tail: fix handling of PermissionDenied Error

* add tests for opening unreadable files

src/uu/tail/src/tail.rs

@@ -383,11 +383,12 @@ fn uu_tail(mut settings: Settings) -> UResult<()> {
                 }
             }
         } else if path.is_tailable() {
+            match File::open(&path) {
+                Ok(mut file) => {
                     if settings.verbose {
                         files.print_header(&path, !first_header);
                         first_header = false;
                     }
-            let mut file = File::open(&path).unwrap();
                     let mut reader;
 
                     if is_seekable(&mut file) && get_block_size(md.as_ref().unwrap()) > 0 {
@@ -408,6 +409,21 @@ fn uu_tail(mut settings: Settings) -> UResult<()> {
                             },
                         );
                     }
+                }
+                Err(e) if e.kind() == std::io::ErrorKind::PermissionDenied => {
+                    settings.return_code = 1;
+                    show_error!(
+                        "cannot open {} for reading: Permission denied",
+                        display_name.quote()
+                    );
+                }
+                Err(e) => {
+                    return Err(USimpleError::new(
+                        1,
+                        format!("{}: {}", display_name.quote(), e),
+                    ));
+                }
+            }
         } else if settings.retry && settings.follow.is_some() {
             if path.is_relative() {
                 path = std::env::current_dir().unwrap().join(&path);
@@ -931,8 +947,7 @@ fn handle_event(
                                     );
                                 }
                             }
-                            if event_path.is_orphan() {
+                            if event_path.is_orphan() && !orphans.contains(event_path) {
-                                if !orphans.contains(event_path) {
                                 show_error!("directory containing watched file was removed");
                                 show_error!(
                                     "{} cannot be used, reverting to polling",
@@ -940,7 +955,6 @@ fn handle_event(
                                 );
                                 orphans.push(event_path.to_path_buf());
                             }
-                            }
                             let _ = watcher.unwatch(event_path);
                         } else {
                             show_error!("{}: {}", display_name.display(), text::NO_SUCH_FILE);

tests/by-util/test_tail.rs

@@ -97,6 +97,46 @@ fn test_stdin_redirect_file() {
     assert!(buf_stderr.is_empty());
 }
 
+#[test]
+#[cfg(not(target_os = "windows"))]
+#[cfg(feature = "chmod")]
+fn test_permission_denied() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+
+    at.touch("unreadable");
+    ts.ccmd("chmod").arg("0").arg("unreadable").succeeds();
+
+    ts.ucmd()
+        .set_stdin(Stdio::null())
+        .arg("unreadable")
+        .fails()
+        .stderr_is("tail: cannot open 'unreadable' for reading: Permission denied\n")
+        .no_stdout()
+        .code_is(1);
+}
+
+#[test]
+#[cfg(not(target_os = "windows"))]
+#[cfg(feature = "chmod")]
+fn test_permission_denied_multiple() {
+    let ts = TestScenario::new(util_name!());
+    let at = &ts.fixtures;
+
+    at.touch("file1");
+    at.touch("file2");
+    at.touch("unreadable");
+    ts.ccmd("chmod").arg("0").arg("unreadable").succeeds();
+
+    ts.ucmd()
+        .set_stdin(Stdio::null())
+        .args(&["file1", "unreadable", "file2"])
+        .fails()
+        .stderr_is("tail: cannot open 'unreadable' for reading: Permission denied\n")
+        .stdout_is("==> file1 <==\n\n==> file2 <==\n")
+        .code_is(1);
+}
+
 #[test]
 #[cfg(target_os = "linux")]
 fn test_follow_redirect_stdin_name_retry() {