mirror of https://github.com/hak5/bolt.git
70 lines
1.5 KiB
Go
70 lines
1.5 KiB
Go
package bolt
|
|
|
|
import (
|
|
"errors"
|
|
"hash/fnv"
|
|
"unsafe"
|
|
)
|
|
|
|
const magic uint32 = 0xED0CDAED
|
|
|
|
var (
|
|
// 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")
|
|
)
|
|
|
|
type meta struct {
|
|
magic uint32
|
|
version uint32
|
|
pageSize uint32
|
|
flags uint32
|
|
buckets pgid
|
|
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()
|
|
}
|