1999-06-18 Roland McGrath <roland@baalperazim.frob.com>

	* runsystem.sh: New file.
	* Makefile (targets, special-targets): Add runsystem.
	(runsystem): New target.

1 files changed, 146 insertions, 0 deletions

diff --git a/daemons/runsystem.sh b/daemons/runsystem.sh
new file mode 100644
index 00000000..afedd5c9
--- /dev/null
+++ b/daemons/runsystem.sh
@@ -0,0 +1,146 @@
+#!/bin/sh
+#
+# This program is run by /hurd/init at boot time after the essential
+# servers are up, and is responsible for running the "userland" parts of a
+# normal system.  This includes running the single-user shell as well as a
+# multi-user system.  This program is expected never to exit.
+#
+
+
+###
+### Where to find programs, etc.
+###
+
+PATH=/bin:/sbin
+export PATH
+
+# If we lose badly, try to exec each of these in turn.
+fallback_shells='/bin/sh /bin/bash /bin/csh /bin/ash /bin/shd'
+
+# Shell used for normal single-user startup.
+SHELL=/bin/sh
+
+# Programs that do multi-user startup.
+RUNCOM=/libexec/rc
+RUNTTYS=/libexec/runttys
+# Signals that we should pass down to runttys.
+runttys_sigs='TERM INT HUP TSTP'
+
+###
+
+
+# If we get a SIGLOST, attempt to reopen the console in case
+# our console ports were revoked.  This lets us print messages.
+function reopen_console ()
+{
+  exec 1>/dev/console 2>&1 || exit 3
+}
+trap 'reopen_console' SIGLOST
+
+
+# Call this when we are losing badly enough that we want to punt normal
+# startup entirely.  We exec a single-user shell, so we will not come back
+# here.  The only way to get to multi-user from that shell will be
+# explicitly exec this script or something like that.
+function singleuser ()
+{
+  test $# -eq 0 || echo "$0: $*"
+  for try in ${fallback_shells}; do
+    SHELL=${try}
+    exec ${SHELL}
+  done
+  exit 127
+}
+
+
+# We expect to be started by console-run, which gives us no arguments and
+# puts FALLBACK_CONSOLE=file-name in the environment if our console is
+# other than a normal /dev/console.  The MULTIBOOT_CMDLINE environment
+# variable gives us the kernel command line from the boot loader, which is
+# where any interesting boot options will be found.
+
+if [ "${FALLBACK_CONSOLE+set}" = set ]; then
+  singleuser "Running on fallback console ${FALLBACK_CONSOLE}"
+elif [ $# -ne 0 ]; then
+  singleuser "Unexpected arguments: $*"
+elif [ "${MULTIBOOT_CMDLINE+set}" != set ]; then
+  singleuser "No multiboot command line!"
+fi
+
+
+###
+### Normal startup procedures
+###
+
+# Parse the multiboot command line.  We only pay attention to -s and -f.
+set -- ${MULTIBOOT_CMDLINE}
+shift
+flags=
+while [ $# -gt 0 ]; do
+  arg="$1"
+  shift
+  case "$arg" in
+  --*) ;;
+  *=*) ;;
+  -*)
+    flags="${flags}${arg#-}"
+    ;;
+  'single'|'emergency') # Linux compat
+    flags="${flags}s"
+    ;;
+  'fastboot')
+    flags="${flags}f"
+    ;;
+  esac
+done
+
+# Check boot flags.
+case "$flags" in
+*s*)
+  rc=false			# force single-user
+  ;;
+*f*)
+  rc="${RUNCOM}"		# fastboot
+  ;;
+*)
+  rc="${RUNCOM} autoboot"	# multi-user default
+  ;;
+esac
+
+# Large infinite loop.  If this script ever exits, init considers that
+# a serious bogosity and punts to a fallback single-user shell.
+# We handle here the normal transitions between single-user and multi-user.
+while : ; do
+
+  # Run the rc script.  As long as it exits nonzero, punt to single-user.
+  # After the single-user shell exits, we will start over attempting to
+  # run rc; but later invocations strip the `autoboot' argument.
+  until $rc; do
+    rc=${RUNCOM}
+
+    # Run single-user shell and repeat as long as it dies with a signal.
+    until ${SHELL} || test $? -lt 128; do
+      :
+    done
+  done
+
+  # Now we are officially ready for normal multi-user operation.
+
+  # Trap certain signals and send them on to runttys.  For this to work, we
+  # must run it asynchronously and wait for it with the `wait' built-in.
+  runttys_pid=0
+  for sig in $runttys_sigs; do
+    trap "kill -$sig \${runttys_pid}" $sig
+  done
+
+  # This program reads /etc/ttys and starts the programs it says to.
+  ${RUNTTYS} &
+  runttys_pid=$!
+
+  # Wait for runttys to die, meanwhile handling trapped signals.
+  wait
+
+  # Go back to the top of the infinite loop, as if booting single-user.
+  rc=false
+
+done