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Ryan
952402d6ab
# Description of Changes This PR fixes a C# reducer error-reporting issue where exceptions thrown in reducers were returned to clients with full stack traces, as reported in [#3959](https://github.com/clockworklabs/SpacetimeDB/issues/3959). - Updated the C# reducer host-call error serialization to return only `Exception.Message` (instead of `Exception.ToString()`), preventing server-side stack traces from being leaked to clients. - Added a C# regression-test client assertion to validate reducer failures do not contain stack traces: - `exception.Message` matches the thrown message exactly - the message does not contain newlines or `" at "` stack-trace markers # API and ABI breaking changes None. - No schema or wire-format changes. - Behavior change is limited to the *contents* of reducer error strings returned to clients (stack traces removed). # Expected complexity level and risk 2 - Low - Change is isolated to C# reducer error formatting plus a regression assertion. - Removes unintended information exposure without affecting reducer success paths. # Testing - [X] Ran C# regression-tests client; verified reducer error message is preserved and stack trace is not present.
SpacetimeDB.Runtime
This project contains the core SpacetimeDB SATS typesystem, attributes for the codegen as well as runtime bindings for SpacetimeDB WebAssembly modules.
The runtime bindings are currently implementing via Wasi.Sdk package, which is a .NET implementation of the WASI standard. This is likely to change in the future.
While not really documented, it allows to build raw WebAssembly modules with custom bindings as well, which is what we're using here. The process is somewhat complicated, but here are the steps:
bindings.cdeclares raw C bindings to the SpacetimeDB FFI imports and marks them with attributes like__attribute__((import_module("spacetime"), import_name("_insert")))that make them WebAssembly imports. (unfortunately, function name duplication is currently unavoidable)bindings.cimplements a bunch of Mono-compatible wrappers that convert between Mono types and raw types expected by the SpacetimeDB FFI and invoke corresponding raw bindings.Runtime.csdeclares corresponding functions with compatible signatures for Mono-compatible wrappers to attach to. It marks them all with[MethodImpl(MethodImplOptions.InternalCall)].bindings.cattaches all those Mono-compatible wrappers to their C# declarations in amono_stdb_attach_bindingsfunction.bindings.cadds FFI-compatible exports that search for a method by assembly name, namespace, class name and a method name in the Mono runtime and invoke it. Those exports are marked with attributes like__attribute__((export_name("__call_reducer__")))so that they're exported from Wasm by the linker.- Finally,
bindings.cimplements no-op shims for all the WASI APIs so that they're linked internally and not attempted to be imported from the runtime itself.
The result is a WebAssembly module FFI-compatible with SpacetimeDB and with no WASI imports, which is what we need.
Regenerating RawModuleDef
To regenenerate the Autogen folder, run:
cargo run -p spacetimedb-codegen --example regen-csharp-moduledef