diff options
Diffstat (limited to 'libsolidity')
| -rw-r--r-- | libsolidity/codegen/ExpressionCompiler.cpp | 43 |
1 files changed, 38 insertions, 5 deletions
diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp index 41c14517..1f93cf8c 100644 --- a/libsolidity/codegen/ExpressionCompiler.cpp +++ b/libsolidity/codegen/ExpressionCompiler.cpp @@ -1449,6 +1449,19 @@ void ExpressionCompiler::appendExternalFunctionCall( argumentTypes.push_back(_arguments[i]->annotation().type); } + if (funKind == FunctionKind::ECRecover) + { + // Clears 32 bytes of currently free memory and advances free memory pointer. + // Output area will be "start of input area" - 32. + // The reason is that a failing ECRecover cannot be detected, it will just return + // zero bytes (which we cannot detect). + solAssert(0 < retSize && retSize <= 32, ""); + utils().fetchFreeMemoryPointer(); + m_context << Instruction::DUP1 << u256(0) << Instruction::MSTORE; + m_context << u256(32) << Instruction::ADD; + utils().storeFreeMemoryPointer(); + } + // Copy function identifier to memory. utils().fetchFreeMemoryPointer(); if (!_functionType.isBareCall() || manualFunctionId) @@ -1457,7 +1470,7 @@ void ExpressionCompiler::appendExternalFunctionCall( utils().storeInMemoryDynamic(IntegerType(8 * CompilerUtils::dataStartOffset), false); } // If the function takes arbitrary parameters, copy dynamic length data in place. - // Move argumenst to memory, will not update the free memory pointer (but will update the memory + // Move arguments to memory, will not update the free memory pointer (but will update the memory // pointer on the stack). utils().encodeToMemory( argumentTypes, @@ -1475,12 +1488,24 @@ void ExpressionCompiler::appendExternalFunctionCall( // function identifier [unless bare] // contract address - // Output data will replace input data. + // Output data will replace input data, unless we have ECRecover (then, output + // area will be 32 bytes just before input area). // put on stack: <size of output> <memory pos of output> <size of input> <memory pos of input> m_context << u256(retSize); - utils().fetchFreeMemoryPointer(); - m_context << Instruction::DUP1 << Instruction::DUP4 << Instruction::SUB; - m_context << Instruction::DUP2; + utils().fetchFreeMemoryPointer(); // This is the start of input + if (funKind == FunctionKind::ECRecover) + { + // In this case, output is 32 bytes before input and has already been cleared. + m_context << u256(32) << Instruction::DUP2 << Instruction::SUB << Instruction::SWAP1; + // Here: <input end> <output size> <outpos> <input pos> + m_context << Instruction::DUP1 << Instruction::DUP5 << Instruction::SUB; + m_context << Instruction::SWAP1; + } + else + { + m_context << Instruction::DUP1 << Instruction::DUP4 << Instruction::SUB; + m_context << Instruction::DUP2; + } // CALL arguments: outSize, outOff, inSize, inOff (already present up to here) // [value,] addr, gas (stack top) @@ -1543,6 +1568,14 @@ void ExpressionCompiler::appendExternalFunctionCall( utils().loadFromMemoryDynamic(IntegerType(160), false, true, false); utils().convertType(IntegerType(160), FixedBytesType(20)); } + else if (funKind == FunctionKind::ECRecover) + { + // Output is 32 bytes before input / free mem pointer. + // Failing ecrecover cannot be detected, so we clear output before the call. + m_context << u256(32); + utils().fetchFreeMemoryPointer(); + m_context << Instruction::SUB << Instruction::MLOAD; + } else if (!_functionType.returnParameterTypes().empty()) { utils().fetchFreeMemoryPointer(); |