[PATCH 11/15] midx: use 64-bit multiplication for chunk sizes

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: Dec 3, 2020, 16:16 UTC
Message-ID: <c6a433efba3214e83a7265e53c24cb4001345f14.1607012215.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.804.git.1607012215.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

When calculating the sizes of certain chunks, we should use 64-bit multiplication always. This allows us to properly predict the chunk sizes without risk of overflow.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/midx.c b/midx.c
index 0548266bea..47f5f60fcd 100644
--- a/midx.c
+++ b/midx.c
@@ -946,12 +946,12 @@ static int write_midx_internal(const char *object_dir, struct multi_pack_index *
 	chunks[2].write_fn = write_midx_oid_lookup;
 
 	chunks[3].id = MIDX_CHUNKID_OBJECTOFFSETS;
-	chunks[3].size = ctx.entries_nr * MIDX_CHUNK_OFFSET_WIDTH;
+	chunks[3].size = (uint64_t)ctx.entries_nr * MIDX_CHUNK_OFFSET_WIDTH;
 	chunks[3].write_fn = write_midx_object_offsets;
 
 	if (ctx.large_offsets_needed) {
 		chunks[4].id = MIDX_CHUNKID_LARGEOFFSETS;
-		chunks[4].size = ctx.num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
+		chunks[4].size = (uint64_t)ctx.num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 		chunks[4].write_fn = write_midx_large_offsets;
 	}

-- 
gitgitgadget