From 8b218188c6f780f71bec0cdc333c262402ae9408 Mon Sep 17 00:00:00 2001
From: david <mmw@tagmar.net>
Date: Sat, 5 Dec 2020 17:36:51 +0000
Subject: [PATCH] Initial commit

---
 _do_self_checks.sh | 116 +++++++++++++++++++++++++++++++++++++++++++++
 do_chroot.sh       |  14 ++++++
 do_umount.sh       |  20 ++++++++
 3 files changed, 150 insertions(+)
 create mode 100755 _do_self_checks.sh
 create mode 100755 do_chroot.sh
 create mode 100644 do_umount.sh

diff --git a/_do_self_checks.sh b/_do_self_checks.sh
new file mode 100755
index 0000000..6c6245a
--- /dev/null
+++ b/_do_self_checks.sh
@@ -0,0 +1,116 @@
+#!/bin/bash
+set -Eeuo pipefail
+
+# Used to check environment variables have been set.
+# In use it is called by do_chroot.sh and do_umount.sh
+#
+# Works safely, but not expected to be run independently.
+# It mounts the FILE_SYSTEM_DIR specified in ARM_root.sh.
+# If necessary, you can run do_umount.sh to unmount it.
+
+# Define chroot mounts, without a leading /.
+# Needed by do_chroot.sh.
+# Used as $i in:
+#    mount --bind /$i ./$i
+#    umount ./$i
+export CHROOT_MOUNT_SET="dev dev/pts proc sys"
+
+#
+# Check environment variables, then mount the filesystem.
+#
+main(){
+	local CONFIG_FILE="${1}"
+
+	check_config_file_is_specified "$CONFIG_FILE"
+	check_config_file_exists "$CONFIG_FILE"
+	check_config_file_is_executable "$CONFIG_FILE"
+
+	. $CONFIG_FILE
+
+	check_for_unset_variables "$CONFIG_FILE"
+	mount_filesystem_if_not_mounted "$CONFIG_FILE"
+}
+
+check_config_file_is_specified() {
+	local CONFIG_FILE="${1}"
+
+	if [ -z "$CONFIG_FILE" ]; then
+		echo "Error: CONFIG_FILE not specified."
+		exit 1
+	fi
+}
+
+check_config_file_exists() {
+	local CONFIG_FILE="${1}"
+
+	if [ ! -f "$CONFIG_FILE" ]; then
+		cat <<-!
+		Error: $CONFIG_FILE is missing.
+		Expecting $CONFIG_FILE to set FILE_SYSTEM_DIR and POOL_PREFIX,
+		perhaps something like:
+		  export FILE_SYSTEM_DIR=/space/amd64/devuan/beowulf/tasmotizer
+		  
+		  # On our zfs, /space/amd64/... is the mount of rpool/amd64/...
+		  # RPOOL_ROOT is specified to convert from one to the other.
+		  export POOL_PREFIX=/space
+		  export RPOOL_ROOT=rpool
+		!
+		exit 1
+	fi
+}
+
+check_config_file_is_executable() {
+	local CONFIG_FILE="${1}"
+
+	if [ ! -x "$CONFIG_FILE" ]; then
+		echo "Error: $CONFIG_FILE is not executable."
+		exit 2
+	fi
+}
+
+check_for_unset_variables() {
+	local CONFIG_FILE="${1}"
+
+	# Check for unset variables. Allow unset variables here.
+	set +u;
+	    if [ -z "$FILE_SYSTEM_DIR" ]; then
+		echo "Error: FILE_SYSTEM_DIR was not set in $CONFIG_FILE."
+		exit 3
+	    fi;
+	set -u
+
+	# Check for unset variables. Allow unset variables here.
+	set +u;
+	    if [ -z "$POOL_PREFIX" ]; then
+		echo "Error: POOL_PREFIX was not set in $CONFIG_FILE."
+		exit 4
+	    fi;
+	set -u
+	
+	# Check for unset variables. Allow unset variables here.
+	set +u;
+	    if [ -z "$RPOOL_ROOT" ]; then
+		echo "Error: RPOOL_ROOT was not set in $CONFIG_FILE."
+		exit 5
+	    fi;
+	set -u
+	
+}
+
+mount_filesystem_if_not_mounted() {
+	local CONFIG_FILE="${1}"
+
+	check_for_unset_variables $CONFIG_FILE
+
+	# On our zfs, /space/amd64/... is the mount of rpool/amd64/...
+	# Get the pool name (change POOL_PREFIX for RPOOL_ROOT).
+	local RPOOL=${FILE_SYSTEM_DIR/${POOL_PREFIX}/${RPOOL_ROOT}}
+	
+	# Mount if not mounted
+	if [ -z "$(grep "${RPOOL} "  /proc/mounts)" ]; then
+		sudo zfs mount $RPOOL
+	fi
+}
+
+# Entry point.
+main ./ARM_root.sh
diff --git a/do_chroot.sh b/do_chroot.sh
new file mode 100755
index 0000000..dbc746e
--- /dev/null
+++ b/do_chroot.sh
@@ -0,0 +1,14 @@
+#!/bin/bash
+set -Eeuo pipefail
+
+# Check and set environment, and mount file system.
+. ./_do_self_checks.sh
+
+cd $FILE_SYSTEM_DIR
+if [ ! -z "$CHROOT_MOUNT_SET" ]; then
+	for i in $CHROOT_MOUNT_SET; do
+		sudo mount --bind /$i ./$i
+	done
+fi
+sudo /usr/sbin/chroot . /bin/bash
+
diff --git a/do_umount.sh b/do_umount.sh
new file mode 100644
index 0000000..029c308
--- /dev/null
+++ b/do_umount.sh
@@ -0,0 +1,20 @@
+# Deliberately not executable.  Run as:
+#  bash ./do_umount
+
+# Check the environment and mount the file system if it is not mounted (to be
+# sure it makes sense to umount it, rather than be umounting something else).
+. ./_do_self_checks.sh
+
+(
+	# If the file system had been mounted before _do_self_checks.sh, above,
+	# the umounts might fail for being busy, so allow errors.
+	set +Ee
+
+	cd $FILE_SYSTEM_DIR
+	for i in $CHROOT_MOUNT_SET; do
+		sudo umount --lazy ./$i
+	done 2>/dev/null
+	exit 0
+)
+
+sudo umount $FILE_SYSTEM_DIR