Fix binstalk_downloader::Download for data-verifier (#1313)

To make sure the `data_verifier` consumes the entire file and produces
the correct checksum.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/binstalk-downloader/src/download.rs

@@ -2,9 +2,9 @@ use std::{fmt, io, marker::PhantomData, path::Path};
 
 use binstalk_types::cargo_toml_binstall::PkgFmtDecomposed;
 use bytes::Bytes;
-use futures_util::{Stream, StreamExt};
+use futures_util::{stream::FusedStream, Stream, StreamExt};
 use thiserror::Error as ThisError;
-use tracing::{debug, instrument};
+use tracing::{debug, error, instrument};
 
 pub use binstalk_types::cargo_toml_binstall::{PkgFmt, TarBasedFmt};
 
@@ -142,19 +142,42 @@ impl<'a> Download<'a> {
     async fn get_stream(
         self,
     ) -> Result<
-        impl Stream<Item = Result<Bytes, DownloadError>> + Send + Sync + Unpin + 'a,
+        impl Stream<Item = Result<Bytes, DownloadError>> + FusedStream + Send + Sync + Unpin + 'a,
         DownloadError,
     > {
         let mut data_verifier = self.data_verifier;
-        Ok(self.client.get_stream(self.url).await?.map(move |res| {
-            let bytes = res?;
+        Ok(self
+            .client
+            .get_stream(self.url)
+            .await?
+            .map(move |res| {
+                let bytes = res?;
 
-            if let Some(data_verifier) = &mut data_verifier {
-                data_verifier.update(&bytes);
-            }
+                if let Some(data_verifier) = &mut data_verifier {
+                    data_verifier.update(&bytes);
+                }
 
-            Ok(bytes)
-        }))
+                Ok(bytes)
+            })
+            // Call `fuse` at the end to make sure `data_verifier` is only
+            // called when the stream still has elements left.
+            .fuse())
+    }
+}
+
+/// Make sure `stream` is an alias instead of taking the value to avoid
+/// exploding size of the future generated.
+///
+/// Accept `FusedStream` only since the `stream` could be already consumed.
+async fn consume_stream<S>(stream: &mut S)
+where
+    S: Stream<Item = Result<Bytes, DownloadError>> + FusedStream + Unpin,
+{
+    while let Some(res) = stream.next().await {
+        if let Err(err) = res {
+            error!(?err, "failed to consume stream");
+            break;
+        }
     }
 }
 
@@ -172,15 +195,23 @@ impl Download<'_> {
         fmt: TarBasedFmt,
         visitor: &mut dyn TarEntriesVisitor,
     ) -> Result<(), DownloadError> {
-        let stream = self.get_stream().await?;
+        let has_data_verifier = self.data_verifier.is_some();
+        let mut stream = self.get_stream().await?;
 
         debug!("Downloading and extracting then in-memory processing");
 
-        extract_tar_based_stream_and_visit(stream, fmt, visitor).await?;
-
-        debug!("Download, extraction and in-memory procession OK");
-
-        Ok(())
+        match extract_tar_based_stream_and_visit(&mut stream, fmt, visitor).await {
+            Ok(()) => {
+                debug!("Download, extraction and in-memory procession OK");
+                Ok(())
+            }
+            Err(err) => {
+                if has_data_verifier {
+                    consume_stream(&mut stream).await;
+                }
+                Err(err)
+            }
+        }
     }
 
     /// Download a file from the provided URL and extract it to the provided path.
@@ -197,19 +228,31 @@ impl Download<'_> {
             fmt: PkgFmt,
             path: &Path,
         ) -> Result<ExtractedFiles, DownloadError> {
-            let stream = this.get_stream().await?;
+            let has_data_verifier = this.data_verifier.is_some();
+            let mut stream = this.get_stream().await?;
 
             debug!("Downloading and extracting to: '{}'", path.display());
 
-            let extracted_files = match fmt.decompose() {
-                PkgFmtDecomposed::Tar(fmt) => extract_tar_based_stream(stream, path, fmt).await?,
-                PkgFmtDecomposed::Bin => extract_bin(stream, path).await?,
-                PkgFmtDecomposed::Zip => extract_zip(stream, path).await?,
+            let res = match fmt.decompose() {
+                PkgFmtDecomposed::Tar(fmt) => {
+                    extract_tar_based_stream(&mut stream, path, fmt).await
+                }
+                PkgFmtDecomposed::Bin => extract_bin(&mut stream, path).await,
+                PkgFmtDecomposed::Zip => extract_zip(&mut stream, path).await,
             };
 
-            debug!("Download OK, extracted to: '{}'", path.display());
-
-            Ok(extracted_files)
+            match res {
+                Ok(extracted_files) => {
+                    debug!("Download OK, extracted to: '{}'", path.display());
+                    Ok(extracted_files)
+                }
+                Err(err) => {
+                    if has_data_verifier {
+                        consume_stream(&mut stream).await;
+                    }
+                    Err(err)
+                }
+            }
         }
 
         inner(self, fmt, path.as_ref()).await