runtime: export abi_decode

graphprotocol · Apr 5, 2021 · 88154d8 · 88154d8
1 parent 5d039ec
commit 88154d8
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Showing 2 changed files with 33 additions and 1 deletion.
diff --git a/runtime/wasm/src/host_exports.rs b/runtime/wasm/src/host_exports.rs
@@ -4,7 +4,8 @@ use crate::{
     UnresolvedContractCall,
 };
 use bytes::Bytes;
-use ethabi::{encode, Address, Token};
+use ethabi::param_type::{ParamType, Reader};
+use ethabi::{decode, encode, Address, Token};
 use graph::components::ethereum::*;
 use graph::components::store::EntityKey;
 use graph::components::subgraph::{ProofOfIndexingEvent, SharedProofOfIndexing};
@@ -816,6 +817,23 @@ pub(crate) fn abi_encode(params: Vec<Token>) -> Result<Vec<u8>, anyhow::Error> {
     Ok(encode(&params))
 }
 
+pub(crate) fn abi_decode(mut types: String, data: Vec<u8>) -> Result<Vec<Token>, anyhow::Error> {
+    if !(types.starts_with('(') && types.ends_with(')')) {
+        return Err(anyhow::anyhow!("'ethabi' requires types to start and finish with parentheses, eg: '(uint256,address,(bytes32,int8,address))'"));
+    }
+
+    types.pop();
+    types.remove(0);
+
+    let param_types: Vec<ParamType> = types
+        .split(',')
+        .map(Reader::read)
+        .collect::<Result<_, _>>()
+        .or_else(|e| Err(anyhow::anyhow!("Failed to read types: {}", e)))?;
+
+    decode(&param_types, &data).map_err(|e| anyhow::anyhow!("Failed to decode: {}", e))
+}
+
 #[test]
 fn test_string_to_h160_with_0x() {
     assert_eq!(

diff --git a/runtime/wasm/src/module/mod.rs b/runtime/wasm/src/module/mod.rs
@@ -575,6 +575,7 @@ impl WasmInstance {
         link!("log.log", log_log, level, msg_ptr);
 
         link!("abi.encode", abi_encode, params_ptr);
+        link!("abi.decode", abi_decode, params_ptr, data_ptr);
 
         link!("arweave.transactionData", arweave_transaction_data, ptr);
 
@@ -1402,6 +1403,19 @@ impl WasmInstanceContext {
             .unwrap_or(Ok(AscPtr::null()))
     }
 
+    /// function decode(types: String, data: Bytes): Array<ethereum.Value> | null
+    fn abi_decode(
+        &mut self,
+        types_ptr: AscPtr<AscString>,
+        data_ptr: AscPtr<Uint8Array>,
+    ) -> Result<AscPtr<Array<AscPtr<AscEnum<EthereumValueKind>>>>, DeterministicHostError> {
+        let result = host_exports::abi_decode(self.asc_get(types_ptr)?, self.asc_get(data_ptr)?);
+        // return `null` if it fails
+        result
+            .map(|params| self.asc_new(&*params))
+            .unwrap_or(Ok(AscPtr::null()))
+    }
+
     /// function arweave.transactionData(txId: string): Bytes | null
     fn arweave_transaction_data(
         &mut self,