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diff --git a/hurd/translator/term.mdwn b/hurd/translator/term.mdwn new file mode 100644 index 00000000..834ef9bd --- /dev/null +++ b/hurd/translator/term.mdwn @@ -0,0 +1,220 @@ +[[!meta copyright="Copyright © 2013, 2014 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +The *term* translator implements POSIX termios discipline. + + +# Open Issues + +## [[open_issues/Term_Blocking]] + +## Leaks/Not Re-used/Not Terminating + +[[!tag open_issue_hurd]] + + +### IRC, freenode, #hurd, 2013-10-14 + + <braunr> good news + <braunr> the terminal leak is related to privilege separation + +[[tschwinge]] confirming (using `ssh -t [machine] tty`) that with privilege +separation enabled there is this problem, and once disabled it goes away. + + <atheia> I love how, as an unknowing by-stander, that is somehow good news + :-) + <braunr> :) + <braunr> it's a good news because 1/ we have more knowledge about the issue + <braunr> and 2/ it may not even be a hurd bug + <braunr> but rather an openssh-on-hurd bug + <braunr> this explains why i didn't see the issue on anything else + (mach/hurd consoles, x terminals) + <braunr> and this will also indirectly solve the screen lockup issue + <teythoon> braunr: good catch :) + <braunr> s/a good news/good news/ + <atheia> ah, yes, both definitely good news. Congrats on the progress. + <braunr> i remember we used to disable privilege separation in the past + <braunr> i'll have to dig what made us use it + +[[news/2010-09]]. + + <braunr> interesting, screen seems to be affected nonetheless + <braunr> so it's something common to both screen and ssh privsep + <braunr> apparently, what sshd+privse and screen have in common is a fifo + <braunr> so it's probably a tricky hurd bug actually + + +### IRC, freenode, #hurd, 2013-10-16 + + <braunr> pflocal is leaking ports .. + <braunr> this might be what blocks terminals + * pinotree gives braunr a stick of glue + <braunr> thanks + + <braunr> pflocal leaks struct sock .. + <braunr> grmbl + + <braunr> hm nice, pflocal leaks each time a socket is bound and/or accepted + on + <braunr> looks like a simple ref mess + <pinotree> braunr: really? + <braunr> yes + <pinotree> a leak in pflocal feels strange, never noticed it taking lots of + memory (and it's used a lot) + <braunr> it's a port leak + <braunr> well + <braunr> no it's both a memory and port leak + <braunr> not sure which one is the root cause yet + <braunr> i guess server sockets aren't automatically unbound + <braunr> if you want to see the leak, just disable priv separation in ssh + (to avoid the terminal leak ....) and write a shell loop to start ssh + your_server echo hello + <braunr> google shows mails about the leak in the past + <braunr> i also hope it fixes the terminal leak, although i'm really not + sure :( + + +### IRC, freenode, #hurd, 2013-10-17 + + <braunr> hm nice, apparently, there is no pflocal leak + <braunr> but a libdiskfs one ! + <braunr> since ext2fs enables the ifsock shortcut + <braunr> seems like it leaks a reference on sock node deletion + <teythoon> braunr: have you looked at libdiskfs/dead-name.c? + <teythoon> braunr: I think I'm hunting a very similar problem + <braunr> i'm doing it now + <teythoon> I had the problem of dead name notifications not being delivered + <braunr> wow + <teythoon> b/c I held no reference to the ports_info thing, so the dead + name handler in libports could no longer find the pi struct, so the + notification was silently dropped + <braunr> i see + <braunr> but it looks like dropping a node makes sure the associated + sockaddr has been deleted if any + <teythoon> are you sure the node is dropped in the first place? + <braunr> no + <braunr> well + <braunr> i see something happenning at the pflocal side when removing the + node + <braunr> but there is still a send right lingering somewhere + <braunr> (see why we need a global lsof :p) + <teythoon> indeed + <braunr> i'll try portinfo with that option we talked about + <teythoon> yes + <braunr> 121 => 1682: send (refs: 1) + <braunr> yep, ext2fs still has it + <teythoon> (I wonder how portinfo does that...) + <braunr> i guess it imports rights from the target task + <braunr> and see if it gets the same name as a local right + <teythoon> makes sense + <braunr> easy to check + <teythoon> well, no, it cannot do that for receive rights + <braunr> it creates an empty task just for that purpose + <braunr> and uses mach_port_extract_right + <teythoon> but it works as you described, yes + <braunr> so yes it does work for receive rights too + <teythoon> yes + <teythoon> cool :) + <braunr> so it assumes identical port names are part of the ipc interface + <braunr> something neal said we shouldn't rely on + <braunr> iirc + <teythoon> yes, I remember something like that too + <braunr> here is the strange thing + <braunr> node->sockaddr is deallocated on a dead name notification + <braunr> drop_node checks that sockaddr is null + <braunr> so how can the dead name notification occur before the node is + dropped ? + <braunr> so maybe the node is still around indeed + <braunr> apparently, libdiskfs considers the address holds a reference on + the node + <braunr> on the other hand, the server socket won't get released unless the + address gets a no-sender notification ... + <braunr> this should probably be turned into a weak reference + <braunr> teythoon: indeed, the node is leaked + + <braunr> pflocal crashes when removing correctly deallocating addresses and + removing server sockets :/ + + <braunr> ok, pflocal bug fixed + <braunr> still have to fix the libdiskfs leak + <braunr> and libdiskfs leak fixed too + <braunr> :) + <braunr> i'll build hurd packages with my changes to make sure i don't + break something before comitting + <braunr> and see if this fixes the term issue + + <braunr> looks like my patches work just fine :) + <braunr> it doesn't solve the term issue though + + <braunr> so, according to portinfo, pflocal has send rights to terminals oO + + <braunr> mhhhmmmmmm + <braunr> openssh seems to pass terminal file descriptors through unix + sockets when using privilege separation + <pinotree> braunr: i a write(sock, &pid, sizeof int) (or the like)? + <pinotree> *ie + <braunr> not pid, file descriptors + <braunr> SCM_RIGHTS + <pinotree> ah ok + <braunr> the socket send/recv interface does support passing mach ports + <braunr> and the leaked ports do turn into dead names when i kill terminals + <pinotree> yes, we support with a patch pochu did few years ago + <braunr> so it seems the leak is related to libpipe this time + <braunr> ok got it :) + <braunr> pflocal used copy_send instead of move_send + <braunr> \o/ + <braunr> that bug was such a pain + * braunr happy + <teythoon> :) + <pinotree> speaking of it, in pflocal' S_socket_recv is it correct the + "out_flags = 0;"? + <braunr> nice catch + <braunr> although i wonder why flags are returned + <braunr> it may have been set to null to tell us that we don't want to + return flags + <braunr> pfinet seems to use it + <pinotree> but you change a local variable anyway + <braunr> yes it's not useful + <braunr> hmm + <braunr> out_flags is what gets in struct msghdr -> msg_flags + <braunr> so i guess it makes sense to fix it to *out_flags = 0, just to be + safe + <braunr> pinotree: do you want me to push it tonight along with the others + ? + <pinotree> yes please + <braunr> ok + <pinotree> thanks! + <braunr> pflocal seems to not leak any memory or ports at all + <braunr> great :> + + <braunr> there, patches pushed :) + + +### IRC, freenode, #hurd, 2014-02-07 + + <braunr> btw, as a note, there really are leaks in terminals + <braunr> i managed to get a term server eat up to 300M of memory yesterday + + +## `screen` Logout Hang + +[[!tag open_issue_hurd]] + + +### IRC, freenode, #hurd, 2013-10-14 + + <braunr> i fixed term so that screen can shutdown properly + <braunr> read() wouldn't return EIO after terminal hangup + + +### IRC, freenode, #hurd, 2013-10-17 + + <braunr> and the missing EOI prevented screen from correctly shutting down + windows |