tail: fix panic on header write error

src/uu/tail/src/follow/files.rs

@@ -143,7 +143,7 @@ impl FileHandling {
         if chunks.has_data() {
             if self.needs_header(path, verbose) {
                 let display_name = self.get(path).display_name.clone();
-                self.header_printer.print(display_name.as_str());
+                self.header_printer.print(display_name.as_str())?;
             }
 
             let mut writer = BufWriter::new(stdout().lock());

src/uu/tail/src/paths.rs

@@ -8,7 +8,7 @@
 use crate::text;
 use std::ffi::OsStr;
 use std::fs::{File, Metadata};
-use std::io::{Seek, SeekFrom};
+use std::io::{self, Seek, SeekFrom, Write, stdout};
 #[cfg(unix)]
 use std::os::unix::fs::{FileTypeExt, MetadataExt};
 use std::path::{Path, PathBuf};
@@ -127,18 +127,26 @@ impl HeaderPrinter {
         }
     }
 
-    pub fn print_input(&mut self, input: &Input) {
-        self.print(input.display_name.as_str());
+    pub fn print_input(&mut self, input: &Input) -> io::Result<()> {
+        self.print(input.display_name.as_str())
     }
 
-    pub fn print(&mut self, string: &str) {
+    pub fn print(&mut self, string: &str) -> io::Result<()> {
         if self.verbose {
-            println!(
-                "{}==> {string} <==",
+            let header_string = format!(
+                "{}==> {string} <==\n",
                 if self.first_header { "" } else { "\n" },
             );
+
+            let stdout = stdout();
+            let mut stdout = stdout.lock();
+
+            stdout.write_all(header_string.as_bytes())?;
+            stdout.flush()?;
+
             self.first_header = false;
         }
+        Ok(())
     }
 }
 pub trait FileExtTail {

src/uu/tail/src/tail.rs

@@ -136,7 +136,7 @@ fn tail_file(
     if path.is_dir() {
         set_exit_code(1);
 
-        header_printer.print_input(input);
+        header_printer.print_input(input)?;
         let err_msg = translate!("tail-is-a-directory");
 
         show_error!(
@@ -168,7 +168,7 @@ fn tail_file(
             Ok(mut file) => {
                 let st = file.metadata()?;
                 let blksize_limit = uucore::fs::sane_blksize::sane_blksize_from_metadata(&st);
-                header_printer.print_input(input);
+                header_printer.print_input(input)?;
                 let mut reader;
                 if !settings.presume_input_pipe
                     && file.is_seekable(if input.is_stdin() { offset } else { 0 })
@@ -304,7 +304,7 @@ fn tail_stdin(
         )?;
     } else {
         // pipe
-        header_printer.print_input(input);
+        header_printer.print_input(input)?;
         if paths::stdin_is_bad_fd() {
             set_exit_code(1);
             show_error!(

tests/by-util/test_tail.rs

@@ -5033,6 +5033,16 @@ fn test_failed_write_is_reported() {
         .stderr_is("tail: No space left on device\n");
 }
 
+#[cfg(target_os = "linux")]
+#[test]
+fn test_multiple_input_files_failed_write_is_reported() {
+    new_ucmd!()
+        .args(&["/etc/hosts", "/etc/hosts"])
+        .set_stdout(File::create("/dev/full").unwrap())
+        .fails()
+        .stderr_is("tail: No space left on device\n");
+}
+
 #[cfg(target_os = "linux")]
 #[test]
 fn test_failed_write_is_reported_on_seekable_input() {