From 0a30154198fa39b0595889d053851074f4fa14b9 Mon Sep 17 00:00:00 2001
From: Zachary Dremann <dremann@gmail.com>
Date: Tue, 19 Mar 2024 22:01:39 -0400
Subject: [PATCH] Make use of CompressorImpl::extra_size

---
 crates/applesauce-core/src/compressor/mod.rs  | 1 -
 crates/applesauce-core/src/compressor/zlib.rs | 9 +++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/crates/applesauce-core/src/compressor/mod.rs b/crates/applesauce-core/src/compressor/mod.rs
index 4471a8e..b044f1f 100644
--- a/crates/applesauce-core/src/compressor/mod.rs
+++ b/crates/applesauce-core/src/compressor/mod.rs
@@ -21,7 +21,6 @@ mod zlib;
 pub(crate) trait CompressorImpl {
     /// The offset to start data at, for the specified number of blocks
     #[must_use]
-
     fn header_size(block_count: u64) -> u64;
 
     #[must_use]
diff --git a/crates/applesauce-core/src/compressor/zlib.rs b/crates/applesauce-core/src/compressor/zlib.rs
index 397bb0c..181176d 100644
--- a/crates/applesauce-core/src/compressor/zlib.rs
+++ b/crates/applesauce-core/src/compressor/zlib.rs
@@ -131,6 +131,15 @@ impl super::CompressorImpl for Zlib {
             u32::try_from(writer.stream_position()?).map_err(|_| io::ErrorKind::InvalidInput)?;
         writer.write_all(&ZLIB_TRAILER)?;
 
+        // This is logically a non-modifying operation, even if it takes &mut self, and can fail
+        #[allow(clippy::debug_assert_with_mut_call)]
+        {
+            debug_assert_eq!(
+                writer.stream_position()?,
+                u64::from(data_end) + Self::extra_size(block_count.into())
+            );
+        }
+
         writer.rewind()?;
         writer.write_all(&header(data_end))?;