pub fn set_contract_storage<K, V>(key: &K, value: &V) -> Option<u32>Writes the value to the contract storage under the given storage key and returns the size of pre-existing value if any.
set_contract_storage allows storing values of up to 16 KiB (2^14 bytes) per key. With an additional 32-bit 'length' datum required for variable-length values, this allows storing an array of 2^14 - 4 bytes.
Tests that the Ink! Integration and End-to-End tests correctly implement set_contract_storage checks. In particular, that Integration reject attempts to set data that the E2E would reject (more than maximum size).
| # | Test | Integration | E2E |
|---|---|---|---|
| 1 | Attempts to store an array of 2^14 - 4 bytes. | ✅ | ✅ |
| 2 | Attempts to store an array of 2^14 - 3 bytes. This should always fail. | ❌ | ✅ |
Test 2 passes on E2E (correctly failing to store the array), but failed on Integration (incorrectly succeding to store the array). This is due to the emulated set_contract_storage implementation not checking the size of the input array.
This feature is practically complete, it's just missing a size check. Implementing this check should be fairly trivial; it shouldn't take more than a few minutes. The best place to do it would probably be in the set_storage() implementation in ink/crates/engine/src/ext.rs, probably by simply panic!()ing (as there's no way to communicate an error).
The function set_contract_storage() sets the storage in a contract. There was a missing validation in integration tests that was present in e2e. This validation checked that the size of the storage set did not exceed 16380 bytes.
In our proposed implementation in PR #1961, we added a validation to the function set_contract_storage() in integration tests that checks the size of the input value against the same limit set in e2e test: 16380 bytes. In case this limit is exceeded, a panic is raised with the message: "Value too large to be stored in contract storage, maximum size is {} bytes".