Progress

example/alpine/init

@@ -1,11 +1,13 @@
 #!/bin/sh
 
-# Mount special filesystems
-mkdir -p /dev /proc /sys
+# Create console device
+# TODO: is this necessary?
 [ -c /dev/console ] || mknod -m 600 /dev/console c 5 1
+
+# Mount special filesystems
+mkdir -p /proc /sys
 mount -t proc proc /proc
 mount -t sysfs sysfs /sys
-mount -t devtmpfs dev /dev
 
 # Networking
 echo slim > /proc/sys/kernel/hostname

example/archlinux/init

@@ -5,7 +5,6 @@ mkdir -p /dev /proc /sys
 [ -c /dev/console ] || mknod -m 600 /dev/console c 5 1
 mount -t proc proc /proc
 mount -t sysfs sysfs /sys
-mount -t devtmpfs dev /dev
 
 # Networking
 echo slim > /proc/sys/kernel/hostname

src/build.rs

@@ -43,10 +43,10 @@ pub(crate) fn build(BuildCmd { kind, name, init }: BuildCmd) -> Result<()> {
         ImageKind::Qcow2 => build_qcow2(image, &mount_path),
     };
 
-    let unmounted = Command::new("podman")
-        .args(["unshare", "--", "podman", "image", "unmount", image])
-        .output()
-        .is_ok_and(|out| out.status.success());
+    let unmounted = cmd(&[
+        "podman", "unshare", "--", "podman", "image", "unmount", image,
+    ])
+    .is_ok();
     if unmounted {
         println!("Unmounted image.");
     } else {
@@ -137,19 +137,15 @@ fn build_initrd(image: &str, mount_path: &Path) -> Result<()> {
     println!("Registry: {}", reg_dir.display());
 
     let vmlinuz_dst = reg_dir.join("vmlinuz");
-    let cp_status = Command::new("podman")
-        .args([
-            "unshare",
-            "--",
-            "cp",
-            &vmlinuz_src,
-            vmlinuz_dst.to_str().context("registry path is not UTF-8")?,
-        ])
-        .status()
-        .context("Failed to copy vmlinuz out of the image mount")?;
-    if !cp_status.success() {
-        bail!("Failed to copy vmlinuz to registry");
-    }
+    cmd(&[
+        "podman",
+        "unshare",
+        "--",
+        "cp",
+        &vmlinuz_src,
+        vmlinuz_dst.to_str().context("registry path is not UTF-8")?,
+    ])
+    .context("Failed to copy vmlinuz out of the image mount")?;
     println!("Copied vmlinuz -> {}", vmlinuz_dst.display());
 
     // Pack the rootfs as a gzipped newc cpio archive; vmlinuz is excluded

src/command.rs

@@ -2,6 +2,10 @@ use std::process::Command;
 
 use anyhow::{Context, anyhow, bail};
 
+/// Spawn a subprocess with arguments.
+///
+/// Collects `stdout` and returns it on success.
+/// Returns `Err` if the exit code isn't 0, or if the process failed to spawn.
 pub fn cmd(cmd: &[&str]) -> anyhow::Result<String> {
     let [cmd, args @ ..] = cmd else {
         bail!("missing command");

src/forward.rs

@@ -0,0 +1,121 @@
+use std::{
+    fmt::{self, Display},
+    net::{Ipv4Addr, SocketAddr},
+    str::FromStr,
+};
+
+use anyhow::{Context, anyhow, bail};
+use serde::{Deserialize, Serialize, de::Error};
+
+#[derive(Clone, Copy, Debug)]
+pub enum Protocol {
+    Tcp,
+    Udp,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct PortForward {
+    pub protocol: Protocol,
+    pub from: SocketAddr,
+    pub to_addr: Option<Ipv4Addr>,
+    pub to_port: u16,
+}
+
+impl Display for Protocol {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match self {
+            Protocol::Tcp => "tcp",
+            Protocol::Udp => "udp",
+        })
+    }
+}
+
+impl Display for PortForward {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}:{}-", self.protocol, self.from)?;
+        if let Some(to_addr) = self.to_addr {
+            write!(f, ":{}", to_addr)?;
+        }
+        write!(f, ":{}", self.to_port)
+    }
+}
+
+impl FromStr for PortForward {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let result = || {
+            let (protocol, s) = s.split_once(':').context("Missing ':'")?;
+            let (from, to) = s.split_once('-').context("Missing '-'")?;
+            let (to_addr, to_port) = to.split_once(':').context("Missing ':'")?;
+
+            let from = if let Some(from) = from.strip_prefix(':') {
+                let port: u16 = from.parse().context("Invalid port number")?;
+                SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), port)
+            } else {
+                from.parse()?
+            };
+
+            let to_addr = if to_addr.is_empty() {
+                None
+            } else {
+                Some(to_addr.parse()?)
+            };
+
+            Ok(PortForward {
+                from,
+                to_addr,
+                to_port: to_port.parse()?,
+                protocol: match protocol {
+                    "udp" => Protocol::Udp,
+                    "tcp" => Protocol::Tcp,
+                    _ => bail!("Invalid protocol, expected 'udp' or 'tcp'"),
+                },
+            })
+        };
+
+        result()
+            .with_context(|| anyhow!("Expected '(tcp|udp):<address>-<address>', got {s:?}"))
+            .context("Malformed PortForward string")
+    }
+}
+
+impl Serialize for PortForward {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        format_args!("{}", self).serialize(serializer)
+    }
+}
+
+impl<'de> Deserialize<'de> for PortForward {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s: String = Deserialize::deserialize(deserializer)?;
+        s.parse().map_err(D::Error::custom)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::str::FromStr;
+
+    use super::PortForward;
+
+    #[test]
+    fn parse_port_forwards() {
+        let valid = [
+            "tcp:0.0.0.0:80-:8080",
+            "udp::1234-:1234",
+            "tcp:0.0.0.0:80-1.2.3.4:8080",
+            "udp::1234-255.255.255.255:1234",
+        ];
+
+        for valid in valid {
+            PortForward::from_str(valid).expect("Failed to parse a valid port forward string");
+        }
+    }
+}

src/main.rs

@@ -1,5 +1,6 @@
 mod build;
 mod command;
+mod forward;
 mod image;
 mod meta;
 mod qemu;

src/qemu.rs

@@ -3,9 +3,10 @@
 
 use anyhow::{Context, Result, bail};
 use clap::Args;
-use std::process::Command;
+use std::{fmt::Write as _, process::Command};
 
 use crate::{
+    forward::PortForward,
     meta::Meta,
     registry::{registry_base_dir, registry_dir},
 };
@@ -18,9 +19,19 @@ pub struct RunCmd {
     /// Amount of memory to give the VM, in qemu's format.
     #[clap(short, long, default_value = "1024M")]
     memory: String,
+
+    /// Forward ports from host to guest. Example: `tcp:0.0.0.0:80-:8080`
+    #[clap(long)]
+    forward: Vec<PortForward>,
 }
 
-pub(crate) fn run(RunCmd { name, memory }: RunCmd) -> Result<()> {
+pub(crate) fn run(
+    RunCmd {
+        name,
+        memory,
+        forward,
+    }: RunCmd,
+) -> Result<()> {
     let reg_dir = registry_dir(&name)?;
     let vmlinuz_path = registry_base_dir()?.join("vmlinuz");
     let initrd_path = reg_dir.join("initrd");
@@ -41,6 +52,7 @@ pub(crate) fn run(RunCmd { name, memory }: RunCmd) -> Result<()> {
         "earlyprintk=serial",
         "nokaslr",
         &init_arg,
+        "devtmpfs.mount=1", // Automatically mount /dev at boot
     ];
 
     let qcow2_arg = format!("file={},format=qcow2,if=virtio", qcow2_path.display());
@@ -63,15 +75,26 @@ pub(crate) fn run(RunCmd { name, memory }: RunCmd) -> Result<()> {
 
     let cmdline = cmdline.join(" ");
 
+    // add NIC and forward any user specified ports
+    let mut network = "user,model=virtio-net-pci".to_string();
+    for forward in &forward {
+        _ = write!(&mut network, ",hostfwd={forward}");
+    }
+
     let mut command = Command::new("qemu-system-x86_64");
+
+    // TODO: make a lot of this configurable. especially -cpus
     command
+        .args(["-accel", "kvm"])
+        .args(["-cpu", "host", "-smp", "cpus=8"])
         .args(["-m", &memory])
         .arg("-kernel")
         .arg(vmlinuz_path.as_os_str())
         .args(fs_args)
+        .args(["-snapshot"])
         .args(["-append", &cmdline])
         .args(["-nographic"])
-        .args(["-nic", "user,model=virtio-net-pci"]);
+        .args(["-nic", &network]);
 
     println!("{command:?}");