Added groups and clear applets

src/cmd/clear/mod.rs

@@ -0,0 +1,28 @@
+use clap::Command;
+use super::Cmd;
+
+#[derive(Debug, Default)]
+pub struct Clear;
+
+impl Cmd for Clear {
+    fn name(&self) -> &str {
+        "clear"
+    }
+
+    fn cli(&self) -> Command {
+        Command::new("clear")
+            .about("clear the terminal's screen")
+            .author("Nathan Fisher")
+            .version(env!("CARGO_PKG_VERSION"))
+    }
+
+    fn run(&self, _matches: Option<&clap::ArgMatches>) -> Result<(), Box<dyn std::error::Error>> {
+        print!("\x1b[2J\x1b[H");
+        print!("\x1b[3J\x1b[H");
+        Ok(())
+    }
+
+    fn path(&self) -> Option<crate::Path> {
+        Some(crate::Path::UsrBin)
+    }
+}

src/cmd/groups/mod.rs

@@ -0,0 +1,55 @@
+use super::Cmd;
+use crate::pw;
+use clap::{Arg, Command};
+use std::io;
+
+#[derive(Debug, Default)]
+pub struct Groups;
+
+impl Cmd for Groups {
+    fn name(&self) -> &str {
+        "groups"
+    }
+
+    fn cli(&self) -> clap::Command {
+        Command::new("groups")
+            .about("display current group names")
+            .author("Nathan Fisher")
+            .version(env!("CARGO_PKG_VERSION"))
+            .after_help(
+                "The groups command displays the current group names or ID values. \
+                If the value does not have a corresponding entry in /etc/group, the \
+                value will be displayed as the numerical group value. The optional \
+                user parameter will display the groups for the named user.",
+            )
+            .arg(Arg::new("user"))
+    }
+
+    fn run(&self, matches: Option<&clap::ArgMatches>) -> Result<(), Box<dyn std::error::Error>> {
+        let Some(matches) = matches else {
+            return Err(Box::new(io::Error::new(io::ErrorKind::Other, "no input")))
+        };
+        let groups = match matches.get_one::<String>("user") {
+            Some(u) => {
+                pw::get_group_names_for_name(&u)?
+            },
+            None => {
+                pw::get_group_names()?
+            },
+        };
+        let len = groups.len();
+        for (idx, group) in groups.into_iter().enumerate() {
+            if idx < len - 1 {
+                print!("{group} ");
+            } else {
+                println!("{group}");
+            }
+        }
+
+        Ok(())
+    }
+
+    fn path(&self) -> Option<crate::Path> {
+        Some(crate::Path::UsrBin)
+    }
+}

src/cmd/mod.rs

@@ -7,6 +7,7 @@ pub mod basename;
 pub mod bootstrap;
 mod cat;
 mod chmod;
+pub mod clear;
 mod cp;
 mod date;
 mod dd;
@@ -16,6 +17,7 @@ pub mod factor;
 pub mod r#false;
 pub mod fold;
 mod getty;
+pub mod groups;
 pub mod head;
 pub mod hostname;
 mod ln;
@@ -38,9 +40,9 @@ pub mod yes;
 
 pub use {
     self::hostname::Hostname, base32::Base32, base64::Base64, basename::Basename,
-    bootstrap::Bootstrap, dirname::Dirname, echo::Echo, factor::Factor, fold::Fold, head::Head,
-    mountpoint::Mountpoint, nologin::Nologin, nproc::Nproc, r#false::False, r#true::True, rev::Rev,
-    shitbox::Shitbox, sleep::Sleep, which::Which, whoami::Whoami, yes::Yes,
+    bootstrap::Bootstrap, clear::Clear, dirname::Dirname, echo::Echo, factor::Factor, fold::Fold, groups::Groups,
+    head::Head, mountpoint::Mountpoint, nologin::Nologin, nproc::Nproc, r#false::False,
+    r#true::True, rev::Rev, shitbox::Shitbox, sleep::Sleep, which::Which, whoami::Whoami, yes::Yes,
 };
 
 pub trait Cmd: fmt::Debug + Sync {
@@ -56,11 +58,13 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
         "base32" => Some(Box::new(Base32::default())),
         "basename" => Some(Box::new(Basename::default())),
         "bootstrap" => Some(Box::new(Bootstrap::default())),
+        "clear" => Some(Box::new(Clear::default())),
         "dirname" => Some(Box::new(Dirname::default())),
         "echo" => Some(Box::new(Echo::default())),
         "factor" => Some(Box::new(Factor::default())),
         "false" => Some(Box::new(False::default())),
         "fold" => Some(Box::new(Fold::default())),
+        "groups" => Some(Box::new(Groups::default())),
         "head" => Some(Box::new(Head::default())),
         "mountpoint" => Some(Box::new(Mountpoint::default())),
         "nologin" => Some(Box::new(Nologin::default())),
@@ -76,16 +80,18 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
     }
 }
 
-pub static COMMANDS: [&'static str; 21] = [
+pub static COMMANDS: [&'static str; 23] = [
     "base32",
     "base64",
     "basename",
     "bootstrap",
+    "clear",
     "dirname",
     "echo",
     "false",
     "factor",
     "fold",
+    "groups",
     "head",
     "hostname",
     "mountpoint",

src/cmd/which/mod.rs

@@ -62,9 +62,7 @@ fn which(command: &str, path: &[&str]) -> Option<String> {
             if let Ok(exe) = File::open(&file) {
                 if let Ok(meta) = exe.metadata() {
                     let mode = meta.mode();
-                    let myuid = unsafe {
-                        libc::geteuid()
-                    };
+                    let myuid = unsafe { libc::geteuid() };
                     let mygroups = crate::pw::get_gids();
                     // we own the file and it has u+x
                     if myuid == meta.uid() && mode & 0o100 != 0 {

src/pw/mod.rs

@@ -1,4 +1,4 @@
-use std::{error::Error, ffi::CStr, num};
+use std::{error::Error, ffi::{CStr, CString, c_int}, num, io};
 
 pub fn get_username<'a>() -> Result<&'a str, std::str::Utf8Error> {
     let user = unsafe {
@@ -20,6 +20,38 @@ pub fn get_eusername<'a>() -> Result<&'a str, std::str::Utf8Error> {
     user.to_str()
 }
 
+pub fn get_uid_for_name(name: &str) -> Option<u32> {
+    let user = match CString::new(name.as_bytes()) {
+        Ok(n) => n,
+        Err(_) => return None,
+    };
+    let uid = unsafe {
+        let pw = libc::getpwnam(user.as_ptr());
+        if pw.is_null() {
+            None
+        } else {
+            Some((*pw).pw_uid)
+        }
+    };
+    uid
+}
+
+pub fn get_pgid_for_name(name: &str) -> Option<u32> {
+    let user = match CString::new(name.as_bytes()) {
+        Ok(n) => n,
+        Err(_) => return None,
+    };
+    let gid = unsafe {
+        let pw = libc::getpwnam(user.as_ptr());
+        if pw.is_null() {
+            None
+        } else {
+            Some((*pw).pw_gid)
+        }
+    };
+    gid
+}
+
 pub fn get_grpname<'a>() -> Result<&'a str, std::str::Utf8Error> {
     let group = unsafe {
         let gid = libc::getgid();
@@ -53,16 +85,57 @@ pub fn get_gids() -> Result<Vec<u32>, num::TryFromIntError> {
     Ok(buf)
 }
 
+pub fn get_gids_for_name(name: &str) -> Result<Vec<u32>, Box<dyn Error>> {
+    let gid = match get_pgid_for_name(name) {
+        Some(g) => g as libc::gid_t,
+        None => return Err(Box::new(io::Error::new(io::ErrorKind::Other, "cannot get primary group"))),
+    };
+    let mut buf: Vec<libc::gid_t> = vec![0; 1024];
+    let name = CString::new(name.as_bytes())?;
+    let mut ct: c_int = 1024;
+    unsafe {
+        let res = libc::getgrouplist(name.as_ptr(), gid, buf.as_mut_ptr(), &mut ct);
+        if res < 0 {
+            return Err(Box::new(io::Error::new(io::ErrorKind::Other, "too many groups")))
+        }
+    }
+    Ok(buf[0..ct as usize].iter().map(|x| *x as u32).collect())
+}
+
 pub fn get_group_names() -> Result<Vec<String>, Box<dyn Error>> {
     let gids = get_gids()?;
     let mut names = vec![];
     for id in gids {
         let name = unsafe {
             let gr = libc::getgrgid(id);
+            if gr.is_null() {
+                id.to_string()
+            } else {
                 let name = (*gr).gr_name;
                 // if we don't take ownership here the OS can (and will)
                 // reuse the memory
                 CStr::from_ptr(name).to_str()?.to_string()
+            }
+        };
+        names.push(name);
+    }
+    Ok(names)
+}
+
+pub fn get_group_names_for_name(name: &str) -> Result<Vec<String>, Box<dyn Error>> {
+    let gids = get_gids_for_name(name)?;
+    let mut names = vec![];
+    for id in gids {
+        let name = unsafe {
+            let gr = libc::getgrgid(id);
+            if gr.is_null() {
+                id.to_string()
+            } else {
+                let name = (*gr).gr_name;
+                // if we don't take ownership here the OS can (and will)
+                // reuse the memory
+                CStr::from_ptr(name).to_str()?.to_string()
+            }
         };
         names.push(name);
     }