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Message-ID: <3E54354C.5040502@ece.gatech.edu>
Date: Wed, 19 Feb 2003 20:54:20 -0500
From: Charles Wilson <cwilson AT ece DOT gatech DOT edu>
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To: cygwin AT cygwin DOT com
CC: Ralf Habacker <Ralf DOT Habacker AT freenet DOT de>
Subject: Re: [avail for test] libtool-devel-20030121-1
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Ralf Habacker wrote:

>>Now, the relative *offset* of that symbol might move around.  But the
>>symname is not likely to change.
>>
> 
> Thanks for this additional note.
> 
>>from a previous mail:
> 
>>>So, it's important, Ralf, that your 'file' changes NEVER generate a
>>>false positive (e.g. saying something is an import lib when it is not).
>>> If your code generates a false negative (saying something is static
>>>when it's actually an import) -- because for false negatives, my slower
>>>code will catch it, and mark it "import".
> 
> 
> There is only one open issue : 'file' reads the first 16K into a buffer.
> 
> My currently proposal is to search for the string _dll_iname starting at the
> position of the first object file until the end of the archive (if it is less
> than 16KB) or at least the first 16 KB, if the archive is longer.

How do you get `file` to do that??? "if filesize < 16kb, then...' etc?

> That means, if the above mentioned string is found in that area, this archive
> will be identified as import library otherwise as static archive.

That sounds okay.  You'd get false negatives (very few), and no false 
positives.  That's good -- false positives are really bad.  False 
negatives, we let the slower code deal with.

> Because ar puts an offset table to each object file after it's ar header and a
> symbol cache, (the first symbol is a dll_iname symbol, there are some
> limitations.
> I've recognized, that the limit is by about 4070 object files.
> One can estimate, that this proposal will fail with import libs bigger than
> about 1-1.5 MB. For cygwin I've found this true for only one library:
> libcrypto.dll.a with 1.6 MB file size.

Hmm...but, if the `file`-based test misses an import lib, the slower 
could could be used to catch it.  And, that slower could *does* 
successfully detect that libcrypto.dll.a is an import lib, even though 
it only looks at the first 100 lines of the `nm` output. So, I see no 
problems there.

> 
> For kde I have found four import libraries which exceeds this limit (the biggest
> import library is about 4.5 MB), but this is no problem, because definitly there
> will not be any further kde releases with import libraries.

I assume you mean because you're going to link directly to the DLL.  A 
request: in your packaged releases, include a symlink with the 
"official" import lib name:
   lib/libkdefoo.dll.a  --> ../bin/cygkdefooX.dll

> 
> So as result I see the following:
> 
> 1. the file patch would generate some false negative in case of very big import
> libraries created  with recent binutils.

this is okay.  See above.

> 2. This could be fixed by using the new direct-linking-to-dll functionality for
> libraries with many symbols rsp. big import libraries, which I hope will be
> available soon.

right.  What's the holdup there?  IIRC, there are two outstanding 
patches to binutils with cygwin impact;  one of yours, I think, plus 
another one from Fabrizio Gennari (as modified by Danny Smith).  Last I 
heard, we were still waiting on Fabrizio's copyright assignment; it 
doesn't appear that the patch has been added. Are we still waiting? 
Anybody know what's up with that?

--Chuck





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