Fix: Check if mtime before and after hash calculation match.

Check if mtime before and after hash calculation is matching,
not sure how bad it is going to be from performace point of
view, but this is temporary fix as discused in PR 35 here:
laktak#35

Author: varmint708

index.go

@@ -222,6 +222,25 @@ func (i *Index) calcFile(name string, algo string) (*idxInfo, error) {
 	if err != nil {
 		return nil, err
 	}
+	check_mtime, check_size, err := getMtS(path)
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if mtime before and after hash calculation is matching,
+	// not sure how bad it is going to be from performace point of
+	// view, but this is temporary fix as discused in PR 35 here:
+	// https://github.com/laktak/chkbit/pull/35
+	if check_mtime != mtime && check_size != size {
+		// re-calculate the hash for new check_mtime
+		hash, err = Hashfile(path, algo, i.context.perfMonBytes)
+		if err != nil {
+			return nil, err
+		}
+		mtime = check_mtime
+		size = check_size
+	}
+
 	i.context.perfMonFiles(1)
 	return &idxInfo{
 		ModTime: mtime,