Removal of a pre-existing library interface

[Xin Li]

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On 12/12/13, 9:26 PM, Peter Wemm wrote:
> On 12/12/13, 2:37 PM, Xin Li wrote:
>> Hi,
>> 
>> Recently, OpenBSD have moved from RC4 to ChaCha20 for their 
>> arc4random(3) family of functions and they have later removed a
>> few interfaces for good reasons.
>> 
>> On FreeBSD, we aim to maintain ABI stability so we can not
>> simply remove the interface; we can not remove it from -HEAD
>> because they are established by previous -STABLE branches, or we
>> would have to bump major number of shared libraries.  After
>> thinking about some other alternatives, I have created two dummy
>> (well, they also log the event) compatibility shims for these two
>> interfaces that gets removed from OpenBSD.
>> 
>> Is this a reasonable approach of handling changes like this?
> 
> If you wish to avoid a major bump and the symbols are versioned (as
> they are in libc), the one option is this:
> 
> rename function from arcfour_foo to arcfour_foo_compat and 
> _sym_compat(arcfour_foo, arcfour_foo_compat, FBSD_1.3);
> 
> That then provides a versioned symbol to satisfy runtime
> dependencies but will not allow new references.
> 
> We did this with the iconv stuff for early 10.x binaries that we
> didn't want to break but make sure there were no new unintended
> references.

Yes I know this.  Forgot to add the link in previous email.

https://github.com/delphij/freebsd/blob/featurefork/chacha20/lib/libc/gen/arc4random-compat.c

What I'm not clear is whether it's Okay to call syslog() in the context.

Cheers,

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