Read/Write to unformatted SD Card on Windows - c++

Question

I am trying to read/write to an SD card that is unformatted and I am having issues. I am using the windows API to open a handle to the SD card and read/write to it, however I get various errors depending on my approach.
Below is me trying to access the SD card by volume label:
HANDLE sdCardHandle = CreateFile("\\\\.\\E:", GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if(sdCardHandle == INVALID_HANDLE_VALUE)
{
CloseHandle(sdCardHandle);
return;
}
// I have also tried using VirtualAlloc() to get a sector aligned buffer
unit8_t buffer[512] = { 0 };
DWORD bytesWritten = 0;
if(WriteFile(sdCardHandle, buffer, 512, &bytesWritten, NULL) != TRUE)
{
DWORD lastError = GetLastError();
CloseHandle(sdCardHandle);
return;
}
However the WriteFile fails and the last error is 87 which is invalid parameter. I have tried locking the volume and also unmounting the volume before writing also and it failed.
The next attempt was to try and write to the physical drive instead by running the following in administrator mode:
HANDLE sdCardHandle = CreateFile("\\\\.\\PhysicalDrive1", GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if(sdCardHandle == INVALID_HANDLE_VALUE)
{
CloseHandle(sdCardHandle);
return;
}
// I have also tried using VirtualAlloc() to get a sector aligned buffer
unit8_t buffer[512] = { 0 };
DWORD bytesWritten = 0;
if(WriteFile(sdCardHandle, buffer, 512, &bytesWritten, NULL) != TRUE)
{
DWORD lastError = GetLastError();
CloseHandle(sdCardHandle);
return;
}
Which also fails but return error 23 which is a bad CRC error. I have also tried unmounting and locking the volume first but nothing changed. If there is any thing else I need to do or try please let me know.

Answer 1

Thank you everyone for all of your help and suggestions. It turns out I was doing the operation correct the entire time. However the SD card reader was causing the error. The issue I believe is that BitDefender might not be allowing the read/write operations to go out to the physical disk. I instead used a USB adapter that shows the SD card as USB drive and my read/write works! Hopefully this helps anyone having a similar issue.

Answer 2

from CreateFile
Volume handles can be opened as noncached at the discretion of the
particular file system, even when the noncached option is not
specified in CreateFile. You should assume that all Microsoft file
systems open volume handles as noncached. The restrictions on
noncached I/O for files also apply to volumes.
so we need assume that FILE_FLAG_NO_BUFFERING (FILE_NO_INTERMEDIATE_BUFFERING) will be used:
Specifying this flag places the following restrictions on the caller's
parameters to other ZwXxxFile routines.
Any optional ByteOffset passed to NtReadFile or NtWriteFile must be a multiple of the sector size.
The Length passed to NtReadFile or NtWriteFile must be an integral of the sector size. Note that specifying a read operation to
a buffer whose length is exactly the sector size might result in a
lesser number of significant bytes being transferred to that buffer
if the end of the file was reached during the transfer.
Buffers must be aligned in accordance with the alignment requirement of the underlying device. To obtain this information,
call NtCreateFile to get a handle for the file object that
represents the physical device, and pass that handle to NtQueryInformationFile. For a list of the system's FILE_XXX_ALIGNMENT values, see DEVICE_OBJECT.
note, that here - Alignment and File Access Requirements was wrong information:
File access buffer addresses for read and write operations should be
physical sector-aligned, which means aligned on addresses in memory
that are integer multiples of the volume's physical sector size.
Depending on the disk, this requirement may not be enforced.
this is false - buffer addresses for read and write operations must not be physical sector-aligned. it must be aligned in accordance with the alignment requirement of the underlying device. this is absolute different things.
we can get this align from FILE_ALIGNMENT_INFO (win 8+) or by using FILE_ALIGNMENT_INFORMATION via NtQueryInformationFile with FileAlignmentInformation
in your current code you hardcode buffer size to 512. however sector size of device can be bigger size.
// I have also tried using VirtualAlloc() to get a sector aligned
buffer
how i say - you not need sector aligned buffer (usual device align 2-4 bytes). but you need buffer integral of the sector size. so before read data - you need first query sector size and device align required
HANDLE sdCardHandle = CreateFile(L"\\\\.\\PhysicalDrive1", GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
if (sdCardHandle != INVALID_HANDLE_VALUE)
{
FILE_ALIGNMENT_INFO fai;
if (GetFileInformationByHandleEx(sdCardHandle, FileAlignmentInfo, &fai, sizeof(fai)))
{
ULONG BytesReturned;
STORAGE_ACCESS_ALIGNMENT_DESCRIPTOR saad;
STORAGE_PROPERTY_QUERY spq = { StorageAccessAlignmentProperty, PropertyStandardQuery };
if (DeviceIoControl(sdCardHandle, IOCTL_STORAGE_QUERY_PROPERTY, &spq, sizeof(spq), &saad, sizeof(saad), &BytesReturned, 0))
{
if (PBYTE pb = new BYTE[saad.BytesPerPhysicalSector + fai.AlignmentRequirement])
{
PBYTE buf = (PBYTE)(((ULONG_PTR)pb + fai.AlignmentRequirement) & ~(ULONG_PTR)fai.AlignmentRequirement);
if (ReadFile(sdCardHandle, buf, saad.BytesPerPhysicalSector, &BytesReturned, 0))
{
__nop();
}
else
{
GetLastError();//RtlGetLastNtStatus();
}
delete [] pb;
}
}
}
CloseHandle(sdCardHandle);
}
also as separate note - when you use OPEN_EXISTING - any file attributes is ignored (it used only when you create new file). as result use FILE_ATTRIBUTE_NORMAL - senseless (but not error - simply will be ignored)