c#判断exe文件是不是7z或者rar的自解压文件

亲测可以实现检测7z的自解压，但是对于rar的自解压格式，最新版不支持，尝试修改回发现几乎检测成了exe文件，这显然是不正确的，其他版本未测试。

如下图所示，可以检测出自解压格式的7z文件，黑色显示。

直接上代码：

public class SelfExtractingChecker{public static bool Is7zOrRarSfx(string filePath){try{using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read)){// 检查RAR自解压文件签名if (CheckRarSignature(fs)){return true;}// 检查7z自解压文件签名if (Check7zSignature(fs)){return true;}}}catch{// 处理文件访问异常return false;}return false;}private static bool CheckRarSignature(FileStream fs){// RAR签名："Rar!\x1A\x07\x00"（7字节）byte[] rarSig = { 0x52, 0x61, 0x72, 0x21, 0x1A, 0x07, 0x00 };// 常见偏移量（按优先级排序）int[] possibleOffsets = { 0x200, 0x210, 0x400, 0x1000 };foreach (int offset in possibleOffsets){if (fs.Length > offset + rarSig.Length){fs.Seek(offset, SeekOrigin.Begin);byte[] buffer = new byte[rarSig.Length];int bytesRead = fs.Read(buffer, 0, buffer.Length);if (bytesRead == buffer.Length && buffer.SequenceEqual(rarSig)){return true;}}}return false;}private static bool Check7zSignature(FileStream fs){// 7z签名："7z\xBC\xAF\x27\x1C"（6字节）byte[] sevenZipSig = { 0x37, 0x7A, 0xBC, 0xAF, 0x27, 0x1C };const int bufferSize = 4096;byte[] buffer = new byte[bufferSize];int overlap = sevenZipSig.Length - 1;int bytesRead;long totalRead = 0;fs.Seek(0, SeekOrigin.Begin);while ((bytesRead = fs.Read(buffer, 0, bufferSize)) > 0){// 检查当前缓冲区for (int i = 0; i < bytesRead - overlap; i++){bool match = true;for (int j = 0; j < sevenZipSig.Length; j++){if (i + j >= bytesRead || buffer[i + j] != sevenZipSig[j]){match = false;break;}}if (match){return true;}}// 处理边界情况：保留最后几个字节与下一块组合if (bytesRead >= overlap){Array.Copy(buffer, bytesRead - overlap, buffer, 0, overlap);totalRead += bytesRead - overlap;}else{Array.Copy(buffer, 0, buffer, 0, bytesRead);totalRead += bytesRead;}// 检查是否超过合理搜索范围（前20MB）if (totalRead > 20 * 1024 * 1024){break;}}return false;}}

以上，谨此纪念。