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#!/bin/sh
# Everything this machine needs before the session starts, and nothing else.
#
# Quiet on purpose: this writes to the console the visitor is about to watch
# slosh draw on, and a wall of boot chatter under a terminal multiplexer
# reads as something having gone wrong.
#
# Deliberately not `set -e`: a mount that is already there must not stop the
# ones after it, and one of those is devpts -- without which the demo has no
# panes at all.
mountpoint -q /proc || mount -t proc proc /proc
mountpoint -q /sys || mount -t sysfs sysfs /sys
# The guest kernel is built with CONFIG_DEVTMPFS_MOUNT, so /dev is already
# populated by the time init runs. Kept as a guard rather than dropped: it is
# one line, and it is what makes the rest of this script true on a kernel
# without that option.
mountpoint -q /dev || mount -t devtmpfs devtmpfs /dev
# Load-bearing, and the first thing to look at if the demo comes up with no
# panes in it: slosh gives every pane a pty of its own through
# posix_openpt(3), which is devpts or nothing. gid 5 is `tty` in Alpine's
# /etc/group, and ptmxmode is what makes /dev/ptmx openable at all.
mkdir -p /dev/pts
mountpoint -q /dev/pts ||
mount -t devpts -o ptmxmode=0666,gid=5,mode=620 devpts /dev/pts
[ -e /dev/ptmx ] || ln -s pts/ptmx /dev/ptmx
# Somewhere to write. The session's control socket lands under /tmp
# (/tmp/slosh-0/<name>.sock, since $XDG_RUNTIME_DIR is unset here), so a
# read-only /tmp is a session that cannot start. /dev/shm is not used by
# anything we ship, but musl's shm_open expects it and the cost is nothing.
mountpoint -q /tmp || mount -t tmpfs -o size=16m,mode=1777 tmpfs /tmp
mountpoint -q /run || mount -t tmpfs -o size=4m,mode=0755 tmpfs /run
mkdir -p /dev/shm
mountpoint -q /dev/shm || mount -t tmpfs -o size=8m,mode=1777 tmpfs /dev/shm
hostname slosh-demo
# The console is a terminal a full-screen program is about to own, and a kernel
# message arriving mid-session would be painted straight over it. Only panics
# get through from here on.
dmesg -n 1 2>/dev/null
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