Fix possible panic when file info cannot be gotten

closes #2061

CHANGELOG.md

@@ -27,6 +27,7 @@
 - [#2146](https://github.com/influxdata/telegraf/issues/2146): Fix potential panic in aggregator plugin metric maker.
 - [#1843](https://github.com/influxdata/telegraf/pull/1843) & [#1668](https://github.com/influxdata/telegraf/issues/1668): Add optional ability to define PID as a tag.
 - [#1730](https://github.com/influxdata/telegraf/issues/1730): Fix win_perf_counters not gathering non-English counters.
+- [#2061](https://github.com/influxdata/telegraf/issues/2061): Fix panic when file stat info cannot be collected due to permissions or other issue(s).
 
 ## v1.1.2 [2016-12-12]
 

plugins/inputs/filestat/filestat.go

@@ -4,6 +4,7 @@ import (
 	"crypto/md5"
 	"fmt"
 	"io"
+	"log"
 	"os"
 
 	"github.com/influxdata/telegraf"
@@ -79,7 +80,13 @@ func (f *FileStat) Gather(acc telegraf.Accumulator) error {
 			}
 			fields := map[string]interface{}{
 				"exists": int64(1),
-				"size_bytes": fileInfo.Size(),
+			}
+
+			if fileInfo == nil {
+				log.Printf("E! Unable to get info for file [%s], possible permissions issue",
+					fileName)
+			} else {
+				fields["size_bytes"] = fileInfo.Size()
 			}
 
 			if f.Md5 {