* win32/win32.c (rb_w32_fdisset): check whether the handle is valid.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@7561 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 1 deletions

diff --git a/win32/win32.c b/win32/win32.c
index 7a7078335f..c21fca6fbc 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -1827,7 +1827,12 @@ rb_w32_fdclr(int fd, fd_set *set)
 int
 rb_w32_fdisset(int fd, fd_set *set)
 {
-       return __WSAFDIsSet(TO_SOCKET(fd), set);
+    int ret;
+    SOCKET s = TO_SOCKET(fd);
+    if (s == (SOCKET)INVALID_HANDLE_VALUE)
+        return 0;
+    RUBY_CRITICAL(ret = __WSAFDIsSet(s, set));
+    return ret;
 }
 
 //