Rollup merge of #145746 - ivmarkov:fix-nofollow-espidf, r=ibraheemdev

Fix STD build failing for target_os = "espidf"

A regression from #142938

cc `@lolbinarycat`
cc `@ibraheemdev`

ESP-IDF (and a few other embedded Tier-3 systems) is considered `cfg(unix)`, but it does not have the `O_NOFOLLOW` flag because neither of its three supported filesystems (FATFS, LitteLF and Spiffs) has symbolic links in the first place.

What this fix does is to keep the `set_permissions_nofollow` method available and non-failing for ESP-IDF, but it behaves as if no `O_NONFOLLOW` was set. This should be fine as there is nothing to follow in the first place, as there are no symbolic links there.

EDIT: Also added the same fix for Horizon, as requested by `@Meziu.`

Author: jhpratt

library/std/src/sys/fs/mod.rs

@@ -117,9 +117,18 @@ pub fn set_permissions(path: &Path, perm: FilePermissions) -> io::Result<()> {
 #[cfg(unix)]
 pub fn set_permissions_nofollow(path: &Path, perm: crate::fs::Permissions) -> io::Result<()> {
     use crate::fs::OpenOptions;
-    use crate::os::unix::fs::OpenOptionsExt;
 
-    OpenOptions::new().custom_flags(libc::O_NOFOLLOW).open(path)?.set_permissions(perm)
+    let mut options = OpenOptions::new();
+
+    // ESP-IDF and Horizon do not support O_NOFOLLOW, so we skip setting it.
+    // Their filesystems do not have symbolic links, so no special handling is required.
+    #[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
+    {
+        use crate::os::unix::fs::OpenOptionsExt;
+        options.custom_flags(libc::O_NOFOLLOW);
+    }
+
+    options.open(path)?.set_permissions(perm)
 }
 
 #[cfg(not(unix))]