[glib] GRand: avoid overflow

[Matthias Clasen <matthiasc src gnome org>]

commit 77be95cdce7f875a10576ac72624024b04b86a65
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jun 3 23:37:23 2011 -0400

    GRand: avoid overflow
    
    Otherwise, g_random_double_range (-G_MAXDOUBLE, G_MAXDOUBLE)
    doesn't work as expected.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=502560

 glib/grand.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/glib/grand.c b/glib/grand.c
index b97617b..bb1bffe 100644
--- a/glib/grand.c
+++ b/glib/grand.c
@@ -586,7 +586,11 @@ g_rand_double (GRand* rand)
 gdouble 
 g_rand_double_range (GRand* rand, gdouble begin, gdouble end)
 {
-  return g_rand_double (rand) * (end - begin) + begin;
+  gdouble r;
+
+  r = g_rand_double (rand);
+
+  return r * end - (r - 1) * begin;
 }
 
 /**