How to get Drive Letter and Name - winapi

Question

I want to get Drive Letter and Name.
I used "DeviceIoControl" and "IOCTL_DISK_GET_DRIVE_LAYOUT_EX" for this reason. I am using Microsoft Visual C++ ultimate Edition.
#define wszDrive L"\\\\.\\PhysicalDrive0"
BOOL GetDriveParition(LPWSTR wszPath, DRIVE_LAYOUT_INFORMATION_EX *pdg)
{
HANDLE hDevice = INVALID_HANDLE_VALUE; // handle to the drive to be examined
BOOL bResult = FALSE; // results flag
DWORD junk = 0; // discard results
hDevice = CreateFileW(wszPath, // drive to open
0, // no access to the drive
FILE_SHARE_READ | // share mode
FILE_SHARE_WRITE,
NULL, // default security attributes
OPEN_EXISTING, // disposition
0, // file attributes
NULL); // do not copy file attributes
if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive
{
return (FALSE);
}
bResult = DeviceIoControl(hDevice, // device to be queried
IOCTL_DISK_GET_DRIVE_LAYOUT_EX, // operation to perform
NULL,
0, // no input buffer
pdg,
sizeof(*pdg), // output buffer
&junk, // # bytes returned
NULL); // synchronous I/O
CloseHandle(hDevice);
return (bResult);
}
int wmain(int argc, wchar_t *argv[])
{
DRIVE_LAYOUT_INFORMATION_EX pdg; // disk drive partition structure
BOOL bResult = FALSE; // generic results flag
bResult = GetDriveParition (wszDrive, &pdg);
if (bResult)
{
wprintf(L"Drive path = %ws\n", wszDrive);
wprintf(L"Partition Style = %I64d\n", pdg.PartitionStyle);
wprintf(L"Partition Count = %ld\n", pdg.PartitionCount);
}
else
{
wprintf (L"GetDrivePartition failed. Error %ld.\n", GetLastError ());
}
getch();
}
but when I was performing I confronted to an error which was "error 122".

Answer 1

I think that you meant to say error code 122 rather than 22. That error is ERROR_INSUFFICIENT_BUFFER. As documented, you will need to allocate a larger buffer and try again.
The point here is that the struct is a variable sized struct. You need to allocate dynamic memory large enough to hold information for all the partitions.
Something like this should get you going in the right direction:
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#define wszDrive L"\\\\.\\PhysicalDrive0"
BOOL GetDriveParition(LPWSTR wszPath, DRIVE_LAYOUT_INFORMATION_EX *pdg, size_t size)
{
HANDLE hDevice = INVALID_HANDLE_VALUE; // handle to the drive to be examined
BOOL bResult = FALSE; // results flag
DWORD junk = 0; // discard results
hDevice = CreateFileW(wszPath, // drive to open
0, // no access to the drive
FILE_SHARE_READ | // share mode
FILE_SHARE_WRITE,
NULL, // default security attributes
OPEN_EXISTING, // disposition
0, // file attributes
NULL); // do not copy file attributes
if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive
{
return (FALSE);
}
bResult = DeviceIoControl(hDevice, // device to be queried
IOCTL_DISK_GET_DRIVE_LAYOUT_EX, // operation to perform
NULL,
0, // no input buffer
pdg,
size, // output buffer
&junk, // # bytes returned
NULL); // synchronous I/O
CloseHandle(hDevice);
return (bResult);
}
int wmain(int argc, wchar_t *argv[])
{
DRIVE_LAYOUT_INFORMATION_EX* pdg; // disk drive partition structure
BOOL bResult = FALSE; // generic results flag
size_t size = sizeof(DRIVE_LAYOUT_INFORMATION_EX) + 10*sizeof(PARTITION_INFORMATION_EX);
pdg = (DRIVE_LAYOUT_INFORMATION_EX*) malloc(size);
bResult = GetDriveParition (wszDrive, pdg, size);
if (bResult)
{
wprintf(L"Drive path = %ws\n", wszDrive);
wprintf(L"Partition Style = %I64d\n", pdg->PartitionStyle);
wprintf(L"Partition Count = %ld\n", pdg->PartitionCount);
}
else
{
wprintf (L"GetDrivePartition failed. Error %ld.\n", GetLastError ());
}
free(pdg);
}
I've cast the return value of malloc since you state that you are using a C++ compiler.