[Explain] Ignore blank lines as crowdsec will anyways

cmd/crowdsec-cli/explain.go

@@ -14,16 +14,26 @@ import (
 	"github.com/crowdsecurity/crowdsec/pkg/hubtest"
 )
 
+var (
+	dir string
+)
+
 func GetLineCountForFile(filepath string) (int, error) {
 	f, err := os.Open(filepath)
 	if err != nil {
 		return 0, err
 	}
 	defer f.Close()
 	lc := 0
-	fs := bufio.NewScanner(f)
-	for fs.Scan() {
-		lc++
+	fs := bufio.NewReader(f)
+	for {
+		input, err := fs.ReadBytes('\n')
+		if len(input) > 1 {
+			lc++
+		}
+		if err != nil && err == io.EOF {
+			break
+		}
 	}
 	return lc, nil
 }
@@ -95,7 +105,7 @@ func runExplain(cmd *cobra.Command, args []string) error {
 	var f *os.File
 
 	// using empty string fallback to /tmp
-	dir, err := os.MkdirTemp("", "cscli_explain")
+	dir, err = os.MkdirTemp("", "cscli_explain")
 	if err != nil {
 		return fmt.Errorf("couldn't create a temporary directory to store cscli explain result: %s", err)
 	}
@@ -121,6 +131,9 @@ func runExplain(cmd *cobra.Command, args []string) error {
 				if err != nil && err == io.EOF {
 					break
 				}
+				if len(input) <= 1 {
+					continue
+				}
 				_, err = f.Write(input)
 				if err != nil {
 					errCount++
@@ -145,6 +158,10 @@ func runExplain(cmd *cobra.Command, args []string) error {
 		if err != nil {
 			return err
 		}
+		log.Debug("line count: ", lineCount)
+		if lineCount == 0 {
+			return fmt.Errorf("the log file is empty: %s", absolutePath)
+		}
 		if lineCount > 100 {
 			log.Warnf("The log file contains %d lines. This may take a lot of resources.", lineCount)
 		}
@@ -166,12 +183,6 @@ func runExplain(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("fail to run crowdsec for test: %v", err)
 	}
 
-	// rm the temporary log file if only a log line/stdin was provided
-	if tmpFile != "" {
-		if err := os.Remove(tmpFile); err != nil {
-			return fmt.Errorf("unable to remove tmp log file '%s': %+v", tmpFile, err)
-		}
-	}
 	parserDumpFile := filepath.Join(dir, hubtest.ParserResultFileName)
 	bucketStateDumpFile := filepath.Join(dir, hubtest.BucketPourResultFileName)
 
@@ -187,10 +198,6 @@ func runExplain(cmd *cobra.Command, args []string) error {
 
 	hubtest.DumpTree(*parserDump, *bucketStateDump, opts)
 
-	if err := os.RemoveAll(dir); err != nil {
-		return fmt.Errorf("unable to delete temporary directory '%s': %s", dir, err)
-	}
-
 	return nil
 }
 
@@ -210,6 +217,14 @@ tail -n 5 myfile.log | cscli explain --type nginx -f -
 		Args:              cobra.ExactArgs(0),
 		DisableAutoGenTag: true,
 		RunE:              runExplain,
+		PersistentPostRunE: func(cmd *cobra.Command, args []string) error {
+			if _, err := os.Stat(dir); !os.IsNotExist(err) {
+				if err := os.RemoveAll(dir); err != nil {
+					return fmt.Errorf("unable to delete temporary directory '%s': %s", dir, err)
+				}
+			}
+			return nil
+		},
 	}
 
 	flags := cmdExplain.Flags()