In case the support is not available, just stop building the
libbsd-ctor.a library, which is a nice to have thing, but should not
have been a hard requirement from the start. This should allow to
build libbsd on non-glibc based systems using another libc.
This is a wrapper over the glibc fopencookie() function.
We diverge from the FreeBSD, OpenBSD and DragonFlyBSD declarations,
because seekfn() there wrongly uses fpos_t, assuming it's an integral
type, and any code using that on a system where fpos_t is a struct
(such as GNU-based systems or NetBSD) will fail to build. In which case,
as the code has to be modified anyway, we might just as well use the
correct declaration.
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
This centralizes the setting so there's no duplication anymore,
makes sure the user supplied variables are never overridden, and
are only set when using gcc.
Reported-by: Samuli Suominen <ssuominen@gentoo.org>
