From 4e8c092266e28589abd5ca149ee8b3a43a9a6ee0 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= <thomas@t-8ch.de>
Date: Mon, 13 May 2024 20:21:24 +0200
Subject: [PATCH] include/pidfd-utils: provide ENOSYS stubs if pidfd functions
 are missing
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This allows code which can gracefully fall back to compile.

This should fix the CI on Ubuntu 18.04.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 include/pidfd-utils.h | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/pidfd-utils.h b/include/pidfd-utils.h
index 4f6f51b81..4ac9f79d9 100644
--- a/include/pidfd-utils.h
+++ b/include/pidfd-utils.h
@@ -5,6 +5,9 @@
 #ifndef UTIL_LINUX_PIDFD_UTILS
 #define UTIL_LINUX_PIDFD_UTILS
 
+#include <sys/types.h>
+#include <sys/wait.h>
+
 #ifdef HAVE_SYS_SYSCALL_H
 # include <sys/syscall.h>
 # include <unistd.h>
@@ -13,9 +16,7 @@
 #  ifdef HAVE_SYS_PIDFD_H
 #   include <sys/pidfd.h>
 #  endif
-#  include <sys/types.h>
 #  ifndef HAVE_PIDFD_SEND_SIGNAL
-#   include <sys/wait.h>
 static inline int pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
 				    unsigned int flags)
 {
@@ -34,4 +35,23 @@ static inline int pidfd_open(pid_t pid, unsigned int flags)
 
 # endif	/* SYS_pidfd_send_signal */
 #endif /* HAVE_SYS_SYSCALL_H */
+
+#ifndef UL_HAVE_PIDFD
+static inline int pidfd_send_signal(int pidfd __attribute__((unused)),
+				    int sig __attribute__((unused)),
+				    siginfo_t *info __attribute__((unused)),
+				    unsigned int flags __attribute__((unused)))
+{
+	errno = ENOSYS;
+	return -1;
+}
+
+static inline int pidfd_open(pid_t pid __attribute__((unused)),
+			     unsigned int flags __attribute__((unused)))
+{
+	errno = ENOSYS;
+	return -1;
+}
+#endif
+
 #endif /* UTIL_LINUX_PIDFD_UTILS */
-- 
2.47.2