Red Hat Bugzilla – Bug 102042
process stops when backgrounding
Last modified: 2007-11-30 17:10:31 EST
I found a strange problem when recompiling some SRPMs: When backgrounding rpmbuild, it gets stopped at some point. If you put the job in the foreground, it continues running correctly (however, job control does not seem to work correctly then - after stopping the build process with Strg-C, building continues until I have killed the processes). I saw this when rebuilding zsh-4.0.7-1.src.rpm and coreutils-4.5.3-22.src.rpm. This is 100% reproduceable for me (the zsh and coreutils rebuild always hangs at the same point.) zsh: $ rpmbuild --rebuild zsh-4.0.7-1.src.rpm & ... checking if link() works... yes checking if kill(pid, 0) returns ESRCH correctly... yes checking if POSIX sigsuspend() works... yes checking if tcsetpgrp() actually works... Here the process hangs. If I hit enter now: [1]+ Stopped rpmbuild --rebuild zsh-4.0.7-1.src.rpm Now forgrounding it: $ fg ... everything continues correctly If I attach strace to the hanging/stopped process, I get the following: --- SIGSTOP (Stopped (signal)) @ 0 (0) --- --- SIGSTOP (Stopped (signal)) @ 0 (0) --- ioctl(0, TIOCSPGRP, [1387]) = ? ERESTARTSYS (To be restarted) --- SIGTTOU (Stopped (tty output)) @ 0 (0) --- --- SIGTTOU (Stopped (tty output)) @ 0 (0) --- ioctl(0, TIOCSPGRP, [1387]) = ? ERESTARTSYS (To be restarted) --- SIGTTOU (Stopped (tty output)) @ 0 (0) --- --- SIGTTOU (Stopped (tty output)) @ 0 (0) --- ioctl(0, TIOCSPGRP, [1387]) = ? ERESTARTSYS (To be restarted) --- SIGTTOU (Stopped (tty output)) @ 0 (0) --- --- SIGTTOU (Stopped (tty output)) @ 0 (0) --- "TIOCSPGRP / SIGTTOU" continues infinitely This is on a Dell PowerEdge 2400 dual-cpu server, I am connected to the server using (Open)SSH. I also tried the single processor kernel, same result. I also tried to run it from the console, same problem.
*** Bug 102033 has been marked as a duplicate of this bug. ***
The kernel is behaving correctly. The zsh configure script runs a program that does tcsetpgrp on fd 0 (stdin), which is broken in multiple ways. If the input were redirected then the test would give a false negative. Since the input is your terminal and the job is in the background, it rightly gets SIGTTOU for trying to perform tcsetpgrp. The only way a test of this nature can be safe is if it's done on a specially created pty, e.g. in the child of a forkpty call, but using ptys is not fully portable so zsh is kind of stuck here. If you would like to see this addressed, file a bug against zsh.
Reopening and changing to zsh then. (I suppose it is something similar with coreutils, therefore changing that one from duplicate to reopen)
Reproduced.
Mailed zsh-users for input.
http://www.zsh.org/mla/workers/2003/msg00895.html
Patch from http://www.zsh.org/mla/workers/2003/msg00896.html unfortunately breaks build in buildsystem ("no tty"). Adding weaker patch from http://www.zsh.org/mla/workers/2003/msg00895.html in zsh-4.0.7-2.
Updating to better patch from upstream in 4.0.9-1.