From 4e2410742a7a3466359bc871be963fa4a8415d0b Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 19 Apr 2021 10:22:00 +0930
Subject: [PATCH] tests/fuzz: update for fmt_amount changes, create pseudorand
 for fuzzing.

Reported-by: Christian Reitter
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 tests/fuzz/fuzz-amount.c |  8 ++++----
 tests/fuzz/libfuzz.c     | 17 +++++++++++++++--
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/tests/fuzz/fuzz-amount.c b/tests/fuzz/fuzz-amount.c
index 3e5701926..512ff2d19 100644
--- a/tests/fuzz/fuzz-amount.c
+++ b/tests/fuzz/fuzz-amount.c
@@ -43,15 +43,15 @@ void run(const uint8_t *data, size_t size)
 	/* Format should inconditionally produce valid amount strings according to our
 	 * parser */
 
-	fmt_msat = fmt_amount_msat(NULL, &msat);
-	fmt_msatbtc = fmt_amount_msat_btc(NULL, &msat, true);
+	fmt_msat = fmt_amount_msat(NULL, msat);
+	fmt_msatbtc = fmt_amount_msat_btc(NULL, msat, true);
 	assert(parse_amount_msat(&msat, fmt_msat, tal_count(fmt_msat)));
 	assert(parse_amount_msat(&msat, fmt_msatbtc, tal_count(fmt_msatbtc)));
 	tal_free(fmt_msat);
 	tal_free(fmt_msatbtc);
 
-	fmt_sat = fmt_amount_sat(NULL, &sat);
-	fmt_satbtc = fmt_amount_sat_btc(NULL, &sat, true);
+	fmt_sat = fmt_amount_sat(NULL, sat);
+	fmt_satbtc = fmt_amount_sat_btc(NULL, sat, true);
 	assert(parse_amount_sat(&sat, fmt_sat, tal_count(fmt_sat)));
 	assert(parse_amount_sat(&sat, fmt_satbtc, tal_count(fmt_satbtc)));
 	tal_free(fmt_sat);
diff --git a/tests/fuzz/libfuzz.c b/tests/fuzz/libfuzz.c
index a940fcb08..1907a5b16 100644
--- a/tests/fuzz/libfuzz.c
+++ b/tests/fuzz/libfuzz.c
@@ -1,15 +1,28 @@
 #include <tests/fuzz/libfuzz.h>
 
+#include <assert.h>
 #include <ccan/tal/tal.h>
+#include <ccan/isaac/isaac64.h>
+#include <common/pseudorand.h>
 #include <common/utils.h>
 #include <string.h>
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
 int LLVMFuzzerInitialize(int *argc, char ***argv);
 
-int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
-	run(data, size);
+/* Provide a non-random pseudo-random function to speed fuzzing. */
+static isaac64_ctx isaac64;
 
+uint64_t pseudorand(uint64_t max)
+{
+	assert(max);
+	return isaac64_next_uint(&isaac64, max);
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+	isaac64_init(&isaac64, NULL, 0);
+
+	run(data, size);
 	return 0;
 }