Merge casper:intergrate-20iso_scan into casper:main

[Łukasz Zemczak]

Integrate 20iso_scan into casper (from lupin-casper)"

I tried to cherry-pick only the relevant bits from lupin-casper into casper itself.

[Dimitri John Ledkov (xnox)]

review: Approve

diff --git a/debian/changelog b/debian/changelog
index 0fb5823..a7f8ee0 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+casper (1.469) UNRELEASED; urgency=medium
+
+  * Integrate lupin-casper's 20iso_scan casper-premount script so that users
+    can continue to use images that provide multiple iso's to choose to boot
+    from. This was no longer possible after the removal of the lupin packages
+    from jammy (LP: #1960457). 
+
+ -- Łukasz 'sil2100' Zemczak <[e-mail]>  Thu, 14 Apr 2022 15:04:19 +0200
+
 casper (1.468) jammy; urgency=medium
 
   * casper-md5check: correctly detect fsck.mode=skip if last
diff --git a/scripts/casper-helpers b/scripts/casper-helpers
index 6fed1f9..72a0cfe 100644
--- a/scripts/casper-helpers
+++ b/scripts/casper-helpers
@@ -363,4 +363,77 @@ find_files()
     done
 }
 
+# Helpers originally from lupin-helpers
+is_supported_fs(){
+    [ -z "${1}" ] && return 1
+    case ${1} in
+        ext2|ext3|ext4|xfs|jfs|reiserfs|vfat|ntfs|iso9660|btrfs)
+            return 0
+            ;;
+    esac
+    return 1
+}
+
+wait_for_devs(){
+    if [ -e /dev/.initramfs/lupin-waited-for-devs ]; then
+        return
+    fi
+    [ "$quiet" != "y" ] && log_begin_msg "...waiting for devs..."
+    udevadm trigger --subsystem-match=block
+    udevadm settle
+    #TBD, modprobe on demand?
+    modprobe ext3
+    modprobe ext4
+    modprobe reiserfs
+    modprobe xfs
+    modprobe jfs
+    modprobe vfat
+    modprobe fuse
+    [ "$quiet" != "y" ] && log_end_msg "...devs loaded..."
+    touch /dev/.initramfs/lupin-waited-for-devs
+}
+
+find_path()
+{
+    local path="${1}"
+    # must match find_path_cleanup
+    local default_mountpoint="${2:-/tmpmountpoint}"
+    local mountoptions="${3:-ro}"
+    local mountpoint=
+    local dev devname devfstype
+    local trial_number
+    FOUNDDEV=
+    FOUNDPATH=
+    [ -z "${path}" ] && return 1
+    wait_for_devs
+    mkdir -p "${default_mountpoint}"
+    for trial_number in 1 2 3; do
+        [ $trial_number -gt 1 ] && sleep 3
+        for sysblock in $(echo /sys/block/* | tr ' ' '\n' | grep -v /ram | grep -v /loop | grep -v /fd); do
+            for dev in $(subdevices "${sysblock}"); do
+                devname=$(sys2dev "${dev}")
+                devfstype="$(get_fstype ${devname})"
+                if is_supported_fs "${devfstype}" ; then
+                                    #if device is already mounted, do not remount
+                    if grep -q "^${devname} " /proc/mounts; then
+                        mountpoint=$(grep "^${devname} " /proc/mounts|cut -d ' ' -f 2)
+                        unmount=false
+                    else
+                        mountpoint="${default_mountpoint}"
+                        try_mount "$devname" "$mountpoint" "$mountoptions" || continue
+                        unmount=true
+                    fi
+                    if [ -e "${mountpoint}${path}" ]; then
+                        FOUNDDEV="${devname}"
+                        FOUNDPATH="${mountpoint}${path}"
+                        return 0
+                    fi
+                    [ "${unmount}" = "true" ] && umount ${mountpoint} 2> /dev/null || true
+                fi
+            done
+        done
+    done
+    return 1
+}
+
 
diff --git a/scripts/casper-premount/20iso_scan b/scripts/casper-premount/20iso_scan
new file mode 100755
index 0000000..117011b
--- /dev/null
+++ b/scripts/casper-premount/20iso_scan
@@ -0,0 +1,39 @@
+#!/bin/sh
+
+PREREQ=""
+
+prereqs()
+{
+       echo "$PREREQ"
+}
+
+case $1 in
+# get pre-requisites
+    prereqs)
+           prereqs
+           exit 0
+           ;;
+esac
+
+. /scripts/casper-functions
+
+iso_path=
+for x in $(cat /proc/cmdline); do
+    case ${x} in
+        iso-scan/filename=*)
+            iso_path=${x#iso-scan/filename=}
+            ;;
+    esac
+done
+if [ "$iso_path" ]; then
+    if find_path "${iso_path}" /isodevice rw; then
+        echo "LIVEMEDIA=${FOUNDPATH}" >> /conf/param.conf
+        if [ -f "${FOUNDPATH}" ]; then
+            echo "LIVEMEDIA_OFFSET=0" >> /conf/param.conf
+        fi
+    else
+        panic "
+Could not find the ISO $iso_path
+"
+    fi
+fi