ABI
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上传日期:2018-10-23
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- libcurl's binary interface
- ABI - Application Binary Interface
- First, allow me to define the word for this context: ABI describes the
- low-level interface between an application program and a library. Calling
- conventions, function arguments, return values, struct sizes/defines and
- more.
- For a longer descricption, see
- http://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
- parallell 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.
- 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.