added stdin support to cat

src/rs/cat.rs

@@ -2,7 +2,8 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
 use std::fs::read_to_string;
-use std::io::{stdin, stdout, Write};
+use std::io;
+use std::io::Write;
 use std::env;
 use std::process;
 
@@ -25,7 +26,7 @@ fn main() {
         "-u" => {},
 
         _ => {
-          println! ("Usage: {} [options...] [files...]", argv0);
+          println!("Usage: {} [options...] [files...]", argv0);
           process::exit(64); // sysexits(3) EX_USAGE
         },
       };
@@ -33,15 +34,33 @@ fn main() {
   }
   else { 
     for path in args {
-      match read_to_string(&path) {
+      let mut val = String::new();
-        Ok(val) => println!("{}", val),
+
-        Err(_) => {
+      match path.as_str() {
-          println!("{}: {}: No such file or directory.", argv0, path);
+        "-" => {
-          process::exit(66); // sysexits(3) EX_NOINPUT
+          let mut content = String::new();
+          match io::stdin().read_line(&mut content) {
+            Ok(_) => { val.push_str(&content); },
+            Err(_) => {
+              println!("Usage: {} [options...] [files...]", argv0);
+              process::exit(64); // sysexits(3) EX_USAGE
+            },
+          };
         },
-      };
+
+        _ => {
+          match read_to_string(&path) {
+            Ok(output) => { val.push_str(&output); },
+            Err(_) => {
+              println!("{}: {}: No such file or directory.", argv0, path);
+              process::exit(66); // sysexits(3) EX_NOINPUT
+            },
+          };
+        },
+      }
+      print!("{}", val);
     }
   }
 
-  stdout().flush().unwrap();
+  io::stdout().flush().unwrap();
 }