forked from knqyf263/go-rpmdb
/
hash_metadata_page.go
66 lines (53 loc) · 1.83 KB
/
hash_metadata_page.go
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package bdb
import (
"bytes"
"encoding/binary"
"golang.org/x/xerrors"
)
// source: https://github.com/berkeleydb/libdb/blob/5b7b02ae052442626af54c176335b67ecc613a30/src/dbinc/db_page.h#L130
type HashMetadata struct {
GenericMetadataPage
MaxBucket uint32 `struct:"uint32"` /* 72-75: ID of Maximum bucket in use */
HighMask uint32 `struct:"uint32"` /* 76-79: Modulo mask into table */
LowMask uint32 `struct:"uint32"` /* 80-83: Modulo mask into table lower half */
FillFactor uint32 `struct:"uint32"` /* 84-87: Fill factor */
NumKeys uint32 `struct:"uint32"` /* 88-91: Number of keys in hash table */
CharKeyHash uint32 `struct:"uint32"` /* 92-95: Value of hash(CHARKEY) */
// don't care about the rest...
}
type HashMetadataPage struct {
HashMetadata
Swapped bool
}
func ParseHashMetadataPage(data []byte) (*HashMetadataPage, error) {
var pageMetadata HashMetadataPage
var metadata HashMetadata
pageMetadata.Swapped = false
err := binary.Read(bytes.NewReader(data), binary.LittleEndian, &metadata)
if err != nil {
return nil, xerrors.Errorf("failed to unpack HashMetadataPage: %w", err)
}
if metadata.Magic == HashMagicNumberBE {
// Re-read the generic metadata as BigEndian
pageMetadata.Swapped = true
err := binary.Read(bytes.NewReader(data), binary.BigEndian, &metadata.GenericMetadataPage)
if err != nil {
return nil, xerrors.Errorf("failed to unpack HashMetadataPage: %w", err)
}
}
pageMetadata.HashMetadata = metadata
return &pageMetadata, pageMetadata.validate()
}
func (p *HashMetadata) validate() error {
err := p.GenericMetadataPage.validate()
if err != nil {
return err
}
if p.Magic != HashMagicNumber {
return xerrors.Errorf("unexpected DB magic number: %+v", p.Magic)
}
if p.PageType != HashMetadataPageType {
return xerrors.Errorf("unexpected page type: %+v", p.PageType)
}
return nil
}