From 9f46fb699a68c2d8b721b0b1d0e3419a830a4052 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Sat, 5 Dec 2020 16:37:59 +0100
Subject: [PATCH] Content-range fix

---
 src/api/s3_get.rs | 44 +++++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/src/api/s3_get.rs b/src/api/s3_get.rs
index a68c485b..a5e7b342 100644
--- a/src/api/s3_get.rs
+++ b/src/api/s3_get.rs
@@ -161,7 +161,7 @@ pub async fn handle_get(
 					}
 				})
 				.buffered(2);
-			//let body: Body = Box::new(StreamBody::new(Box::pin(body_stream)));
+
 			let body = hyper::body::Body::wrap_stream(body_stream);
 			Ok(resp_builder.body(body)?)
 		}
@@ -183,7 +183,7 @@ pub async fn handle_get_range(
 	let resp_builder = object_headers(version, version_meta)
 		.header(
 			"Content-Range",
-			format!("bytes {}-{}/{}", begin, end, version_meta.size),
+			format!("bytes {}-{}/{}", begin, end - 1, version_meta.size),
 		)
 		.status(StatusCode::PARTIAL_CONTENT);
 
@@ -206,35 +206,49 @@ pub async fn handle_get_range(
 				None => return Err(Error::NotFound),
 			};
 
-			let blocks = version
-				.blocks()
-				.iter()
-				.cloned()
-				.filter(|block| block.offset + block.size > begin && block.offset < end)
-				.collect::<Vec<_>>();
+			// We will store here the list of blocks that have an intersection with the requested
+			// range, as well as their "true offset", which is their actual offset in the complete
+			// file (whereas block.offset designates the offset of the block WITHIN THE PART
+			// block.part_number, which is not the same in the case of a multipart upload)
+			let mut blocks = Vec::with_capacity(std::cmp::min(
+				version.blocks().len(),
+				4 + ((end - begin) / std::cmp::max(version.blocks()[0].size as u64, 1024)) as usize,
+			));
+			let mut true_offset = 0;
+			for b in version.blocks().iter() {
+				if true_offset >= end {
+					break;
+				}
+				// Keep only blocks that have an intersection with the requested range
+				if true_offset < end && true_offset + b.size > begin {
+					blocks.push((b.clone(), true_offset));
+				}
+				true_offset += b.size;
+			}
 
 			let body_stream = futures::stream::iter(blocks)
-				.map(move |block| {
+				.map(move |(block, true_offset)| {
 					let garage = garage.clone();
 					async move {
 						let data = garage.block_manager.rpc_get_block(&block.hash).await?;
-						let start_in_block = if block.offset > begin {
+						let data = Bytes::from(data);
+						let start_in_block = if true_offset > begin {
 							0
 						} else {
-							begin - block.offset
+							begin - true_offset
 						};
-						let end_in_block = if block.offset + block.size < end {
+						let end_in_block = if true_offset + block.size < end {
 							block.size
 						} else {
-							end - block.offset
+							end - true_offset
 						};
 						Result::<Bytes, Error>::Ok(Bytes::from(
-							data[start_in_block as usize..end_in_block as usize].to_vec(),
+							data.slice(start_in_block as usize..end_in_block as usize),
 						))
 					}
 				})
 				.buffered(2);
-			//let body: Body = Box::new(StreamBody::new(Box::pin(body_stream)));
+
 			let body = hyper::body::Body::wrap_stream(body_stream);
 			Ok(resp_builder.body(body)?)
 		}