From 25806878c9975dd769e2e193eae22f470ef4c71a Mon Sep 17 00:00:00 2001
From: Brett Holman <bholman.devel@gmail.com>
Date: Fri, 19 Jan 2024 18:43:26 -0700
Subject: [PATCH] Force dumplease to parse stdin

Checking if data exists in the stdin buffer via an ioctl is
unreliable. Allow a user to pass '-' to force stdin parsing.
This provides a fix that will allow "no interfaces" to still
mean "dump all interfaces".

Fixes #285
---
 src/dhcpcd.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/dhcpcd.c b/src/dhcpcd.c
index a94dbdac..84b4d8f1 100644
--- a/src/dhcpcd.c
+++ b/src/dhcpcd.c
@@ -29,7 +29,6 @@
 static const char dhcpcd_copyright[] = "Copyright (c) 2006-2023 Roy Marples";
 
 #include <sys/file.h>
-#include <sys/ioctl.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/time.h>
@@ -2278,8 +2277,10 @@ printpidfile:
 
 #ifndef SMALL
 	if (ctx.options & DHCPCD_DUMPLEASE &&
-	    ioctl(fileno(stdin), FIONREAD, &i, sizeof(i)) == 0 &&
-	    i > 0)
+	    i > 0 &&
+	    ctx.ifc == 1 &&
+	    strlen(ctx.ifv[0]) == 1 &&
+	    ctx.ifv[0][0] == '-')
 	{
 		ctx.options |= DHCPCD_FORKED; /* pretend child process */
 #ifdef PRIVSEP
-- 
2.47.2