Make get_tree_size robust against git bombs
#7766
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For pathological repositories like git bombs with deeply nested tree structures, the previous implementation could hang indefinitely even with a file limit, because it had to visit every tree object to discover the blobs. This change adds a separate tree count that also triggers the limit, ensuring the method terminates promptly regardless of repository structure. The return value is still the blob count for normal repos, preserving existing behavior.
get_tree_count robust against git bombs
get_tree_count robust against git bombsget_tree_size robust against git bombs
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This reimplements def get_tree_size(commit_id, limit)
tree_count = 0
blob_count = 0
get_tree(commit_id).walk(:preorder) do |root, entry|
if blob_count >= limit || tree_count >= limit
blob_count = limit # If we have too many trees we return the limit
raise StopIteration
end
case entry[:type]
when :blob
blob_count += 1
when :tree
tree_count += 1
end
true # go into a tree if that's what we were given
end
blob_count
rescue StopIteration
blob_count
end |
The previous test created 1000 git trees, taking 11s. This creates 32 in <0.5s. This now creates an actual git bomb, if you cloned the repo you'd get 2^32-1 directories.
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I ended up with this. This is now ready for review. |
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Description
For pathological repositories like git bombs with deeply nested tree structures, Rugged's
count_recursivemethod can hang indefinitely even with a file limit, because it has to visit every tree object to find and count the blobs. See libgit2/rugged#995.That causes
RuggedRepository#get_tree_sizeto hang, sogit-linguist statscan hang.This PR works around that issue by using a custom count method that also applies a tree limit, so that it terminates promptly regardless of repository structure. The return value is still the blob count for normal repos, preserving existing behavior.
Checklist: