如何从 SD 卡读取原始字节？

Question

在 Windows PC 上，有没有办法从通过 USB 读卡器连接的 SD 卡读取原始字节？SD 卡是从嵌入式系统写入的，根本不使用文件系统，因此我无法使用标准文件访问例程。这类似于 unix dd实用程序所做的，但我需要将其集成到 .NET 应用程序中。

Answer 1

我不确定这是否有帮助，但假设即使未格式化的磁盘在 Win32 设备命名空间（我认为必须）中获得物理驱动器编号，您也可以扩展此处显示的代码以识别驱动器号并从设备上的任何位置读取原始字节。

更新：原始链接已关闭。来自互联网档案馆的代码。有关上下文，请参阅原始博客文章（上面链接）的 Internet Archive 副本：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.IO;

namespace RawDump
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public enum EMoveMethod : uint
        {
            Begin = 0,
            Current = 1,
            End = 2
        }

        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern uint SetFilePointer(
            [In] SafeFileHandle hFile,
            [In] int lDistanceToMove,
            [Out] out int lpDistanceToMoveHigh,
            [In] EMoveMethod dwMoveMethod);

        [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);

        [DllImport("kernel32", SetLastError = true)]
        internal extern static int ReadFile(SafeFileHandle handle, byte[] bytes,
           int numBytesToRead, out int numBytesRead, IntPtr overlapped_MustBeZero);

        private void buttonDump_Click(object sender, EventArgs e)
        {
            short FILE_ATTRIBUTE_NORMAL = 0x80;
            short INVALID_HANDLE_VALUE = -1;
            uint GENERIC_READ = 0x80000000;
            uint GENERIC_WRITE = 0x40000000;
            uint CREATE_NEW = 1;
            uint CREATE_ALWAYS = 2;
            uint OPEN_EXISTING = 3;

            SaveFileDialog mySFD = new SaveFileDialog();
            mySFD.FileName = "dump.bin";
            mySFD.InitialDirectory = Path.GetDirectoryName(Application.StartupPath);
            if(mySFD.ShowDialog() == DialogResult.OK)
            {
                SafeFileHandle handleValue = CreateFile(textBoxPath.Text, GENERIC_READ, 0, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);
                if (handleValue.IsInvalid)
                {
                    Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
                }

                int offset = int.Parse(textBoxOffset.Text, System.Globalization.NumberStyles.HexNumber);
                int size = int.Parse(textBoxSize.Text, System.Globalization.NumberStyles.HexNumber);
                byte[] buf = new byte[size];
                int read = 0;
                int moveToHigh;
                SetFilePointer(handleValue, offset, out moveToHigh, EMoveMethod.Begin);
                ReadFile(handleValue, buf, size, out read, IntPtr.Zero);
                FileStream myStream = File.OpenWrite(mySFD.FileName);
                myStream.Write(buf, 0, size);
                myStream.Flush();
                myStream.Close();
                handleValue.Close();
            }
        }
    }
}