Kernel Mode: How read a txt file line by line?

I need read each line of a txt file and pass this line as parameter to a method.

I have found this example:

LARGE_INTEGER      byteOffset;

    ntstatus = ZwCreateFile(&handle,
                            GENERIC_READ,
                            &objAttr, &ioStatusBlock,
                            NULL,
                            FILE_ATTRIBUTE_NORMAL,
                            0,
                            FILE_OPEN, 
                            FILE_SYNCHRONOUS_IO_NONALERT,
                            NULL, 0);
    if(NT_SUCCESS(ntstatus)) {
        byteOffset.LowPart = byteOffset.HighPart = 0;
        ntstatus = ZwReadFile(handle, NULL, NULL, NULL, &ioStatusBlock,
                              buffer, BUFFER_SIZE, &byteOffset, NULL);
        if(NT_SUCCESS(ntstatus)) {
            buffer[BUFFER_SIZE-1] = '\0';
            DbgPrint("%s\n", buffer);
        }
        ZwClose(handle);
    }

Reference

but this read all content of file and not line by line.

Some idea about how do this?

read all file to buffer or map it as section. than execute next code:

extern "C" PCSTR __fastcall findRN(SIZE_T cb, PCSTR sz);

void processLine(SIZE_T len, PCSTR line)
{
    DbgPrint("%.*s\n", len, line);
}

NTSTATUS process(PCSTR buf, SIZE_T cb)
{
    PCSTR end = buf + cb, line = buf;

    while (buf = findRN(end - line, line))
    {
        processLine(buf - line, line);
        line = buf + 2;
    }

    if (line != end)
    {
        processLine(end - line, line);
    }
    return 0;
}

implementation of findRN on c/c++

PCSTR __fastcall findRN(SIZE_T cb, PCSTR sz)
{
    if (cb < 2)
    {
        return 0;
    }

    cb--;

    do 
    {
        if (*sz++ == '\r')
        {
            if (*sz == '\n')
            {
                return sz - 1;
            }
        }
    } while (--cb);

    return 0;
}

if you need/want ultra fast most effective implementation, do this in asm. for example x64:

findRN proc
    cmp rcx,1
    ja  @@0
    xor rax,rax
    ret
@@0:
    mov ax,0a0dh
    xchg rdi,rdx
    dec rcx
@@1:
    repne scasb
    jne @@2
    cmp [rdi],ah
    jne @@1
@@2:
    sete al
    dec rdi
    movzx rax,al
    neg rax
    and rax,rdi
    xchg rdi,rdx
    ret
findRN endp

on x86 code the same, only change r to e in register names

map file:

NTSTATUS process(POBJECT_ATTRIBUTES poa)
{
    HANDLE hFile, hSection = 0;
    IO_STATUS_BLOCK iosb;
    NTSTATUS status = NtOpenFile(&hFile, FILE_GENERIC_READ, poa, &iosb, 
        FILE_SHARE_VALID_FLAGS, FILE_SYNCHRONOUS_IO_NONALERT);

    if (0 <= status)
    {
        FILE_STANDARD_INFORMATION fsi;

        if (0 <= (status = NtQueryInformationFile(hFile, &iosb, &fsi, sizeof(fsi), FileStandardInformation)))
        {
            if (fsi.EndOfFile.HighPart)
            {
                status = STATUS_FILE_TOO_LARGE;
            }
            else if (!fsi.EndOfFile.LowPart)
            {
                status = STATUS_MAPPED_FILE_SIZE_ZERO;
            }
            else
            {
                status = NtCreateSection(&hSection, SECTION_MAP_READ, 0, 0, PAGE_READONLY, SEC_COMMIT, hFile);
            }
        }

        NtClose(hFile);

        if (0 <= status)
        {
            PVOID BaseAddress = 0;
            SIZE_T ViewSize = 0;

            status = ZwMapViewOfSection(hSection, NtCurrentProcess(), &BaseAddress, 0,
                0, 0, &ViewSize, ViewUnmap, 0, PAGE_READONLY);

            NtClose(hSection);

            if (0 <= status)
            {
                status = process((PCSTR)BaseAddress, fsi.EndOfFile.LowPart);
                ZwUnmapViewOfSection(NtCurrentProcess(), BaseAddress);
            }
        }
    }

    return status;
}