bin/live-snapshot: Vastly rework script

This patch vastly reworks the live-snapshot script; it fixes a number of
bugs related to argument handling (such as ignored parameters), as well
as improving the general robustness of the operation.

The script can also be run successfully with set -e and set -u, pending
some other patches in 'scripts/live-helpers'

diff --git a/bin/live-snapshot b/bin/live-snapshot
index 8a05500..141d266 100755 (executable)
--- a/bin/live-snapshot
+++ b/bin/live-snapshot
@@ -7,6 +7,7 @@
 #   in another live-initramfs session. Look at manpage for more info.
 #
 # Copyright (C) 2006 Marco Amadori <marco.amadori@gmail.com>
+# Copyright (C) 2008 Chris Lamb <chris@chris-lamb.co.uk>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -25,86 +26,73 @@
 # On Debian systems, the complete text of the GNU General Public License
 # can be found in /usr/share/common-licenses/GPL-2 file.
 
-PROGRAM="$(basename $0)"
-VERSION=0.0.1
+set -eu
 
-# Source live conf
-if [ -e /etc/live.conf ]
-then
-       . /etc/live.conf
-else
-       USERNAME=$(cat /etc/passwd | grep "999" | cut -f1 -d ':')
-       HOSTNAME=$(hostname)
-fi
+. /usr/share/initramfs-tools/scripts/live-helpers
+. /etc/live.conf
 
 export USERNAME USERFULLNAME HOSTNAME
 
-# Source helper functions
-helpers="/usr/share/initramfs-tools/scripts/live-helpers"
+PROGRAM="$(basename $0)"
+VERSION=0.0.2
 
-if [ -e "${helpers}" ]
-then
-       . "${helpers}"
-else
-       echo "Error: I cannot found helper functions \"${helpers}\"."
-       exit 1
-fi
+MOUNTP="/mnt/live-snapshot"
+SNAP_COW="/live/cow"
+SNAP_DEV=""
+DEST="${MOUNTP}/live-sn.cpio.gz"
+SNAP_TYPE="cpio"
+DESKTOP_LINK="/home/${USERNAME}/Desktop/live-snapshot"
+SNAP_RESYNC_STRING=""
 
-# Define LSB log_* functions.
-# Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
-. /lib/lsb/init-functions
+Error ()
+{
+       echo "${PROGRAM}: error:" ${@}
+       exit 1
+}
 
-MOUNTP=""
-COW=""
-DEV=""
-DEST="${MOUNTP}/live-sn.cpio.gz"
-TYPE=""
-DESKTOP_LINK=""
+panic ()
+{
+       Error ${@}
+}
 
 Header ()
 {
-       echo "${PROGRAM} - utility to do Debian Live snapshots"
+       echo "${PROGRAM} - utility to perform snapshots of Debian Live systems"
        echo
-       echo "Usage: ${PROGRAM} [-c|--cow DIRECTORY] [-d|--device DEVICE] [-o|--output FILE] [-t|--type TYPE]"
-       echo "Usage: ${PROGRAM} [-r|--resync-string STRING]"
-       echo "Usage: ${PROGRAM} [-h|--help]"
-       echo "Usage: ${PROGRAM} [-u|--usage]"
-       echo "Usage: ${PROGRAM} [-v|--version]"
+       echo "usage: ${PROGRAM} [-c|--cow DIRECTORY] [-d|--device DEVICE] [-o|--output FILE] [-t|--type TYPE]"
+       echo "       ${PROGRAM} [-r|--resync-string STRING]"
+       echo "       ${PROGRAM} [-h|--help]"
+       echo "       ${PROGRAM} [-u|--usage]"
+       echo "       ${PROGRAM} [-v|--version]"
 }
 
-Usage ()
+Help ()
 {
-       MESSAGE=${1}
-
        Header
 
        echo
-       echo "Try \"${PROGRAM} --help\" for more information."
+       echo "Options:"
+       echo "  -c, --cow: copy on write directory (default: ${SNAP_COW})."
+       echo "  -d, --device: output snapshot device (default: ${SNAP_DEV:-auto})."
+       echo "  -o, --output: output image file (default: ${DEST})."
+       echo "  -r, --resync-string: internally used to resync previous made snapshots."
+       echo "  -t, --type: snapshot filesystem type. Options: \"squashfs\", \"ext2\", \"ext3\", \"jffs2\" or \"cpio\".gz archive (default: ${SNAP_TYPE})"
+       echo
+       echo "Look at live-snapshot(1) man page for more information."
 
-       if [ ! -z "${MESSAGE}" ]
-       then
-               /bin/echo -e "${MESSAGE}"
-               exit 1
-       else
-               exit 0
-       fi
+       exit 0
 }
 
-Help ()
+Usage ()
 {
        Header
 
        echo
-       echo "Options:"
-       echo "  -c, --cow: specifies the copy on write directory (default: /live/cow)."
-       echo "  -d, --device: specifies the output snapshot device (default: none)."
-       echo "  -o, --output: specifies the output image file (default: ${type} dependent)."
-       echo "  -r, --resync-string: internally used to resync previous made snapshots."
-       echo "  -t, --type: specifies the snapshot type between \"squashfs\", \"ext2\", \"ext3\", \"jffs2\" or \"cpio\".gz archive (default: cpio)"
-       /bin/echo -e "\nLook at live-snapshot(1) man page for more information."
+       echo "Try \"${PROGRAM} --help\" for more information."
 
        exit 0
 }
+       
 
 Version ()
 {
@@ -134,37 +122,6 @@ Version ()
        exit 0
 }
 
-Do_snapshot ()
-{
-       case "${TYPE}" in
-               squashfs)
-                       echo "./tmp/exclude_list" > /tmp/exclude_list
-                       ( cd "${COW}" && find . -name '*.wh.*' >> /tmp/exclude_list )
-                       mksquashfs "${COW}" "${DEST}" -ef /tmp/exclude_list || exit 1
-                       rm /tmp/exclude_list
-                       ;;
-
-               cpio)
-                       ( cd "${COW}" && find . -path '*.wh.*' -prune -o -print0 | cpio --quiet -o0 -H newc | gzip -9c > "${DEST}" ) || exit 1
-                       ;;
-
-               ext2|ext3)
-                       DU_DIM="$(du -ks ${COW} | cut -f1)"
-                       REAL_DIM="$(expr ${DU_DIM} + ${DU_DIM} / 20)" # Just 5% more to be sure, need something more sophistcated here...
-                       genext2fs --size-in-blocks=${REAL_DIM} --reserved-blocks=0 --root="${COW}" "${DEST}" || exit 1
-                       ;;
-
-               jffs2)
-                       mkfs.jffs2 --root="${COW}" --output="${DEST}" || exit 1
-                       ;;
-
-               *)
-                       echo "Internal error."
-                       exit 1
-                       ;;
-       esac
-}
-
 Is_same_mount ()
 {
        dir1="$(Base_path ${1})"
@@ -184,12 +141,6 @@ Parse_args ()
        ARGS="${*}"
        ARGUMENTS="$(getopt --longoptions cow:,device:,output,resync-string:,type:,help,usage,version --name=${PROGRAM} --options c:d:o:t:r:,h,u,v --shell sh -- ${ARGS})"
 
-       if [ "${?}" != "0" ]
-       then
-               echo "Terminating." >&2
-               exit 1
-       fi
-
        eval set -- "${ARGUMENTS}"
 
        while true
@@ -216,7 +167,7 @@ Parse_args ()
                                ;;
 
                        -r|--resync-string)
-                               SNAP_RSTRING="${2}"
+                               SNAP_RESYNC_STRING="${2}"
                                break
                                ;;
 
@@ -238,144 +189,142 @@ Parse_args ()
                                ;;
 
                        *)
-                               echo "Internal error."; exit 1 ;;
+                               Error "internal error."
+                               ;;
 
                esac
        done
-}
-
-Mount_device ()
-{
-       dev="${1}"
-
-       if [ ! -d "${MOUNTP}" ]
-       then
-               mkdir -p "${MOUNTP}"
-       fi
-
-       if [ -z "${dev}" ]
-       then
-               # create a temp
-               mount -t tmpfs -o rw tmpfs "${MOUNTP}"
 
-               if [ ! -L /home/${USERNAME}/Desktop/live-snapshot ]
-               then
-                       ln -s "${MOUNTP}" /home/${USERNAME}/Desktop/live-snapshot
-               fi
-       else
-               if [ -b "${dev}" ]
-               then
-                       try_mount "${dev}" "${MOUNTP}" rw
-               fi
-       fi
 }
 
 Defaults ()
 {
-       MOUNTP="/mnt/live-snapshot"
-       COW="/live/cow"
-       DEV=""
-       DEST="${MOUNTP}/live-sn.cpio.gz"
-       TYPE="cpio"
-       DESKTOP_LINK=/home/${USERNAME}/Desktop/live-snapshot
-
-       if [ -n "${SNAP_RSTRING}" ]
+       # Parse resync string
+       if [ -n "${SNAP_RESYNC_STRING}" ]
        then
-               COW=$(echo "${SNAP_RSTRING}" | cut -f1 -d ':')
-               DEV=$(echo "${SNAP_RSTRING}" | cut -f2 -d ':')
-               DEST=$(echo "${SNAP_RSTRING}" | cut -f3 -d ':')
+               SNAP_COW=$(echo "${SNAP_RESYNC_STRING}" | cut -f1 -d ':')
+               SNAP_DEV=$(echo "${SNAP_RESYNC_STRING}" | cut -f2 -d ':')
+               DEST=$(echo "${SNAP_RESYNC_STRING}" | cut -f3 -d ':')
 
                case "${DEST}" in
                        *.cpio.gz)
-                               TYPE="cpio"
+                               SNAP_TYPE="cpio"
                                ;;
 
                        *.squashfs)
-                               TYPE="squashfs"
+                               SNAP_TYPE="squashfs"
                                ;;
 
                        *.jffs2)
-                               TYPE="jffs2"
+                               SNAP_TYPE="jffs2"
                                ;;
 
                        ""|*.ext2|*.ext3)
-                               TYPE="ext2"
+                               SNAP_TYPE="ext2"
                                ;;
-
                        *)
-                               Usage "Unregognized String"
+                               Error "unrecognized resync string"
                                ;;
                esac
-       else
-               DEF_COW="/live/cow"
-
-               # Bad options handling
-               if [ -z "${SNAP_COW}" ]
-               then
-                       COW="${DEF_COW}"
-               else
-                       COW="${SNAP_COW}"
-               fi
 
+       else
+               # Set target file based on image
                case "${SNAP_TYPE}" in
-                       "cpio"|"squashfs"|"ext2"|"ext3"|"jffs2")
-                               TYPE="${SNAP_TYPE}"
-                               ;;
-
-                       "")
-                               TYPE="cpio"
-                               ;;
-
-                       *)
-                               Usage "Error: unrecognized snapshot type"
-                               ;;
-               esac
-
-               case "${TYPE}" in
                        cpio)
                                DEST="${MOUNTP}/live-sn.cpio.gz"
                                ;;
 
-                       squashfs)
-                               DEST="${MOUNTP}/live-sn.squashfs"
+                       squashfs|jffs2|ext2)
+                               DEST="${MOUNTP}/live-sn.${SNAP_TYPE}"
                                ;;
 
-                       ext2)
+                       ext3)
                                DEST="${MOUNTP}/live-sn.ext2"
                                ;;
+               esac
+       fi
 
-                       *)
-                               echo "Internal error."
-                               exit 1
+}
+
+Validate_input ()
+{
+       case "${SNAP_TYPE}" in 
+               cpio|squashfs|jffs2|ext2|ext3)
                        ;;
-               esac
+               *)
+                       Error "invalid filesystem type \"${SNAP_TYPE}\""
+                       ;;
+       esac
+
+       if [ ! -d "${SNAP_COW}" ]
+       then
+               Error "${SNAP_COW} is not a directory"
        fi
 
-       # check vars
-       if [ ! -d "${COW}" ]
+       if [ "$(id -u)" -ne 0 ]
        then
-               Usage "Error: ${COW} is not a directory"
+               Error "you are not root"
        fi
+}
+
+Mount_device ()
+{
+       mkdir -p "${MOUNTP}"
 
-       Mount_device ${DEV}
+       case "${SNAP_DEV}" in
+               "")
+                       # create a temp
+                       mount -t tmpfs -o rw tmpfs "${MOUNTP}"
+                       ;;
+               *)
+                       if [ -b "${SNAP_DEV}" ]
+                       then
+                               try_mount "${SNAP_DEV}" "${MOUNTP}" rw
+                       fi
+                       ;;
+       esac
+}
+
+Do_snapshot ()
+{
+       case "${SNAP_TYPE}" in
+               squashfs)
+                       echo "./tmp/exclude_list" > /tmp/exclude_list
+                       ( cd "${SNAP_COW}" && find . -name '*.wh.*' >> /tmp/exclude_list )
+                       mksquashfs "${SNAP_COW}" "${DEST}" -ef /tmp/exclude_list
+                       rm /tmp/exclude_list
+                       ;;
+
+               cpio)
+                       ( cd "${SNAP_COW}" && find . -path '*.wh.*' -prune -o -print0 | cpio --quiet -o0 -H newc | gzip -9c > "${DEST}" ) || exit 1
+                       ;;
+
+               ext2|ext3)
+                       DU_DIM="$(du -ks ${SNAP_COW} | cut -f1)"
+                       REAL_DIM="$(expr ${DU_DIM} + ${DU_DIM} / 20)" # Just 5% more to be sure, need something more sophistcated here...
+                       genext2fs --size-in-blocks=${REAL_DIM} --reserved-blocks=0 --root="${SNAP_COW}" "${DEST}"
+                       ;;
+
+               jffs2)
+                       mkfs.jffs2 --root="${SNAP_COW}" --output="${DEST}"
+                       ;;
+       esac
 }
 
 Clean ()
 {
-       if [ -n "${DEV}" ]
-       then
-               umount "${MOUNTP}"
-               rmdir "${MOUNTP}"
-               #rm
-       fi
+       umount "${MOUNTP}"
+       rmdir "${MOUNTP}"
 }
 
 Main ()
 {
        Parse_args "${@}"
        Defaults
+       Validate_input
+       trap 'Clean' EXIT 
+       Mount_device
        Do_snapshot
-       Clean
 }
 
-Main "${@}"
+Main "${@:-}"