Akihiro Sagawa : quartz: Ensure error text is terminated with NUL character.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: fc4ef8692e82b3e480b76daf088f099897a790e8
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=fc4ef8692e82b3e480b76daf0...

Author: Akihiro Sagawa <sagawa.aki(a)gmail.com>
Date:   Thu May 30 22:58:09 2019 +0900

quartz: Ensure error text is terminated with NUL character.

Signed-off-by: Akihiro Sagawa <sagawa.aki(a)gmail.com>
Signed-off-by: Alexandre Julliard <julliard(a)winehq.org>

---

 dlls/quartz/main.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/dlls/quartz/main.c b/dlls/quartz/main.c
index 08287a7..282104e 100644
--- a/dlls/quartz/main.c
+++ b/dlls/quartz/main.c
@@ -313,7 +313,13 @@ DWORD WINAPI AMGetErrorTextA(HRESULT hr, LPSTR buffer, DWORD maxlen)
         return 0;
 
     res = AMGetErrorTextW(hr, errorW, ARRAY_SIZE(errorW));
-    return WideCharToMultiByte(CP_ACP, 0, errorW, res, buffer, maxlen, 0, 0);
+    if (!res)
+        return 0;
+
+    res = WideCharToMultiByte(CP_ACP, 0, errorW, -1, NULL, 0, 0, 0);
+    if (res > maxlen || !res)
+        return 0;
+    return WideCharToMultiByte(CP_ACP, 0, errorW, -1, buffer, maxlen, 0, 0) - 1;
 }
 
 /***********************************************************************