From a20f6a53f2d2cafc0c48262d39753637b41d742a Mon Sep 17 00:00:00 2001
From: Stuart Pernsteiner <spernsteiner@galois.com>
Date: Tue, 10 Sep 2024 16:54:14 -0700
Subject: [PATCH] ardupilot: add more comments to build scripts

---
 components/autopilot/ardupilot_build.sh           | 2 +-
 components/autopilot/ardupilot_init_submodules.sh | 3 ++-
 components/autopilot/ardupilot_install_deps.sh    | 5 +++++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/components/autopilot/ardupilot_build.sh b/components/autopilot/ardupilot_build.sh
index 89bdd256..a38028d4 100644
--- a/components/autopilot/ardupilot_build.sh
+++ b/components/autopilot/ardupilot_build.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -euo pipefail
 
-# Script for installing ArduPilot build dependencies.
+# Build the ArduPilot SITL binary for aarch64.
 
 cd "$(dirname "$0")/ardupilot"
 
diff --git a/components/autopilot/ardupilot_init_submodules.sh b/components/autopilot/ardupilot_init_submodules.sh
index 75c82ace..9bc67988 100644
--- a/components/autopilot/ardupilot_init_submodules.sh
+++ b/components/autopilot/ardupilot_init_submodules.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -euo pipefail
 
-# Initialize additional submodules that are needed for the ArduPilot build.
+# Initialize ArduPilot submodules that are needed for the SITL build.
 
 cd "$(dirname "$0")/ardupilot"
 
@@ -17,6 +17,7 @@ modules=(
     DroneCAN/DSDL
     DroneCAN/libcanard
 )
+
 for x in "${modules[@]}"; do
     edo git submodule update --init "modules/$x"
 done
diff --git a/components/autopilot/ardupilot_install_deps.sh b/components/autopilot/ardupilot_install_deps.sh
index 4af56fc2..b0264663 100644
--- a/components/autopilot/ardupilot_install_deps.sh
+++ b/components/autopilot/ardupilot_install_deps.sh
@@ -10,10 +10,15 @@ edo() {
     "$@"
 }
 
+# Echo the first argument.  This is useful for expanding a (possible) glob
+# pattern to a single concrete filename.
 first() {
     echo "$1"
 }
 
+# Install a package with `apt-get`, but only if a certain file is missing from
+# the system.  Running `apt-get install` on an already-installed package is a
+# no-op, but we'd like to avoid asking for `sudo` privileges unnecessarily.
 install_if_missing() {
     local package="$1"
     local file="$2"