the exec handshake to return.
In addition to being The Right Thing To Do, fixes some nasty
conditions for CLOEXEC fd's (or at least does so in theory, I
couldn't create any problems although I tried).
rump tcp/ip stack:
* sshd likes to fork and then re-exec itself
==> trap execve() and augment the env with the current parameters
essential to a rump kernel (kernel communication fd, information
about dup2'd file descriptors)
* sshd likes to play lots of games with pipes, socketpairs and dup{,2}()
==> make sure we do not close essential rump client descriptors:
dup() them to a safe place, except for F_CLOSEM where we
simply leave them alone. also, partially solved by the above,
make sure the process's set of rump kernel descriptors persists
over exec()
* sshd likes to chdir() before exec
==> for unix-style rump_sp(7) sockets save the full path on the
initial exec and use it afterwards. thread the path through
the environment in execve()
a wedge. This still lacks the proplibistic query of the sector
size and just assumes 512. It's good that we make asking a file's
size as simple as requiring one stat(), one open() and three (3)
different ioctls plus some proplist mumbojumbo. I'm surprised it's
available at all by means other than #wish.
code mostly from Taylor R Campbell, rant from me.
two or more syscall requests before any worker thread ran, we might
not have enough threads to handle the requests. In some scenarios
this could lead to a deadlock.
the kernel server is lost, the client will now automatically attempt
to reconnect.
Among other things, this makes it possible to "reboot" and restart
the TCP/IP stack from under firefox without any perceivable less
of service. If pages were loading at the time the TCP/IP server
was killed, there may be some broken links, but nothing a ctrl-r
cannot fix.
in the socket before we shut down. This way the response to the
syscall travels to the caller and they know things worked correctly
instead of having to just assume.
* don't hold spc mutex while sending data
* use send() for the banner to avoid SIGPIPE in case a client
connects and immediately goes away
* fix error path locking
* use kevent() instead of pollts() in the client. Apparently that
is the only sensible way for a library to support both multithreading
and signal-reentrancy in a race-free manner.
(can I catch all signals with one kevent instead of installing
NSIG different ones??)
* mark client comm descriptor non-blocking so that clients have
better signal-interruptibility (we now sleep in signal-accepting
kevent() instead of signal-masked recvfrom())
requests which have a 0-length response (such as copyin 0/0).
This change makes links(1) work against a rump kernel which contains
rumpnet_local. The presence of unix domain sockets caused links
to select() with 0 fds and a timeout, and because copyin never woke
up in the kernel the application blocked indefinitely.
dlsym(RTLD_NEXT) to lookup a host_syscall() function pointer which
is used instead of syscall() to communicate with the kernel server.
WARNING: popular opinion classifies this as "ugly code". if you
have a weak heart/mind/soul/sole meuniere, read max. 1 line of the
diff per day, preferably with food.
violent disconnect. Fixes some race conditions (maybe the one
occasionally showing up on tests/rump/rumpkern/t_stress).
thanks to schmonz for some discussion
It's pretty much a placeholder for now. One plan for the future
is to require some sort of authentication for superuser clients.
The code will need a little massage then, though, to prevent DoS
attacks.
is done in rumpuser for simplicity, since on the kernel side things
we assume we have only one pointer of space). As a side-effect,
we can no longer know if the current thread is holding on to a
mutex locked without curlwp context (basically all mutexes inited
outside of mutex_init()). The only thing that called rumpuser_mutex_held()
for a non-kmutex was the giant lock. So, instead implement recursive
locking for the giant lock in the rump kernel and get rid of the
now-unused recursive pthread mutex in the hypercall interface.
Also, add rump_daemonize_begin() / rump_daemonize_end() to help
with the "can't daemon() after pthread_create()" problem. Applications
could accomplish the same, but since it's such a common operation,
provide a little help.
limits. This improves syscall throughput about 2x for non-userio
syscalls (no copyin/out, e.g. getpid()) and almost 1.5x even for
things like __sysctl().
(measured for cases where the remote process is on the local machine)
XXX: if the pthread deadqueue sucks for anything which cares about
performance, why does it exist? Nuking it would make supporting
variable stack size easier.
