#!/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. 
#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. As the
#main function of this script is to help you find files that contain
#hardwired paths to /tools or other unwanted references to
#your build system, you will usually prune any directories that don't contain
#files of interest, such as /tools (whose files naturally refer to /tools)
#and your package users' home directories (which may also test positive if
#you have unpacked and configured sources lying around).
#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.
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##*/}"' <grep-commands>'
    echo 1>&2 
    echo 1>&2 '  grep -l <grep-commands> -- <file>'
    echo 1>&2 '  will be executed for each *regular file* <file>'
    echo 1>&2 '  ATTENTION! If you override the -l switch with a switch that makes grep'
    echo 1>&2 '  output all individual matches rather than just the matching files,'
    echo 1>&2 '  then DO NOT redirect output to a file that is in a directory that will be'
    echo 1>&2 '  scanned, or you risk creating an endless loop that will cause your'
    echo 1>&2 '  output file to grow till your disk is full.'
    echo 1>&2 
    exit 1
fi

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

#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[@]}]=')'

cmd_pre=(-type f -exec grep -l)
cmd_post=(-- {} \;)

#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 "${y[@]}" may seem redundant, but it isn't, because
#-prune has no effect and is always false when -depth is used (which someone
#might do in the future).
#The -true before "$@" ensures that -depth can be passed as 1st parameter
#of $cmd_pre (should someone change it in the future).
find "${fs_to_scan[@]}" -xdev -noleaf \
    -not \( \( "${y[@]}" -prune \) -or "${y[@]}" \) \
    -and \( -true "${cmd_pre[@]}" "$@" "${cmd_post[@]}" \)