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Merge pull request #236 from urbit/pq/fix-weird-bugs

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fix two weird bugs
This commit is contained in:
Edward Amsden 2024-05-31 12:40:34 -05:00 committed by GitHub
commit 0f45645a58
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1 changed files with 32 additions and 10 deletions
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42
rust/ares/src/hamt.rs
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@ -345,18 +345,22 @@ impl<T: Copy + Preserve> Hamt<T> {
*new_leaf_buffer = (*n, t);
let split = stem.hypothetical_index(chunk);
let new_buffer = stack.struct_alloc(stem.size() + 1);
copy_nonoverlapping(stem.buffer, new_buffer, split);
if split > 0 {
copy_nonoverlapping(stem.buffer, new_buffer, split);
}
*new_buffer.add(split) = Entry {
leaf: Leaf {
len: 1,
buffer: new_leaf_buffer,
},
};
copy_nonoverlapping(
stem.buffer.add(split),
new_buffer.add(split + 1),
stem.size() - split,
);
if stem.size() - split > 0 {
copy_nonoverlapping(
stem.buffer.add(split),
new_buffer.add(split + 1),
stem.size() - split,
);
}
*dest = Stem {
bitmap: stem.bitmap | chunk_to_bit(chunk),
typemap: stem.typemap & !chunk_to_bit(chunk),
@ -628,8 +632,17 @@ impl<T: Copy + Persist> Persist for Hamt<T> {
let next_chunk = traversal[depth].bitmap.trailing_zeros();
let next_type = traversal[depth].typemap & (1 << next_chunk) != 0;
let next_entry = *traversal[depth].buffer;
traversal[depth].bitmap >>= next_chunk + 1;
traversal[depth].typemap >>= next_chunk + 1;
if next_chunk >= 31 {
// if next_chunk == 31, then we will try to shift the bitmap by next_chunk+1 = 32 bits.
// The datatype is a u32, so this is equivalent to setting it to 0. If we do try
// to shift a u32 by 32 bits, then rust's overflow checking will catch it
// and crash the process.
traversal[depth].bitmap = 0;
traversal[depth].typemap = 0;
} else {
traversal[depth].bitmap >>= next_chunk + 1;
traversal[depth].typemap >>= next_chunk + 1;
}
traversal[depth].buffer = traversal[depth].buffer.add(1);
if next_type {
@ -707,8 +720,17 @@ impl<T: Copy + Persist> Persist for Hamt<T> {
let next_type = traversal[depth].typemap & (1 << next_chunk) != 0;
let next_entry_ptr = traversal[depth].buffer;
traversal[depth].bitmap >>= next_chunk + 1;
traversal[depth].typemap >>= next_chunk + 1;
if next_chunk >= 31 {
// if next_chunk == 31, then we will try to shift the bitmap by next_chunk+1 = 32 bits.
// The datatype is a u32, so this is equivalent to setting it to 0. If we do try
// to shift a u32 by 32 bits, then rust's overflow checking will catch it
// and crash the process.
traversal[depth].bitmap = 0;
traversal[depth].typemap = 0;
} else {
traversal[depth].bitmap >>= next_chunk + 1;
traversal[depth].typemap >>= next_chunk + 1;
}
traversal[depth].buffer = traversal[depth].buffer.add(1);
if next_type {