towel/towel.sh

#!/bin/bash -e

#
#  Towel:  Randomly Useful Bash Functions
#          Never Leave Home Without Your Towel
#
#  Copyright (C) 2019 Scott Duensing <scott@kangaroopunch.com>
#
#  This software is provided 'as-is', without any express or implied
#  warranty.  In no event will the authors be held liable for any damages
#  arising from the use of this software.
#
#  Permission is granted to anyone to use this software for any purpose,
#  including commercial applications, and to alter it and redistribute it
#  freely, subject to the following restrictions:
#
#  1. The origin of this software must not be misrepresented; you must not
#     claim that you wrote the original software. If you use this software
#     in a product, an acknowledgment in the product documentation would be
#     appreciated but is not required.
#  2. Altered source versions must be plainly marked as such, and must not be
#     misrepresented as being the original software.
#  3. This notice may not be removed or altered from any source distribution.
#


#
#  Color constants for tBoldBox.
#
tRED=1
tGREEN=2
tYELLOW=3
tBLUE=4
tPURPLE=5
tCYAN=6


#
#  Global variables used by Towel.
#
__tG__PARENTPATH="${BASH_SOURCE[0]}"
__tG__SUDOPASS=


#
#   Argument helper to process things intended for Towel.
#
# Parameters:
#   ARGS  - All command line arguments passed to script.
#
function tArgsHandler() {
	local __FIRST=$1

	# Is SUDO after us?
	if [[ "${__FIRST}" == "TOWEL_ASKPASS" ]]; then
		tSudoAskPass  # Does not return.
	fi
}


#
#   Draws bold white text inside a colored box.
#
# Parameters:
#
#   COLOR - Towel color constant for box background color.
#   TEXT  - Text to display.
#
function tBoldBox() {
	local __COLOR=$1
	local __TEXT=$2
	local __LEN=$((${#__TEXT}+6))
	local __SPACES=$(printf "%${__LEN}s")

	__COLOR=${!__COLOR}

	echo -e "\e[1m\e[4${__COLOR}m${__SPACES}\e[0m"
	echo -e "\e[1m\e[4${__COLOR}m   ${__TEXT}   \e[0m"
	echo -e "\e[1m\e[4${__COLOR}m${__SPACES}\e[0m"
}


#
#   Checks to see if listed packages have been installed.
#   Currently DEB packages only.
#
# Parameters:
#
#   RESULT - Variable in which to return the packages that are missing.
#   VAR    - List of packages to check, sparated by spaces.
#
function tCheckPackages() {
	local __RESULT=$1
	local __PACKAGES=${*:2}
	local __MISSING=
	local __P=

	set +e
	for __P in ${__PACKAGES}; do
		dpkg-query -s ${__P} 2> /dev/null | grep -q ^"Status: install ok installed"$
		if [ "$?x" == "1x" ]; then
			__MISSING="${__MISSING} ${__P}"
		fi
	done
	set -e

	tTrimL __MISSING "${__MISSING}"

	eval $__RESULT=\${__MISSING}
}


#
#   Downloads file.
#
# Parameters:
#
#   URL  - URL of file to download.
#   FILE - Optional alternate name to save downloaded file under.
#
function tDownload() {
	local __URL=$1
	local __FILE=

	tTrim __FILE "$2"

	if [[ -z ${__FILE} ]]; then
		__FILE=${__URL##*/}
	fi

	if [[ -e "${__FILE}" ]]; then
		rm -f "${__FILE}"
	fi

	wget -O "${__FILE}" ${__URL}
}


#
#   Escapes a given string so it's safe to write into an XML document.
#
# Parameters:
#
#   RESULT - Variable in which to return the escaped string.
#   VAR    - String to escape.
#
function tEscapeXml() {
	local __RESULT=$1
	local __VAR=${*:2}

	__VAR=$(echo ${__VAR} | sed -e 's~&~\&amp;~g' -e 's~<~\&lt;~g' -e 's~>~\&gt;~g')

	eval $__RESULT=\${__VAR}
}


#
#   Downloads the latest release of a project from GitHub.
#
# Parameters:
#
#   RESULT     - Variable in which to return the name of the downloaded file.
#   DEVELOPER  - GitHub developer name that owns the project.
#   PROJECT    - Which project from that developer to download.
#   EXTENSION  - Which file extension to download from the release list.
#
function tFetchGitHubRelease() {
	local __RESULT=$1
	local __DEVELOPER=$2
	local __PROJECT=$3
	local __EXTENSION=$4
	local __URL=$(curl -s https://api.github.com/repos/${__DEVELOPER}/${__PROJECT}/releases \
		| grep "browser_download_url.*${__EXTENSION}" \
		| cut -d : -f 2,3 \
		| tr -d \" \
		| head -n 1)
	local __FILE=${__URL##*/}
	tDownload ${__URL}
	eval $__RESULT=\${__FILE}
}


#
#   Displays a whiptail-based file browser for selecting a particular type of file.
#
# Parameters:
#
#   RESULT    - Variable in which to store selected filename, or empty if dialog is canceled.
#   TITLE     - Title to display in the file browser window.
#   EXTENSION - The extension to allow to be selected (in ".ext" format).
#   START     - Optional.  Path to begin browsing from.
#
function tFileBrowser() {
	local __RESULT=$1
	local __TITLE=$2
	local __EXTENSION=$3
	local __START=$4
	local __SELECTION=
	local __DIRLIST=()
	local __CURDIR=
	local __RET=
	local __LOOPING=1

	pushd . > /dev/null

	if [[ ! -z ${__START} ]]; then
		cd "${__START}"
	fi

	while [[ ${__LOOPING} -eq 1 ]]; do
		__DIRLIST=()
		if [[ "${__CURDIR}" != "/" ]]; then
			__DIRLIST[${#__DIRLIST[@]}+1]=".."
			__DIRLIST[${#__DIRLIST[@]}+1]="Up"
		fi
		for F in *; do
			if [[ -d "${F}" ]]; then
				__DIRLIST[${#__DIRLIST[@]}+1]=$(echo "${F}/   ")
			else
				__DIRLIST[${#__DIRLIST[@]}+1]=$(echo "${F}   ")
			fi
			__DIRLIST[${#__DIRLIST[@]}+1]=$(ls -lah "${F}" | awk '{ print $5 }')
		done

		__CURDIR=$(pwd)

		set +e
		__SELECTION=$(whiptail --title "${__TITLE}" \
			--menu "PgUp/PgDn/Arrows ENTER Selects File/Folder or TAB Key\n\n${__CURDIR}" 0 0 0 \
			--cancel-button "Cancel" \
			--ok-button "Select" "${__DIRLIST[@]}" 3>&1 1>&2 2>&3)
		__RET=$?
		set -e

		if [[ ${__RET} -eq 1 ]]; then
			# User Selected Cancel
			__SELECTION=
			__LOOPING=0
		elif [[ ${__RET} -eq 0 ]]; then
			tTrim __SELECTION "${__SELECTION}"
			if [[ -d "${__SELECTION}" ]]; then
				# Was a directory selected?
				cd "${__SELECTION}"
			elif [[ -f "${__SELECTION}" ]]; then
				# Was a file selected?
				if [[ ${__SELECTION} == *${__EXTENSION} ]]; then
					# Check if file has given extension
					if (whiptail --title "Confirm Selection" \
						--yesno "Directory:  ${__CURDIR}\n Filename:  ${__SELECTION}" 0 0 \
						--yes-button "Confirm" \
						--no-button "Reselect"); then
							__SELECTION="$(pwd)/${__SELECTION}"
							__LOOPING=0
					fi
				else
					# Not requested extension
					whiptail --title "Error" \
						--msgbox "Not a ${__EXTENSION} file" 0 0
				fi
			else
				# Not a file or folder
				whiptail --title "Error" \
					--msgbox "Unable to change to directory ${__SELECTION}" 0 0
			fi
		fi
	done

	eval $__RESULT=\${__SELECTION}

	popd > /dev/null
}


#
#   Returns the absolute path of a given file.
#
# Parameters:
#
#   RESULT - Variable in which to return the absolute path.
#   SOURCE - File which we wish to find the absolute path.
#
function tFindPath() {
	local __RESULT=$1
	local __SOURCE=$2
	local __DIR=

	while [[ -h "${__SOURCE}" ]]; do
		__DIR="$( cd -P "$( dirname "${__SOURCE}" )" && pwd )"
		__SOURCE="$(readlink "${__SOURCE}")"
		# If $__SOURCE was a relative symlink, we need to resolve it
		# relative to the path where the symlink file was located.
		[[ ${__SOURCE} != /* ]] && __SOURCE="${__DIR}/${__SOURCE}"
	done
	__DIR="$( cd -P "$( dirname "${__SOURCE}" )" && pwd )"

	eval $__RESULT=\${__DIR}
}


#
#   Returns the location and name of the parent script that included us.
#
# Parameters:
#
#   RESULT - Variable in which we want the absolute filename returned.
#
function tGetParentPath() {
	local __RESULT=$1
	local __PARENTPATH=

	# We have to initialize __tG__PARENTPATH before the calling script
	# changes directories elsewhere.  We set it on load.
	tFindPath __PARENTPATH "${__tG__PARENTPATH}"
	__TOWELPATH="${__PARENTPATH}/`basename \"${__tG__PARENTPATH}\"`"

	eval $__RESULT=\${__PARENTPATH}
}


#
#   Returns the location and name of this Towel script.
#
# Parameters:
#
#   RESULT - Variable in which we want the absolute filename returned.
#
function tGetTowelPath() {
	local __RESULT=$1
	local __TOWELPATH=

	tFindPath __TOWELPATH "${BASH_SOURCE[0]}"
	__TOWELPATH="${__TOWELPATH}/`basename \"${BASH_SOURCE[0]}\"`"

	eval $__RESULT=\${__TOWELPATH}
}


#
#   Runs program with sudo asking for password using a nice dialog box.
#
# Parameters:
#
#   ARGS - Command to execute with sudo.
#
function tSudo() {
	local __ARGS="$@"
	local __ASK="$(mktemp --suffix=.sh -q)"

	if [[ "${__tG__SUDOPASS}x" == "x" ]]; then
		cat <<- ASKPASS > "${__ASK}"
			#!/bin/bash
			"${BASH_SOURCE[1]}" TOWEL_ASKPASS
		ASKPASS
	else
		cat <<- ASKPASS > "${__ASK}"
			#!/bin/bash
			echo "${__tG__SUDOPASS}"
		ASKPASS
	fi

	chmod +x "${__ASK}"

	if [[ "${__ARGS}x" == "x" ]]; then
		SUDO_ASKPASS="${__ASK}" sudo -A -v
	else
		SUDO_ASKPASS="${__ASK}" sudo -A ${__ARGS}
	fi

	rm "${__ASK}"
}


#
#   Helper function for asking for password using a nice dialog box.
#
# Parameters:
#
#   None.
#
function tSudoAskPass() {
	local __RET=
	local __PASSWORD=

	set +e
	__PASSWORD=$(
		whiptail --passwordbox "\n$(basename "${BASH_SOURCE[1]}") needs superuser access.\n\nPlease enter your password:" 12 60 --title "Need Root" 3>&1 1>&2 2>&3
	)
	__RET=$?
	set -e

	if [[ ${__RET} -ne 0 ]]; then
		echo "Cannot continue without superuser access." 1>&2
		exit 1
	fi

	printf "${__PASSWORD}\n"
	exit 0
}


#
#   Allows specifying the sudo password for automated installs.
#
# Parameters:
#
#   PASSWORD - The sudo password to use.
#
function tSudoSetPassword() {
	local __PASSWORD=$1

	__tG__SUDOPASS=${__PASSWORD}
}


#
#   Removes whitespace from the beginning and end of a string.
#
# Parameters:
#
#   RESULT - Variable in which to return the trimmed string.
#   VAR    - String to trim.
#
function tTrim() {
	local __RESULT=$1
	local __VAR="${*:2}"

	# remove leading whitespace characters
	__VAR="${__VAR#"${__VAR%%[![:space:]]*}"}"
	# remove trailing whitespace characters
	__VAR="${__VAR%"${__VAR##*[![:space:]]}"}"

	eval $__RESULT=\${__VAR}
}


#
#   Removes whitespace from the beginning of a string.
#
# Parameters:
#
#   RESULT - Variable in which to return the trimmed string.
#   VAR    - String to trim.
#
function tTrimL() {
	local __RESULT=$1
	local __VAR="${*:2}"

	# remove leading whitespace characters
	__VAR="${__VAR#"${__VAR%%[![:space:]]*}"}"

	eval $__RESULT=\${__VAR}
}


#
#   Removes whitespace from the end of a string.
#
# Parameters:
#
#   RESULT - Variable in which to return the trimmed string.
#   VAR    - String to trim.
#
function tTrimR() {
	local __RESULT=$1
	local __VAR="${*:2}"

	# remove trailing whitespace characters
	__VAR="${__VAR%"${__VAR##*[![:space:]]}"}"

	eval $__RESULT=\${__VAR}
}


#
# We're a library.  Don't run us.
#
if [ -z "${BASH_SOURCE[1]}" ]; then
	echo "This is a library.  Include it into other scripts.  Don't execute it."
	echo "Visit https://skunkworks.kangaroopunch.com/skunkworks/towel for more."
	exit 0
fi