Solidity SafeMath Checker - check if any math calculations in your solidity contracts don't use SafeMath. If yes, replace the math operators by SafeMath operators.

SafeMath is a solidity math library especially designed to support safe math operations: safe means that it prevents overflow when working with uint. You can find it in zeppelin-solidity SafeMath.

Workflow

Please copy the project to be checked to "./to_check" folder, the run:

python ./main.py  

Then you can find the backup files in "./backup" folder, the new files applying SafeMath in "./to_check" folder. Please note: if you encounter the exception below, please ignore it:

re.py:212: FutureWarning: split() requires a non-empty pattern match.
  return _compile(pattern, flags).split(string, maxsplit)

File Requirements

1. All Solidity files in the project to be checked are named as "*.sol".
2. All SafeMath files in the project to be checked are named as "SafeMath*.sol", and their file names are the same as the uint type they protect from overflow. e.g., SafeMath8.sol is to protect the uint8 calculation. Please note: there will be no SafeMath256.sol file but SafeMath.sol, which protects uint (uint256) from overflow.
3. All "*.sol" files are valid.

Running environment

• Windows, Linux

Software requirement

• Python3 with Anaconda installed

Logic

Take the files in "./example" folder as an example ("./example/backup" stores the files before running the program, "./example/to_check" stores the files after running):

1. Copy all .sol files (excluding SafeMath.sol files) to "./backup" folder.
2. Check all .sol files (excluding SafeMath.sol files) to record how many uint types are used.
3. Check all SafeMath*.sol files, find out which uint types are used (from the result of #1) without SafeMath*.sol file. e.g., C1.sol defines a uint32 variable v1, but the are no SafeMath32.sol file in the project.
4. According to the result of #2, create all missing SafeMath*.sol files in "./to_check/math" folder. e.g., create "./to_check/math/SafeMath32.sol" file.
5. In each file of .sol files (excluding SafeMath.sol files):
   5.1. Import all SafeMath*.sol files, and add "using" statements. e.g., add "using SafeMath8 for uint8;". 5.2. Change all ++ to add(1), -- to sub(1). e.g., change "v1++" to "v1.add(1)".

Limitation

1. The program doesn't support the left operand of a math operator is integer literal. e.g., 3*a will be changed to 3.mul(a) which is invalid.
2. The program doesn't support a statement with the left and right operands of a math operator across 2 lines. e.g., if (a>b +1) cannot be parsed correctly.
3. The program cannot protect the result of **, << from overflow. You can find how to protect them in Avoiding Integer Overflows: SafeMath Isn't Enough.

Solidity SafeMath Checker - 检查Solidity合同中的是否有数学计算未使用SafeMath。如有，替换数学符号为SafeMath运算符

SafeMath是一个专为支持安全数学运算而设计的可靠数学库：安全意味着它在使用uint时防止溢出。你可以在zeppelin-solidity SafeMath中找到它。

工作流程

请将要检查的项目复制到“./to_check”文件夹中，运行：

python./main.py

然后您可以在“./backup”文件夹中找到备份文件，在“./to_check”文件夹中找到应用了SafeMath的新文件。 请注意：如果你遇到以下异常，请忽略它：

re.py:212: FutureWarning: split() requires a non-empty pattern match.
  return _compile(pattern, flags).split(string, maxsplit)

文件要求

1. 要检查的项目中的所有Solidity文件都命名为“*.sol”。
2. 要检查的项目中的所有SafeMath文件都命名为“SafeMath*.sol”，它们的文件名与防止溢出的uint类型相同。例如，SafeMath8.sol将保护uint8计算。 请注意：防止uint和uint256的溢出的是SafeMath.sol，而不是SafeMath256.sol。
3. 所有“*.sol”文件都是合法的。

运行环境

• Windows，Linux

软件要求

• 安装了Anaconda的Python3

逻辑

以“./example”文件夹中的文件为例（“./example/backup”存储了运行程序前的文件，“./example/to_check”存储了运行程序后的文件）：

1. 将所有*.sol文件（不包括SafeMath*.sol文件）复制到“./backup”文件夹中。
2. 检查所有*.sol文件（不包括SafeMath*.sol文件）以记录使用了哪些uint类型。
3. 检查所有SafeMath*.sol文件，找出在没有SafeMath*.sol文件的情况下使用哪些uint类型（来自#1的结果）。例如，C1.sol定义了uint32变量v1，但项目中没有SafeMath32.sol文件。
4. 根据#2的结果，在“./to_check/math”文件夹中创建所有缺少的SafeMath*.sol文件。例如，创建“./to_check/math/SafeMath32.sol”文件。
5. 在*.sol文件的每个文件（不包括SafeMath*.sol文件）中： 5.1. 导入所有SafeMath*.sol文件，并添加“using”语句。例如，添加“using SafeMath8 for uint8;”。 5.2. 更改所有++为添加（1）， --为sub(1)。例如，将“v1++”改变为“v1.add(1)”。

局限性

1. 程序不支持数学运算符的左操作数是整数。例如，3*a，会被改变为3.mul(a)，这是非法的。
2. 程序不支持同一数学运算符的左操作数和右操作数跨2行的语句。例如： if (a>b +1) 不能被正确地处理
3. 程序无法保护**，<<的结果不会溢出。 你可以在Avoiding Integer Overflows: SafeMath Isn't Enough中找到保护这些运算的思路。