From: Valentin Bartenev <vbart@nginx.com>
Date: Sun, 28 Jul 2019 14:19:51 +0000 (+0300)
Subject: Fixed undefined behaviour in left shift of negative numbers.
X-Git-Url: http://www.kaiwu.me/postgresql/commit/?a=commitdiff_plain;h=2d7ba6381876d9592bf804bb15e0037ebdec5800;p=njs.git

Fixed undefined behaviour in left shift of negative numbers.

Now it's implementation defined.
---

diff --git a/njs/njs_vmcode.c b/njs/njs_vmcode.c
index fae0ca7f..f6068240 100644
--- a/njs/njs_vmcode.c
+++ b/njs/njs_vmcode.c
@@ -421,7 +421,8 @@ next:
                         i32 = njs_number_to_int32(num);
 
                         if (op == NJS_VMCODE_LEFT_SHIFT) {
-                            i32 <<= u32;
+                            /* Shifting of negative numbers is undefined. */
+                            i32 = (uint32_t) i32 << u32;
                         } else {
                             i32 >>= u32;
                         }