From 9833b45b3b766813d36df2811d35d2bd8942897e Mon Sep 17 00:00:00 2001
From: Stephen Buttolph <stephen@avalabs.org>
Date: Sat, 23 Mar 2024 22:21:23 -0400
Subject: [PATCH] Revert removal of legacy P-chain block parsing (#2866)

---
 vms/platformvm/state/state.go      |  34 ++++++++-
 vms/platformvm/state/state_test.go | 111 +++++++++++++++++++++++++++++
 2 files changed, 144 insertions(+), 1 deletion(-)

diff --git a/vms/platformvm/state/state.go b/vms/platformvm/state/state.go
index 77047389c1c1..45360a13b764 100644
--- a/vms/platformvm/state/state.go
+++ b/vms/platformvm/state/state.go
@@ -21,6 +21,7 @@ import (
 	"github.com/ava-labs/avalanchego/database/versiondb"
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/snow"
+	"github.com/ava-labs/avalanchego/snow/choices"
 	"github.com/ava-labs/avalanchego/snow/uptime"
 	"github.com/ava-labs/avalanchego/snow/validators"
 	"github.com/ava-labs/avalanchego/utils"
@@ -178,6 +179,16 @@ type State interface {
 	Close() error
 }
 
+// Prior to https://github.com/ava-labs/avalanchego/pull/1719, blocks were
+// stored as a map from blkID to stateBlk. Nodes synced prior to this PR may
+// still have blocks partially stored using this legacy format.
+//
+// TODO: Remove after v1.12.x is activated
+type stateBlk struct {
+	Bytes  []byte         `serialize:"true"`
+	Status choices.Status `serialize:"true"`
+}
+
 /*
  * VMDB
  * |-. validators
@@ -1789,7 +1800,7 @@ func (s *state) GetStatelessBlock(blockID ids.ID) (block.Block, error) {
 		return nil, err
 	}
 
-	blk, err := block.Parse(block.GenesisCodec, blkBytes)
+	blk, _, err := parseStoredBlock(blkBytes)
 	if err != nil {
 		return nil, err
 	}
@@ -2260,3 +2271,24 @@ func (s *state) writeMetadata() error {
 	}
 	return nil
 }
+
+// Returns the block and whether it is a [stateBlk].
+// Invariant: blkBytes is safe to parse with blocks.GenesisCodec
+//
+// TODO: Remove after v1.12.x is activated
+func parseStoredBlock(blkBytes []byte) (block.Block, bool, error) {
+	// Attempt to parse as blocks.Block
+	blk, err := block.Parse(block.GenesisCodec, blkBytes)
+	if err == nil {
+		return blk, false, nil
+	}
+
+	// Fallback to [stateBlk]
+	blkState := stateBlk{}
+	if _, err := block.GenesisCodec.Unmarshal(blkBytes, &blkState); err != nil {
+		return nil, false, err
+	}
+
+	blk, err = block.Parse(block.GenesisCodec, blkState.Bytes)
+	return blk, true, err
+}
diff --git a/vms/platformvm/state/state_test.go b/vms/platformvm/state/state_test.go
index 17343de5eb8f..b0f6afa596f9 100644
--- a/vms/platformvm/state/state_test.go
+++ b/vms/platformvm/state/state_test.go
@@ -18,6 +18,7 @@ import (
 	"github.com/ava-labs/avalanchego/database/memdb"
 	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/snow"
+	"github.com/ava-labs/avalanchego/snow/choices"
 	"github.com/ava-labs/avalanchego/snow/validators"
 	"github.com/ava-labs/avalanchego/utils/constants"
 	"github.com/ava-labs/avalanchego/utils/crypto/bls"
@@ -1293,6 +1294,116 @@ func requireEqualPublicKeysValidatorSet(
 	}
 }
 
+func TestParsedStateBlock(t *testing.T) {
+	require := require.New(t)
+
+	var blks []block.Block
+
+	{
+		blk, err := block.NewApricotAbortBlock(ids.GenerateTestID(), 1000)
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		blk, err := block.NewApricotAtomicBlock(ids.GenerateTestID(), 1000, &txs.Tx{
+			Unsigned: &txs.AdvanceTimeTx{
+				Time: 1000,
+			},
+		})
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		blk, err := block.NewApricotCommitBlock(ids.GenerateTestID(), 1000)
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		tx := &txs.Tx{
+			Unsigned: &txs.RewardValidatorTx{
+				TxID: ids.GenerateTestID(),
+			},
+		}
+		require.NoError(tx.Initialize(txs.Codec))
+		blk, err := block.NewApricotProposalBlock(ids.GenerateTestID(), 1000, tx)
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		tx := &txs.Tx{
+			Unsigned: &txs.RewardValidatorTx{
+				TxID: ids.GenerateTestID(),
+			},
+		}
+		require.NoError(tx.Initialize(txs.Codec))
+		blk, err := block.NewApricotStandardBlock(ids.GenerateTestID(), 1000, []*txs.Tx{tx})
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		blk, err := block.NewBanffAbortBlock(time.Now(), ids.GenerateTestID(), 1000)
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		blk, err := block.NewBanffCommitBlock(time.Now(), ids.GenerateTestID(), 1000)
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		tx := &txs.Tx{
+			Unsigned: &txs.RewardValidatorTx{
+				TxID: ids.GenerateTestID(),
+			},
+		}
+		require.NoError(tx.Initialize(txs.Codec))
+
+		blk, err := block.NewBanffProposalBlock(time.Now(), ids.GenerateTestID(), 1000, tx, []*txs.Tx{})
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	{
+		tx := &txs.Tx{
+			Unsigned: &txs.RewardValidatorTx{
+				TxID: ids.GenerateTestID(),
+			},
+		}
+		require.NoError(tx.Initialize(txs.Codec))
+
+		blk, err := block.NewBanffStandardBlock(time.Now(), ids.GenerateTestID(), 1000, []*txs.Tx{tx})
+		require.NoError(err)
+		blks = append(blks, blk)
+	}
+
+	for _, blk := range blks {
+		stBlk := stateBlk{
+			Bytes:  blk.Bytes(),
+			Status: choices.Accepted,
+		}
+
+		stBlkBytes, err := block.GenesisCodec.Marshal(block.CodecVersion, &stBlk)
+		require.NoError(err)
+
+		gotBlk, isStateBlk, err := parseStoredBlock(stBlkBytes)
+		require.NoError(err)
+		require.True(isStateBlk)
+		require.Equal(blk.ID(), gotBlk.ID())
+
+		gotBlk, isStateBlk, err = parseStoredBlock(blk.Bytes())
+		require.NoError(err)
+		require.False(isStateBlk)
+		require.Equal(blk.ID(), gotBlk.ID())
+	}
+}
+
 func TestStateSubnetOwner(t *testing.T) {
 	require := require.New(t)