#!/bin/ksh 

# Location of new mounted boot disk(s)
_NewBase=$1
# Shortcut to Updates directory under _NewBase
_Updates=$_NewBase/RedHat/Updates
# Shortcut name to RPMS for Updates comparison
_RPMS=./RedHat/RPMS
# location of saved files.  Arg2 can be used to specify if default of ./OLD 
# is not wanted.  This may be useful if you want to immediately generate a 
# new ISO of the changed files.
_olddir=${2:-./OLD}

# Directory to save old version of changed files
mkdir -p $_olddir

# We now will cmp(1) each file under the new release with what we have
# for this baseline.  Changed file will be saved under a new directory
# created above ($_olddir).  We skip directories, assuming nothing of
# importance for an empty directory.  We only care about files.
for old in $( cd $_NewBase; find . ! -type d )
do
    local new=$_NewBase/$old
    if [[ $old == ./isolinux/*.msg || $old == ./isolinux/*.cfg ]]; then
        print "Skipping $old..."
        continue
    fi
    if [[ -f $old ]]; then
        cmp $old $new > /dev/null 2>&1
        if (( $? )); then
            # files differ so save under $_olddir
            local adir=${old%/*}                # cut off file leaving dir path
            print "Updating $old with $new"
            mkdir -p $_olddir/$adir
            mv $old $_olddir/$adir
            cp -p $new $adir
        fi
    fi
done
print "Skipped files should be verified against new file under $_NewBase!"

# Now deal with thw new RPMS under $_NewBase/RedHat/Updates replacing older
# files here with the newer version.  We make an assumption here that all
# RPMS have NUMBERIC versions.  We really should use librpm and read the
# internal RPM name for comparison, but that is for a later date.
# _Updates, _RPMS
RPMsv=$_olddir/RedHat/RPMS
mkdir -p $RPMsv
for new in $_Updates/*.rpm 
do 
    if [[ "$new" == "$_Updates/*.rpm" ]]; then
        print "No RPM updates, continuing..."
        break
    fi
    local snm=${new%-*}; snm=${snm%-*}; snm=${snm##*/}
    for old in $_RPMS/${snm}* 
    do
        if [[ $old == "$_RPMS/${snm}*" ]]; then break; fi

        local osnm=${old%-*}; osnm=${osnm%-*}; osnm=${osnm##*/}
        if [[ $osnm == $snm ]]; then
            old=${old##*/}
            new=${new##*/}
            if mv $_RPMS/$old $RPMsv && cp $_Updates/$new $_RPMS; then
                print Replacing $old with $new and archiving $old in $RPMsv
            else
                print -u2 Failed to replace $old wih $new
            fi
            break
        fi
    done
done