fuzz: add check-fuzz.sh

The script runs each fuzz target on its seed corpus and prints any
failures.

tests/fuzz/check-fuzz.sh

@@ -0,0 +1,36 @@
+#!/bin/bash -eu
+
+# Runs each fuzz target on its seed corpus and prints any failures.
+
+readonly FUZZ_DIR=$(dirname "$0")
+readonly TARGETS=$(find "${FUZZ_DIR}" -type f -name "fuzz-*" ! -name "*.*")
+
+export UBSAN_OPTIONS="halt_on_error=1:print_stacktrace=1"
+
+passes=0
+fails=0
+for t in ${TARGETS}; do
+	target_name=$(basename "${t}")
+	corpus_dir="${FUZZ_DIR}/corpora/${target_name}/"
+	cmd="${t} -runs=0 ${corpus_dir}"
+
+	echo -n "Checking ${target_name}... "
+	if output=$(${cmd} 2>&1); then
+		echo "PASS"
+		passes=$((passes + 1))
+	else
+		echo "FAIL"
+		echo
+		echo "Failing command: ${cmd}"
+		echo "Output:"
+		echo "${output}"
+		echo
+		fails=$((fails + 1))
+	fi
+done
+
+echo
+echo "TOTAL PASSED: ${passes}"
+echo "TOTAL FAILED: ${fails}"
+
+exit ${fails}