fix: use a consistent tipset in commands

It's very easy to write an incorrect command that operates over
different heads by using the "empty" tipset. This change makes the
`LoadTipSet` command helper get the latest head from the lotus daemon if
its unset.

The cost is an extra call to get the head. That should be trivial in
most cases.

cli/chain.go

@@ -723,12 +723,6 @@ var ChainGetCmd = &cli.Command{
 				return err
 			}
 
-			if ts == nil {
-				ts, err = api.ChainHead(ctx)
-				if err != nil {
-					return err
-				}
-			}
 			p = "/ipfs/" + ts.ParentState().String() + p
 			if cctx.Bool("verbose") {
 				fmt.Println(p)

cli/state.go

@@ -180,10 +180,13 @@ func ParseTipSetString(ts string) ([]cid.Cid, error) {
 	return cids, nil
 }
 
+// LoadTipSet gets the tipset from the context, or the head from the API.
+//
+// It always gets the head from the API so commands use a consistent tipset even if time pases.
 func LoadTipSet(ctx context.Context, cctx *cli.Context, api v0api.FullNode) (*types.TipSet, error) {
 	tss := cctx.String("tipset")
 	if tss == "" {
-		return nil, nil
+		return api.ChainHead(ctx)
 	}
 
 	return ParseTipSetRef(ctx, api, tss)
@@ -850,14 +853,6 @@ var StateListMessagesCmd = &cli.Command{
 			return err
 		}
 
-		if ts == nil {
-			head, err := api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-			ts = head
-		}
-
 		windowSize := abi.ChainEpoch(100)
 
 		cur := ts
@@ -957,13 +952,6 @@ var StateComputeStateCmd = &cli.Command{
 		}
 
 		h := abi.ChainEpoch(cctx.Uint64("vm-height"))
-		if ts == nil {
-			head, err := api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-			ts = head
-		}
 		if h == 0 {
 			h = ts.Height()
 		}
@@ -1765,13 +1753,6 @@ var StateSectorCmd = &cli.Command{
 			return err
 		}
 
-		if ts == nil {
-			ts, err = api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-		}
-
 		maddr, err := address.NewFromString(cctx.Args().Get(0))
 		if err != nil {
 			return err

cmd/lotus-shed/frozen-miners.go

@@ -35,12 +35,6 @@ var frozenMinersCmd = &cli.Command{
 		if err != nil {
 			return err
 		}
-		if ts == nil {
-			ts, err = api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-		}
 
 		queryEpoch := ts.Height()
 

cmd/lotus-shed/postfind.go

@@ -49,12 +49,6 @@ var postFindCmd = &cli.Command{
 		if err != nil {
 			return err
 		}
-		if startTs == nil {
-			startTs, err = api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-		}
 		stopEpoch := startTs.Height() - abi.ChainEpoch(c.Int("lookback"))
 		if verbose {
 			fmt.Printf("Collecting messages between %d and %d\n", startTs.Height(), stopEpoch)

cmd/lotus-shed/stateroot-stats.go

@@ -56,13 +56,6 @@ var staterootDiffsCmd = &cli.Command{
 			return err
 		}
 
-		if ts == nil {
-			ts, err = api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-		}
-
 		fn := func(ts *types.TipSet) (cid.Cid, []cid.Cid) {
 			blk := ts.Blocks()[0]
 			strt := blk.ParentStateRoot
@@ -134,13 +127,6 @@ var staterootStatCmd = &cli.Command{
 			return err
 		}
 
-		if ts == nil {
-			ts, err = api.ChainHead(ctx)
-			if err != nil {
-				return err
-			}
-		}
-
 		var addrs []address.Address
 
 		for _, inp := range cctx.Args().Slice() {