functions to be used by the dynamic linker. This can be called by
threads packages at start-up time. I will add the call to libc_r
soon.
Also add a default locking method that is used up until dllockinit()
is called. The default method works by blocking SIGVTALRM, SIGPROF,
and SIGALRM in critical sections. It is based on the observation
that most user-space threads packages implement thread preemption
with one of these signals (usually SIGVTALRM).
The dynamic linker has never been reentrant, but it became less
reentrant in revision 1.34 of "src/libexec/rtld-elf/rtld.c".
Starting with that revision, multiple threads each doing lazy
binding could interfere with each other. The usual symptom was
that a symbol was falsely reported as undefined at start-up time.
It was rare but not unseen. This commit fixes it.
function. It was an ill-considered feature. It didn't solve the
problem I wanted it to solve. And it added Yet Another Version
Number that would have to be maintained at every release point.
I'm nuking it now before anybody grows too fond of it.
into libc. This reduces the size of every dynamically linked
executable by 248 bytes, and it reduces the size of static executables
by a lesser amount. It also eliminates some global namespace
pollution.
With this change in place, the source for dlfcn.h should probably
be moved to "/usr/src/include". I'll save that for another day.
Compatibility note: Programs which use dlopen, if compiled on
systems with this change, will not run on systems with a libc from
prior to this change. Very few programs use dlopen, so I think
that is OK.
