#!/bin/bash
# Copyright (c) 2004 Matthias S. Benkmann <article AT winterdrache DOT de>
# You may do everything with this code except misrepresent its origin.
# PROVIDED `AS IS' WITH ABSOLUTELY NO WARRANTY OF ANY KIND!

#The following list should contain the mount points of all filesystems
#that are to be scanned as a space-separated list within parentheses. 
#/ will usually be in this list and if you have /usr
#on a separate partition, it will also be in this list. Other non-special
#filesystems where package users could own files should also be put in this
#list.
#Mount points whose filesystems are special, such as procfs or sysfs must
#not be in this list. While a simple find on those special filesystems should 
#be harmless, operations such as "-exec grep something" are NOT SAFE and may 
#have HARMFUL SIDE-EFFECTS, especially when performed as root. 

## Bastard settings
# fs_to_scan=(/ /opt /usr /usr/local /var)

fs_to_scan=(/)

#Files with a path prefix found in the following list are ignored.
#This list will usually contain the parent directory of your package users'
#home directories, because normally you don't want to scan those. You can
#also add other directories that will never contain package user files, such
#as /home. This reduces scan time.
#NOTE: The LFS-6.0 book uses a ramfs mounted on /dev and with that setup
#/dev does not need to be in the prune list. But since there is no requirement
#that /dev have its on filesystem it's better to prune it explicitly.

## Bastard settings
# prune_prefixes=(\
#      /tools \
#      /usr/local/LFS/tools \
#      /home \
#      /usr/src \
#      /dev \
#      /mnt \
#      /tmp \
#      /sys \
#      /etc/apache/ssl.key \
#      /etc/cups/ssl \
#      /etc/firewall \
#      /etc/skel \
#      /etc/ssl/private \
#      /lost+found \
#      /**/lost+found \
#      /root \
#      /usr/local/lost+found \
#      /**/.{mc,ssh,mozilla,spamassassin} \
#      /usr/local/media/pr0n \
#      /usr/local/LFS \
#      /usr/share/mailman \
#      /var/{cache,chroot,run,snmp,spool} \
#      /var/lib/{sshd,nfs,spamassassin,pulse} \
#      /var/www/htdocs/SXEmacs-issues{,.old} \
#      /var/lost+found) #NO TRAILING SLASHES!!!!

prune_prefixes=(/home /usr/src /dev /tools) #NO TRAILING SLASHES!!!!

if [ $# -lt 1 -o "$1" = "--help" ]; then
    echo 1>&2
    echo 1>&2 'USAGE: '"${0##*/}"' <user_or_group_name> [<find-commands>]'
    echo 1>&2
    echo 1>&2 '  If <find-commands> contains no action other than -prune, -print will be'
    echo 1>&2 '    executed for all matching files.'
    echo 1>&2 '  Entries will be matched if group and/or user equals <user_or_group_name>'
    echo 1>&2 '    (numeric UID/GID allowed).'
    echo 1>&2 '  All matching entries will be acted on, including device special files, so'
    echo 1>&2 '    you should be extra careful with the <find-commands> you provide!'
    echo 1>&2
    exit 1
fi

#suppress ugly debug output from shell
trap ':' SIGPIPE

ugname="$1"
shift 1  #remove user_or_group_name from argument list

ugmatcher=(-false)
#test if find accepts ugname as a user, and append to ugmatcher if it does
if find / -maxdepth 0 -user "$ugname" >/dev/null 2>&1 ; then
    ugmatcher[${#ugmatcher[@]}]="-or"
    ugmatcher[${#ugmatcher[@]}]="-user"
    ugmatcher[${#ugmatcher[@]}]="$ugname"
fi
#test if find accepts ugname as a group, and append to ugmatcher if it does
if find / -maxdepth 0 -group "$ugname" >/dev/null 2>&1 ; then
    ugmatcher[${#ugmatcher[@]}]="-or"
    ugmatcher[${#ugmatcher[@]}]="-group"
    ugmatcher[${#ugmatcher[@]}]="$ugname"
fi

#if find accepted ugname as neither user nor group, then exit
if [ "${#ugmatcher[@]}" = 1 ]; then
    echo 1>&2 'find does not accept `'"$ugname'"' as group or user name'
    exit 1
fi

#construct find commands that match the prune_prefixes. Each prefix will be
#matched as -path <prefix> -or -path <prefix>/*
#so that the directory itself and all subdirectories are matched.
y=(\( -false)
for ((i=0; $i<${#prune_prefixes[@]}; i=$i+1))
do
    y[${#y[@]}]='-or'
    y[${#y[@]}]=-path
    y[${#y[@]}]="${prune_prefixes[$i]}"
    y[${#y[@]}]='-or'
    y[${#y[@]}]=-path
    y[${#y[@]}]="${prune_prefixes[$i]}/*"
done
y[${#y[@]}]=')'

#In the following find command, the part
# -not ( ( "${y[@]}" -prune ) -or "${y[@]}" )
#is responsible for preventing the files that match prune_prefixes from
#being processed. The 2nd "${y[@]}" may seem redundant, but it isn't, because
#-prune has no effect and is always false when -depth is used.
#The -true before "$@" ensures that -depth can be passed as only parameter.
find "${fs_to_scan[@]}" -xdev -noleaf \
    -not \( \( "${y[@]}" -prune \) -or "${y[@]}" \) \
    -and \( "${ugmatcher[@]}" \) -and \( -true "$@" \)