with no data
 
 func Script(cmds string) int {
 	// split on new lines (while we are at it, handle stupid windows text files
@@ -40,6 +41,10 @@ func SpewOn() {
 	spewOn = true
 }
 
+func SetDelayInMsec(msecs int) {
+	msecDelay = msecs
+}
+
 func SetStdout(newout *os.File) {
 	shellStdout = newout
 }
@@ -85,74 +90,45 @@ func Run(cmdline string) int {
 	newreader := bufio.NewReader(pstdout)
 	nbr := nbreader.NewNBReader(newreader, 1024)
 
-	newerrreader := bufio.NewReader(pstderr)
-	nbrerr := nbreader.NewNBReader(newerrreader, 1024)
+	// nbrerr := nbreader.NewNBReader(newerrreader, 1024)
+
+	tmp := bufio.NewReader(pstderr)
+	go NonBlockingReader(tmp, shellStderr)
 
 	totalCount := 0
 
-	for {
-		time.Sleep(2 * time.Millisecond)   // only check the buffer 500 times a second
+	var dead bool = false
+	for (dead == false) {
+		time.Sleep(time.Duration(msecDelay) * time.Millisecond)   // only check the buffer 500 times a second
 		// log.Println("sleep done")
 
+		var empty bool = false
 		// tight loop that reads 1K at a time until buffer is empty
-		for {
+		for (empty == false) {
 			oneByte := make([]byte, 1024)
 			count, err := nbr.Read(oneByte)
 			totalCount += count
 
 			if (err != nil) {
-				// log.Println("Read() count = ", count, "err = ", err)
+				log.Println("Read() count = ", count, "err = ", err)
 				oneByte = make([]byte, 1024)
 				count, err = nbr.Read(oneByte)
 				f.Write([]byte(string(oneByte)))
 				f.Flush()
+				empty = true
+				dead = true
 			}
 			f.Write([]byte(string(oneByte)))
 			f.Flush()
 			if (count == 0) {
-				break
+				empty = true
 			}
 		}
 
 		if (totalCount != 0) {
-			log.Println("totalCount = ", totalCount)
+			log.Println("STDOUT: totalCount = ", totalCount)
+			totalCount = 0
 		}
-
-		//
-		// HANDLE STDERR
-		// HANDLE STDERR
-		//
-		oneByte := make([]byte, 1024)
-		count, err := nbrerr.Read(oneByte)
-
-		if (err != nil) {
-			oneByte = make([]byte, 1024)
-			count, err = nbrerr.Read(oneByte)
-			f.Write([]byte(string(oneByte)))
-			f.Flush()
-
-			log.Println("Read() count = ", count, "err = ", err)
-			// spew.Dump(process.Process)
-			// spew.Dump(process.ProcessState)
-			err := process.Wait()
-			if err != nil {
-				if (spewOn) {
-					spew.Dump(err.(*exec.ExitError))
-					spew.Dump(process.ProcessState)
-				}
-				stuff := err.(*exec.ExitError)
-				log.Println("ERROR ", stuff)
-				log.Println("END   ", cmdline)
-				return -1
-			}
-			log.Println("END   ", cmdline)
-			return 0
-		} else {
-			f.Write([]byte(string(oneByte)))
-			f.Flush()
-		}
-
-		// spew.Dump(reflect.ValueOf(cmd.Process).Elem())
 	}
 
 	err := process.Wait()
@@ -177,3 +153,35 @@ func Daemon(cmdline string, timeout time.Duration) int {
 		time.Sleep(timeout)
 	}
 }
+
+// pass in two file handles (1 read, 1 write)
+func NonBlockingReader(buffReader *bufio.Reader, writeFileHandle *os.File) {
+	// newreader := bufio.NewReader(readFileHandle)
+
+	// create a nonblocking GO reader
+        nbr := nbreader.NewNBReader(buffReader, 1024)
+
+	for {
+		// defer buffReader.Close()
+		// defer writeFileHandle.Flush()
+		defer writeFileHandle.Close()
+		totalCount := 0
+		for {
+			oneByte := make([]byte, 1024)
+			count, err := nbr.Read(oneByte)
+			if (err != nil) {
+				log.Println("count, err =", count, err)
+				return
+			}
+			totalCount += count
+			if (count == 0) {
+				time.Sleep(time.Duration(msecDelay) * time.Millisecond)   // without this delay this will peg the CPU
+				if (totalCount != 0) {
+					log.Println("STDERR: totalCount = ", totalCount)
+					totalCount = 0
+				}
+			}
+			writeFileHandle.Write([]byte(string(oneByte)))
+		}
+	}
+}