nsscash: add alignBufferTo() helper

diff --git a/group.go b/group.go
index b7f7d1b8e8b9c4ce71252570c5d9cc6182b972d9..4513758df41c4a8d22eb32f8fac5653e773ca3dd 100644 (file)
--- a/group.go
+++ b/group.go
@@ -114,10 +114,7 @@ func SerializeGroup(g Group) []byte {
        offPasswd := uint16(data.Len())
        data.Write([]byte(g.Passwd))
        data.WriteByte(0)
-       // Padding to align the following uint16
-       if data.Len()%2 != 0 {
-               data.WriteByte(0)
-       }
+       alignBufferTo(&data, 2) // align the following uint16
        offMemOff := uint16(data.Len())
        // Offsets for group members
        offMem := offMemOff + 2*uint16(len(mems_off))
@@ -154,12 +151,7 @@ func SerializeGroup(g Group) []byte {
        res.Write(data.Bytes())
        // We must pad each entry so that all uint64 at the beginning of the
        // struct are 8 byte aligned
-       l := res.Len()
-       if l%8 != 0 {
-               for i := 0; i < 8-l%8; i++ {
-                       res.WriteByte(0)
-               }
-       }
+       alignBufferTo(&res, 8)
 
        return res.Bytes()
 }

diff --git a/misc.go b/misc.go
new file mode 100644 (file)
index 0000000..2e60507
--- /dev/null
+++ b/misc.go
@@ -0,0 +1,37 @@
+// Miscellaneous functions
+
+// Copyright (C) 2019  Simon Ruderich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package main
+
+import (
+       "bytes"
+       "fmt"
+)
+
+func alignBufferTo(b *bytes.Buffer, align int) {
+       if align <= 0 {
+               panic(fmt.Sprintf("invalid alignment %v", align))
+       }
+
+       l := b.Len()
+       if l%align == 0 {
+               return
+       }
+       for i := 0; i < align-l%align; i++ {
+               b.WriteByte(0)
+       }
+}

diff --git a/passwd.go b/passwd.go
index 90351900b334b4e9154683eeb437aedff54d0b06..90fed68a6b9f1d959f6ab9b03e4ebf89a081ec49 100644 (file)
--- a/passwd.go
+++ b/passwd.go
@@ -134,12 +134,7 @@ func SerializePasswd(p Passwd) []byte {
        res.Write(data.Bytes())
        // We must pad each entry so that all uint64 at the beginning of the
        // struct are 8 byte aligned
-       l := res.Len()
-       if l%8 != 0 {
-               for i := 0; i < 8-l%8; i++ {
-                       res.WriteByte(0)
-               }
-       }
+       alignBufferTo(&res, 8)
 
        return res.Bytes()
 }