From: emperor06 <github@draxar.com>
Date: Tue, 4 Jun 2024 14:42:11 +0000 (+0200)
Subject: ply-utils: Ensure random ints are big enough
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f9f90fc3dec73dce21d7a012d31cc9b682d10264;p=thirdparty%2Fplymouth.git

ply-utils: Ensure random ints are big enough

Using Math.Random() in a theme script practically always returns zero.
This is because ply_get_random_number uses mrand48 which, while
returning a 64-bit long, restricts the range of its return value
to be no more than 32-bit, and so gets improperly normalized.

This commit addresses the problem by calling mrand48() twice, once for
each 32-bits of the returned value.

https://gitlab.freedesktop.org/plymouth/plymouth/-/issues/256
---

diff --git a/src/libply/ply-utils.c b/src/libply/ply-utils.c
index 44a93099..0e317b67 100644
--- a/src/libply/ply-utils.c
+++ b/src/libply/ply-utils.c
@@ -1308,7 +1308,7 @@ ply_get_random_number (long lower_bound,
                 seed_initialized = true;
         }
 
-        offset = mrand48 ();
+        offset = (mrand48 () << 32) | (mrand48 () & 0xffffffff);
 
         offset = labs (offset) % range;