
Simon McVittie
authored
This works around ABI divergence from upstream in the libcurl in
Debian/Ubuntu between about 2005 and 2018, which unfortunately includes
the time at which Steam Runtime 1 'scout' started. Modern versions of
libcurl have versioned symbols attached to a verdef CURL_OPENSSL_4,
but Debian introduced versioned symbols before upstream did, and used
CURL_OPENSSL_3. We want to be compatible with both.
Similarly, modern upstream versions of libcurl when built against GNUTLS
have versioned symbols attached to a verdef CURL_GNUTLS_4, but Debian
introduced versioned symbols attached to a verdef CURL_GNUTLS_3, and
is still using that verdef as of 2022. We want to be compatible with
both, if we can.
The trick here is that since glibc 2.30, the dynamic linker does not
require triples (SONAME, version, symbol), but only looks for pairs of
(SONAME, version) and, independently, (version, symbol). This means that
dependencies on versioned symbols can be satisfied by any of the
recursive dependencies of the library found when searching for the
SONAME, and not just the library itself. glibc seems to have introduced
this functionality so that glibc itself would be able to move symbols
from its smaller libraries into libc.so.6 without breaking compatibility.
The shim library has verdefs for both sets of versioned symbols, so it
can be positioned in the search path as libcurl.so.4 and will satisfy
both sets of requirements for the verdefs. For the actual symbols, it
delegates to libsteam-runtime-system-libcurl.so.4 and
libsteam-runtime-our-libcurl.so.4, which are expected to be set up by
the runtime's setup.sh as symlinks to the real libraries that implement
the two faces of libcurl.
This requires some setup, which will be coordinated by a new version of
setup.sh, in each of the pinned_libs_* directories. The real work is done
by libcurl-compat/compat-setup.c, which uses the steam-runtime-tools
library to find out whether the system libcurl is compatible with the
expected ABIs.
If there is no system copy of libcurl, then we do not need to do all
this and can use the runtime's libcurl directly: binaries that rely on
having a newer libcurl will fail, but by definition those binaries
can't have been built or tested against the scout runtime.
Helps: steamrt/tasks#119
Signed-off-by:
Simon McVittie <smcv@collabora.com>
Name | Last commit | Last update |
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.. | ||
meson | ||
git-version-gen | ||
many-builds.md | ||
many-builds.py | ||
run-in-sysroot.py | ||
scout-builds.py |