tail: report PermissionDenied instead of No such file when metadata f…

src/uu/tail/src/tail.rs

@@ -117,14 +117,24 @@ fn tail_file(
     observer: &mut Observer,
     offset: u64,
 ) -> UResult<()> {
-    if !path.exists() {
-        set_exit_code(1);
-        show_error!(
-            "{}",
-            translate!("tail-error-cannot-open-no-such-file", "file" => input.display_name.clone(), "error" => translate!("tail-no-such-file-or-directory"))
-        );
-        observer.add_bad_path(path, input.display_name.as_str(), false)?;
-    } else if path.is_dir() {
+    let md = path.metadata();
+    if let Err(ref e) = md {
+        if e.kind() == ErrorKind::NotFound {
+            set_exit_code(1);
+            show_error!(
+                "{}",
+                translate!(
+                    "tail-error-cannot-open-no-such-file",
+                    "file" => input.display_name.clone(),
+                    "error" => translate!("tail-no-such-file-or-directory")
+                )
+            );
+            observer.add_bad_path(path, input.display_name.as_str(), false)?;
+            return Ok(());
+        }
+    }
+
+    if path.is_dir() {
         set_exit_code(1);
 
         header_printer.print_input(input);
@@ -146,7 +156,6 @@ fn tail_file(
             );
         }
         if !observer.follow_name_retry() {
-            // skip directory if not retry
             return Ok(());
         }
         observer.add_bad_path(path, input.display_name.as_str(), false)?;

tests/by-util/test_tail.rs

@@ -574,6 +574,31 @@ fn test_follow_non_utf8_bytes() {
     child.kill();
 }
 
+#[test]
+#[cfg(unix)]
+fn test_permission_denied_is_not_reported_as_not_found() {
+    use std::fs;
+    use std::os::unix::fs::PermissionsExt;
+
+    if unsafe { libc::geteuid() } == 0 {
+        return;
+    }
+
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    at.mkdir("noexec");
+    at.touch("noexec/file");
+
+    let dir = at.plus("noexec");
+    fs::set_permissions(&dir, fs::Permissions::from_mode(0o000)).unwrap();
+
+    ucmd.arg("noexec/file")
+        .fails()
+        .stderr_contains("Permission denied");
+
+    fs::set_permissions(&dir, fs::Permissions::from_mode(0o700)).unwrap();
+}
+
 #[test]
 #[cfg(not(target_os = "windows"))] // FIXME: test times out
 fn test_follow_multiple() {