#!/bin/bash
#
# Copyright 2016-2017 Authors of Cilium
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -x
set -e
set -u

LIB=$1
RUNDIR=$2

PROBE_DIR=$(mktemp -d)
FEATURE_FILE="$RUNDIR/globals/bpf_features.h"
INFO_FILE="$RUNDIR/bpf_features.log"
WARNING_FILE="$RUNDIR/bpf_requirements.log"

function cleanup {
	if [ ! -z "$PROBE_DIR" ]; then
		rm -rf "$PROBE_DIR"
	fi
}

trap cleanup EXIT

# High level probes that require to invoke tc.
function probe_run_tc()
{
	PROBE="${LIB}/probes/$1"
	OUT="$PROBE_DIR/${1}.o"
	FEATURE=$2
	tc qdisc del dev $DEV clsact 2> /dev/null

	PROBE_OPTS="-D__NR_CPUS__=$(nproc) -O2 -target bpf -I$DIR -I. -I$LIB/include -Wall -Wno-address-of-packed-member -Wno-unknown-warning-option"

	clang $PROBE_OPTS -c "$PROBE" -o "$OUT" &&
	tc qdisc add dev $DEV clsact &&
	tc filter add dev $DEV ingress bpf da obj $OUT sec probe &&
	echo "#define $FEATURE" >> "$FEATURE_FILE"
}

function prep_probe()
{
	OUT_FILE=$1
	# Various extensions for textual replacement go here.
	awk -F":" '/insn-repeat/ { for(i = 0;i < $2; i++) print }; { print }' "$OUT_FILE" > \
	      "$OUT/tmp.t" && mv "$OUT/tmp.t" "$OUT_FILE"
}

# Low level probes that only check verifier.
function probe_run_ll()
{
	PROBE_BASE="${LIB}/probes"
	OUT="$PROBE_DIR"
	LIB_INCLUDE="${LIB}/include"
	PROBE_OPTS="-O2 -I$OUT -I$PROBE_BASE -I$LIB_INCLUDE -Wall"

	for PROBE in "${PROBE_BASE}"/*.t
	do
		OUT_BIN=`basename "$PROBE"`
		cp "$PROBE" "$OUT/raw_probe.t"
		prep_probe "$OUT/raw_probe.t"
		clang $PROBE_OPTS "$PROBE_BASE/raw_main.c" -o "$OUT/$OUT_BIN" &&
		"$OUT/$OUT_BIN" 1>> "$FEATURE_FILE" 2>> "$INFO_FILE"
	done
}

for file in $INFO_FILE $WARNING_FILE
do
	rm -f "$file"
done

echo "#ifndef BPF_FEATURES_H_"  > "$FEATURE_FILE"
echo "#define BPF_FEATURES_H_" >> "$FEATURE_FILE"
echo "" >> "$FEATURE_FILE"

#probe_run_tc "skb_change_tail.c" "HAVE_SKB_CHANGE_TAIL"
probe_run_ll

echo "#endif /* BPF_FEATURES_H_ */" >> "$FEATURE_FILE"

for file in $INFO_FILE $WARNING_FILE
do
	if [ ! -s "$file" ]; then
		rm -f "$file"
	fi
done