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TomasCvincek asked a question.

January 22, 2024 at 3:53 PM
error LNK2019: unresolved external symbol __iob_func

Hello guys,

I am updating Flexnet on our software and I am facing following error:

 

libredir_std.lib(lm_redir_std.obj) : error LNK2019: unresolved external symbol __iob_func referenced in function lm_flex_stderr.

I am updating Flexnet from version 11.14 to 11.18.

I found some hints on stackoverflow:

 

https://stackoverflow.com/questions/30412951/unresolved-external-symbol-imp-fprintf-and-imp-iob-func-sdl2

 

I implemented missing function where needed on my own:
  1. FILE _iob[] = {*stdin, *stdout, *stderr};extern "C" FILE * __cdecl __iob_func(void){ return _iob;}

 

With this function implemented in DLLs that require Flexnet, it compiles successfully and runtime seems OK as well.

 

But I do not think this is good solution - it is more like a workaround. Why does libredir_std.lib requires this function? When I checked Flexnet version 11.14, it used __acrt_iob_func instead of __iob_func. 

 

How can I fix this? Is there any other way to do it than defining this function on my own?

 

I build our app using Visual Studio 2015. Here are dependencies:
  1. FNP_Act_InstallerlibFNPloadlibcrvslibFNPloadliblmutillibpthreadlibsblibsimplifierlmgrlmgraslmgrd lmgrslmgr_donglelmgr_dongle_stublmgr_trllmsignlibredir_std.libuserenv.libiphlpapi.liblegacy_stdio_wide_specifiers.liblegacy_stdio_definitions.lib

linker options:

 

  1. lm_new.obj /NODEFAULTLIB:LIBCMT.lib

 

Thanks for answers in advance.

Tomas C.

 

  • 7 answers
  • 412 views

  • TomasCvincek

    Hi  @mrathinam  ,

    I have probably used wrong distribution of Flexnet (for newer Visual Studio).

    When I used correct one for Visual Studio 2015, this __iob_func is not used.  __acrt_iob_func is used instead of  __iob_func.

     

    Thanks. 

    Tomas C.

     

     

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  • Y Vernekar (Flexera Software)

    The LNK2019 error is usually due to a missing lib file. Below is a list that I refer. Can you please check if something is missing on your end:

    lmflex.obj

    lm_new.obj

    lmgr_trl.lib

    libsb.lib

    libcrvs.lib

    libpthread.lib

    libredir_std.lib

    libredir_std.lib

    legacy_stdio_wide_specifiers.lib

    legacy_stdio_definitions.lib

    libvcruntime.lib

    libucrt.lib

    oldnames.lib

    kernel32.lib

    user32.lib

    netapi32.lib

    gdi32.lib

    comdlg32.lib

    comctl32.lib

    wsock32.lib

    shell32.lib

    Rpcrt4.lib

    oleaut32.lib

    Ole32.lib

    Wbemuuid.lib

    wintrust.lib

    crypt32.lib

    Ws2_32.lib

    iphlpapi.lib

    Psapi.lib

    advapi32.lib

    Shlwapi.lib

    dhcpcsvc.lib

    userenv.lib

    libcmt.lib

    lmgr_dongle_stub.lib

    .\activation\lib\libnoact.lib

    Expand Post

    • TomasCvincek

      Hi Yvernekar,

       

      thanks for answer. I checked your dependency list with mine. I added libvcruntime.lib

       

      libucrt.lib but those threw some further problems:
      1. vcruntime.lib(VCRUNTIME140.dll) : error LNK2005: memmove already defined in libvcruntime.lib(memcpy.obj)ucrt.lib(api-ms-win-crt-runtime-l1-1-0.dll) : error LNK2005: _invalid_parameter_noinfo_noreturn already defined in libucrt.lib(invalid_parameter.obj)ucrt.lib(api-ms-win-crt-runtime-l1-1-0.dll) : error LNK2005: _errno already defined in libucrt.lib(errno.obj)ucrt.lib(api-ms-win-crt-runtime-l1-1-0.dll) : error LNK2005: abort already defined in libucrt.lib(abort.obj)ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll) : error LNK2005: __stdio_common_vfprintf already defined in libucrt.lib(output.obj)ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll) : error LNK2005: fclose already defined in libucrt.lib(fclose.obj)ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll) : error LNK2005: __acrt_iob_func already defined in libucrt.lib(_file.obj)ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll) : error LNK2005: __stdio_common_vsprintf already defined in libucrt.lib(output.obj)ucrt.lib(api-ms-win-crt-time-l1-1-0.dll) : error LNK2005: _time64 already defined in libucrt.lib(time.obj)ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll) : error LNK2005: __stdio_common_vswprintf already defined in libucrt.lib(output.obj)ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll) : error LNK2005: fflush already defined in libucrt.lib(fflush.obj)ucrt.lib(api-ms-win-crt-heap-l1-1-0.dll) : error LNK2005: free already defined in libucrt.lib(free.obj)ucrt.lib(api-ms-win-crt-heap-l1-1-0.dll) : error LNK2005: malloc already defined in libucrt.lib(malloc.obj)ucrt.lib(api-ms-win-crt-string-l1-1-0.dll) : error LNK2005: wcsncmp already defined in libucrt.lib(wcsncmp.obj)libucrt.lib(unlink.obj) : error LNK2005: remove already defined in ucrt.lib(api-ms-win-crt-filesystem-l1-1-0.dll)libucrt.lib(open.obj) : error LNK2005: _wopen already defined in ucrt.lib(api-ms-win-crt-stdio-l1-1-0.dll)libucrt.lib(environment_initialization.obj) : error LNK2005: _initialize_narrow_environment already defined in ucrt.lib(api-ms-win-crt-runtime-l1-1-0.dll)libucrt.lib(waccess.obj) : error LNK2005: _waccess already defined in ucrt.lib(api-ms-win-crt-filesystem-l1-1-0.dll)libucrt.lib(strnicmp.obj) : error LNK2005: _strnicmp already defined in ucrt.lib(api-ms-win-crt-string-l1-1-0.dll)

       

      I am not sure.... am I using incorrect VS C++ libs? 

      Do you know, which exact .lib defines this __iob_func?

       

      Thanks.  

      Tomas C.

      Expand Post

      • mrathinam (Flexera Software)

        Hi @TomasCvincek  As you are using VS 2019, please check the supported version of the VS in 11.18.0.  I think the support of VS 2019 stated from 11.19.1.0. You can find the release notes with the following information. 

        A new 64bit Windows FNP kit having suffix _vc16 is made available to support newer versions of Visual Studio(VS 2017, VS 2019...etc).

        The Windows FNP kits(both 32 & 64bits) without _vc16 suffix can be used to support VS 2013 and VS 2015.

        Best Regards,

        Expand Post

            • TomasCvincek

              Hi  @mrathinam  ,

              I have probably used wrong distribution of Flexnet (for newer Visual Studio).

              When I used correct one for Visual Studio 2015, this __iob_func is not used.  __acrt_iob_func is used instead of  __iob_func.

               

              Thanks. 

              Tomas C.

               

               

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error LNK2019: unresolved external symbol __iob_func