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Re: Does Cygwin setup modify dlls?




On 22/09/2017 16:11, Eliot Moss wrote:
On 9/22/2017 10:00 AM, Joachim Eibl wrote:
Hi,
In our project we like the Cygwin-Setup tool so much that we use it for our own files too. Adding our archives to our setup.ini was easy enough and almost everything worked as expected. But then a certain tool didn't work and we found that dll-files that were unpacked by the Cygwin-installer didn't match the files in the archive.
The problem seems to be dll-specific. Other filetypes are not modified.


Cygwin's rebasing of DLLs does modify the files (slightly).
Others can probably detail the exact nature of what changes,
and perhaps the comparison tool can be refined to ignore that
as a difference.

the change is on ImageBase address

$ objdump -x /usr/bin/cygglpk-40.dll |grep ImageBase
ImageBase               00000003e1710000

 $ rebase -si |grep  /usr/bin/cygglpk-40.dll
/usr/bin/cygglpk-40.dll base 0x0003e1710000 size 0x000ec000

To perform a proper fork all the dlls should be loaded
at not colliding address

This activity is performed by the script
/etc/postinstall/0p_000_autorebase.dash

after the files installation.


Regards - Eliot Moss

Regards
Marco


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