add cat command

Sponsored-by: author

5 files changed, 52 insertions, 2 deletions

diff --git a/Cargo.lock b/Cargo.lock
index c826b51..6fb7012 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3,6 +3,12 @@
 version = 3
 
 [[package]]
+name = "anyhow"
+version = "1.0.65"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "98161a4e3e2184da77bb14f02184cdd111e83bbbcc9979dfee3c44b9a85f5602"
+
+[[package]]
 name = "atty"
 version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -20,6 +26,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
+name = "check"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "89beada3dfaf43501b20ab69f1d1dd2d43b4a600eb16ca05ea0e093a100634b1"
+
+[[package]]
 name = "clap"
 version = "4.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -167,6 +179,8 @@ checksum = "6ceab39d59e4c9499d4e5a8ee0e2735b891bb7308ac83dfb4e80cad195c9f6f3"
 name = "unixtool"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
+ "check",
  "clap",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 0ef4c77..83e0d33 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,4 +6,6 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+anyhow = "1.0.65"
+check = "1.0.0"
 clap = { version = "4.0.15", features = ["derive"] }
diff --git a/src/bin/unixtool.rs b/src/bin/unixtool.rs
index 59feac1..80c69b1 100644
--- a/src/bin/unixtool.rs
+++ b/src/bin/unixtool.rs
@@ -1,11 +1,13 @@
 use clap::{Parser, Subcommand};
-use unixtool::cmd::Echo;
+use unixtool::cmd::*;
 
-fn main() {
+fn main() -> anyhow::Result<()> {
     let args = Args::parse();
     match args.command {
+        Command::Cat(x) => x.run()?,
         Command::Echo(x) => x.run(),
     }
+    Ok(())
 }
 
 #[derive(Parser)]
@@ -16,5 +18,6 @@ struct Args {
 
 #[derive(Subcommand)]
 enum Command {
+    Cat(Cat),
     Echo(Echo),
 }
diff --git a/src/cmd/cat.rs b/src/cmd/cat.rs
new file mode 100644
index 0000000..31fdbdf
--- /dev/null
+++ b/src/cmd/cat.rs
@@ -0,0 +1,28 @@
+use clap::Parser;
+use std::fs::read;
+use std::io::{stdin, stdout, Read, Write};
+use std::path::PathBuf;
+
+/// Read files named on the command line and write them to stdout. If
+/// no files are named, read stdin instead.
+#[derive(Parser)]
+pub struct Cat {
+    /// Files to read. If none given, read stdin.
+    filenames: Vec<PathBuf>,
+}
+
+impl Cat {
+    pub fn run(&self) -> anyhow::Result<()> {
+        if self.filenames.is_empty() {
+            let mut data = vec![];
+            stdin().read_to_end(&mut data)?;
+            stdout().write_all(&data)?;
+        } else {
+            for filename in self.filenames.iter() {
+                let data = read(filename)?;
+                stdout().write_all(&data)?;
+            }
+        }
+        Ok(())
+    }
+}
diff --git a/src/cmd/mod.rs b/src/cmd/mod.rs
index d1744e5..5315fc1 100644
--- a/src/cmd/mod.rs
+++ b/src/cmd/mod.rs
@@ -1,2 +1,5 @@
 mod echo;
 pub use echo::Echo;
+
+mod cat;
+pub use cat::Cat;