Revert "Replace PostmasterRandom() with a stronger way of generating randomness."

This reverts commit 9e083fd4683294f41544e6d0d72f6e258ff3a77c. That was a
few bricks shy of a load:

* Query cancel stopped working
* Buildfarm member pademelon stopped working, because the box doesn't have
  /dev/urandom nor /dev/random.

This clearly needs some more discussion, and a quite different patch, so
revert for now.

1 files changed, 16 insertions, 24 deletions

diff --git a/contrib/pgcrypto/internal.c b/contrib/pgcrypto/internal.c
index ad942f733a2..02ff976c25a 100644
--- a/contrib/pgcrypto/internal.c
+++ b/contrib/pgcrypto/internal.c
@@ -626,6 +626,8 @@ static time_t check_time = 0;
 static void
 system_reseed(void)
 {
+	uint8		buf[1024];
+	int			n;
 	time_t		t;
 	int			skip = 1;
 
@@ -640,34 +642,24 @@ system_reseed(void)
 	else if (check_time == 0 ||
 			 (t - check_time) > SYSTEM_RESEED_CHECK_TIME)
 	{
-		uint8		buf;
-
 		check_time = t;
 
 		/* roll dice */
-		px_get_random_bytes(&buf, 1);
-		skip = (buf >= SYSTEM_RESEED_CHANCE);
-
-		/* clear 1 byte */
-		px_memset(&buf, 0, sizeof(buf));
-	}
-	if (!skip)
-	{
-		/*
-		 * fortuna_add_entropy passes the input to SHA-256, so there's no
-		 * point in giving it more than 256 bits of input to begin with.
-		 */
-		uint8		buf[32];
-
-		if (!pg_strong_random(buf, sizeof(buf)))
-			ereport(ERROR,
-					(errcode(ERRCODE_INTERNAL_ERROR),
-					 errmsg("could not acquire random data")));
-		fortuna_add_entropy(buf, sizeof(buf));
-
-		seed_time = t;
-		px_memset(buf, 0, sizeof(buf));
+		px_get_random_bytes(buf, 1);
+		skip = buf[0] >= SYSTEM_RESEED_CHANCE;
 	}
+	/* clear 1 byte */
+	px_memset(buf, 0, sizeof(buf));
+
+	if (skip)
+		return;
+
+	n = px_acquire_system_randomness(buf);
+	if (n > 0)
+		fortuna_add_entropy(buf, n);
+
+	seed_time = t;
+	px_memset(buf, 0, sizeof(buf));
 }
 
 int