Source: bglibs Version: 2.04+dfsg-9 Severity: normal Tags: patch User: [email protected] Usertags: origin-ubuntu stonking ubuntu-patch
Hi, libbg ships a default "const int msg_show_pid = 0" (msg/show_pid.c) which programs override with their own definition (include/msg.h declares it weak); msg_common()/msg_commonfv() are supposed to use whichever definition wins at runtime. When the library is built with -flto (the default in Ubuntu on amd64, arm64, ppc64el and s390x), GCC sees the library-local const definition while linking libbg.so, folds it to 0 and drops the PID-printing branch entirely: the resulting libbg.so has no GLOB_DAT relocation for msg_show_pid and no getpid() call in msg_common. Programs such as mailfront that set msg_show_pid = 1 then lose the "[pid]" in their log lines, and mailfront's testsuite fails (tests/backend-queuedir): https://bugs.launchpad.net/bugs/2170282 Debian is not affected today since LTO isn't enabled by default, but it would be with DEB_BUILD_MAINT_OPTIONS=optimize=+lto. Making the default definition weak isn't sufficient (GCC 13 and 15 still fold the const initializer); the attached patch reads the variable through a volatile lvalue instead. Tested with GCC 15.3 and LTO: bglibs selftests pass, libbg.so references msg_show_pid through the GOT again, and mailfront 2.12-3 built against it passes all 124 tests. The patch has also been sent upstream, https://github.com/bruceg/bglibs/pull/12 Thanks, Sebastien Bacher
bglibs.debdiff
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