From 0e0756cf0d1b55f3de4815088276a584e2c31f14 Mon Sep 17 00:00:00 2001
From: beetrees <b@beetr.ee>
Date: Sun, 4 Sep 2022 10:22:36 +0100
Subject: [PATCH] Don't duplicate file descriptors into stdio fds

---
 library/std/src/os/fd/owned.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/library/std/src/os/fd/owned.rs b/library/std/src/os/fd/owned.rs
index a463bc41db7aa..71e33fb9ed864 100644
--- a/library/std/src/os/fd/owned.rs
+++ b/library/std/src/os/fd/owned.rs
@@ -104,7 +104,8 @@ impl BorrowedFd<'_> {
         #[cfg(target_os = "espidf")]
         let cmd = libc::F_DUPFD;
 
-        let fd = cvt(unsafe { libc::fcntl(self.as_raw_fd(), cmd, 0) })?;
+        // Avoid using file descriptors below 3 as they are used for stdio
+        let fd = cvt(unsafe { libc::fcntl(self.as_raw_fd(), cmd, 3) })?;
         Ok(unsafe { OwnedFd::from_raw_fd(fd) })
     }