Special characters

elDimas

Hello everyone! I'm writing a driver, and what I want to do is write a message to a file, but when there is a special character, like: "á", it returns an invalid character, that when I call "ZwWriteFile", could someone help me? here's my code:

VOID Alert(PUNICODE_STRING Message, PUNICODE_STRING FileNameOriginal)
{
    UNICODE_STRING FileName;
    OBJECT_ATTRIBUTES Attributes;

    RtlInitUnicodeString(&FileName, FileNameOriginal);

    InitializeObjectAttributes(&Attributes, &FileName,
        OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
        NULL, NULL);

    HANDLE FileHandle;
    NTSTATUS Status;

    IO_STATUS_BLOCK ioStatusBlock;

    if (KeGetCurrentIrql() != PASSIVE_LEVEL)
        return STATUS_INVALID_DEVICE_STATE;

    Status = ZwCreateFile(&FileHandle,
        GENERIC_WRITE,
        &Attributes, &ioStatusBlock, NULL,
        FILE_ATTRIBUTE_NORMAL,
        0,
        FILE_OVERWRITE_IF,
        FILE_SYNCHRONOUS_IO_NONALERT,
        NULL, 0);

    CHAR     buffer[BUFFER_SIZE];
    size_t  cb;

    if (NT_SUCCESS(Status)) 
    {
        Status = RtlStringCbPrintfA(buffer, sizeof(buffer), Message, 0x0);

        if (NT_SUCCESS(Status))
        {
            Status = RtlStringCbLengthA(buffer, sizeof(buffer), &cb);

            if (NT_SUCCESS(Status))
                       {
                Status = ZwWriteFile(FileHandle, NULL, NULL, NULL, &ioStatusBlock,
                    buffer, cb, NULL, NULL);
            }
        }
        ZwClose(FileHandle);
    }
}

I got this code from Microsoft

Peter_Viscarola_(OSR)

it returns an invalid character

What does "returns an invalid character" mean and "it" being WHAT in that code, exactly?

I can assure you that ZwWriteFile doesn't look at or care about the contents of the data buffer.

Peter

elDimas

@Peter_Viscarola_(OSR) said:

it returns an invalid character

What does "returns an invalid character" mean and "it" being WHAT in that code, exactly?

I can assure you that ZwWriteFile doesn't look at or care about the contents of the data buffer.

Peter

For example: "á", it will return a: "⚠"

Peter_Viscarola_(OSR)

I'm very sorry, but I still don't understand what you mean.

"will return" WHERE?? When output/viewed/displayed by WHAT?

Remember, we're not in your head.

OK... your code looks "problematic" as well. The third argument to RtlStringCbPrintfA (which is just a fancy version of printf) is a format string... but you're passing a UNICODE_STRING?? And the fourth parameter is the arguments... of which there presumably are none? So, the buffer part of the UNICODE_STRING is (presumably) in UNICODE format, and thus 2 bytes per character. Sooo.... that's not going to work. What do you hope to accomplish with this call, that a simple call to memcpy wouldn't do?

RtlStringCbLengthA is just a fancy version of strlen... but, it's not going to work properly with UNICODE characters?

So, yeah... I'm confused.

Let's go back to the beginning: WHAT is it that you're trying to accomplish?

Peter

elDimas

@Peter_Viscarola_(OSR) said:
I'm very sorry, but I still don't understand what you mean.

"will return" WHERE?? When output/viewed/displayed by WHAT?

Remember, we're not in your head.

OK... your code looks "problematic" as well. The third argument to RtlStringCbPrintfA (which is just a fancy version of printf) is a format string... but you're passing a UNICODE_STRING?? And the fourth parameter is the arguments... of which there presumably are none? So, the buffer part of the UNICODE_STRING is (presumably) in UNICODE format, and thus 2 bytes per character. Sooo.... that's not going to work. What do you hope to accomplish with this call, that a simple call to memcpy wouldn't do?

RtlStringCbLengthA is just a fancy version of strlen... but, it's not going to work properly with UNICODE characters?

So, yeah... I'm confused.

Let's go back to the beginning: WHAT is it that you're trying to accomplish?

Peter

Excuse me if I'm not clear, the question is: I try to write a message in a file, like "Olá todos" because I'm Brazilian, but when I write this, "Olá" does not return the original message, it will be: "Ol⚠ ", how do I resolve this?

I got this code from Microsoft and I don't have much experience in developing mini filters. Can you help me?

Peter_Viscarola_(OSR)

Well, to start: You seem to be missing the fact that UNICODE_STRING is a data structure that implies a particular string encoding.

And you seem to have ignored the last two thirds of what I wrote...

Does that help at all?

Peter

elDimas

@Peter_Viscarola_(OSR) said:
Well, to start: You seem to be missing the fact that UNICODE_STRING is a data structure that implies a particular string encoding.

And you seem to have ignored the last two thirds of what I wrote...

Does that help at all?

Peter

Thanks for the answer, you try to fix my code, sorry I took too long to answer.