Break the fs package up into smaller parts.

The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.

fs/log/syslog_unix.go

@@ -0,0 +1,67 @@
+// Syslog interface for Unix variants only
+
+// +build !windows,!nacl,!plan9
+
+package log
+
+import (
+	"log"
+	"log/syslog"
+	"os"
+	"path"
+
+	"github.com/ncw/rclone/fs"
+)
+
+var (
+	syslogFacilityMap = map[string]syslog.Priority{
+		"KERN":     syslog.LOG_KERN,
+		"USER":     syslog.LOG_USER,
+		"MAIL":     syslog.LOG_MAIL,
+		"DAEMON":   syslog.LOG_DAEMON,
+		"AUTH":     syslog.LOG_AUTH,
+		"SYSLOG":   syslog.LOG_SYSLOG,
+		"LPR":      syslog.LOG_LPR,
+		"NEWS":     syslog.LOG_NEWS,
+		"UUCP":     syslog.LOG_UUCP,
+		"CRON":     syslog.LOG_CRON,
+		"AUTHPRIV": syslog.LOG_AUTHPRIV,
+		"FTP":      syslog.LOG_FTP,
+	}
+)
+
+// Starts syslog
+func startSysLog() bool {
+	facility, ok := syslogFacilityMap[*syslogFacility]
+	if !ok {
+		log.Fatalf("Unknown syslog facility %q - man syslog for list", *syslogFacility)
+	}
+	Me := path.Base(os.Args[0])
+	w, err := syslog.New(syslog.LOG_NOTICE|facility, Me)
+	if err != nil {
+		log.Fatalf("Failed to start syslog: %v", err)
+	}
+	log.SetFlags(0)
+	log.SetOutput(w)
+	fs.LogPrint = func(level fs.LogLevel, text string) {
+		switch level {
+		case fs.LogLevelEmergency:
+			_ = w.Emerg(text)
+		case fs.LogLevelAlert:
+			_ = w.Alert(text)
+		case fs.LogLevelCritical:
+			_ = w.Crit(text)
+		case fs.LogLevelError:
+			_ = w.Err(text)
+		case fs.LogLevelWarning:
+			_ = w.Warning(text)
+		case fs.LogLevelNotice:
+			_ = w.Notice(text)
+		case fs.LogLevelInfo:
+			_ = w.Info(text)
+		case fs.LogLevelDebug:
+			_ = w.Debug(text)
+		}
+	}
+	return true
+}