142 lines
3.2 KiB
Go
142 lines
3.2 KiB
Go
package backupds
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import (
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"bytes"
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"crypto/sha256"
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"io"
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"os"
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"github.com/ipfs/go-datastore"
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cbg "github.com/whyrusleeping/cbor-gen"
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"golang.org/x/xerrors"
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)
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func ReadBackup(r io.Reader, cb func(key datastore.Key, value []byte) error) error {
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scratch := make([]byte, 9)
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// read array[2](
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if _, err := r.Read(scratch[:1]); err != nil {
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return xerrors.Errorf("reading array header: %w", err)
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}
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if scratch[0] != 0x82 {
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return xerrors.Errorf("expected array(2) header byte 0x82, got %x", scratch[0])
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}
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hasher := sha256.New()
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hr := io.TeeReader(r, hasher)
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// read array[*](
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if _, err := hr.Read(scratch[:1]); err != nil {
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return xerrors.Errorf("reading array header: %w", err)
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}
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if scratch[0] != 0x9f {
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return xerrors.Errorf("expected indefinite length array header byte 0x9f, got %x", scratch[0])
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}
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for {
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if _, err := hr.Read(scratch[:1]); err != nil {
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return xerrors.Errorf("reading tuple header: %w", err)
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}
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// close array[*]
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if scratch[0] == 0xff {
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break
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}
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// read array[2](key:[]byte, value:[]byte)
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if scratch[0] != 0x82 {
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return xerrors.Errorf("expected array(2) header 0x82, got %x", scratch[0])
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}
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keyb, err := cbg.ReadByteArray(hr, 1<<40)
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if err != nil {
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return xerrors.Errorf("reading key: %w", err)
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}
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key := datastore.NewKey(string(keyb))
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value, err := cbg.ReadByteArray(hr, 1<<40)
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if err != nil {
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return xerrors.Errorf("reading value: %w", err)
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}
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if err := cb(key, value); err != nil {
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return err
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}
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}
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sum := hasher.Sum(nil)
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// read the [32]byte checksum
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expSum, err := cbg.ReadByteArray(r, 32)
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if err != nil {
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return xerrors.Errorf("reading expected checksum: %w", err)
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}
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if !bytes.Equal(sum, expSum) {
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return xerrors.Errorf("checksum didn't match; expected %x, got %x", expSum, sum)
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}
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// read the log, set of Entry-ies
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var ent Entry
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bp := cbg.GetPeeker(r)
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for {
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_, err := bp.ReadByte()
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switch err {
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case io.EOF, io.ErrUnexpectedEOF:
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return nil
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case nil:
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default:
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return xerrors.Errorf("peek log: %w", err)
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}
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if err := bp.UnreadByte(); err != nil {
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return xerrors.Errorf("unread log byte: %w", err)
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}
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if err := ent.UnmarshalCBOR(bp); err != nil {
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switch err {
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case io.EOF, io.ErrUnexpectedEOF:
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if os.Getenv("LOTUS_ALLOW_TRUNCATED_LOG") == "1" {
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panic("handleme; just ignore and tell the caller about the corrupted file") // todo
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} else {
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return xerrors.Errorf("log entry potentially truncated, set LOTUS_ALLOW_TRUNCATED_LOG=1 to proceed: %w", err)
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}
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default:
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return xerrors.Errorf("unmarshaling log entry: %w", err)
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}
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}
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key := datastore.NewKey(string(ent.Key))
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if err := cb(key, ent.Value); err != nil {
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return err
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}
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}
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}
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func RestoreInto(r io.Reader, dest datastore.Batching) error {
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batch, err := dest.Batch()
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if err != nil {
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return xerrors.Errorf("creating batch: %w", err)
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}
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err = ReadBackup(r, func(key datastore.Key, value []byte) error {
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if err := batch.Put(key, value); err != nil {
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return xerrors.Errorf("put key: %w", err)
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}
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return nil
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})
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if err != nil {
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return xerrors.Errorf("reading backup: %w", err)
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}
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if err := batch.Commit(); err != nil {
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return xerrors.Errorf("committing batch: %w", err)
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}
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return nil
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}
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