shred: fix permissions_set_readonly_false clippy error

src/uu/shred/src/shred.rs

@@ -6,7 +6,7 @@
 // * For the full copyright and license information, please view the LICENSE
 // * file that was distributed with this source code.
 
-// spell-checker:ignore (words) writeback wipesync
+// spell-checker:ignore (words) writeback wipesync IWRITE
 
 use clap::{crate_version, Arg, ArgAction, Command};
 use rand::prelude::SliceRandom;
@@ -16,9 +16,13 @@ use std::fs;
 use std::fs::{File, OpenOptions};
 use std::io;
 use std::io::prelude::*;
+#[cfg(target_family = "unix")]
+use std::os::unix::fs::PermissionsExt;
 use std::path::{Path, PathBuf};
 use uucore::display::Quotable;
 use uucore::error::{FromIo, UResult, USimpleError, UUsageError};
+#[cfg(target_family = "unix")]
+use uucore::libc::S_IWRITE;
 use uucore::{format_usage, show, show_if_err, util_name};
 
 const BLOCK_SIZE: usize = 512;
@@ -462,6 +466,14 @@ fn wipe_file(
  if force {
  let metadata = fs::metadata(path).map_err_context(String::new)?;
  let mut perms = metadata.permissions();
+ #[cfg(target_family = "unix")]
+ // NOTE: set_readonly(false) makes the file world-writable on Unix.
+ #[allow(clippy::unnecessary_cast)]
+ // NOTE: S_IWRITE type is u16 on macOS.
+ perms.set_mode(perms.mode() | (S_IWRITE as u32));
+ #[cfg(not(target_family = "unix"))]
+ #[allow(clippy::permissions_set_readonly_false)]
+ // FIXME: Clippy still throws error on non-UNIX platforms.
  perms.set_readonly(false);
  fs::set_permissions(path, perms).map_err_context(String::new)?;
  }