From d854572ccc5f524ba48a158c2c26614def9e39e5 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Fri, 14 Aug 2020 15:45:08 +0200
Subject: [PATCH] socketpair: allow CURL_DISABLE_SOCKETPAIR

... to completely disable the use of socketpair

Closes #5850
---
 configure.ac         | 18 ++++++++++++++++++
 docs/CURL-DISABLE.md |  5 +++++
 lib/multihandle.h    |  4 ++--
 lib/socketpair.c     |  4 ++--
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/configure.ac b/configure.ac
index 918003e02..0d3e4e103 100755
--- a/configure.ac
+++ b/configure.ac
@@ -4686,6 +4686,24 @@ AC_HELP_STRING([--disable-cookies],[Disable cookies support]),
        AC_MSG_RESULT(yes)
 )
 
+dnl ************************************************************
+dnl disable socketpair
+dnl
+AC_MSG_CHECKING([whether to support socketpair])
+AC_ARG_ENABLE(socketpair,
+AC_HELP_STRING([--enable-socketpair],[Enable socketpair support])
+AC_HELP_STRING([--disable-socketpair],[Disable socketpair support]),
+[ case "$enableval" in
+  no)
+       AC_MSG_RESULT(no)
+       AC_DEFINE(CURL_DISABLE_SOCKETPAIR, 1, [to disable socketpair support])
+       ;;
+  *)   AC_MSG_RESULT(yes)
+       ;;
+  esac ],
+       AC_MSG_RESULT(yes)
+)
+
 dnl ************************************************************
 dnl disable HTTP authentication support
 dnl
diff --git a/docs/CURL-DISABLE.md b/docs/CURL-DISABLE.md
index 83436b473..2dd250c7f 100644
--- a/docs/CURL-DISABLE.md
+++ b/docs/CURL-DISABLE.md
@@ -97,6 +97,11 @@ Disable the SMB(S) protocols
 
 Disable the SMTP(S) protocols
 
+## CURL_DISABLE_SOCKETPAIR
+
+Disable the use of socketpair internally to allow waking up and canceling
+curl_multi_poll().
+
 ## CURL_DISABLE_TELNET
 
 Disable the TELNET protocol
diff --git a/lib/multihandle.h b/lib/multihandle.h
index 0c9ce7f74..46eb12146 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -67,11 +67,11 @@ typedef enum {
 
 #define CURLPIPE_ANY (CURLPIPE_MULTIPLEX)
 
-#if defined(USE_SOCKETPAIR) && !defined(USE_BLOCKING_SOCKETS)
+#if defined(USE_SOCKETPAIR) && !defined(USE_BLOCKING_SOCKETS) &&        \
+  !defined(CURL_DISABLE_SOCKETPAIR)
 #define ENABLE_WAKEUP
 #endif
 
-
 /* value for MAXIMUM CONCURRENT STREAMS upper limit */
 #define INITIAL_MAX_CONCURRENT_STREAMS ((1U << 31) - 1)
 
diff --git a/lib/socketpair.c b/lib/socketpair.c
index 1ec0d75a4..9e1f9ef4c 100644
--- a/lib/socketpair.c
+++ b/lib/socketpair.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 2019 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -23,7 +23,7 @@
 #include "curl_setup.h"
 #include "socketpair.h"
 
-#ifndef HAVE_SOCKETPAIR
+#if !defined(HAVE_SOCKETPAIR) && !defined(CURL_DISABLE_SOCKETPAIR)
 #ifdef WIN32
 /*
  * This is a socketpair() implementation for Windows.