1 files changed, 54 insertions, 43 deletions

diff --git a/src/dedo.go b/src/dedo.go
index 8e37154..416d575 100644
--- a/src/dedo.go
+++ b/src/dedo.go
@@ -96,6 +96,10 @@ type elemRef struct {
 	index int
 }
 
+type dbops struct {
+	writeAt func(b []byte, off int64) (n int, err error)
+}
+
 // DB represents a collection of buckets persisted to a file on disk.
 // All data access is performed through transactions which can be obtained through the DB.
 // All the functions on DB will return a ErrDatabaseNotOpen if accessed before Open() is called.
@@ -153,9 +157,7 @@ type DB struct {
 	mmaplock sync.RWMutex // Protects mmap access during remapping.
 	statlock sync.RWMutex // Protects stats access.
 
-	ops struct {
-		writeAt func(b []byte, off int64) (n int, err error)
-	}
+	ops dbops
 }
 
 type call struct {
@@ -1726,6 +1728,19 @@ func (db *DB) String() string {
 	return fmt.Sprintf("DB<%q>", db.path)
 }
 
+func newDB(path string, file *os.File) *DB {
+	db := &DB{
+		MaxBatchSize:  DefaultMaxBatchSize,
+		MaxBatchDelay: DefaultMaxBatchDelay,
+		AllocSize:     DefaultAllocSize,
+		opened:        true,
+		path:          path,
+		file:          file,
+		ops:           dbops{file.WriteAt},
+	}
+	return db
+}
+
 func openFile(path string) (*os.File, error) {
 	const (
 		fileMode = 0o666
@@ -1749,23 +1764,18 @@ func openFile(path string) (*os.File, error) {
 // If the file does not exist then it will be created automatically.
 // Passing in nil options will cause Bolt to open the database with the default options.
 func Open(path string) (*DB, error) {
-	var db = &DB{
-		opened: true,
-		path:   path,
+	file, err := openFile(path)
+	if err != nil {
+		return nil, err
 	}
 
-	// Set default values for later DB operations.
-	db.MaxBatchSize = DefaultMaxBatchSize
-	db.MaxBatchDelay = DefaultMaxBatchDelay
-	db.AllocSize = DefaultAllocSize
-
-	file, err := openFile(path)
+	info, err := file.Stat()
 	if err != nil {
-		_ = db.close()
+		file.Close()
 		return nil, err
 	}
-	db.file = file
 
+	db := newDB(path, file)
 	// Lock file so that other processes using Bolt in read-write mode cannot
 	// use the database  at the same time. This would cause corruption since
 	// the two processes would write meta pages and free pages separately.
@@ -1778,35 +1788,9 @@ func Open(path string) (*DB, error) {
 		return nil, err
 	}
 
-	// Default values for test hooks
-	db.ops.writeAt = db.file.WriteAt
-
-	// Initialize the database if it doesn't exist.
-	if info, err := db.file.Stat(); err != nil {
+	err = initDB(db, info.Size())
+	if err != nil {
 		return nil, err
-	} else if info.Size() == 0 {
-		// Initialize new files with meta pages.
-		if err := db.init(); err != nil {
-			return nil, err
-		}
-	} else {
-		// Read the first meta page to determine the page size.
-		var buf [0x1000]byte
-		if _, err := db.file.ReadAt(buf[:], 0); err == nil {
-			m := db.pageInBuffer(buf[:], 0).meta()
-			if err := m.validate(); err != nil {
-				// If we can't read the page size, we can assume it's the same
-				// as the OS -- since that's how the page size was chosen in the
-				// first place.
-				//
-				// If the first page is invalid and this OS uses a different
-				// page size than what the database was created with then we
-				// are out of luck and cannot access the database.
-				db.pageSize = os.Getpagesize()
-			} else {
-				db.pageSize = int(m.pageSize)
-			}
-		}
 	}
 
 	// Initialize page pool.
@@ -1929,8 +1913,35 @@ func (db *DB) mmapSize(size int) (int, error) {
 	return int(sz), nil
 }
 
+func readPageSize(db *DB) (int, error) {
+	// Read the first meta page to determine the page size.
+	var buf [0x1000]byte
+	_, err := db.file.ReadAt(buf[:], 0)
+	if err != nil {
+		return 0, err
+	}
+
+	m := db.pageInBuffer(buf[:], 0).meta()
+	err = m.validate()
+	if err != nil {
+		// return 0, err
+		return os.Getpagesize(), nil
+	}
+
+	return int(m.pageSize), nil
+}
+
 // init creates a new database file and initializes its meta pages.
-func (db *DB) init() error {
+func initDB(db *DB, size int64) error {
+	if size != 0 {
+		pageSize, err := readPageSize(db)
+		if err != nil {
+			return err
+		}
+
+		db.pageSize = pageSize
+		return nil
+	}
 	// Set the page size to the OS page size.
 	db.pageSize = os.Getpagesize()