1 files changed, 133 insertions, 0 deletions
diff --git a/core/storage.go b/core/storage.go
new file mode 100644
index 0000000..7475bef
--- /dev/null
+++ b/core/storage.go
@@ -0,0 +1,133 @@
+package core
+
+import (
+	"bufio"
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"os"
+
+	bolt "go.etcd.io/bbolt"
+)
+
+type Header struct {
+	MagicNumber    int
+	Signature      string
+	FilesystemSize int
+	TableSize      int
+}
+
+type Node struct {
+	BlockStart  int
+	BlockEnd    int
+	BlockSum    string
+	PrevNodeSum string
+}
+
+func ReadHeader(partition string) (Header, error) {
+	_, exist := os.Stat(partition)
+	if os.IsNotExist(exist) {
+		return Header{}, fmt.Errorf("Cannot find partition %s", partition)
+	}
+	part, err := os.Open(partition)
+	if err != nil {
+		return Header{}, err
+	}
+	defer part.Close()
+
+	header := Header{}
+	reader := bufio.NewReader(part)
+	MagicNumber := make([]byte, 2)
+	Signature := make([]byte, 302)
+	FileSystemSize := make([]byte, 4)
+	TableSize := make([]byte, 4)
+
+	_, err = reader.Read(MagicNumber)
+	MagicNum := binary.BigEndian.Uint16(MagicNumber)
+	if MagicNum != 0xACAB { // The Silliest of magic numbers
+		return Header{}, err
+	}
+	header.MagicNumber = int(MagicNum)
+
+	_, err = reader.Read(Signature)
+	if err != nil {
+		return Header{}, err
+	}
+	_, err = reader.Read(FileSystemSize)
+	if err != nil {
+		return Header{}, err
+	}
+	_, err = reader.Read(TableSize)
+	if err != nil {
+		return Header{}, err
+	}
+
+	header.Signature = string(Signature)
+	header.FilesystemSize = int(binary.BigEndian.Uint16(FileSystemSize))
+	header.TableSize = int(binary.BigEndian.Uint16(TableSize))
+	return header, nil
+}
+
+func OpenDB() (*bolt.DB, error) {
+	_, exist := os.Stat("my.db") // TODO: use configuration file for db path
+	if os.IsNotExist(exist) {
+		os.Create("my.db")
+	}
+	db, err := bolt.Open("my.db", 0777, nil)
+	if err != nil {
+		return nil, err
+	}
+	return db, nil
+}
+
+func AddNode(node Node, db *bolt.DB) error {
+	var err error
+	var deferDB bool
+	if db == nil {
+		db, err = OpenDB()
+		if err != nil {
+			return err
+		}
+		deferDB = true
+	}
+	err = db.Update(func(tx *bolt.Tx) error {
+		nodes, err := tx.CreateBucketIfNotExists([]byte("Nodes"))
+		if err != nil {
+			return err
+		}
+		if buf, err := json.Marshal(node); err != nil {
+			return err
+		} else if err := nodes.Put([]byte(node.PrevNodeSum), buf); err != nil {
+			return err
+		}
+		return nil
+
+	})
+	if deferDB {
+		defer db.Close()
+	}
+	return err
+}
+
+func GetNode(checksum string, db *bolt.DB) (Node, error) {
+	var err error
+	var deferDB bool
+	if db == nil {
+		db, err = OpenDB()
+		if err != nil {
+			return Node{}, err
+		}
+		deferDB = true
+	}
+	var node Node
+	err = db.View(func(tx *bolt.Tx) error {
+		nodes := tx.Bucket([]byte("Nodes"))
+		app := nodes.Get([]byte(checksum))
+		err := json.Unmarshal(app, &node)
+		return err
+	})
+	if deferDB {
+		defer db.Close()
+	}
+	return node, err
+}