Consolidate code for clarity.

This commit consolidates some of the smaller files into some of the larger files.
The smaller files cluttered the file tree and made it harder to see the logical
groupings of structs.

1 files changed, 88 insertions, 0 deletions

diff --git a/db.go b/db.go
index 7e8dd7f..9754f21 100644
--- a/db.go
+++ b/db.go
@@ -3,6 +3,7 @@ package bolt
 import (
 	"errors"
 	"fmt"
+	"hash/fnv"
 	"io"
 	"os"
 	"sync"
@@ -16,6 +17,12 @@ const minMmapSize = 1 << 22 // 4MB
 // The largest step that can be taken when remapping the mmap.
 const maxMmapStep = 1 << 30 // 1GB
 
+// The data file format version.
+const version = 2
+
+// Represents a marker value to indicate that a file is a Bolt DB.
+const magic uint32 = 0xED0CDAED
+
 var (
 	// ErrDatabaseNotOpen is returned when a DB instance is accessed before it
 	// is opened or after it is closed.
@@ -24,6 +31,16 @@ var (
 	// ErrDatabaseOpen is returned when opening a database that is
 	// already open.
 	ErrDatabaseOpen = errors.New("database already open")
+
+	// ErrInvalid is returned when a data file is not a Bolt-formatted database.
+	ErrInvalid = errors.New("invalid database")
+
+	// ErrVersionMismatch is returned when the data file was created with a
+	// different version of Bolt.
+	ErrVersionMismatch = errors.New("version mismatch")
+
+	// ErrChecksum is returned when either meta page checksum does not match.
+	ErrChecksum = errors.New("checksum error")
 )
 
 // DB represents a collection of buckets persisted to a file on disk.
@@ -652,3 +669,74 @@ type Info struct {
 	Data     []byte
 	PageSize int
 }
+
+type meta struct {
+	magic    uint32
+	version  uint32
+	pageSize uint32
+	flags    uint32
+	root     bucket
+	freelist pgid
+	pgid     pgid
+	txid     txid
+	checksum uint64
+}
+
+// validate checks the marker bytes and version of the meta page to ensure it matches this binary.
+func (m *meta) validate() error {
+	if m.checksum != 0 && m.checksum != m.sum64() {
+		return ErrChecksum
+	} else if m.magic != magic {
+		return ErrInvalid
+	} else if m.version != version {
+		return ErrVersionMismatch
+	}
+	return nil
+}
+
+// copy copies one meta object to another.
+func (m *meta) copy(dest *meta) {
+	*dest = *m
+}
+
+// write writes the meta onto a page.
+func (m *meta) write(p *page) {
+	// Page id is either going to be 0 or 1 which we can determine by the transaction ID.
+	p.id = pgid(m.txid % 2)
+	p.flags |= metaPageFlag
+
+	// Calculate the checksum.
+	m.checksum = m.sum64()
+
+	m.copy(p.meta())
+}
+
+// generates the checksum for the meta.
+func (m *meta) sum64() uint64 {
+	var h = fnv.New64a()
+	_, _ = h.Write((*[unsafe.Offsetof(meta{}.checksum)]byte)(unsafe.Pointer(m))[:])
+	return h.Sum64()
+}
+
+// ErrorList represents a slice of errors.
+type ErrorList []error
+
+// Error returns a readable count of the errors in the list.
+func (l ErrorList) Error() string {
+	return fmt.Sprintf("%d errors occurred", len(l))
+}
+
+// _assert will panic with a given formatted message if the given condition is false.
+func _assert(condition bool, msg string, v ...interface{}) {
+	if !condition {
+		panic(fmt.Sprintf("assertion failed: "+msg, v...))
+	}
+}
+
+func warn(v ...interface{}) {
+	fmt.Fprintln(os.Stderr, v...)
+}
+
+func warnf(msg string, v ...interface{}) {
+	fmt.Fprintf(os.Stderr, msg+"\n", v...)
+}