ABI change in cyrus sasl 2.1.25

Ondřej Surý ondrej at sury.org
Tue May 29 12:38:26 EDT 2012

On Tue, May 29, 2012 at 6:16 PM, Alexey Melnikov
<alexey.melnikov at isode.com> wrote:
> On 29/05/2012 17:10, Ondřej Surý wrote:
>> When you change interface and break binary compatibility you need to
>> increase .so.NUMBER. Existing binaries has to be recompiled to use this new
>> library. And older binaries can still use older version of the library
>> without breaking.

Let me explain in greater detail now.

cyrus-sasl now produces:

library: /usr/lib/x86_64-linux-gnu/libsasl2.so.2.0.25
symlink: /usr/lib/x86_64-linux-gnu/libsasl2.so.2

Binaries (as for example slapd) are linked to libsasl2.so.2 (which is
the SONAME) and dynamic linker looks for this file in it's paths.

When you break binary compatibility as happened in 2.1.24 you need to
increase SONAME of the library to something higher (usually just
increase it by one).

So cyrus-sasl >= 2.1.24 should really have: libsasl2.so.3 SONAME.

Also as one can see the last (patch) number of the library matches the
release, which is also probably wrong. You need to change the number
only in case you actually change something in the ABI (like add a new

You can read more about Library interfaces in the libtool manual,
especially this part is relevant:

Here are a set of rules to help you update your library version information:

1. Start with version information of ‘0:0:0’ for each libtool library.
2. Update the version information only immediately before a public
release of your software. More frequent updates are unnecessary, and
only guarantee that the current interface number gets larger faster.
3. If the library source code has changed at all since the last
update, then increment revision (‘c:r:a’ becomes ‘c:r+1:a’).
4. If any interfaces have been added, removed, or changed since the
last update, increment current, and set revision to 0.
5. If any interfaces have been added since the last public release,
then increment age.
6. If any interfaces have been removed or changed since the last
public release, then set age to 0.

>> I can prepare patch...
>> There is also some short info here:
>> http://www.netfort.gr.jp/~dancer/column/libpkg-guide/libpkg-guide.html#sonameapiabi
> If you can prepare the patch, that would be great. Will save me time anyway
> ;-).

Will do, but not today :).

Ondřej Surý <ondrej at sury.org>

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