logo标签列表

文件未找到异常随机抛出。

c#
9
我正在开发一个C#工具，用于从未格式化的SD卡中读取8 GB的十六进制数据。
它能够做到这一点，但会随机抛出文件未找到异常。例如，它会读取一两个GB，然后抛出异常。其他时候，它会连续几次读取所有8 GB，然后抛出异常。换句话说，它似乎完全是随机弹出的。
我不知道可能是什么原因导致的。
编辑：我已经使用反馈来微调一些东西。下面粘贴的是更新后的代码。
它仍然会随机抛出文件未找到异常，但现在在尝试读取第8 GB的第432 MB时始终会抛出参数异常（如果没有随机抛出文件未找到异常）。
错误提示文件句柄不支持同步操作。
class Program
{
    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    static extern SafeFileHandle CreateFile(string lpFileName, uint dwDesiredAccess,
      uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition,
      uint dwFlagsAndAttributes, IntPtr hTemplateFile);

    static void Main(string[] args)
    {
        string testOutputDirectory = @"C:\\Users\\aiovanna\\Desktop\\out1.txt"; //Specifies where to write the results of the read.
        try
        {
            SafeFileHandle fileHandle = CreateFile("\\\\.\\E:", 0x80000000, 0, IntPtr.Zero, 3, 0, IntPtr.Zero);
            FileStream readStream = new FileStream(fileHandle, FileAccess.Read); //The stream to be read. Is converted to binary.
            BufferedStream bufStream = new BufferedStream(readStream, 1048576);
            FileStream writeStream = File.OpenWrite(testOutputDirectory); //Writing stream opened at the specified directory of output.
            //BinaryReader reader = new BinaryReader(readStream); //Changes the read stream to binary. Has more powerful methods.

            long gigsRead; //Loop counter that specifies the number of gigabytes read thus far.
            long megsRead; //Loop counter that specifies the number of megabytes read thus far within the current gigabyte.

            Stopwatch totalStopwatch = new Stopwatch(); //Stopwatch to time the total execution of the card read.
            Stopwatch megStopwatch = new Stopwatch(); //Stopwatch to time the execution of reading the current megabyte.
            Stopwatch gigStopwatch = new Stopwatch(); //Stopwatch to time the executation of reading the current gigabyte. 
            totalStopwatch.Start(); //Start timing the program. 
            int bytesRead; 

            for (gigsRead = 0; gigsRead < 8; gigsRead++) //Gigabyte loop
            {
                gigStopwatch.Start(); //Start timer for current gigabyte. 
                for (megsRead = 0; megsRead < 1024; megsRead++) //Megabyte loop
                {
                    megStopwatch.Start(); //Start timer for current megabyte. 

                    try
                    {
                        byte[] buffer = new byte[1048576]; //Buffer to be read into from card
                        long test = gigsRead * 1073741824 + megsRead * 1048576;
                        bufStream.Position = test;
                        bytesRead = bufStream.Read(buffer, 0, 1048576); //Read from SD card to buffer
                        if (bytesRead < 1048576)
                        {
                            Console.WriteLine("Didn't read whole chunk!");
                        }
                        writeStream.Write(buffer, 0, 1048576); //Write from buffer to output text file.
                        megStopwatch.Stop(); //Stop timer for current megabyte. 
                        Console.WriteLine("Finished mb {0} of gig {1} in {2}", megsRead + 1, gigsRead + 1, megStopwatch.Elapsed);
                        megStopwatch.Reset(); //Reset for next megabyte. 
                    }

                    catch (System.IO.FileNotFoundException ex)
                    {
                        System.Console.WriteLine("The error was: {0}", Marshal.GetLastWin32Error());
                        System.Console.WriteLine("Message: {0}", ex.Message);
                        System.Console.WriteLine("Source: {0}", ex.Source);
                        System.Console.WriteLine("Stack Trace: {0}", ex.StackTrace);
                        System.Console.WriteLine("Target Site: {0}", ex.TargetSite);
                        System.Console.WriteLine(ex.ToString());
                        writeStream.Close(); //Close writing stream.
                        //reader.Close(); //Close the binary reader stream.
                        bufStream.Close();
                        fileHandle.Close(); //Close the SD card file.
                        readStream.Close(); //Close the filestream reader.
                        System.Console.WriteLine("You will need to turn off your computer, take out the card, turn the computer back on, put the SD card back in, and re-run the program.");
                        System.Console.WriteLine("Press any key to terminate.");
                        System.Console.ReadKey();
                        System.Environment.Exit(1);
                    }

                    catch (System.ArgumentException ex)
                    {
                        System.Console.WriteLine("The error was: {0}", Marshal.GetLastWin32Error());
                        System.Console.WriteLine("Message: {0}", ex.Message);
                        System.Console.WriteLine("Param Name: {0}", ex.ParamName);
                        System.Console.WriteLine("Source: {0}", ex.Source);
                        System.Console.WriteLine("Stack Trace: {0}", ex.StackTrace);
                        System.Console.WriteLine("Target Site: {0}", ex.TargetSite);
                        System.Console.WriteLine(ex.ToString());
                        writeStream.Close(); //Close writing stream.
                        //reader.Close(); //Close the binary reader stream.
                        fileHandle.Close(); //Close the SD card file.
                        readStream.Close(); //Close the filestream reader.
                        System.Console.WriteLine("You will need to turn off your computer, take out the card, turn the computer back on, put the SD card back in, and re-run the program.");
                        System.Console.WriteLine("Press any key to terminate.");
                        System.Console.ReadKey();
                        System.Environment.Exit(1);
                    }
                }
                gigStopwatch.Stop(); //Stop timer for current gigabyte. 
                Console.WriteLine("Finished gig {0} in {1}", gigsRead + 1, gigStopwatch.Elapsed);
                gigStopwatch.Reset(); //Reset for next gigabyte. 
            }
            totalStopwatch.Stop(); //Stop total execution timer.
            Console.WriteLine(totalStopwatch.Elapsed); //Print total execution timer.
            writeStream.Close(); //Close writing stream.
            //reader.Close(); //Close the binary reader stream.
            writeStream.Close(); //Close writing stream.
            fileHandle.Close(); //Close the SD card file.
            readStream.Close(); //Close the filestream reader.
            bufStream.Close();
        }

        catch (System.IO.IsolatedStorage.IsolatedStorageException ex)
        {
            System.Console.WriteLine("The error was: {0}", Marshal.GetLastWin32Error());
            System.Console.WriteLine("Isolated Storage Exception");
            System.Console.WriteLine("Data: {0}", ex.Data);
            System.Console.WriteLine("Help Link: {0}", ex.HelpLink);
            System.Console.WriteLine("Inner Exception: {0}", ex.InnerException);
            System.Console.WriteLine("Message: {0}", ex.Message);
            System.Console.WriteLine("Source: {0}", ex.Source);
            System.Console.WriteLine("Stack Trace {0}", ex.StackTrace);
            System.Console.WriteLine("Target Site: {0}", ex.TargetSite);
            Console.ReadKey();
        }

        catch (System.ArgumentException ex)
        {
            System.Console.WriteLine("The error was: {0}", Marshal.GetLastWin32Error());
            System.Console.WriteLine("Argument Exception");
            System.Console.WriteLine("Data: {0}", ex.Data);
            System.Console.WriteLine("Help Link: {0}", ex.HelpLink);
            System.Console.WriteLine("Inner Exception: {0}", ex.InnerException);
            System.Console.WriteLine("Message: {0}", ex.Message);
            System.Console.WriteLine("Param Name: {0}", ex.ParamName);
            System.Console.WriteLine("Source: {0}", ex.Source);
            System.Console.WriteLine("Stack Trace {0}", ex.StackTrace);
            System.Console.WriteLine("Target Site: {0}", ex.TargetSite);
            Console.ReadKey();
        }

        catch (System.IO.DirectoryNotFoundException ex)
        {
            System.Console.WriteLine("The error was: {0}", Marshal.GetLastWin32Error());
            System.Console.WriteLine("Directory Not Found Exception");
            System.Console.WriteLine("Data: {0}", ex.Data);
            System.Console.WriteLine("Help Link: {0}", ex.HelpLink);
            System.Console.WriteLine("Inner Exception: {0}", ex.InnerException);
            System.Console.WriteLine("Message: {0}", ex.Message);
            System.Console.WriteLine("Source: {0}", ex.Source);
            System.Console.WriteLine("Stack Trace {0}", ex.StackTrace);
            System.Console.WriteLine("Target Site: {0}", ex.TargetSite);
            System.Console.ReadKey();
        }

        catch (System.ObjectDisposedException ex)
        {
            System.Console.WriteLine("The error was: {0}", Marshal.GetLastWin32Error());
            System.Console.WriteLine("Object Disposed Exception");
            System.Console.WriteLine("Data: {0}", ex.Data);
            System.Console.WriteLine("Help Link: {0}", ex.HelpLink);
            System.Console.WriteLine("Inner Exception: {0}", ex.InnerException);
            System.Console.WriteLine("Message: {0}", ex.Message);
            System.Console.WriteLine("Object Name {0}", ex.ObjectName);
            System.Console.WriteLine("Source: {0}", ex.Source);
            System.Console.WriteLine("Stack Trace {0}", ex.StackTrace);
            System.Console.WriteLine("Target Site: {0}", ex.TargetSite);
            Console.ReadKey();
        }
    }
}

以下是 filenotfoundexception 抛出的错误：

消息：无法找到指定文件。
来源：mscorlib
堆栈跟踪：在 System.IO.__Error.WinIOError(int32 errorcode, String maybeFullPath) 中
在 System.IO.FileStream.ReadCore(Byte[] buffer, int32 offset, int32 count) 中
在 System.IO.FileStream.Read(Byte[] array, Int32 offset, Int32 count) 中
在 System.IO.BinaryReader.Read(Byte[] buffer, Int32 index, Int32 count) 中
在 RawSDAccessTest.Program.Main(String{} args) 中的 C:\Users\etc... 的第67行
目标站点：Void WinIOError(Int32, System.String)
System.IO.FileNotFoundException: 无法找到指定文件。
第67行为：
reader.Read(buffer, 0, 1048576);

我在这里发现很奇怪的是，该程序对于使用相同的读取对象的第65行非常正常。不知道怎么回事，在执行第65行和第67行之间，它决定该文件不再存在。我在两行代码之间加了一个等待来看是否会解决问题。但效果却没有。

您有什么想法是什么原因导致它随机抛出此异常，或者如何解决它？

编辑：进程监视器显示如下内容

8:40:26.1077157 AM SDCardReadAttempt3.vshost.exe 2432 ReadFile E: SUCCESS Offset: 3,228,565,504, Length: 1,048,576, I/O Flags: Non-cached, Priority: Normal

8:40:26.1745974 AM SDCardReadAttempt3.vshost.exe 2432 ReadFile E: NO SUCH DEVICE Offset: 3,229,614,080, Length: 131,072, I/O Flags: Non-cached, Priority: Normal

因此，在读取期间，设备停止存在。我将文件的创建和删除移动到内部循环中，以便每次尝试从中读取时都会创建该文件。问题仍然存在。这让我想到可能是硬件引起的。

编辑2：现在它偶尔会抛出异步读取异常。

9:16:16.1129926 AM SDCardReadAttempt3.vshost.exe 3752 ReadFile E: INVALID PARAMETER Offset: 7,969,177,600, Length: 1,048,576, I/O Flags: Non-cached, Priority: Normal

我不知道 .net 是如何深入工作的。也许它将其转换为多线程过程，而该文件没有打开，以供多个线程读取。我将等待时间加回去来看是否可以消除这个错误，以便我可以回到原始错误进行修复。

3
您尝试使用Process Monitor（http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx）吗？它可以提供更多细节信息。 - Nicole DesRosiers
1
我会参与进来。你提到它是一张SD卡，可能是一张相当大的卡。我知道CompactFlash卡特别慢（尤其是8GB的卡）。我不认为这会成为SD卡的一个巨大问题。但是，也许在等待调用之后，Read方法在卡寻找下一个要读取的MB时超时了？因此，在Read等待卡寻找和返回数据时，它达到了超时并假定文件找不到。只是一个想法... - fourpastmidnight
1
从未格式化的SD卡中读取数据是自相矛盾的。当然会失败。 - Hans Passant
1
你正在从一个未格式化的设备中读取数据，这个设备可能包含或不包含文件系统，而你想知道为什么会出现未定义的行为？看起来答案是显而易见的。 - Cody Gray
请确保您的读卡器兼容SDHC。如果将SDHC卡放入仅支持SD的读卡器中，设备的行为可能非常奇怪。 - JamieSee
显示剩余11条评论
2个回答
1
我曾经遇到过类似的扫描仪读取问题。最终我不得不捕获异常，等待一段时间（对我的目的来说250毫秒效果很好），然后再尝试重新读取相同的数据。我定义了一个阈值（6对我来说效果很好），在此处放弃并向用户引发错误。

这似乎给硬件足够的时间来在大多数情况下追上进度。
此外，请尝试只读取给你麻烦的块。如果您在读取特定块时始终出现错误，则显然存在硬件问题。
0
网页内容由stack overflow 提供, 点击上面的
可以查看英文原文，
原文链接