Thread: Unicode c++, unable to write to the pipe.

  1. #1
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    Unicode c++, unable to write to the pipe.

    Goal: To be able to send the data to the pipe after serializing using msgpack(have attached the link to the header files).


    insert
    Code:
    LPDWORD  lpNumberOfBytesWritten = 0;
    CStringA strEvalResultW= "abcdefghijklmnopqrstuwxyz";
            
            //// serialize the object into the buffer.
            //// any classes that implements write(const char*,size_t) can be a buffer.
        std::stringstream buffer;
        msgpack::type::tuple<std::string, std::string> src("SECURITY_BASELINE_BLOB", (LPCSTR)strEvalResultW);
        msgpack::pack(buffer,src);
            
        printf("\n\nThe length of the string is %ld \n\n", strlen(strEvalResultW));
        BOOL result = WriteFile(hPipe, (LPCVOID)buffer.str(), strlen(buffer), lpNumberOfBytesWritten, NULL);
        if (result) {
            printf("\Successfully wrote to the pipe \n");
        }

    I am fairly new to unicode in c++ and very confused about why I am not getting the right arguments for writeFile..(I am trying to write to a pipe and have been able to connect to the pipe successfully, hPipe is the handler to the pipe).

    I want to be able to send the packed data(using msg pack available at NuGet Gallery
    | msgpack-c 0.5.9.1
    ) to the pipe. Any help will be really appreciated and I am willing to provide more details if needed. I am not too sure of the highlighted code as well. The highlighted code in writeFile is failing.

  2. #2
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    Is it logical to assume Unicode data has no /0 bytes in it?
    Because your code assumes that is true.

    Tim S.
    "...a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match.." Bill Bryson

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    Post unable to understand your reply..

    Code:
    LPDWORD  lpNumberOfBytesWritten = 0;
    CStringA testString= "abcdefghijklmnopqrstuwxyz";
            
            
    msgpack::sbuffer buffer;    LPCSTR toWrite = testString;
    
    msgpack::pack(buffer,toWrite);
            
    printf("\n\nThe length of the string is %ld \n\n", strlen(strEvalResultW));
    BOOL result = WriteFile(hPipe, buffer.data(), buffer.size(), lpNumberOfBytesWritten, NULL);
        if (result) {
            printf("\Successfully wrote to the pipe \n");
        }
    I have edited the question, I also don't clearly understand what you mean. Can you help me with this?

  4. #4
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    The function strlen() and likely the .str() assumes you are dealing with C string this is an /0 terminated char array.
    C string can not have embedded /0 in it!

    Therefore, you can NOT use UTF-16 with your code!

    MS Windows uses some version of UTF-16.

    Edit: I am not an expert on Unicode; you should verify what I post in this thread.

    Tim S.
    Last edited by stahta01; 09-25-2020 at 10:07 PM.
    "...a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match.." Bill Bryson

  5. #5
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    This seems to have very little (if anything) to do with Unicode.

    Are you knowingly using ATL/MFC?
    Are you sure you want to use CString (more specifically, for some reason, CStringA)?
    Using CString | Microsoft Docs

    Are you sure you want to use this NuGet thing?
    Why?
    What is NuGet and what does it do? | Microsoft Docs

    This is incorrect:
    Code:
    LPDWORD lpNumberOfBytesWritten = 0;
    Presumably you mean
    Code:
    DWORD numberOfBytesWritten = 0;
    which you would pass to WriteFile as a pointer like &numberOfBytesWritten.

    It may be best to describe what exactly you are trying to do in general terms, without reference to any specific technologies.
    Philosophy is a battle against the bewitchment of our intelligence by means of language. - Wittgenstein

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    I already have some string in CStringA. My main goal is to be able to serialize this data using msgpack (MessagePack: It's like JSON. but fast and small.) and be able to send it to the pipe. The reason I am using the nuget package is for the header files.

    Thank you for the suggestion for the numberOfBytesWritten, I agree with the change.
    Also, to answer your question, yes I am knowingly using ATL/MFC because the code already uses it and I am just trying to add the functionality to send it to the pipe. I have replaced the CStringA with some random string in this case.

    The pipe can accept data in fluentd protocol only(hence using msgpack) in my case. I basically want to pack(serialize this data) and send it across.

    Thank you so much for your reply. Any help would be appreciated. I am fairly new to Unicode and even though I am reading a lot about it, I am not understanding how to send that data.

  7. #7
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    I don't see what this has to do with Unicode.
    Nothing, apparently, or at least the underlying UTF-8 encoding is not part of your problem.
    But you obviously can't use strlen on a stringstream.
    How about buffer.str().length().
    Philosophy is a battle against the bewitchment of our intelligence by means of language. - Wittgenstein

  8. #8
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    Got it, so you are saying that UTF-8 is not a problem in this case. I am just trying to understand how to send the data using msgpack.Initially, I thought the way my data is formatted could be a problem...
    In that case, if I want to use the msgpack-c "pack" function, can I change the name of the thread or create a new thread for the same?

    Also, thank you so much for your prompt replies Means a lot!

  9. #9
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    You've lost me. I don't see any mention of threads.

    A nitpick: you should probably remove the W at the end of strEvalResultW since that would usually indicate you are using CStringW (char16_t-based) instead of CStringA (char-based). Just strEvalResult is good.
    Philosophy is a battle against the bewitchment of our intelligence by means of language. - Wittgenstein

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