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From: David Brown <david.brown@hesbynett.no>
Newsgroups: comp.lang.c
Subject: Re: Writing own source disk
Date: Tue, 4 Jun 2024 09:30:53 +0200
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On 04/06/2024 02:35, Keith Thompson wrote:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> bart <bc@freeuk.com> writes:
>> [...]
>>> I assume you can use __FILE__ with #embed? (I can do that with my
>>> version of it).
>>
>> Yes, but not reliably.
>>
>> __FILE__ expands to "The presumed name of the current source file (a
>> character string literal)".  That's rather vague.
>>
>> With gcc and clang, it expands to the file name argument given to the
>> compiler, or to the argument of the #include directive.  The running
>> program may or may not be able to access the source file using that
>> name.  The source file might not even exist when the program runs.
> 
> I was thinking of using __FILE__ to access the source file at run time.
> #embed is of course handled at compile time.  It's very likely, but
> still not quite guaranteed, that `#embed __FILE__` will be able to
> access the source file.
> 

The key question for that will be directory handling.  If everything is 
being done within the same directory, than I'd expect "#embed __FILE__" 
to work fine.  But if you are calling the compiler from a different 
directory, specifying a path for the source file, that might not be 
reflected in __FILE__.  The result could vary between compilers.

There is also the possibility that the search path for #embed might 
result in finding a different file with the same name.  But I think that 
would probably need specific command-line switches to specify the #embed 
search path (again, this will be compiler-specific).