Rollup merge of rust-lang#101426 - beetrees:dup-no-stdio, r=thomcc

Don't duplicate file descriptors into stdio fds Ensures that file descriptors are never duplicated into the stdio fds even if a stdio fd has been closed.
JohnTitor · Sep 5, 2022 · 4687b72 · 4687b72
2 parents 8f1ac8c + 0e0756c
commit 4687b72
Showing 1 changed file with 2 additions and 1 deletion.
diff --git 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) })
     }