#!/bin/bash
# probe libc's inet_pton & backtrace it with ping (exclusive)

# Installs a probe on libc's inet_pton function, that will use uprobes,
# then use 'perf trace' on a ping to localhost asking for just one packet
# with the a backtrace 3 levels deep, check that it is what we expect.
# This needs no debuginfo package, all is done using the libc ELF symtab
# and the CFI info in the binaries.

# SPDX-License-Identifier: GPL-2.0
# Arnaldo Carvalho de Melo <acme@kernel.org>, 2017

# shellcheck source=lib/probe.sh
. "$(dirname "$0")/lib/probe.sh"
# shellcheck source=lib/probe_vfs_getname.sh
. "$(dirname "$0")/lib/probe_vfs_getname.sh"

libc=$(grep -w libc /proc/self/maps | head -1 | sed -r 's/.*[[:space:]](\/.*)/\1/g')
nm -Dg $libc 2>/dev/null | grep -F -q inet_pton || exit 254

event_pattern='probe_libc:inet_pton(_[[:digit:]]+)?'

add_libc_inet_pton_event() {

	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | tail -n +2 | head -n -5 | \
			awk -v ep="$event_pattern" -v l="$libc" '$0 ~ ep && $0 ~ \
			("\\(on inet_pton in " l "\\)") {print $1}')

	if [ $? -ne 0 ] || [ -z "$event_name" ] ; then
		printf "FAIL: could not add event\n"
		return 1
	fi
}

trace_libc_inet_pton_backtrace() {

	expected=`mktemp -u /tmp/expected.XXX`

	echo "ping[][0-9 \.:]+$event_name: \([[:xdigit:]]+\)" > $expected
	echo ".*inet_pton\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
	case "$(uname -m)" in
	s390x)
		eventattr='call-graph=dwarf,max-stack=4'
		echo "((__GI_)?getaddrinfo|text_to_binary_address)\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
		echo "(gaih_inet|main)\+0x[[:xdigit:]]+[[:space:]]\(inlined|.*/bin/ping.*\)$" >> $expected
		;;
	*)
		eventattr='max-stack=4'
		echo ".*(\+0x[[:xdigit:]]+|\[unknown\])[[:space:]]\(.*/bin/ping.*\)$" >> $expected
		;;
	esac

	perf_data=`mktemp -u /tmp/perf.data.XXX`
	perf_script=`mktemp -u /tmp/perf.script.XXX`

	# Check presence of libtraceevent support to run perf record
	skip_no_probe_record_support "$event_name/$eventattr/"
	if [ $? -eq 2 ]; then
		echo "WARN: Skipping test trace_libc_inet_pton_backtrace. No libtraceevent support."
		return 2
	fi

	perf record -e $event_name/$eventattr/ -o $perf_data ping -6 -c 1 ::1 > /dev/null 2>&1
	# check if perf data file got created in above step.
	if [ ! -e $perf_data ]; then
		printf "FAIL: perf record failed to create \"%s\" \n" "$perf_data"
		return 1
	fi
	perf script -i $perf_data | tac | grep -m1 ^ping -B9 | tac > $perf_script

	exec 4<$expected
	while read -r pattern <&4; do
		echo "Pattern: $pattern"
		[ -z "$pattern" ] && break

		found=0

		# Search lines in the perf script result
		exec 3<$perf_script
		while read line <&3; do
			[ -z "$line" ] && break
			echo "  Matching: $line"
			! echo "$line" | grep -E -q "$pattern"
			found=$?
			[ $found -eq 1 ] && break
		done

		if [ $found -ne 1 ] ; then
			printf "FAIL: Didn't find the expected backtrace entry \"%s\"\n" "$pattern"
			return 1
		fi
	done

	# If any statements are executed from this point onwards,
	# the exit code of the last among these will be reflected
	# in err below. If the exit code is 0, the test will pass
	# even if the perf script output does not match.
}

delete_libc_inet_pton_event() {

	if [ -n "$event_name" ] ; then
		perf probe -q -d $event_name
	fi
}

# Check for IPv6 interface existence
ip a sh lo | grep -F -q inet6 || exit 2
[ "$(id -u)" = 0 ] || exit 2

skip_if_no_perf_probe && \
add_libc_inet_pton_event && \
trace_libc_inet_pton_backtrace
err=$?
rm -f ${perf_data} ${perf_script} ${expected}
delete_libc_inet_pton_event
exit $err
