Initial commit

An extremely miniamal shell. It is capable of forking processes, and
passing arguments to them, but that's pretty much it.

4 files changed, 108 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
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index 0000000..73fb9be
--- /dev/null
+++ b/Cargo.lock
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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "dwarvish"
+version = "0.0.0"
diff --git a/Cargo.toml b/Cargo.toml
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index 0000000..e7d40d3
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+++ b/Cargo.toml
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+[package]
+name = "dwarvish"
+version = "0.0.0"
+edition = "2021"
+license = "MIT"
+description = "A POSIX compliance shell and tiny functional programming language"
+
+[[bin]]
+name = "dwvsh"
+path = "src/main.rs"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/main.rs b/src/main.rs
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+++ b/src/main.rs
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+use std::fs;
+use std::io;
+use std::io::Write;
+use std::process::Command;
+
+fn eval(paths: &[&str], prompt: &str) {
+    let mut bins: Vec<String> = Vec::new();
+
+    for path in paths {
+        let files = fs::read_dir(path).expect("Unable to read files in your path");
+        for file in files {
+            bins.push(file.unwrap().path().display().to_string());
+        }
+    }
+
+    loop {
+        // Output the prompt
+        io::stdout().flush().unwrap();
+        print!("{}", prompt);
+        io::stdout().flush().unwrap();
+
+        // Wait for user input
+        let mut input = String::new();
+        io::stdin()
+            .read_line(&mut input)
+            .expect("Unable to evaluate the input string");
+        let input = input.trim();
+
+        // Check if user wants to exit the shell
+        if input == "exit" || input == "quit" {
+            break;
+        }
+
+        // Parse command and arguments
+        let mut split = input.split(' ');
+        let cmd = match split.next() {
+            Some(str) if str.trim().is_empty() => continue,
+            Some(str) => str.trim(),
+            None => continue,
+        };
+
+        // Parse arguments
+        let mut args = vec![];
+        loop {
+            let next = split.next();
+            match next {
+                Some(str) => args.push(str),
+                None => break,
+            }
+        }
+
+        // Check if the command exists
+        let cmd = match bins.iter().find(|b| b.split("/").last().unwrap() == cmd) {
+            Some(cmd) => cmd,
+            None => {
+                println!("Command not found");
+                continue;
+            }
+        };
+
+        // Run the command (and wait for it to finish)
+        let mut child = match Command::new(cmd).args(args).spawn() {
+            Ok(ch) => ch,
+            Err(_) => {
+                println!("Unable to fork");
+                continue;
+            }
+        };
+        child.wait().unwrap();
+    }
+}
+
+fn main() {
+    let paths = [
+        "/bin",
+        "/sbin",
+        "/usr/bin",
+        "/usr/sbin",
+        "/usr/local/bin",
+        "/usr/local/sbin",
+    ];
+
+    let prompt = "|> ";
+
+    eval(&paths, prompt);
+}