From 35d05ba9c81ed1016ab88bc3c734b7147c9e7645 Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Mon, 4 Aug 2014 17:10:19 +0200
Subject: [PATCH] LevelDB needs re-coding of positions with zero components.

---
 coords.go  | 22 ++++++++++++++++++++++
 leveldb.go |  7 +++++++
 sqlite.go  |  5 -----
 3 files changed, 29 insertions(+), 5 deletions(-)
 create mode 100644 coords.go

diff --git a/coords.go b/coords.go
new file mode 100644
index 0000000..aa33ed8
--- /dev/null
+++ b/coords.go
@@ -0,0 +1,22 @@
+// Copyright 2014 by Sascha L. Teichmann
+// Use of this source code is governed by the MIT license
+// that can be found in the LICENSE file.
+
+package main
+
+import "strconv"
+
+// Returns database pos as a byte slice.
+func pos2bytes(pos int64) []byte {
+	buf := make([]byte, 8, 8)
+	for i := 7; i >= 0; i-- {
+		buf[i] = byte(pos & 0xff)
+		pos >>= 8
+	}
+	return buf
+}
+
+// Constructs a database key out of byte slice.
+func bytes2pos(key []byte) (pos int64, err error) {
+	return strconv.ParseInt(string(key), 10, 64)
+}
diff --git a/leveldb.go b/leveldb.go
index 85496d8..85060af 100644
--- a/leveldb.go
+++ b/leveldb.go
@@ -64,6 +64,13 @@ func (ldb *LevelDBBackend) keyExists(key []byte) (exists bool, err error) {
 
 func (ldb *LevelDBBackend) Store(hash, key, value []byte) (exists bool, err error) {
 
+	var pos int64
+	if pos, err = bytes2pos(key); err != nil {
+		return
+	}
+    // Re-code it to make LevelDB happy.
+    key = pos2bytes(pos)
+
 	if exists, err = ldb.keyExists(key); err != nil {
 		return
 	}
diff --git a/sqlite.go b/sqlite.go
index f1e015f..90a826e 100644
--- a/sqlite.go
+++ b/sqlite.go
@@ -7,7 +7,6 @@ package main
 import (
 	"database/sql"
 	"log"
-	"strconv"
 	"sync"
 
 	_ "github.com/mattn/go-sqlite3"
@@ -113,10 +112,6 @@ func (sqlb *SqliteBackend) txStmt(stmt *sql.Stmt) *sql.Stmt {
 	return stmt
 }
 
-func bytes2pos(key []byte) (pos int64, err error) {
-	return strconv.ParseInt(string(key), 10, 64)
-}
-
 func (sqlb *SqliteBackend) Fetch(hash, key []byte) (data []byte, err error) {
 	var pos int64
 	if pos, err = bytes2pos(key); err != nil {