[helper] Add key-value util

Can be used to add simple key-value-pairs to files.
It will error if the given key already exists and has a different value.
If it does not exist in the target file, it will be appended/created.
Otherwise, nothing will be done.

2 files changed, 37 insertions, 0 deletions

diff --git a/helper/keyvalueutil.inc b/helper/keyvalueutil.inc
new file mode 100644
index 00000000..a0a89db7
--- /dev/null
+++ b/helper/keyvalueutil.inc
@@ -0,0 +1,32 @@
+# Helper file for managing key-value containing files
+# There are some specialized conveinience functions here first
+# that mostly just pass a predefined filename to the genric function
+# at the end
+
+# Add the given environment variable to /etc/environment
+add_env () {
+	[ $# -ne 2 ] && perror "Usage: $0 'key' 'value'"
+	[ -z "$1" ] && perror "$0: Empty key!"
+	add_key_value "/etc/environment" "$1" "$2"
+}
+
+#
+# Adds the given key-value-pair to a given file
+# The file will be relative to the current target build dir,
+# even if it starts with a slash.
+# Will perror if the key already exists with a different value
+add_key_value () {
+	[ $# -ne 3 ] && perror "Usage: $0 'file' 'key' 'value'"
+	[ -z "$TARGET_BUILD_DIR" ] && perror "No TARGET_BUILD_DIR set. Aborting for safety."
+	local FILE="$TARGET_BUILD_DIR/$1"
+	local KEY="$2"
+	local VALUE="$(echo "$3" | sed "s/'/\\\\'/g")" # \\\\\\\\\\\\\\\\\\\\\\ßß
+	if [ -s "$FILE" ]; then
+		local CURRENT="$(grep -E "^\s*$KEY=.*$" "$FILE" | awk -F '=' '{$1=""; printf $0}' | itrim)"
+		[ -n "$CURRENT" -a "'$VALUE'" != "$CURRENT" ] && perror "Cannot set $KEY to '$VALUE' as it is already set to $CURRENT"
+		[ -n "$CURRENT" ] && return 0
+	fi
+	mkdir -p "$(dirname "$FILE")"
+	echo "$KEY='$VALUE'" >> "$FILE"
+}
+
diff --git a/helper/string.inc b/helper/string.inc
index 9f18e4e0..04809a93 100644
--- a/helper/string.inc
+++ b/helper/string.inc
@@ -7,6 +7,11 @@ trim() {
     echo -n "$var"
 }
 
+# Inline version of trim, use when piping
+itrim () {
+	sed -r 's/^\s+//g;s/\s+$//g'
+}
+
 # usage: CANONICALIZED_STRING=$(canonalize <path>)
 #        usage with relative path requires you to be in the correct directory.
 canonicalize() {