From 5022a7e3f8aad07f1e2b543827830f1f18ca318d Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Fri, 1 May 2020 10:38:26 +0200
Subject: qemu: loop entropy adding until getrandom doesn't block

Before the 256 was just a guess, which was made wrong by qemu 5.0, so
instead actually query whether or not we're all set.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 src/tests/qemu/init.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/tests/qemu/init.c b/src/tests/qemu/init.c
index 90bc981..3e2a237 100644
--- a/src/tests/qemu/init.c
+++ b/src/tests/qemu/init.c
@@ -18,6 +18,7 @@
 #include <sys/types.h>
 #include <sys/io.h>
 #include <sys/ioctl.h>
+#include <sys/random.h>
 #include <sys/reboot.h>
 #include <sys/utsname.h>
 #include <sys/sendfile.h>
@@ -73,7 +74,9 @@ static void seed_rng(void)
 	fd = open("/dev/urandom", O_WRONLY);
 	if (fd < 0)
 		panic("open(urandom)");
-	for (int i = 0; i < 256; ++i) {
+	for (;;) {
+		if (getrandom(entropy.buffer, sizeof(entropy.buffer), GRND_NONBLOCK) != -1 || errno != EAGAIN)
+			break;
 		if (ioctl(fd, RNDADDENTROPY, &entropy) < 0)
 			panic("ioctl(urandom)");
 	}
-- 
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