POC: Support reinstalls via kexec

src/cmdline.rs

@@ -46,6 +46,8 @@ use crate::io::IgnitionHash;
 pub enum Cmd {
     /// Install Fedora CoreOS or RHEL CoreOS
     Install(InstallConfig),
+    /// Re-Install Fedora CoreOS or RHEL CoreOS
+    Reinstall(ReinstallConfig),
     /// Download a CoreOS image
     Download(DownloadConfig),
     /// List available images in a Fedora CoreOS stream
@@ -454,6 +456,101 @@ pub enum PartitionFilter {
     Index(Option<NonZeroU32>, Option<NonZeroU32>),
 }
 
+#[derive(Debug, StructOpt)]
+pub struct ReinstallConfig {
+    // These are all the options we can drive purely from kargs.
+    // XXX: should dedupe with `InstallConfig` and reuse the config-file mechanism.
+
+    // ways to specify the image source
+    /// Fedora CoreOS stream
+    #[structopt(short, long, value_name = "name")]
+    #[structopt(conflicts_with = "image-url")]
+    pub stream: Option<String>,
+    /// Manually specify the image URL
+    #[structopt(short = "u", long, value_name = "URL")]
+    #[structopt(conflicts_with = "stream")]
+    pub image_url: Option<Url>,
+
+    // postprocessing options
+    /// Embed an Ignition config from a URL
+    #[structopt(short = "I", long, value_name = "URL")]
+    #[structopt(conflicts_with = "ignition-file")]
+    pub ignition_url: Option<Url>,
+    /// Override the Ignition platform ID
+    #[structopt(short, long, value_name = "name")]
+    pub platform: Option<String>,
+    /// Save partitions with this label glob
+    #[structopt(long, value_name = "lx")]
+    // Allow argument multiple times, but one value each.  Allow "a,b" in
+    // one argument.
+    #[structopt(number_of_values = 1, require_delimiter = true)]
+    pub save_partlabel: Vec<String>,
+    /// Save partitions with this number or range
+    #[structopt(long, value_name = "id")]
+    // Allow argument multiple times, but one value each.  Allow "1-5,7" in
+    // one argument.
+    #[structopt(number_of_values = 1, require_delimiter = true)]
+    // Allow ranges like "-2".
+    #[structopt(allow_hyphen_values = true)]
+    pub save_partindex: Vec<String>,
+
+    // obscure options without short names
+    /// Skip signature verification
+    // XXX: should have independent switch for immediate vs delayed (e.g. image-url) fetches
+    #[structopt(long)]
+    pub insecure: bool,
+    /// Fetch retries, or "infinite"
+    #[structopt(long, value_name = "N", default_value)]
+    pub fetch_retries: FetchRetries,
+
+    // positional args
+    /// Destination device
+    pub dest_device: String,
+
+    // specific to `reinstall`
+    /// Skip rebooting after reinstall
+    #[structopt(long)]
+    pub skip_reboot: bool,
+    /// URL to initramfs
+    #[structopt(
+        long,
+        value_name = "URL",
+        conflicts_with = "initramfs-file",
+        requires = "rootfs-url"
+    )]
+    pub initramfs_url: Option<Url>,
+    /// Local path to initramfs
+    #[structopt(
+        long,
+        value_name = "PATH",
+        conflicts_with = "initramfs-url",
+        requires = "rootfs-file"
+    )]
+    pub initramfs_file: Option<String>,
+    /// URL to rootfs
+    #[structopt(
+        long,
+        value_name = "URL",
+        conflicts_with = "rootfs-file",
+        requires = "initramfs-url"
+    )]
+    pub rootfs_url: Option<Url>,
+    /// Local path to rootfs
+    #[structopt(
+        long,
+        value_name = "PATH",
+        conflicts_with = "rootfs-url",
+        requires = "initramfs-file"
+    )]
+    pub rootfs_file: Option<String>,
+    /// Use `coreos.live.rootfs_url` instead of appending.
+    #[structopt(long, conflicts_with = "rootfs-file")]
+    pub defer_rootfs: bool,
+    /// Serial console to use
+    #[structopt(long, value_name = "KARG", default_value = "ttyS0")]
+    pub console: String,
+}
+
 #[derive(Debug, StructOpt)]
 pub struct DownloadConfig {
     /// Fedora CoreOS stream

src/download.rs

@@ -410,6 +410,50 @@ pub fn download_to_tempfile(url: &Url, retries: FetchRetries) -> Result<File> {
     Ok(f)
 }
 
+// XXX: try to dedupe with write_image?
+pub fn download_and_verify_to_tempfile(
+    url: &Url,
+    sig_url: &Url,
+    retries: FetchRetries,
+) -> Result<File> {
+    let sig: Vec<u8> = {
+        let client = new_http_client()?;
+        let mut resp = http_get(client, sig_url, retries).context("fetching signature URL")?;
+        let mut sig_bytes = Vec::new();
+        resp.read_to_end(&mut sig_bytes)
+            .context("reading signature content")?;
+        sig_bytes
+    };
+
+    let client = new_http_client()?;
+    let mut resp = http_get(client, url, retries)?;
+
+    // wrap source for signature verification, if available
+    // keep the reader so we can explicitly check the result afterward
+    let mut verify_reader =
+        VerifyReader::new(&mut resp, Some(sig.as_slice()), VerifyKeys::Production)?;
+
+    // wrap in a BufReader to amortize read overhead
+    let mut reader = BufReader::with_capacity(BUFFER_SIZE, &mut verify_reader);
+
+    let mut f = tempfile::tempfile()?;
+    let mut writer = BufWriter::with_capacity(BUFFER_SIZE, &mut f);
+    copy(&mut reader, &mut writer).with_context(|| format!("couldn't copy '{}'", url))?;
+
+    // check signature
+    drop(reader);
+    verify_reader.verify()?;
+
+    writer
+        .flush()
+        .with_context(|| format!("couldn't write '{}' to disk", url))?;
+    drop(writer);
+    f.seek(SeekFrom::Start(0))
+        .with_context(|| format!("rewinding file for '{}'", url))?;
+
+    Ok(f)
+}
+
 struct ProgressReader<'a, R: Read> {
     source: R,
     length: Option<(NonZeroU64, String)>,