Move utilities to a package to keep things clean

conn.go

@@ -14,6 +14,7 @@ import (
 	"net/http"
 
 	log "github.com/Sirupsen/logrus"
+	"github.com/arduino/arduino-create-agent/utilities"
 	"github.com/gin-gonic/gin"
 	"github.com/googollee/go-socket.io"
 )
@@ -95,7 +96,7 @@ func uploadHandler(c *gin.Context) {
 
 	buffer := bytes.NewBuffer(data.Hex)
 
-	path, err := saveFileonTempDir(data.Filename, buffer)
+	path, err := utilities.SaveFileonTempDir(data.Filename, buffer)
 	if err != nil {
 		c.String(http.StatusBadRequest, err.Error())
 	}

discovery.go

@@ -29,11 +29,12 @@
 package main
 
 import (
-	log "github.com/Sirupsen/logrus"
-	"github.com/oleksandr/bonjour"
 	"net"
 	"strings"
 	"time"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/oleksandr/bonjour"
 )
 
 const timeoutConst = 2
@@ -143,3 +144,14 @@ func getPorts() ([]OsSerialPort, error) {
 		return arrPorts, nil
 	}
 }
+
+// Filter returns a new slice containing all OsSerialPort in the slice that satisfy the predicate f.
+func Filter(vs []OsSerialPort, f func(OsSerialPort) bool) []OsSerialPort {
+	var vsf []OsSerialPort
+	for _, v := range vs {
+		if f(v) {
+			vsf = append(vsf, v)
+		}
+	}
+	return vsf
+}

killbrowser_linux.go

@@ -3,14 +3,16 @@ package main
 import (
 	"os/exec"
 	"strings"
+
+	"github.com/arduino/arduino-create-agent/utilities"
 )
 
 func findBrowser(process string) ([]byte, error) {
 	ps := exec.Command("ps", "-A", "-o", "command")
 	grep := exec.Command("grep", process)
 	head := exec.Command("head", "-n", "1")
 
-	return pipe_commands(ps, grep, head)
+	return utilities.PipeCommands(ps, grep, head)
 }
 
 func killBrowser(process string) ([]byte, error) {

seriallist_linux.go

@@ -6,6 +6,8 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+
+	"github.com/arduino/arduino-create-agent/utilities"
 )
 
 func associateVidPidWithPort(ports []OsSerialPort) []OsSerialPort {
@@ -14,7 +16,7 @@ func associateVidPidWithPort(ports []OsSerialPort) []OsSerialPort {
 		ueventcmd := exec.Command("cat", "/sys/class/tty/"+filepath.Base(ports[index].Name)+"/device/uevent")
 		grep3cmd := exec.Command("grep", "PRODUCT=")
 
-		cmdOutput2, _ := pipe_commands(ueventcmd, grep3cmd)
+		cmdOutput2, _ := utilities.PipeCommands(ueventcmd, grep3cmd)
 		cmdOutput2S := string(cmdOutput2)
 
 		if len(cmdOutput2S) == 0 {

utilities/utilities.go

@@ -0,0 +1,89 @@
+package utilities
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+// SaveFileonTempDir creates a temp directory and saves the file data as the
+// filename in that directory.
+// Returns an error if the agent doesn't have permission to create the folder.
+// Returns an error if the filename doesn't form a valid path.
+//
+// Note that path could be defined and still there could be an error.
+func SaveFileonTempDir(filename string, data io.Reader) (path string, err error) {
+	// Create Temp Directory
+	tmpdir, err := ioutil.TempDir("", "arduino-create-agent")
+	if err != nil {
+		return "", errors.New("Could not create temp directory to store downloaded file. Do you have permissions?")
+	}
+
+	// Determine filename
+	filename, err = filepath.Abs(tmpdir + "/" + filename)
+	if err != nil {
+		return "", err
+	}
+
+	// Touch file
+	output, err := os.Create(filename)
+	if err != nil {
+		return filename, err
+	}
+	defer output.Close()
+
+	// Write file
+	_, err = io.Copy(output, data)
+	if err != nil {
+		return filename, err
+	}
+	return filename, nil
+}
+
+// PipeCommands executes the commands received as input by feeding the output of
+// one to the input of the other, exactly like Unix Pipe (|).
+// Returns the output of the final command and the eventual error.
+//
+// code inspired by https://gist.github.com/tyndyll/89fbb2c2273f83a074dc
+func PipeCommands(commands ...*exec.Cmd) ([]byte, error) {
+	var errorBuffer, outputBuffer bytes.Buffer
+	pipeStack := make([]*io.PipeWriter, len(commands)-1)
+	i := 0
+	for ; i < len(commands)-1; i++ {
+		stdinPipe, stdoutPipe := io.Pipe()
+		commands[i].Stdout = stdoutPipe
+		commands[i].Stderr = &errorBuffer
+		commands[i+1].Stdin = stdinPipe
+		pipeStack[i] = stdoutPipe
+	}
+	commands[i].Stdout = &outputBuffer
+	commands[i].Stderr = &errorBuffer
+
+	if err := call(commands, pipeStack); err != nil {
+		return nil, err
+	}
+
+	return outputBuffer.Bytes(), nil
+}
+
+func call(stack []*exec.Cmd, pipes []*io.PipeWriter) (err error) {
+	if stack[0].Process == nil {
+		if err = stack[0].Start(); err != nil {
+			return err
+		}
+	}
+	if len(stack) > 1 {
+		if err = stack[1].Start(); err != nil {
+			return err
+		}
+		defer func() {
+			pipes[0].Close()
+			err = call(stack[1:], pipes[1:])
+		}()
+	}
+	return stack[0].Wait()
+}