Re: Using TLSAlloc to read data into a DLL


"Igor Tandetnik" <itandetnik@xxxxxxxx> wrote in message
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Ben Voigt [C++ MVP] <rbv@xxxxxxxxxxxxx> wrote:
"Igor Tandetnik" <itandetnik@xxxxxxxx> wrote in message
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"Sanjay" <sanjay.gangadhara@xxxxxxxxx> wrote in message
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I am very new to Windows programming, and wanted to learn more about
the use of the function TlsAlloc. My specific application is that I
would like to read data into a file when the DLL is first loaded,
and store that data in a memory block that is untouched until the
DLL is unloaded. For my particular problem, use of the STATIC
keyword is insufficient.

What precisely do you feel is wrong with it? It looks like you can
simply allocate a block of memory in DllMain(DLL_PROCESS_ATTACH) and
save it in a global variable. Then free it in
DllMain(DLL_PROCESS_DETACH).

Note that DllMain shouldn't call any complicated routines because it
is called under OS loader lock. Allocating memory should be ok,
depending on the allocator used. Reading from a file is almost
certainly not safe.

CreateFile et al are in the kernel. It is safe to call APIs from the
kernel in DllMain.

Sanjay was trying to use fopen, not CreateFile. I don't know any guarantee
that the CRT won't play some tricks that cause problems.

--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925




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