pb-plugin: Keep chroot persistent, and create wrapper scripts

Rather than having to 'pb-plugin run' multiple times, we want users to
be able to execute multiple plugin binaries with more accessible
command-line statements.

This change reverts to the previous 'install' (rather than 'run')
behaviour, and creates wrapper scripts to call into the chroot.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/utils/pb-plugin b/utils/pb-plugin
index 4e4165257e21b6bfa11b215c1ace2fa79317d220..598530a66e7a7f5581649a2f76088c94e13abbad 100755 (executable)
--- a/utils/pb-plugin
+++ b/utils/pb-plugin
@@ -7,6 +7,7 @@ plugin_file=pb-plugin.cpio.gz
 plugin_meta=pb-plugin.conf
 plugin_meta_dir=etc/preboot-plugins/
 plugin_meta_path=$plugin_meta_dir$plugin_meta
+plugin_wrapper_dir=/usr/bin
 
 usage()
 {
@@ -14,9 +15,9 @@ usage()
 Usage: $0 <command>
 
 Where <command> is one of:
-  run <FILE|URL>      - run plugin from FILE/URL
-  scan                - look for available plugins on attached devices
-  create <DIR>        - create a new plugin archive from DIR
+  install <FILE|URL> - install plugin from FILE/URL
+  scan               - look for available plugins on attached devices
+  create <DIR>       - create a new plugin archive from DIR
 EOF
 }
 
@@ -62,41 +63,55 @@ plugin_info()
        echo "  (version $PLUGIN_VERSION)"
 }
 
-__run_init()
+do_wrap()
 {
-       local base dir
+       local base binary dir
 
        base=$1
+       binary=$2
+       shift 2
 
-       for dir in etc dev sys proc
+       for dir in etc dev sys proc var
        do
-               mkdir -p $base/$dir
+               [ -e "$base/$dir" ] || mkdir -p "$base/$dir"
        done
 
        cp /etc/resolv.conf $base/etc
        mount -o bind /dev $base/dev
        mount -o bind /sys $base/sys
        mount -o bind /proc $base/proc
+       mount -o bind /var $base/var
+
+       chroot "$base" "$binary" "$@"
+
+       umount $base/dev
+       umount $base/sys
+       umount $base/proc
+       umount $base/var
 }
 
-__run_cleanup()
+__create_wrapper()
 {
-       local base
+       local base binary wrapper
 
        base=$1
+       binary=$2
+       wrapper=$plugin_wrapper_dir/$(basename $binary)
 
-       [ -e $base/dev/null ] && umount $base/dev
-       [ -e $base/sys/kernel ] && umount $base/sys
-       [ -e $base/proc/stat ] && umount $base/proc
-       rm -rf $base
+       cat <<EOF > $wrapper
+#!/bin/sh
+
+exec $(realpath $0) __wrap '$base' '$binary' "\$@"
+EOF
+
+       chmod a+x $wrapper
 }
 
-do_run()
+do_install()
 {
-       local url executable
+       local url name file __dest
 
        url=$1
-       executable=$2
 
        if [ -z "$url" ]
        then
@@ -129,7 +144,7 @@ do_run()
        echo
        sha256sum "$file" | cut -f1 -d' '
        echo
-       echo "Do you want to run this plugin? (y/N)"
+       echo "Do you want to install this plugin? (y/N)"
        read resp
 
        case $resp in
@@ -153,20 +168,13 @@ do_run()
 
        . $__dest/$plugin_meta_path
 
-       (
-               executable=${PLUGIN_EXECUTABLE:-$executable}
-
-               __run_init $__dest
-
-               printf "Entering plugin\n"
-               plugin_info
-
-               chroot $__dest $executable
-
-               printf "\nExiting plugin & cleaning up\n"
-               __run_cleanup $__dest
-       )
+       for binary in ${PLUGIN_EXECUTABLES}
+       do
+               __create_wrapper "$__dest" "$binary"
+       done
 
+       echo "Plugin installed"
+       plugin_info
 }
 
 do_scan()
@@ -259,10 +267,13 @@ EOF
 
 cat <<EOF
 
-Enter the full path (within the plugin root) to the plugin executable file.
-This will be the default action when the plugin is run. (eg /usr/bin/my-util)
+Enter the full path (within the plugin root) to the plugin executable file(s).
+These will be exposed as wrapper scripts, to be run from the standard petitboot
+shell environment (eg, /usr/bin/my-raid-config).
+
+If multiple executables are provided, separate with a space.
 EOF
-       read executable
+       read executables
 
        date=$(date +%Y-%m-%d)
 
@@ -273,7 +284,7 @@ PLUGIN_VENDOR='$vendorname'
 PLUGIN_NAME='$pluginname'
 PLUGIN_VERSION='$version'
 PLUGIN_DATE='$date'
-PLUGIN_EXECUTABLE='$executable'
+PLUGIN_EXECUTABLES='$executables'
 EOF
 
 }
@@ -335,10 +346,9 @@ do_create()
                        echo "error: no PLUGIN_DATE defined in metadata" &>2
                        exit 1
                fi
-               if [ ! -n "$PLUGIN_EXECUTABLE" ]
+               if [ ! -n "$PLUGIN_EXECUTABLES" ]
                then
-                       echo "error: no PLUGIN_EXECUTABLE defined in metadata" \
-                               &>2
+                       echo "error: no PLUGIN_EXECUTABLES defined in metadata"\                                &>2
                        exit 1
                fi
 
@@ -419,7 +429,7 @@ test_scan()
        (
                echo "PLUGIN_NAME=test"
                echo "PLUGIN_VERSION=1"
-               echo "PLUGIN_EXECUTABLE=/bin/sh"
+               echo "PLUGIN_EXECUTABLES=/bin/sh"
        ) > $mnt_dir/$plugin_meta_path
        (
                cd $mnt_dir;
@@ -508,9 +518,9 @@ do_tests()
 }
 
 case "$1" in
-run)
+install)
        shift
-       do_run $@
+       do_install $@
        ;;
 scan)
        shift
@@ -520,6 +530,10 @@ create)
        shift
        do_create $@
        ;;
+__wrap)
+       shift
+       do_wrap $@
+       ;;
 __test)
        shift
        do_tests $@