Merge pull request #2525 from larryk85/fix/wasm_start_idx_adjustment

Fix for eos #2400 (WASM injection damages start index)

libraries/chain/include/eosio/chain/wasm_eosio_injection.hpp

@@ -57,8 +57,7 @@ namespace eosio { namespace chain { namespace wasm_injections {
             if ( exp.kind == IR::ObjectKind::function )
                exports++;
 
-         next_function_index = module.functions.imports.size() + module.functions.defs.size() + registered_injected.size(); // + exports + registered_injected.size()-1;
-         ;
+         next_function_index = module.functions.imports.size() + module.functions.defs.size() + registered_injected.size();
          next_actual_index = next_injected_index++;
       }
 
@@ -75,10 +74,18 @@ namespace eosio { namespace chain { namespace wasm_injections {
             module.functions.imports.insert( module.functions.imports.begin()+(registered_injected.size()-1), new_import.begin(), new_import.end() ); 
             injected_index_mapping.emplace( index, actual_index ); 
             // shift all exported functions by 1
+            bool have_updated_start = false;
             for ( int i=0; i < module.exports.size(); i++ ) {
-               if ( module.exports[i].kind == IR::ObjectKind::function )
+               if ( module.exports[i].kind == IR::ObjectKind::function ) {
+                  // update the start function
+                  if ( !have_updated_start && module.exports[i].index == module.startFunctionIndex ) {
+                     module.startFunctionIndex++;
+                     have_updated_start = true;
+                  }
                   module.exports[i].index++;
+               }
             }
+
             // shift all table entries for call indirect
             for(TableSegment& ts : module.tableSegments) {
                for(auto& idx : ts.indices)
@@ -90,7 +97,7 @@ namespace eosio { namespace chain { namespace wasm_injections {
          }
       }
    };
-
+   
    struct noop_injection_visitor {
       static void inject( IR::Module& m );
       static void initializer();
@@ -189,6 +196,7 @@ namespace eosio { namespace chain { namespace wasm_injections {
       static void accept( wasm_ops::instr* inst, wasm_ops::visitor_arg& arg ) {
          wasm_ops::op_types<>::call_t* call_inst = reinterpret_cast<wasm_ops::op_types<>::call_t*>(inst);
          auto mapped_index = injector_utils::injected_index_mapping.find(call_inst->field);
+
          if ( mapped_index != injector_utils::injected_index_mapping.end() )  {
             call_inst->field = mapped_index->second;
          }

libraries/chain/webassembly/binaryen.cpp

@@ -43,7 +43,7 @@ class binaryen_instantiated_module : public wasm_instantiated_module_interface {
          memset(_shared_linear_memory.data, 0, initial_memory_size);
          //copy back in the initial data
          memcpy(_shared_linear_memory.data, _initial_memory.data(), _initial_memory.size());
-
+         
          //be aware that construction of the ModuleInstance implictly fires the start function
          ModuleInstance instance(*_module.get(), &local_interface);
          instance.callExport(Name(entry_point), args);

tests/wasm_tests/test_wasts.hpp

@@ -16,6 +16,7 @@ static const char f32_add_wast[] = R"=====(
  )
 )=====";
 */
+
 static const char aligned_ref_wast[] = R"=====(
 (module
  (import "env" "sha256" (func $sha256 (param i32 i32 i32)))
@@ -166,21 +167,25 @@ static const char entry_wast[] = R"=====(
  (export "entry" (func $entry))
  (export "apply" (func $apply))
  (func $entry
-  (i32.store offset=4
-   (i32.const 0)
-   (call $now)
+  (block
+   (i32.store offset=4
+    (i32.const 0)
+    (call $now)
+   )
   )
  )
  (func $apply (param $0 i64) (param $1 i64) (param $2 i64)
-  (call $require_auth (i64.const 6121376101093867520))
-  (call $eosio_assert
-   (i32.eq
-    (i32.load offset=4
-     (i32.const 0)
+  (block
+   (call $require_auth (i64.const 6121376101093867520))
+   (call $eosio_assert
+    (i32.eq
+     (i32.load offset=4
+      (i32.const 0)
+     )
+     (call $now)
     )
-    (call $now)
+    (i32.const 0)
    )
-   (i32.const 0)
   )
  )
  (start $entry)