Add basic cat command implementation

Author: morr0ne

docs/cat.txt

@@ -0,0 +1,2 @@
+Usage: cat [OPTION]... [FILE]...
+Concatenate FILE(s) to standard output.

src/bin/cat.rs

@@ -0,0 +1,42 @@
+use std::{
+    fs::File,
+    io::{self, BufReader, BufWriter, Write, stdin, stdout},
+};
+
+use puppyutils::{Result, cli};
+
+pub fn main() -> Result {
+    let mut stdout = stdout();
+    let mut files = Vec::new();
+
+    cli! {
+        "cat", stdout, #error
+        Value(value) => {
+            files.push(value.to_owned());
+        }
+    };
+
+    let mut stdout = BufWriter::new(stdout);
+
+    // FIXME: so much repetition, can we do better?
+    if files.is_empty() {
+        let mut stdin = BufReader::new(stdin());
+        io::copy(&mut stdin, &mut stdout)?;
+    } else {
+        for file_path in files {
+            // "-" means stdin
+            if file_path == "-" {
+                // TODO: maybe the handling for - should be at the arg parser stage?
+                let mut stdin = BufReader::new(stdin());
+                io::copy(&mut stdin, &mut stdout)?;
+            } else {
+                let mut reader = BufReader::new(File::open(&file_path)?); // Is it fine to error here? or should we keep going
+                io::copy(&mut reader, &mut stdout)?;
+            }
+        }
+    }
+
+    stdout.flush()?;
+
+    Ok(())
+}

src/main.rs

@@ -3,6 +3,7 @@ use std::{borrow::Cow, env::current_exe, os::unix::ffi::OsStrExt, path::PathBuf}
 use puppyutils::{Exit, Result};
 
 pub mod bin {
+    pub mod cat;
     pub mod r#false;
     #[path = "ls/main.rs"]
     pub mod ls;
@@ -25,6 +26,7 @@ fn main() -> Result {
         .ok_or::<Exit>("Failed to get util name".into())?;
 
     match util.as_bytes() {
+        b"calse" => bin::cat::main(),
         b"false" => bin::r#false::main(),
         b"ls" => bin::ls::main(),
         b"mkdir" => bin::mkdir::main(),