Improve OS detection, exit on unsupported OSs

docs/system_detection.md

@@ -0,0 +1,9 @@
+tori determines what is the running operating system through the output of `uname -s`. If it cannot get a descriptive enough, it will look for the `/etc/os-release` file.
+
+If a `/etc/os-release` file is present, it takes precedence over the output of `uname`. Both the `NAME` and `ID` values will be looked at. This is aimed at helping to disambiguate between different variants of the same operating system.
+
+The `NAME` value may be the only queried value if for the given supported operating system it is enough to disambiguate between the variants tori needs to be aware of.
+
+In case there is no `/etc/os-release` file found, the output of `uname` is the next value considered.
+
+If a supported operating system is not detected on neither of these, tori will exit with an error.

src/index.sh

@@ -3,3 +3,4 @@
 . "$TORI_ROOT/src/package/package.sh"
 . "$TORI_ROOT/src/package/package_resolution.sh"
 . "$TORI_ROOT/src/utility.sh"
+. "$TORI_ROOT/src/system.sh"

src/system.sh

@@ -0,0 +1,19 @@
+get_operating_system() {
+	local uname_output="$(uname -s)"
+	local os_release_name="$(cat \
+		/etc/os-release | grep '^NAME=' | sed 's/NAME=//')"
+	local os_release_id="$(cat \
+		/etc/os-release | grep '^ID=' | sed 's/ID=//')"
+
+	log debug "uname OS: $uname_output"
+	log debug "os-release OS name: $os_release_name"
+	log debug "os-release OS ID: $os_release_id"
+
+	if [ "$os_release_name" = FreeBSD ]; then
+		echo "FreeBSD"
+		return 0
+	else
+		log fatal "Unsupported operating system"
+		return 1
+	fi
+}

src/tori

@@ -1,5 +1,6 @@
 #! /usr/bin/env sh
 
+# paths
 VERSION="0.0.4 2024-06-30"
 TORI_ROOT="$HOME/tori"
 CONFIG_ROOT="$HOME/.config/tori"
@@ -16,7 +17,7 @@ parameter="$2"
 set_opts -
 
 ## global constants
-OS="$(uname -s)"
+OS="$(get_operating_system)"
 
 ## global state
 base_files=