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12b8aa5c2e
## Why this should be merged
Fixes tracing when a stateful precompile calls another contract that
itself accesses storage.
## How this works
The pre-state tracer from `eth/tracers/native` doesn't implement
`CaptureEnter()` (entry of a new context), instead relying on
`CaptureState()` (per-opcode tracing) to detect that a new contract has
been entered. In doing so, it [maintains an
invariant](cb7eb89341/eth/tracers/native/prestate.go (L160))
that is expected when `CaptureState(vm.SLOAD, ...)` is called—breaking
the invariant results in a panic due to a nil map.
The fix involves (a) maintaining the invariant as part of
`CaptureEnter()` (previously a no-op); and (b) calling said method
inside `vm.PrecompileEnvironment.Call()`. The latter has the added
benefit of properly handling all tracing involving an outbound call from
precompiles.
## How this was tested
New integration test demonstrates that the tracer can log the retrieved
storage value.
---------
Co-authored-by: Darioush Jalali <darioush.jalali@avalabs.org>
37 lines
1.6 KiB
Go
37 lines
1.6 KiB
Go
// Copyright 2024 the libevm authors.
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//
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// The libevm additions to go-ethereum are free software: you can redistribute
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// them and/or modify them under the terms of the GNU Lesser General Public License
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// as published by the Free Software Foundation, either version 3 of the License,
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// or (at your option) any later version.
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//
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// The libevm additions are distributed in the hope that they will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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// General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see
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// <http://www.gnu.org/licenses/>.
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package native
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import (
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"math/big"
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"github.com/ava-labs/libevm/common"
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"github.com/ava-labs/libevm/core/vm"
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)
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// CaptureEnter implements the [vm.EVMLogger] hook for entering a new scope (via
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// CALL*, CREATE or SELFDESTRUCT).
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func (t *prestateTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
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// Although [prestateTracer.lookupStorage] expects
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// [prestateTracer.lookupAccount] to have been called, the invariant is
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// maintained by [prestateTracer.CaptureState] when it encounters an OpCode
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// corresponding to scope entry. This, however, doesn't work when using a
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// call method exposed by [vm.PrecompileEnvironment], and is restored by a
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// call to this CaptureEnter implementation. Note that lookupAccount(x) is
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// idempotent.
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t.lookupAccount(to)
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}
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