From 60fa029fe83af62f27bf833dc86c0aeeb76b412b Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 4 Nov 2022 18:19:29 +0100
Subject: [PATCH] fd-util: make fd_in_set() (and thus close_all_fds()) handle
 invalidated fds in the array

let's handle gracefully if fds in the specified array are already
invalidated (i.e. negative). This is handy when putting together arrays
on the fly.

(cherry picked from commit d11c14a9817f6561a30d96d8faea126a4c811af8)

Related: #2138081
---
 src/basic/fd-util.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/basic/fd-util.c b/src/basic/fd-util.c
index cee20a9a81..6ed04449bf 100644
--- a/src/basic/fd-util.c
+++ b/src/basic/fd-util.c
@@ -177,9 +177,13 @@ int fd_cloexec(int fd, bool cloexec) {
 _pure_ static bool fd_in_set(int fd, const int fdset[], size_t n_fdset) {
         assert(n_fdset == 0 || fdset);
 
-        for (size_t i = 0; i < n_fdset; i++)
+        for (size_t i = 0; i < n_fdset; i++) {
+                if (fdset[i] < 0)
+                        continue;
+
                 if (fdset[i] == fd)
                         return true;
+        }
 
         return false;
 }
@@ -252,6 +256,10 @@ static int close_all_fds_special_case(const int except[], size_t n_except) {
         if (!have_close_range)
                 return 0;
 
+        if (n_except == 1 && except[0] < 0) /* Minor optimization: if we only got one fd, and it's invalid,
+                                             * we got none */
+                n_except = 0;
+
         switch (n_except) {
 
         case 0: