pr: allow character, block, and fifo devices as input

src/uu/pr/src/pr.rs

@@ -757,22 +757,29 @@ fn open(path: &str) -> Result<Box<dyn Read>, PrError> {
         |i| {
             let path_string = path.to_string();
             match i.file_type() {
-                #[cfg(unix)]
-                ft if ft.is_block_device() => Err(PrError::UnknownFiletype { file: path_string }),
-                #[cfg(unix)]
-                ft if ft.is_char_device() => Err(PrError::UnknownFiletype { file: path_string }),
-                #[cfg(unix)]
-                ft if ft.is_fifo() => Err(PrError::UnknownFiletype { file: path_string }),
                 #[cfg(unix)]
                 ft if ft.is_socket() => Err(PrError::IsSocket { file: path_string }),
                 ft if ft.is_dir() => Err(PrError::IsDirectory { file: path_string }),
-                ft if ft.is_file() || ft.is_symlink() => {
-                    Ok(Box::new(File::open(path).map_err(|e| PrError::Input {
-                        source: e,
-                        file: path.to_string(),
-                    })?) as Box<dyn Read>)
+
+                ft => {
+                    #[allow(unused_mut)]
+                    let mut is_valid = ft.is_file() || ft.is_symlink();
+
+                    #[cfg(unix)]
+                    {
+                        is_valid =
+                            is_valid || ft.is_char_device() || ft.is_block_device() || ft.is_fifo();
+                    }
+
+                    if is_valid {
+                        Ok(Box::new(File::open(path).map_err(|e| PrError::Input {
+                            source: e,
+                            file: path.to_string(),
+                        })?) as Box<dyn Read>)
+                    } else {
+                        Err(PrError::UnknownFiletype { file: path_string })
+                    }
                 }
-                _ => Err(PrError::UnknownFiletype { file: path_string }),
             }
         },
     )

tests/by-util/test_pr.rs

@@ -610,3 +610,11 @@ fn test_help() {
 fn test_version() {
     new_ucmd!().arg("--version").succeeds();
 }
+
+#[cfg(unix)]
+#[test]
+fn test_pr_char_device_dev_null() {
+    new_ucmd!()
+        .arg("/dev/null")
+        .succeeds();
+}