From 849d60b47ab8bdce114d9332ec8ca68a14b93edf Mon Sep 17 00:00:00 2001
From: James Smith <james@foxglove.dev>
Date: Fri, 20 Dec 2024 15:59:41 +1100
Subject: [PATCH] handle using padding after chunk

---
 rust/src/sans_io/read.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/rust/src/sans_io/read.rs b/rust/src/sans_io/read.rs
index bedd98185..20826c767 100644
--- a/rust/src/sans_io/read.rs
+++ b/rust/src/sans_io/read.rs
@@ -581,12 +581,19 @@ impl LinearReader {
                             hasher.update(opcode_len_data);
                         }
                         state.compressed_remaining -= (9 + len) as u64;
+                        state.uncompressed_remaining -= (9 + len) as u64;
                         return Some(Ok(ReadAction::GetRecord { data, opcode }));
                     } else {
                         if self.decompressed_content.len() == 0 {
                             self.decompressed_content.clear();
                         }
-                        if state.compressed_remaining == 0 && self.decompressed_content.len() == 0 {
+                        if state.uncompressed_remaining == 0 && self.decompressed_content.len() == 0
+                        {
+                            // Some compressed data regions will have padding inserted at the end by
+                            // the compressor, which we need to skip now that we have all the data we
+                            // need.
+                            state.padding_after_compressed_data +=
+                                check!(len_as_usize(state.compressed_remaining));
                             self.currently_reading = PaddingAfterChunk;
                             continue;
                         }
@@ -1101,7 +1108,9 @@ mod tests {
         let mut f = std::fs::File::open("tests/data/break_zstd_decompression.mcap")
             .expect("failed to open file");
         let blocksize: usize = 1024;
-        let mut reader = LinearReader::new();
+        let mut reader = LinearReader::new_with_options(
+            LinearReaderOptions::default().with_prevalidate_chunk_crcs(true),
+        );
         while let Some(action) = reader.next_action() {
             match action.expect("failed to get next action") {
                 ReadAction::GetRecord { data: _, opcode } => {