From 1d983e9f934bf6aeb9333c763fe1a603b8d8e5c4 Mon Sep 17 00:00:00 2001
From: Patrick Spek <p.spek@tyil.nl>
Date: Sun, 22 Mar 2020 11:48:23 +0100
Subject: Initial commit

---
 lib/util.bash | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 lib/util.bash

(limited to 'lib/util.bash')

diff --git a/lib/util.bash b/lib/util.bash
new file mode 100644
index 0000000..025aeba
--- /dev/null
+++ b/lib/util.bash
@@ -0,0 +1,118 @@
+#!/usr/bin/env bash
+
+# Log a message as error, and exit the program. This is intended for serious
+# issues that prevent the script from running correctly. The exit code can be
+# specified with -i, or will default to 1.
+die() {
+	local OPTIND
+	local code
+
+	while getopts ":i:" opt
+	do
+		case "$opt" in
+			i) code=$OPTARG ;;
+		esac
+	done
+
+	shift $(( OPTIND -1 ))
+
+	alert "$@"
+	exit ${code:-1}
+}
+
+# Fetch a file from an URL. Using this function introduces a dependency on curl.
+fetch() {
+	local OPTIND
+	local buffer
+
+	while getopts ":o:" opt
+	do
+		case "$opt" in
+			o) buffer=$OPTARG ;;
+		esac
+	done
+
+	shift $(( OPTIND -1 ))
+
+	[[ -z $buffer ]] && buffer="$(tempfile)"
+
+	notice "Downloading $1 to $buffer"
+
+	# TODO: Switch to the most appropriate downloading tool, depending on
+	# what is available.
+
+	curl -Ls "$1" > "$buffer"
+	local exit_code=$?
+
+	printf "%s" "$buffer"
+
+	return $exit_code
+}
+
+# Read a particular value from a key/value configuration file. Using this
+# function introduces a dependency on awk.
+config_etc_kv() {
+	local file="$BASEDIR/etc/$1"
+	shift
+
+	if [[ ! -f $file ]]
+	then
+		crit "Tried to read value for $1 from $file, but $file does not exist"
+		return
+	fi
+
+	debug "Reading value for $1 from $file"
+
+	awk -F= '$1 == "'"$1"'" { print $NF }' "$file"
+}
+
+# Create a temporary directory. Similar to tempfile, but you'll get a directory
+# instead.
+tempdir() {
+	local dir="$(mktemp -d)"
+
+	# Ensure the file was created succesfully
+	if [[ ! -d "$dir" ]]
+	then
+		die "Failed to create a temporary directory at $dir"
+	fi
+
+	debug "Temporary file created at $dir"
+
+	printf "$dir"
+}
+
+# Create a temporary file. In usage, this is no different from mktemp itself,
+# however, it will apply additional checks to ensure everything is going
+# correctly, and the files will be cleaned up automatically at the end.
+tempfile() {
+	local OPTIND
+	local extension="tmp"
+
+	while getopts ":x:" opt
+	do
+		case "$opt" in
+			x) extension=$OPTARG ;;
+		esac
+	done
+
+	shift $(( OPTIND -1 ))
+
+	local file="$(mktemp --suffix ".$extension")"
+
+	# Ensure the file was created succesfully
+	if [[ ! -f "$file" ]]
+	then
+		die "Failed to create a temporary file at $file"
+	fi
+
+	debug "Temporary file created at $file"
+
+	printf "$file"
+}
+
+export -f config_etc_kv
+export -f die
+export -f fetch
+export -f tempdir
+export -f tempfile
-- 
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