use openat when encountering ENAMETOOLONG

library/std/src/fs/tests.rs

@@ -1707,3 +1707,26 @@ fn test_file_times() {
         assert_eq!(metadata.created().unwrap(), created);
     }
 }
+
+#[test]
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn deep_traversal() -> crate::io::Result<()> {
+    use crate::fs::{create_dir_all, metadata, remove_dir_all, write};
+    use crate::iter::repeat;
+
+    let tmpdir = tmpdir();
+
+    let segment = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+
+    let mut dir = tmpdir.join(segment);
+    repeat(segment).take(100).for_each(|name| dir.push(name));
+    assert!(dir.as_os_str().len() > libc::PATH_MAX as usize);
+    let file = dir.join("b");
+
+    create_dir_all(&dir).expect("deep create tailed");
+    write(&file, "foo").expect("deep write failed");
+    metadata(&file).expect("deep stat failed");
+    remove_dir_all(&dir).expect("deep remove failed");
+
+    Ok(())
+}

library/std/src/lib.rs

@@ -296,6 +296,7 @@
 #![feature(int_roundings)]
 #![feature(ip)]
 #![feature(ip_in_core)]
+#![feature(iter_advance_by)]
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(maybe_uninit_write_slice)]

library/std/src/sys/common/small_c_string.rs

@@ -1,6 +1,5 @@
-use crate::ffi::{CStr, CString};
+use crate::ffi::{CStr, CString, OsStr};
 use crate::mem::MaybeUninit;
-use crate::path::Path;
 use crate::slice;
 use crate::{io, ptr};
 
@@ -15,11 +14,11 @@ const NUL_ERR: io::Error =
     io::const_io_error!(io::ErrorKind::InvalidInput, "file name contained an unexpected NUL byte");
 
 #[inline]
-pub fn run_path_with_cstr<T, F>(path: &Path, f: F) -> io::Result<T>
+pub fn run_path_with_cstr<T, F>(path: &(impl AsRef<OsStr> + ?Sized), f: F) -> io::Result<T>
 where
     F: FnOnce(&CStr) -> io::Result<T>,
 {
-    run_with_cstr(path.as_os_str().as_os_str_bytes(), f)
+    run_with_cstr(path.as_ref().as_os_str_bytes(), f)
 }
 
 #[inline]