Feature request (with patch): redirect events audit file to stderr

[VA1DER]

As per discussion in the forum, I am submitting a patch to add the ability to direct the events audit file to stderr.

I chose not to use "-audit=stderr" as discussed in the forum since -audit is used currently as a boolean and this would have broken any implementation that used -audit by itself rather than -audit=true. Instead, I added a new command line switch "-auditfile" and gave the user the ability to select stdout ("-"), stderr ("--"), an arbitrary file, or to have the original behaviour of a file with a timestamped filename.

Attached below the diff is a zip file with the diff in it.

diff -u5r /home/Kurt/projects/syncthing/src/github.com/syncthing/syncthing/cmd/syncthing/main.go syncthing/main.go
--- /home/Kurt/projects/syncthing/src/github.com/syncthing/syncthing/cmd/syncthing/main.go	2017-01-02 02:05:09.188656600 -0400
+++ syncthing/main.go	2017-01-02 02:25:59.330766400 -0400
@@ -27,10 +27,11 @@
 	"sort"
 	"strconv"
 	"strings"
 	"syscall"
 	"time"
+	"io"
 
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/connections"
 	"github.com/syncthing/syncthing/lib/db"
 	"github.com/syncthing/syncthing/lib/dialer"
@@ -209,10 +210,11 @@
 	noBrowser      bool
 	browserOnly    bool
 	hideConsole    bool
 	logFile        string
 	auditEnabled   bool
+	auditFile      string
 	verbose        bool
 	paused         bool
 	unpaused       bool
 	guiAddress     string
 	guiAPIKey      string
@@ -271,10 +273,11 @@
 	flag.BoolVar(&options.auditEnabled, "audit", false, "Write events to audit file")
 	flag.BoolVar(&options.verbose, "verbose", false, "Print verbose log output")
 	flag.BoolVar(&options.paused, "paused", false, "Start with all devices and folders paused")
 	flag.BoolVar(&options.unpaused, "unpaused", false, "Start with all devices and folders unpaused")
 	flag.StringVar(&options.logFile, "logfile", options.logFile, "Log file name (use \"-\" for stdout)")
+	flag.StringVar(&options.auditFile, "auditfile", options.auditFile, "Specify audit file (use \"-\" for stdout, \"--\" for stderr)")
 	if runtime.GOOS == "windows" {
 		// Allow user to hide the console window
 		flag.BoolVar(&options.hideConsole, "no-console", false, "Hide console window")
 	}
 
@@ -543,11 +546,11 @@
 	// Set a log prefix similar to the ID we will have later on, or early log
 	// lines look ugly.
 	l.SetPrefix("[start] ")
 
 	if runtimeOptions.auditEnabled {
-		startAuditing(mainService)
+		startAuditing(mainService, runtimeOptions.auditFile)
 	}
 
 	if runtimeOptions.verbose {
 		mainService.Add(newVerboseService())
 	}
@@ -929,25 +932,41 @@
 	}
 
 	return nil
 }
 
-func startAuditing(mainService *suture.Supervisor) {
-	auditFile := timestampedLoc(locAuditLog)
-	fd, err := os.OpenFile(auditFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0600)
-	if err != nil {
-		l.Fatalln("Audit:", err)
+func startAuditing(mainService *suture.Supervisor, auditFile string) {
+
+	var fd io.Writer
+	var err error
+	var auditDest string
+
+	if auditFile == "-" {
+		fd = os.Stdout
+		auditDest = "stdout"
+	} else if auditFile == "--" {
+		fd = os.Stderr
+		auditDest = "stderr"
+	} else {
+		if auditFile == "" {
+			auditFile = timestampedLoc(locAuditLog)
+		}
+		fd, err = os.OpenFile(auditFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0600)
+		if err != nil {
+			l.Fatalln("Audit:", err)
+		}
+		auditDest = auditFile
 	}
 
 	auditService := newAuditService(fd)
 	mainService.Add(auditService)
 
 	// We wait for the audit service to fully start before we return, to
 	// ensure we capture all events from the start.
 	auditService.WaitForStart()
 
-	l.Infoln("Audit log in", auditFile)
+	l.Infoln("Audit log in", auditDest)
 }
 
 func setupGUI(mainService *suture.Supervisor, cfg *config.Wrapper, m *model.Model, apiSub events.BufferedSubscription, diskSub events.BufferedSubscription, discoverer discover.CachingMux, connectionsService *connections.Service, errors, systemLog logger.Recorder, runtimeOptions RuntimeOptions) {
 	guiCfg := cfg.GUI()
 

syncthing_audit_specify.zip

[calmh]

Hi! Please open a pull request with the changes.