From f21a9340cd0c615ead1954eb6b93845a4f8c0897 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Wed, 14 Dec 2022 12:19:31 -0500
Subject: tests/posix/readdir_error: Fix flakiness

---
 tests/posix/readdir_error.sh | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/tests/posix/readdir_error.sh b/tests/posix/readdir_error.sh
index cca71f0..ce06723 100644
--- a/tests/posix/readdir_error.sh
+++ b/tests/posix/readdir_error.sh
@@ -1,21 +1,37 @@
+skip_unless test "$UNAME" = "Linux"
+
 clean_scratch
-mkfifo scratch/{pid,hup}
+mkfifo scratch/{fever,pid,wait,running}
 
 (
     # Create a zombie process
-    echo >/dev/null &
+    cat scratch/fever >/dev/null &
     # Write the PID to scratch/pid
     echo $! >scratch/pid
-    # Don't wait on the processes
-    exec cat scratch/hup >/dev/null
+    # Don't wait on the zombie process
+    exec cat scratch/wait scratch/fever >scratch/running
 ) &
 
-# Kill cat on exit
-trap "echo >scratch/hup" EXIT
+# Kill the parent cat on exit
+trap "kill -9 %1" EXIT
 
-# Read the zombie PID
+# Read the child PID
 read -r pid <scratch/pid
 
+# Make sure the parent cat is running before we kill the child, because bash
+# will wait() on its children
+echo >scratch/wait &
+read -r _ <scratch/running
+
+# Turn the child into a zombie
+kill -9 "$pid"
+
+# Wait until it's really a zombie
+state=R
+while [ "$state" != "Z" ]; do
+    read -r _ _ state _ <"/proc/$pid/stat" || exit 1
+done
+
 # On Linux, open(/proc/$pid/net) will succeed but readdir() will fail
 skip_unless test -r "/proc/$pid/net"
 fail invoke_bfs "/proc/$pid/net" >/dev/null
-- 
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