The automatic initialization cannot be part of the main shared library,
because there is no thread-safe way to change the environ global
variable. This is not a problem if the initializaion happens just at
program load time, but becomes one if the shared library is directly or
indirectly dlopen()ed during the execution of the program, which could
have either kept references to the old environ or could change it in
some other thread. This has been observed for example on systems using
Samba NSS modules.
To avoid any other possible fallout, the constructor is split into a
new static library that needs to be linked explicitly into programs
using setproctitle(). As an additional safety measure the pkg-config
linker flags will mark the program as not allowing to be dlopen()ed
so that we avoid the problem described above.
Reported-by: Jan Alexander Steffens (heftig) <jan.steffens@gmail.com>
Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=66679
Glibc tends to include standard headers with special definitions
that make few declarations or macros visible, this stomps over the
overlay #include_next <> logic.
Based-on-patch-by: Robert Millan <rmh@debian.org>
This means that software being ported should not need to be modified in
the usual case, as the libbsd headers will take over the standard
namespace and fill the missing gaps, and include the system headers.
To use this the new libbsd-transparent.pc file can be used through
pkg-config, which should end up doing the right thing.
