A simple script to demonstrate this problem is attached below. It appears that s6-rc-update will neglect to create the needed pipes in the following situation:
1. A service X is already running before s6-rc-update is invoked 2. Service X was not the consumer-for any other service prior to s6-rc-update 3. Service X is the consumer-for at least one service after s6-rc-update A similar problem occurs with producer-for. The fix is relatively straightforward; in fill_convtable_and_flags() a check is needed to detect if olddb->services[i].x.longrun.nproducers==0 is different from newdb->services[x].x.longrun.nproducers==0; if so, the NEWSTATE_IS_BIJECTIVE_CONVERSION_TARGET flag should not be added to newstate[x] and instead OLDSTATE_RESTART should be added to oldstate[i]. I have a patch that implements this, and the corresponding check for longrun.consumer. Below is a crude shell script which demonstrates the bug. It does not require root. Before running the script below, you must run the following command on a different terminal (you'll want to observe its output): mkdir -p /tmp/live/service s6-svscan -- /tmp/live/service/ Here is the script: #!/bin/bash mkdir -p source/consumer echo longrun > source/consumer/type echo -e '#!/bin/bash\ncat > /dev/null' > source/consumer/run chmod +x source/consumer/run mkdir source/producer echo longrun > source/producer/type echo -e '#!/bin/bash\nwhile true; do sleep 1; date; done\n' > source/producer/run chmod +x source/producer/run s6-rc-compile compiled source s6-rc-init -l /tmp/live/compiled -c $(pwd)/compiled /tmp/live/service/ s6-rc -l /tmp/live/compiled start producer consumer s6rc-fdholder echo <<EOF at this point you will see the output of "producer" in the terminal window where s6-svscan is running -- its output goes to the catch-all logger next, we will add the producer/consumer funnel links. however since the services have already started, they will not be *re*started, and s6-fdholder wont have the necessary file descriptors EOF sleep 5 echo producer > source/consumer/consumer-for echo consumer > source/producer/producer-for s6-rc-compile compiled2 source s6-rc-update -l /tmp/live/compiled $(pwd)/compiled2 echo <<EOF next we restart the producer (only); you should see messages like the following on the catch-all logger: s6-fdholder-retrieve: fatal: unable to retrieve fd for id pipe:s6rc-w-consumer: No such file or directory EOF sleep 5 s6-rc -l /tmp/live/compiled stop producer s6-rc -l /tmp/live/compiled start producer
