Question

How to get disk size and geometry using Windows API in C

Answer 1

#include <windows.h>
#include <stdio.h>

BOOL GetDriveGeometry(DISK_GEOMETRY* dg)
{
    HANDLE hDevice; // handle to the drive
    BOOL bResult;   
    DWORD bytesreturned; 

    /*
    HANDLE CreateFileA(
    [in]           LPCSTR                lpFileName,
    [in]           DWORD                 dwDesiredAccess,
    [in]           DWORD                 dwShareMode,
    [in, optional] LPSECURITY_ATTRIBUTES lpSecurityAttributes,
    [in]           DWORD                 dwCreationDisposition,
    [in]           DWORD                 dwFlagsAndAttributes,
    [in, optional] HANDLE                hTemplateFile
    );
    */

    hDevice = CreateFile(L"\\\\.\\PhysicalDrive0",  // drive to open
        0,               
        FILE_SHARE_READ | 
        FILE_SHARE_WRITE, 
        NULL,             
        OPEN_EXISTING,    // disposition
        0,                
        NULL);            

    if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive
    {
        return (FALSE);
    }

    /*
    BOOL DeviceIoControl(
    [in]                HANDLE       hDevice,
    [in]                DWORD        dwIoControlCode,
    [in, optional]      LPVOID       lpInBuffer,
    [in]                DWORD        nInBufferSize,
    [out, optional]     LPVOID       lpOutBuffer,
    [in]                DWORD        nOutBufferSize,
    [out, optional]     LPDWORD      lpBytesReturned,
    [in, out, optional] LPOVERLAPPED lpOverlapped
    );
    */

    bResult = DeviceIoControl(hDevice,  
        IOCTL_DISK_GET_DRIVE_GEOMETRY,  
        NULL, 0,               
        dg, sizeof(*dg), // output buffer - DISK_GEOMETRY 
        &bytesreturned,   
        (LPOVERLAPPED)NULL);  

    CloseHandle(hDevice);

    return (bResult);
}

int main(int argc, char* argv[])
{
    /*
    typedef struct _DISK_GEOMETRY {
    LARGE_INTEGER Cylinders;
    MEDIA_TYPE    MediaType;
    DWORD         TracksPerCylinder;
    DWORD         SectorsPerTrack;
    DWORD         BytesPerSector;
    } DISK_GEOMETRY, *PDISK_GEOMETRY;
    */

    DISK_GEOMETRY dg;  // drive geometry structure
    BOOL bResult;     

    bResult = GetDriveGeometry(&dg);

    if (bResult)
    {
        //printf("Cylinders = %I64d\n", pdg.Cylinders);
        printf("Cylinders = %lld\n", dg.Cylinders);
        printf("Tracks per cylinder = %ld\n", (ULONG)dg.TracksPerCylinder);
        printf("Sectors per track = %ld\n", (ULONG)dg.SectorsPerTrack);
        printf("Bytes per sector = %ld\n", (ULONG)dg.BytesPerSector);

        ULONGLONG DiskSize = dg.Cylinders.QuadPart * (ULONG)dg.TracksPerCylinder *
                             (ULONG)dg.SectorsPerTrack * (ULONG)dg.BytesPerSector; // in bytes

        printf("Disk size = %I64d(Bytes) = %I64d(GB)\n", DiskSize, DiskSize / (1024 * 1024 * 1024));
    }
    else
    {
        printf("GetDriveGeometry Error: %ld.\n", GetLastError());
    }

    return ((int)bResult);
}



/*
run:

Cylinders = 121601
Tracks per cylinder = 255
Sectors per track = 63
Bytes per sector = 512
Disk size = 1000202273280(Bytes) = 931(GB)

*/

 

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