From d293bf4a789e7a02dd5ea40bcd81d23698859641 Mon Sep 17 00:00:00 2001
From: Mark Swaanenburg <mswaanen@amazon.com>
Date: Fri, 11 Jun 2021 06:27:00 +0000
Subject: [PATCH] lib: don't compare fd to FD_SETSIZE when using poll

FD_SETSIZE is irrelevant when using poll. So ensuring that the file
descriptor is smaller than FD_SETSIZE in VALID_SOCK, can cause
multi_wait to ignore perfectly valid file descriptors and simply wait
for 1s to avoid hammering the CPU in a busy loop.

Fixes #7240
Closes #7241
---
 lib/select.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/select.h b/lib/select.h
index 4db64877bb..19da1e774b 100644
--- a/lib/select.h
+++ b/lib/select.h
@@ -106,7 +106,11 @@ int tpf_select_libcurl(int maxfds, fd_set* reads, fd_set* writes,
   } \
 } while(0)
 #else
+#ifdef HAVE_POLL_FINE
+#define VALID_SOCK(s) ((s) >= 0)  /* FD_SETSIZE is irrelevant for poll */
+#else
 #define VALID_SOCK(s) (((s) >= 0) && ((s) < FD_SETSIZE))
+#endif
 #define VERIFY_SOCK(x) do { \
   if(!VALID_SOCK(x)) { \
     SET_SOCKERRNO(EINVAL); \