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//! A rudimentary kernel-mode command shell, primarily for debugging and testing
//! purposes.
//!
use crate::rt;
use mycelium_util::fmt::{self, Write};
/// Defines a shell command, including its name, help text, and how the command
/// is executed.
#[derive(Debug)]
pub struct Command<'cmd> {
name: &'cmd str,
help: &'cmd str,
run: Option<RunKind<'cmd>>,
usage: &'cmd str,
subcommands: Option<&'cmd [Command<'cmd>]>,
}
#[derive(Debug)]
pub struct Error<'a> {
line: &'a str,
kind: ErrorKind<'a>,
}
pub type Result<'a> = core::result::Result<(), Error<'a>>;
pub trait Run: Send + Sync {
fn run<'ctx>(&'ctx self, ctx: Context<'ctx>) -> Result<'ctx>;
}
#[derive(Debug)]
enum ErrorKind<'a> {
UnknownCommand(&'a [Command<'a>]),
SubcommandRequired(&'a [Command<'a>]),
InvalidArguments { help: &'a str, arg: &'a str },
Other(&'static str),
}
enum RunKind<'a> {
Fn(fn(Context<'_>) -> Result<'_>),
Runnable(&'a dyn Run),
}
pub fn eval(line: &str) {
static COMMANDS: &[Command] = &[
DUMP,
SLEEP,
PANIC,
FAULT,
VERSION,
crate::drivers::pci::LSPCI_CMD,
];
let _span = tracing::info_span!(target: "shell", "$", message = %line).entered();
tracing::info!(target: "shell", "");
if line == "help" {
tracing::info!(target: "shell", "available commands:");
print_help("", COMMANDS);
tracing::info!(target: "shell", "");
return;
}
match handle_command(Context::new(line), COMMANDS) {
Ok(_) => {}
Err(error) => tracing::error!(target: "shell", "error: {error}"),
}
tracing::info!(target: "shell", "");
}
#[derive(Copy, Clone)]
pub struct Context<'cmd> {
line: &'cmd str,
current: &'cmd str,
}
pub fn handle_command<'cmd>(ctx: Context<'cmd>, commands: &'cmd [Command]) -> Result<'cmd> {
let chunk = ctx.current.trim();
for cmd in commands {
if let Some(current) = chunk.strip_prefix(cmd.name) {
let current = current.trim();
return cmd.run(Context { current, ..ctx });
}
}
Err(ctx.unknown_command(commands))
}
// === commands ===
const DUMP: Command = Command::new("dump")
.with_help("print formatted representations of a kernel structure")
.with_subcommands(&[
Command::new("bootinfo")
.with_help("print the boot information structure")
.with_fn(|ctx| Err(ctx.other_error("not yet implemented"))),
Command::new("archinfo")
.with_help("print the architecture information structure")
.with_fn(|ctx| Err(ctx.other_error("not yet implemented"))),
// Command::new("timer")
// .with_help("print the timer wheel")
// .with_fn(|_| {
// tracing::info!(target: "shell", timer = ?rt::TIMER);
// Ok(())
// }),
rt::DUMP_RT,
crate::arch::shell::DUMP_ARCH,
Command::new("heap")
.with_help("print kernel heap statistics")
.with_fn(|_| {
tracing::info!(target: "shell", heap = ?crate::ALLOC.state());
Ok(())
}),
]);
const SLEEP: Command = Command::new("sleep")
.with_help("spawns a task to sleep for SECONDS")
.with_usage("<SECONDS>")
.with_fn(|ctx| {
use maitake::time;
let line = ctx.command().trim();
if line.is_empty() {
return Err(ctx.invalid_argument("expected a number of seconds to sleep for"));
}
let secs: u64 = line
.parse()
.map_err(|_| ctx.invalid_argument("number of seconds must be an integer"))?;
let duration = time::Duration::from_secs(secs);
tracing::info!(target: "shell", ?duration, "spawning a sleep");
rt::spawn(async move {
time::sleep(duration).await;
tracing::info!(target: "shell", ?duration, "slept");
});
Ok(())
});
const PANIC: Command = Command::new("panic")
.with_usage("<MESSAGE>")
.with_help("cause a kernel panic with the given message. use with caution.")
.with_fn(|line| {
panic!("{}", line.current);
});
const FAULT: Command = Command::new("fault")
.with_help("cause a CPU fault (divide-by-zero). use with caution.")
.with_fn(|_| {
unsafe {
core::arch::asm!(
"div {0:e}",
in(reg) 0,
)
}
Ok(())
});
const VERSION: Command = Command::new("version")
.with_help("print verbose build and version info.")
.with_fn(|_| {
tracing::info!("Mycelium v{}", env!("CARGO_PKG_VERSION"));
tracing::info!(build.version = %crate::MYCELIUM_VERSION);
tracing::info!(build.timestamp = %env!("VERGEN_BUILD_TIMESTAMP"));
tracing::info!(build.features = %env!("VERGEN_CARGO_FEATURES"));
tracing::info!(build.profile = %env!("VERGEN_CARGO_PROFILE"));
tracing::info!(build.target = %env!("VERGEN_CARGO_TARGET_TRIPLE"));
tracing::info!(commit.sha = %env!("VERGEN_GIT_SHA"));
tracing::info!(commit.branch = %env!("VERGEN_GIT_BRANCH"));
tracing::info!(commit.date = %env!("VERGEN_GIT_COMMIT_TIMESTAMP"));
tracing::info!(rustc.version = %env!("VERGEN_RUSTC_SEMVER"));
tracing::info!(rustc.channel = %env!("VERGEN_RUSTC_CHANNEL"));
Ok(())
});
// === impl Command ===
impl<'cmd> Command<'cmd> {
/// Constructs a new `Command` with the given `name`.
///
/// By default, this command will have no help text, no subcommands, no
/// usage hints, and do nothing. Use the [`Command::with_help`] and
/// [`Command::with_usage`] to add help text to the command. Use
/// [`Command::with_subcommands`] to add subcommands, and/or
/// [`Command::with_fn`] or [`Command::with_runnable`] to add a function
/// that defines how to execute the command.
#[must_use]
pub const fn new(name: &'cmd str) -> Self {
Self {
name,
help: "",
usage: "",
run: None,
subcommands: None,
}
}
/// Add help text to the command.
///
/// This should define what the command does, and is printed when running
/// `help` commands.
///
/// # Examples
///
/// ```rust
/// use mycelium_kernel::shell::Command;
///
/// const DUMP: Command = Command::new("dump")
/// .with_help("print formatted representations of a kernel structure");
///
/// // The shell will format this command's help text as:
/// let help_text = "dump --- print formatted representations of a kernel structure";
/// assert_eq!(format!("{DUMP}"), help_text);
/// ```
#[must_use]
pub const fn with_help(self, help: &'cmd str) -> Self {
Self { help, ..self }
}
/// Add usage text to the command.
///
/// This should define what, if any, arguments the command takes. If the
/// command does not take any arguments, it is not necessary to call this
/// method.
///
/// # Examples
///
/// ```rust
/// use mycelium_kernel::shell::Command;
///
/// const ECHO: Command = Command::new("echo")
/// .with_help("print the provided text")
/// .with_usage("<TEXT>");
///
/// // The shell will format this command's help text as:
/// let help_text = "echo <TEXT> --- print the provided text";
/// assert_eq!(format!("{ECHO}"), help_text);
/// ```
#[must_use]
pub const fn with_usage(self, usage: &'cmd str) -> Self {
Self { usage, ..self }
}
/// Add a list of subcommands to this command.
///
/// If subcommands are added, they will be handled automatically by checking
/// if the next argument matches the name of a subcommand, before calling
/// the command's [function] or [runnable], if it has one.
///
/// If the next argument matches the name of a subcommand, that subcommand
/// will be automatically executed. If it does *not* match a subcommand, and
/// the command has a function or runnable, that function or runnable will
/// be called with the remainder of the input. If the command does not have
/// a function or runnable, a "subcommand expected" error is returned.
///
/// # Examples
///
/// A command with only subcommands, and no root function/runnable:
///
/// ```rust
/// use mycelium_kernel::shell::Command;
///
/// // let's pretend we're implementing git (inside the mycelium kernel? for
/// // some reason????)...
/// const GIT: Command = Command::new("git")
/// .with_subcommands(&[
/// SUBCMD_ADD,
/// SUBCMD_COMMIT,
/// SUBCMD_PUSH,
/// // more git commands ...
/// ]);
///
/// const SUBCMD_ADD: Command = Command::new("add")
/// .with_help("add file contents to the index")
/// .with_fn(|ctx| {
/// // ...
/// # drop(ctx); Ok(())
/// });
/// const SUBCMD_COMMIT: Command = Command::new("commit")
/// .with_help("record changes to the repository")
/// .with_fn(|ctx| {
/// // ...
/// # drop(ctx); Ok(())
/// });
/// const SUBCMD_PUSH: Command = Command::new("push")
/// .with_help("update remote refs along with associated objects")
/// .with_fn(|ctx| {
/// // ...
/// # drop(ctx); Ok(())
/// });
/// // more git commands ...
/// # drop(GIT);
/// ```
///
/// [function]: Command::with_fn
/// [runnable]: Command::with_runnable
#[must_use]
pub const fn with_subcommands(self, subcommands: &'cmd [Self]) -> Self {
Self {
subcommands: Some(subcommands),
..self
}
}
/// Add a function that's run to execute this command.
///
/// If [`Command::with_fn`] or [`Command::with_runnable`] was previously
/// called, this overwrites the previously set value.
#[must_use]
pub const fn with_fn(self, func: fn(Context<'_>) -> Result<'_>) -> Self {
Self {
run: Some(RunKind::Fn(func)),
..self
}
}
/// Add a [runnable item] that's run to execute this command.
///
/// If [`Command::with_fn`] or [`Command::with_runnable`] was previously
/// called, this overwrites the previously set value.
///
/// [runnable item]: Run
#[must_use]
pub const fn with_runnable(self, run: &'cmd dyn Run) -> Self {
Self {
run: Some(RunKind::Runnable(run)),
..self
}
}
/// Run this command in the provided [`Context`].
pub fn run<'ctx>(&'cmd self, ctx: Context<'ctx>) -> Result<'ctx>
where
'cmd: 'ctx,
{
let current = ctx.current.trim();
if current == "help" {
let name = ctx.line.strip_suffix(" help").unwrap_or("<???BUG???>");
if let Some(subcommands) = self.subcommands {
tracing::info!(target: "shell", "{name} <COMMAND>: {help}", help = self.help);
tracing::info!(target: "shell", "commands:");
print_help(name, subcommands);
} else {
tracing::info!(target: "shell", "{name}");
}
return Ok(());
}
if let Some(subcommands) = self.subcommands {
return match handle_command(ctx, subcommands) {
Err(e) if e.is_unknown_command() => {
if let Some(ref run) = self.run {
run.run(ctx)
} else if current.is_empty() {
Err(ctx.subcommand_required(subcommands))
} else {
Err(e)
}
}
res => res,
};
}
self.run
.as_ref()
.ok_or_else(|| ctx.subcommand_required(self.subcommands.unwrap_or(&[])))
.and_then(|run| run.run(ctx))
}
}
impl fmt::Display for Command<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self {
run: _func,
name,
help,
usage,
subcommands: _subcommands,
} = self;
let usage = if self.subcommands.is_some() && usage.is_empty() {
"<COMMAND>"
} else {
usage
};
write!(
f,
"{name}{usage_pad}{usage} --- {help}",
usage_pad = if !usage.is_empty() { " " } else { "" },
)
}
}
// === impl Error ===
impl Error<'_> {
fn is_unknown_command(&self) -> bool {
matches!(self.kind, ErrorKind::UnknownCommand(_))
}
}
impl fmt::Display for Error<'_> {
fn fmt(&self, mut f: &mut fmt::Formatter<'_>) -> fmt::Result {
fn command_names<'cmd>(
cmds: &'cmd [Command<'cmd>],
) -> impl Iterator<Item = &'cmd str> + 'cmd {
cmds.iter()
.map(|Command { name, .. }| *name)
.chain(core::iter::once("help"))
}
let Self { line, kind } = self;
match kind {
ErrorKind::UnknownCommand(commands) => {
write!(f, "unknown command {line:?}, expected one of: [")?;
fmt::comma_delimited(&mut f, command_names(commands))?;
f.write_char(']')?;
}
ErrorKind::InvalidArguments { arg, help } => {
write!(f, "invalid argument {arg:?}: {help}")?
}
ErrorKind::SubcommandRequired(subcommands) => {
writeln!(
f,
"the '{line}' command requires one of the following subcommands: ["
)?;
fmt::comma_delimited(&mut f, command_names(subcommands))?;
f.write_char(']')?;
}
ErrorKind::Other(msg) => write!(f, "could not execute {line:?}: {msg}")?,
}
Ok(())
}
}
// === impl Context ===
impl<'cmd> Context<'cmd> {
pub const fn new(line: &'cmd str) -> Self {
Self {
line,
current: line,
}
}
pub fn command(&self) -> &'cmd str {
self.current.trim()
}
fn unknown_command(&self, commands: &'cmd [Command]) -> Error<'cmd> {
Error {
line: self.line,
kind: ErrorKind::UnknownCommand(commands),
}
}
fn subcommand_required(&self, subcommands: &'cmd [Command]) -> Error<'cmd> {
Error {
line: self.line,
kind: ErrorKind::SubcommandRequired(subcommands),
}
}
pub fn invalid_argument(&self, help: &'static str) -> Error<'cmd> {
Error {
line: self.line,
kind: ErrorKind::InvalidArguments {
arg: self.current,
help,
},
}
}
pub fn other_error(&self, msg: &'static str) -> Error<'cmd> {
Error {
line: self.line,
kind: ErrorKind::Other(msg),
}
}
}
// === impl RunKind ===
impl RunKind<'_> {
#[inline]
fn run<'ctx>(&'ctx self, ctx: Context<'ctx>) -> Result<'ctx> {
match self {
Self::Fn(func) => func(ctx),
Self::Runnable(runnable) => runnable.run(ctx),
}
}
}
impl fmt::Debug for RunKind<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Fn(func) => f.debug_tuple("Run::Func").field(&fmt::ptr(func)).finish(),
Self::Runnable(runnable) => f
.debug_tuple("Run::Runnable")
.field(&fmt::ptr(runnable))
.finish(),
}
}
}
// === impl Run ===
impl<F> Run for F
where
F: Fn(Context<'_>) -> Result<'_> + Send + Sync,
{
fn run<'ctx>(&'ctx self, ctx: Context<'ctx>) -> Result<'ctx> {
self(ctx)
}
}
fn print_help(parent_cmd: &str, commands: &[Command]) {
let parent_cmd_pad = if parent_cmd.is_empty() { "" } else { " " };
for command in commands {
tracing::info!(target: "shell", " {parent_cmd}{parent_cmd_pad}{command}");
}
tracing::info!(target: "shell", " {parent_cmd}{parent_cmd_pad}help --- prints this help message");
}