[PATCH] Don't let XFD_SETSIZE exceed FD_SETSIZE

[James Clarke]

This fixes 2c94cdb453bc641246cc8b9a876da9799bee1ce7 on the Hurd, as FD_SETSIZE
is only 256, and so anyone using XFD_SETSIZE to iterate over the contents of
an fd_set will overrun the array.
---
 Xpoll.h.in | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/Xpoll.h.in b/Xpoll.h.in
index 2878591..9f127e1 100644
--- a/Xpoll.h.in
+++ b/Xpoll.h.in
@@ -67,10 +67,13 @@ typedef long fd_mask;
 # endif
 #endif
 
-#define XFD_SETSIZE	512
-
-#ifndef FD_SETSIZE
-#define FD_SETSIZE	XFD_SETSIZE
+#if defined(FD_SETSIZE) && FD_SETSIZE < 512
+# define XFD_SETSIZE	FD_SETSIZE
+#else
+# define XFD_SETSIZE	512
+# ifndef FD_SETSIZE
+#  define FD_SETSIZE	XFD_SETSIZE
+# endif
 #endif
 
 #ifndef NBBY
-- 
2.8.1