compression: Add support for ZStd compression

If the manifest contains zst_tar and zst_hash then treat them
as ZStd compressed data.

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

Author: kinnison

src/dist/component/package.rs

@@ -572,3 +572,39 @@ impl<'a> Package for TarXzPackage<'a> {
         self.0.components()
     }
 }
+
+#[derive(Debug)]
+pub struct TarZStdPackage<'a>(TarPackage<'a>);
+
+impl<'a> TarZStdPackage<'a> {
+    pub fn new<R: Read>(
+        stream: R,
+        temp_cfg: &'a temp::Cfg,
+        notify_handler: Option<&'a dyn Fn(Notification<'_>)>,
+    ) -> Result<Self> {
+        let stream = zstd::stream::read::Decoder::new(stream)?;
+        Ok(TarZStdPackage(TarPackage::new(
+            stream,
+            temp_cfg,
+            notify_handler,
+        )?))
+    }
+}
+
+impl<'a> Package for TarZStdPackage<'a> {
+    fn contains(&self, component: &str, short_name: Option<&str>) -> bool {
+        self.0.contains(component, short_name)
+    }
+    fn install<'b>(
+        &self,
+        target: &Components,
+        component: &str,
+        short_name: Option<&str>,
+        tx: Transaction<'b>,
+    ) -> Result<Transaction<'b>> {
+        self.0.install(target, component, short_name, tx)
+    }
+    fn components(&self) -> Vec<String> {
+        self.0.components()
+    }
+}

src/dist/manifest.rs

@@ -55,18 +55,23 @@ pub struct TargetedPackage {
 pub enum CompressionKind {
     GZip,
     XZ,
+    ZStd,
 }
 
 /// Each compression kind, in order of preference for use, from most desirable
 /// to least desirable.
-static COMPRESSION_KIND_PREFERENCE_ORDER: &[CompressionKind] =
-    &[CompressionKind::XZ, CompressionKind::GZip];
+static COMPRESSION_KIND_PREFERENCE_ORDER: &[CompressionKind] = &[
+    CompressionKind::ZStd,
+    CompressionKind::XZ,
+    CompressionKind::GZip,
+];
 
 impl CompressionKind {
     const fn key_prefix(self) -> &'static str {
         match self {
             Self::GZip => "",
             Self::XZ => "xz_",
+            Self::ZStd => "zst_",
         }
     }
 }

src/dist/manifestation.rs

@@ -7,7 +7,9 @@ use retry::delay::NoDelay;
 use retry::{retry, OperationResult};
 
 use crate::config::PgpPublicKey;
-use crate::dist::component::{Components, Package, TarGzPackage, TarXzPackage, Transaction};
+use crate::dist::component::{
+    Components, Package, TarGzPackage, TarXzPackage, TarZStdPackage, Transaction,
+};
 use crate::dist::config::Config;
 use crate::dist::dist::{Profile, TargetTriple, DEFAULT_DIST_SERVER};
 use crate::dist::download::{DownloadCfg, File};
@@ -238,6 +240,7 @@ impl Manifestation {
             };
             let gz;
             let xz;
+            let zst;
             let reader =
                 utils::FileReaderWithProgress::new_file(&installer_file, &notification_converter)?;
             let package: &dyn Package = match format {
@@ -249,6 +252,10 @@ impl Manifestation {
                     xz = TarXzPackage::new(reader, temp_cfg, Some(&notification_converter))?;
                     &xz
                 }
+                CompressionKind::ZStd => {
+                    zst = TarZStdPackage::new(reader, temp_cfg, Some(&notification_converter))?;
+                    &zst
+                }
             };
 
             // If the package doesn't contain the component that the