port forward range test: fix many oopses

Wrong variable. And, wrong index range. And, wrong bash
syntax for extracting end_port. And, add explicit check
for valid range, because die() inside 'foo=$(...)' will not
actually die. And, refactor some confusing code. And,
reformat/clean up a confusing and too-wide comment.

Fixes: #14854

Signed-off-by: Ed Santiago <santiago@redhat.com>

1 files changed, 8 insertions, 6 deletions

diff --git a/test/system/helpers.bash b/test/system/helpers.bash
index 273e8d2f5..ceac48036 100644
--- a/test/system/helpers.bash
+++ b/test/system/helpers.bash
@@ -299,15 +299,17 @@ function random_free_port_range() {
     local maxtries=10
     while [[ $maxtries -gt 0 ]]; do
         local firstport=$(random_free_port)
-        local all_ports_free=1
-        for i in $(seq 2 $size); do
-            if ! port_is_free $((firstport + $i)); then
-                all_ports_free=
+        local lastport=
+        for i in $(seq 1 $((size - 1))); do
+            lastport=$((firstport + i))
+            if ! port_is_free $lastport; then
+                echo "# port $lastport is in use; trying another." >&3
+                lastport=
                 break
             fi
         done
-        if [[ -n "$all_ports_free" ]]; then
-            echo "$firstport-$((firstport + $size - 1))"
+        if [[ -n "$lastport" ]]; then
+            echo "$firstport-$lastport"
             return
         fi