From d5ce90cc92bc274a1906bbc99a33d5ce161878d1 Mon Sep 17 00:00:00 2001
From: "randomizedcoder dave.seddon.ca@gmail.com" <dave.seddon.ca@gmail.com>
Date: Fri, 18 Sep 2026 10:47:59 -0700
Subject: [PATCH] fix(cloudlab): quote ssh arguments in on_nodes (SC2068)

on_nodes forwarded the remote command with a bare, unquoted $@:

    ssh -4 $node $@

An unquoted $@ undergoes word splitting and glob expansion in the caller
before ssh sees it, so any argument that contains spaces is split into
several arguments, an argument containing a glob metacharacter is
expanded against the local filesystem, and an empty-string argument is
dropped entirely. shellcheck reports this as SC2068 (error).

Quote both the node and the forwarded arguments so word boundaries reach
ssh intact:

    ssh -4 "$node" "$@"

Also add the missing newline at end of file.

Gate: `shellcheck --include=SC2068 cloudlab/bin/on_nodes` reports the
SC2068 error before and is clean after. A bats scaffold
(cloudlab/tests/on_nodes.bats) stubs ssh on PATH and asserts argument
boundaries survive: 3 of its cases (spaces / glob char / empty arg) fail
against the old bare-$@ script and all pass after the fix; no new CI is
wired. The pre-existing SC2004 style note on the arithmetic loop is left
untouched as out of scope.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 cloudlab/bin/on_nodes        |  4 +-
 cloudlab/tests/on_nodes.bats | 80 ++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+), 2 deletions(-)
 create mode 100644 cloudlab/tests/on_nodes.bats

diff --git a/cloudlab/bin/on_nodes b/cloudlab/bin/on_nodes
index a13763d9..26c8993e 100755
--- a/cloudlab/bin/on_nodes
+++ b/cloudlab/bin/on_nodes
@@ -25,5 +25,5 @@ for ((i = $first ; i <= $last; i++)); do
     node=node$i
     echo ""
     echo $node:
-    ssh -4 $node $@
-done
\ No newline at end of file
+    ssh -4 "$node" "$@"
+done
diff --git a/cloudlab/tests/on_nodes.bats b/cloudlab/tests/on_nodes.bats
new file mode 100644
index 00000000..a4f08834
--- /dev/null
+++ b/cloudlab/tests/on_nodes.bats
@@ -0,0 +1,80 @@
+#!/usr/bin/env bats
+
+# SPDX-License-Identifier: BSD-1-Clause
+#
+# Regression tests for cloudlab/bin/on_nodes.
+#
+# These document the SC2068 fix: the remote command and its arguments
+# must be forwarded to ssh with their word boundaries intact, which
+# requires "$@" (quoted) rather than a bare $@. With an unquoted $@ an
+# argument containing spaces or glob characters is re-split / expanded by
+# the loop's word splitting before ssh ever sees it.
+#
+# Run:  nix shell nixpkgs#bats -c bats cloudlab/tests/on_nodes.bats
+#
+# No new CI is wired; this file is included as executable documentation.
+
+setup() {
+    ON_NODES="${BATS_TEST_DIRNAME}/../bin/on_nodes"
+
+    # Stub PATH with a fake ssh that records exactly the argv it receives,
+    # one argument per line, so tests can assert on argument boundaries.
+    STUB_DIR="$(mktemp -d)"
+    ARGV_LOG="${STUB_DIR}/argv.log"
+    cat > "${STUB_DIR}/ssh" <<EOF
+#!/usr/bin/env bash
+: > "${ARGV_LOG}"
+for a in "\$@"; do
+    printf '%s\n' "\$a" >> "${ARGV_LOG}"
+done
+EOF
+    chmod +x "${STUB_DIR}/ssh"
+    PATH="${STUB_DIR}:${PATH}"
+}
+
+teardown() {
+    rm -rf "${STUB_DIR}"
+}
+
+# Argument count that ssh saw, minus the leading `-4 nodeN` (2 args).
+forwarded_count() {
+    echo $(( $(wc -l < "${ARGV_LOG}") - 2 ))
+}
+
+@test "usage error when fewer than 3 args" {
+    run "$ON_NODES" 1
+    [ "$status" -eq 1 ]
+    [[ "$output" == Usage:* ]]
+}
+
+@test "simple command is forwarded verbatim" {
+    run "$ON_NODES" 1 1 echo hello
+    [ "$status" -eq 0 ]
+    # ssh argv: -4 node1 echo hello
+    run cat "${ARGV_LOG}"
+    [ "${lines[0]}" = "-4" ]
+    [ "${lines[1]}" = "node1" ]
+    [ "${lines[2]}" = "echo" ]
+    [ "${lines[3]}" = "hello" ]
+}
+
+@test "argument containing spaces stays a single argument" {
+    "$ON_NODES" 1 1 echo "one two three"
+    # 2 forwarded args: 'echo' and 'one two three' (NOT split into 4).
+    [ "$(forwarded_count)" -eq 2 ]
+    run cat "${ARGV_LOG}"
+    [ "${lines[3]}" = "one two three" ]
+}
+
+@test "argument with a glob char is not expanded by on_nodes" {
+    "$ON_NODES" 1 1 ls '*.c'
+    [ "$(forwarded_count)" -eq 2 ]
+    run cat "${ARGV_LOG}"
+    [ "${lines[3]}" = "*.c" ]
+}
+
+@test "empty-string argument is preserved as one argument" {
+    "$ON_NODES" 1 1 echo ""
+    # 'echo' + one empty arg = 2 forwarded args.
+    [ "$(forwarded_count)" -eq 2 ]
+}