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56 lines
3 KiB
Text
56 lines
3 KiB
Text
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Here is a hopefully informative mini-rant about shared library support
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for mupdf.
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Upstream doesn't do shared libraries and doesn't recommend distro
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packages use them. This build used to follow that advice. However,
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mupdf is just too large to use as a static library. We end up with a
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47MB libmupdf.a, plus 7 33MB binaries. *Every* distro I've looked at
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ships mupdf as shared libs, despite upstream's policy.
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A long time ago (in 2013), I used to patch mupdf for shared lib support,
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but I removed it when it stopped applying cleanly. Thomas Morper on the
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slackbuilds-users mailing list recently (2018) asked if I could include
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a patch (from LFS) that adds shared library support, so starting with
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mupdf 1.13.0, BUILD 2, we have shared libraries again.
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In case someone *really* disagrees with this change, I added a STATIC=yes
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environment setting. If you use this, you get static libs and no
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shared ones, per upstream's policy. This has been tested and works for
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1.13.0-2, but be aware that I probably won't be testing static builds
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for every mupdf release. If you run into trouble, email me and/or the
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slackbuilds-users list.
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The library versioning scheme I had to use is unfortunate. The major
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soname version is supposed to only change when there's an incompatible ABI
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change. The way I'm doing it, it changes for every mupdf release [*]. This
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is because upstream doesn't tell us when the ABI changes, because it's
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not relevant for them. They support only static libs specifically to
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avoid the headache of having to track and minimize ABI changes. Whenever
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they want to change the ABI, they just do it. Anything built against the
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old version will keep working fine, because it's statically linked. With
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shared libs, I have to invent my own library versioning scheme.
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The end result of this is, I (humble packager) can't easily tell when
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the ABI has changed, so I treat every release [*] as an ABI change. Means
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anything linked with libmupdf will fail with 'cannot open shared object
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file' after a mupdf upgrade, so it'll have to be rebuilt. The alternative
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would be to use unversioned shared libs, which would (seem to) avoid
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the need to rebuild... but whenever the undocumented ABI changed, we'd
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get weird behaviour and segfaults instead of a clean error message.
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The shared library patch used here is by me (B. Watson), based on a
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patch from Linux From Scratch. The original LFS patch doesn't include
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versioned libs, I suspect becase in LFS you tend to upgrade the entire
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OS by rebuilding it, instead of upgrading just one library.
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Right now, the only SBo builds affected by mupdf upgrades will be
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zathura-pdf-mupdf and possibly fbpdf (if built with optional mupdf
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support). Both have been tested with shared mupdf, and both compile and
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run cleanly.
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[*] Actually, not micro-version point releases (e.g. 1.13.0 => 1.13.1).
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Hopefully this doesn't cause a problem later. Upstream has just
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switched to a major.minor.micro version scheme starting with 1.13.0,
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so I don't know how often there will be micro-version bumps, and
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whether or not they'll have ABI changes.
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