Compile rules from their location (#116)

* handle errors while loading rules

* move to rules folder for compiling

1 files changed, 38 insertions, 2 deletions

diff --git a/php-malware-finder/phpmalwarefinder.go b/php-malware-finder/phpmalwarefinder.go
index 799df60..2a641b3 100644
--- a/php-malware-finder/phpmalwarefinder.go
+++ b/php-malware-finder/phpmalwarefinder.go
@@ -210,6 +210,42 @@ func scanDir(dirName string, targets chan<- string, ticker <-chan time.Time) {
         close(targets)
 }
 
+// loadRulesFile reads YARA rules from specified `fileName` and returns
+// them in their compiled form.
+func loadRulesFile(fileName string) (*yara.Rules, error) {
+        var err error = nil
+        // record working directory and move to rules location
+        curDir, err := os.Getwd()
+        if err != nil {
+                return nil, fmt.Errorf("unable to determine working directory: %v", err)
+        }
+        ruleDir, ruleName := filepath.Split(fileName)
+        err = os.Chdir(ruleDir)
+        if err != nil {
+                return nil, fmt.Errorf("unable to move to rules directory: %v", err)
+        }
+
+        // read file content
+        data, err := ioutil.ReadFile(ruleName)
+        if err != nil {
+                return nil, fmt.Errorf("unable to read rules file: %v", err)
+        }
+
+        // compile rules
+        rules, err := yara.Compile(string(data), nil)
+        if err != nil {
+                return nil, fmt.Errorf("unable to load rules: %v", err)
+        }
+
+        // move back to working directory
+        err = os.Chdir(curDir)
+        if err != nil {
+                return nil, fmt.Errorf("unable to move back to working directory: %v", err)
+        }
+
+        return rules, nil
+}
+
 func main() {
         startTime := time.Now()
         _, err := flags.Parse(&args)
@@ -265,8 +301,8 @@ func main() {
 
         // load YARA rules
         rulePath := path.Join(args.RulesDir, RulesFile)
-        data, _ := ioutil.ReadFile(rulePath)
-        rules, _ := yara.Compile(string(data), nil)
+        rules, err := loadRulesFile(rulePath)
+        handleError(err, true)
         if args.Verbose {
                 log.Println("[DEBUG] ruleset loaded:", rulePath)
         }