69 lines
2.5 KiB
Plaintext
69 lines
2.5 KiB
Plaintext
|
ABI - Application Binary Interface
|
||
|
|
==================================
|
||
|
|
|
||
|
|
"ABI" describes the low-level interface between an application program and a
|
||
|
|
library. Calling conventions, function arguments, return values, struct
|
||
|
|
sizes/defines and more.
|
||
|
|
|
||
|
|
[Wikipedia has a longer description](https://en.wikipedia.org/wiki/Application_binary_interface)
|
||
|
|
|
||
|
|
Upgrades
|
||
|
|
--------
|
||
|
|
|
||
|
|
In the vast majority of all cases, a typical libcurl upgrade does not break
|
||
|
|
the ABI at all. Your application can remain using libcurl just as before,
|
||
|
|
only with less bugs and possibly with added new features. You need to read
|
||
|
|
the release notes, and if they mention an ABI break/soname bump, you may have
|
||
|
|
to verify that your application still builds fine and uses libcurl as it now
|
||
|
|
is defined to work.
|
||
|
|
|
||
|
|
Version Numbers
|
||
|
|
---------------
|
||
|
|
|
||
|
|
In libcurl land, you really can't tell by the libcurl version number if that
|
||
|
|
libcurl is binary compatible or not with another libcurl version.
|
||
|
|
|
||
|
|
Soname Bumps
|
||
|
|
------------
|
||
|
|
|
||
|
|
Whenever there are changes done to the library that will cause an ABI
|
||
|
|
breakage, that may require your application to get attention or possibly be
|
||
|
|
changed to adhere to new things, we will bump the soname. Then the library
|
||
|
|
will get a different output name and thus can in fact be installed in
|
||
|
|
parallel with an older installed lib (on most systems). Thus, old
|
||
|
|
applications built against the previous ABI version will remain working and
|
||
|
|
using the older lib, while newer applications build and use the newer one.
|
||
|
|
|
||
|
|
During the first seven years of libcurl releases, there have only been four
|
||
|
|
ABI breakages.
|
||
|
|
|
||
|
|
We are determined to bump the SONAME as rarely as possible. Ideally, we
|
||
|
|
never do it again.
|
||
|
|
|
||
|
|
Downgrades
|
||
|
|
----------
|
||
|
|
|
||
|
|
Going to an older libcurl version from one you're currently using can be a
|
||
|
|
tricky thing. Mostly we add features and options to newer libcurls as that
|
||
|
|
won't break ABI or hamper existing applications. This has the implication
|
||
|
|
that going backwards may get you in a situation where you pick a libcurl that
|
||
|
|
doesn't support the options your application needs. Or possibly you even
|
||
|
|
downgrade so far so you cross an ABI break border and thus a different
|
||
|
|
soname, and then your application may need to adapt to the modified ABI.
|
||
|
|
|
||
|
|
History
|
||
|
|
-------
|
||
|
|
|
||
|
|
The previous major library soname number bumps (breaking backwards
|
||
|
|
compatibility) have happened the following times:
|
||
|
|
|
||
|
|
0 - libcurl 7.1, August 2000
|
||
|
|
|
||
|
|
1 - libcurl 7.5 December 2000
|
||
|
|
|
||
|
|
2 - libcurl 7.7 March 2001
|
||
|
|
|
||
|
|
3 - libcurl 7.12.0 June 2004
|
||
|
|
|
||
|
|
4 - libcurl 7.16.0 October 2006
|