Mercurial > hg
changeset 49001:2593873cda0f stable
rust-dirstate: panic if the DirstateMap counters go below 0
When modifying the API I hit some... interesting errors (trying to allocate
178GB of RAM, for example) because I failed to keep the counters correctly
updated.
This counter underflow is likely to happen when code is changed around
and can have up to eat-your-dirstate level of consequences, which is not nice.
The very small runtime cost of checking these counters should really not be an
issue and will help us uncover bugs when/if they do appear in the future.
Differential Revision: https://phab.mercurial-scm.org/D12430
| author | Raphaël Gomès <rgomes@octobus.net> |
|---|---|
| date | Tue, 05 Apr 2022 10:55:28 +0200 |
| parents | dd6b67d5c256 |
| children | fbc02ccc207e |
| files | rust/hg-core/src/dirstate_tree/dirstate_map.rs |
| diffstat | 1 files changed, 20 insertions(+), 4 deletions(-) [+] |
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--- a/rust/hg-core/src/dirstate_tree/dirstate_map.rs Tue Apr 05 10:55:28 2022 +0200 +++ b/rust/hg-core/src/dirstate_tree/dirstate_map.rs Tue Apr 05 10:55:28 2022 +0200 @@ -831,10 +831,20 @@ )? { dropped = d; if dropped.had_entry { - node.descendants_with_entry_count -= 1; + node.descendants_with_entry_count = node + .descendants_with_entry_count + .checked_sub(1) + .expect( + "descendants_with_entry_count should be >= 0", + ); } if dropped.was_tracked { - node.tracked_descendants_count -= 1; + node.tracked_descendants_count = node + .tracked_descendants_count + .checked_sub(1) + .expect( + "tracked_descendants_count should be >= 0", + ); } // Directory caches must be invalidated when removing a @@ -889,10 +899,16 @@ filename, )? { if dropped.had_entry { - map.nodes_with_entry_count -= 1 + map.nodes_with_entry_count = map + .nodes_with_entry_count + .checked_sub(1) + .expect("nodes_with_entry_count should be >= 0"); } if dropped.had_copy_source { - map.nodes_with_copy_source_count -= 1 + map.nodes_with_copy_source_count = map + .nodes_with_copy_source_count + .checked_sub(1) + .expect("nodes_with_copy_source_count should be >= 0"); } } else { debug_assert!(!was_tracked);