Method wrapJSFuncAsSafeCallType

web/src/runtime.ts:2130–2204

(func: Function)

  }

  private wrapJSFuncAsSafeCallType(func: Function): ctypes.FTVMFFIWasmSafeCallType {
    const lib = this.lib;
    return (
      self: Pointer,
      packedArgs: Pointer,
      numArgs: number,
      ret: Pointer
    ): number => {
      const jsArgs = [];
      // use scope to track js values.
      this.ctx.beginScope();
      for (let i = 0; i < numArgs; ++i) {
        const argPtr = packedArgs + i * SizeOf.TVMFFIAny;
        const typeIndex = lib.memory.loadI32(argPtr);

        if (typeIndex >= TypeIndex.kTVMFFIRawStr) {
          // NOTE: the following code have limitations in asyncify mode.
          // The reason is that the TVMFFIAnyViewToOwnedAny will simply
          // get skipped during the rewinding process, causing memory failure
          if (!this.asyncifyHandler.isNormalStackState()) {
            throw Error("Cannot handle str/object argument callback in asyncify mode");
          }
          lib.checkCall(
            (lib.exports.TVMFFIAnyViewToOwnedAny as ctypes.FTVMFFIAnyViewToOwnedAny)(
              argPtr,
              argPtr
            )
          );
        }
        jsArgs.push(this.retValueToJS(argPtr, true));
      }

      let rv: any;
      try {
        rv = func(...jsArgs);
      } catch (error) {
        // error handling
        // store error via SetLastError
        this.ctx.endScope();
        const errKind = "JSCallbackError"
        const errMsg = error.message;
        const stack = lib.getOrAllocCallStack();
        const errKindOffset = stack.allocRawBytes(errKind.length + 1);
        stack.storeRawBytes(errKindOffset, StringToUint8Array(errKind));
        const errMsgOffset = stack.allocRawBytes(errMsg.length + 1);
        stack.storeRawBytes(errMsgOffset, StringToUint8Array(errMsg));
        stack.commitToWasmMemory();
        (this.lib.exports.TVMFFIErrorSetRaisedFromCStr as ctypes.FTVMFFIErrorSetRaisedFromCStr)(
          stack.ptrFromOffset(errKindOffset),
          stack.ptrFromOffset(errMsgOffset)
        );
        this.lib.recycleCallStack(stack);
        return -1;
      }

      // normal return path
      // recycle all js object value in function unless we want to retain them.
      this.ctx.endScope();