Przemysław Pawełczyk wrote:
> On Thu, 29 Mar 2007 12:09:56 -0400
> "Steven M. Bellovin" <smb@cs.columbia.edu> wrote:
> 
>>I think there's a deeper issue here.  Suppose that he'd started with
>>3.1, installed those packages, then upgraded to (say) 5.0.
>>Presumably, the "delete obsolete files" part of the upgrade would
>>remove libssl.so.3, etc., at which point his packages no longer
>>work.  That seems to be a serious break in backwards compatibility.
>>(Or am I missing something?)
> 
> Hi,
> You shot first but I was thinking about it in simillar way. AFAIK in my
> example, ther was no conflict of libraries but lack of old symlinks. I
> vote for keeping them for one or two generation back. Symlinks cost
> nothing.

No. The problem was not a lack of old symlimks. The problem was a lack 
of old libraries. And this is why I said you were begging for trouble.

What you did was:
a) ln /lib/libz.so.1.0 -> /usr/lib/libz.so.0

Bad, since you now claim that libz.so.0 is the same as libz.so.1.0, 
which are two different major version numbers. I assume that they are 
not that compatible, or the version change wouldn't have taken place.

b) ln /lib/libstdc++.so.6.0 -> /lib/libstdc++.so.5

Same thing here. You're saying that libstdc++ v5 is the same as v6. A 
bad idea.

c) ln /usr/lib/libssl.so.4 -> /usr/lib/libssl.so.3

libssl v3 is the same as v4, which they are not.

d) ln /lib/libcrypto.so.3.1 -> /usr/lib/libcrypto.so.2

and of course, libcrypto v2 is not the same as v3.1.

Understand that libmumble.so.1 is the generic name for version 1 of 
libmumble. libmumble.so.1.0 is explicitly v1.0 of libmumble. 
libmumble.so.1 might very well point to libmumble.so.1.0, but 
libmumble.so.1 should never point to something not version 1 of 
libmumble, or you are asking for problems.
Also, libmumble.so might point at whatever the latest version of 
libmumble, but most programs should not be linked to and be referring to 
a shared library without atleast a major version number, for obvious 
reasons.

	Johnny

	Johnny