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#!/bin/bash
# SPDX-License-Identifier: GPL-3.0+
# Copyright (C) 2026 Daan De Meyer
#
# Regression test for a race between udev and loop_reread_partitions().
#
# When LOOP_CONFIGURE is called with LO_FLAGS_PARTSCAN,
# disk_force_media_change() used to set GD_NEED_PART_SCAN before the
# uevent was sent. When udev opened the device in response,
# blkdev_get_whole() would trigger a partition scan, and then
# loop_reread_partitions() would scan again. The second scan drops all
# partitions from the first scan before re-adding them, causing
# partition devices to briefly disappear.
#
# Verify that setting up a loop device with partscan does not produce
# spurious partition add/remove events.

. tests/loop/rc

DESCRIPTION="check for spurious partition removal when partscan is enabled"
TIMED=1

requires() {
	_have_program sfdisk
	_have_systemd_ver 259
}

test() {
	echo "Running ${TEST_NAME}"

	truncate -s 3MiB "$TMPDIR/img"
	sfdisk "$TMPDIR/img" >"$FULL" 2>&1 <<-EOF
		label: gpt
		size=1MiB
	EOF

	local dev
	dev="$(losetup -f)"

	# Monitor kernel uevents for partition block devices.
	udevadm monitor --kernel -s block/partition >"$TMPDIR/uevents" 2>&1 &
	local mon_pid=$!
	# Give the monitor time to set up its netlink socket.
	sleep 0.5

	local iterations=0
	SECONDS=0
	while ((SECONDS < "${TIMEOUT:-5}")); do
		if ! losetup -P "$dev" "$TMPDIR/img" 2>>"$FULL"; then
			continue
		fi
		losetup -d "$dev" 2>>"$FULL"
		((iterations++))
	done

	sleep 0.5
	kill "$mon_pid"
	wait "$mon_pid" 2>/dev/null

	# Each setup+teardown cycle should produce exactly one add and one
	# remove kernel uevent for the partition device. If the race
	# triggers, a second partition scan produces an extra remove+add
	# pair, inflating the counts beyond the number of iterations.
	local name="${dev##*/}"
	local adds removes
	adds=$(grep -c "^KERNEL\[.*\] add.*${name}p" "$TMPDIR/uevents")
	removes=$(grep -c "^KERNEL\[.*\] remove.*${name}p" "$TMPDIR/uevents")

	if ((adds > iterations)); then
		echo "Fail: $iterations iterations but $adds add events (expected $iterations)"
	fi
	if ((removes > iterations)); then
		echo "Fail: $iterations iterations but $removes remove events (expected $iterations)"
	fi

	echo "Test complete"
}