Alex Henrie : msvcrt: Don't report an underflow for ldexp(0, x) or _scalb( 0, x).

[Alexandre Julliard]

Module: wine
Branch: master
Commit: b6774e38e657bdedb598538cbaf78f42d1f611f4
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=b6774e38e657bdedb598538cbaf78f42d1f611f4

Author: Alex Henrie <alexhenrie24 at gmail.com>
Date:   Mon Sep 10 22:42:03 2018 -0600

msvcrt: Don't report an underflow for ldexp(0, x) or _scalb(0, x).

Signed-off-by: Alex Henrie <alexhenrie24 at gmail.com>
Signed-off-by: piotr at codeweavers.com
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/msvcrt/math.c         | 2 +-
 dlls/ucrtbase/tests/misc.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/dlls/msvcrt/math.c b/dlls/msvcrt/math.c
index 8d5b687..a1ba552 100644
--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -1015,7 +1015,7 @@ double CDECL MSVCRT_ldexp(double num, MSVCRT_long exp)
 
   if (isfinite(num) && !isfinite(z))
     math_error(_OVERFLOW, "ldexp", num, exp, z);
-  else if (isfinite(num) && !z)
+  else if (num && isfinite(num) && !z)
     math_error(_UNDERFLOW, "ldexp", num, exp, z);
   else if (z == 0 && signbit(z))
     z = 0.0; /* Convert -0 -> +0 */
diff --git a/dlls/ucrtbase/tests/misc.c b/dlls/ucrtbase/tests/misc.c
index 2a9648a..bd8034e 100644
--- a/dlls/ucrtbase/tests/misc.c
+++ b/dlls/ucrtbase/tests/misc.c
@@ -694,11 +694,13 @@ static void test_math_errors(void)
     } testsdl[] = {
         {"_scalb", -INFINITY, 1, -1, -1},
         {"_scalb", -1e100, 1, -1, -1},
+        {"_scalb", 0, 1, -1, -1},
         {"_scalb", 1e100, 1, -1, -1},
         {"_scalb", INFINITY, 1, -1, -1},
         {"_scalb", 1, 1e9, ERANGE, _OVERFLOW},
         {"ldexp", -INFINITY, 1, -1, -1},
         {"ldexp", -1e100, 1, -1, -1},
+        {"ldexp", 0, 1, -1, -1},
         {"ldexp", 1e100, 1, -1, -1},
         {"ldexp", INFINITY, 1, -1, -1},
         {"ldexp", 1, -1e9, -1, _UNDERFLOW},