[PATCH 1/1] ntdll: Return an error if count is zero in NtRemoveIoCompletionEx.

[Alex Henrie]

From: Alex Henrie

Without this check, the return value is undefined.
---
 dlls/ntdll/tests/file.c | 3 +++
 dlls/ntdll/unix/sync.c  | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/dlls/ntdll/tests/file.c b/dlls/ntdll/tests/file.c
index 02bdf67796d..3ea0ac50c0f 100644
--- a/dlls/ntdll/tests/file.c
+++ b/dlls/ntdll/tests/file.c
@@ -1039,6 +1039,9 @@ static void test_set_io_completion(void)
         return;
     }

+    res = pNtRemoveIoCompletionEx( h, info, 0, &count, &timeout, FALSE );
+    ok( res == STATUS_INVALID_PARAMETER, "NtRemoveIoCompletionEx failed: %#lx\n", res );
+
     count = 0xdeadbeef;
     res = pNtRemoveIoCompletionEx( h, info, 2, &count, &timeout, FALSE );
     ok( res == STATUS_TIMEOUT, "NtRemoveIoCompletionEx failed: %#lx\n", res );
diff --git a/dlls/ntdll/unix/sync.c b/dlls/ntdll/unix/sync.c
index d486b50001d..bc2aa0271a1 100644
--- a/dlls/ntdll/unix/sync.c
+++ b/dlls/ntdll/unix/sync.c
@@ -2081,6 +2081,8 @@ NTSTATUS WINAPI NtRemoveIoCompletionEx( HANDLE handle, FILE_IO_COMPLETION_INFORM

TRACE( "%p %p %u %p %p %u\n", handle, info, (int)count, written, timeout, alertable );

+    if (!count) return STATUS_INVALID_PARAMETER;
+
     while (i < count)
     {
         SERVER_START_REQ( remove_completion )