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Diffstat (limited to 'third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift')
-rw-r--r-- | third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift new file mode 100644 index 0000000000..a34b128e23 --- /dev/null +++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift @@ -0,0 +1,101 @@ +// An error type for FFI errors. These errors occur at the UniFFI level, not +// the library level. +fileprivate enum UniffiInternalError: LocalizedError { + case bufferOverflow + case incompleteData + case unexpectedOptionalTag + case unexpectedEnumCase + case unexpectedNullPointer + case unexpectedRustCallStatusCode + case unexpectedRustCallError + case unexpectedStaleHandle + case rustPanic(_ message: String) + + public var errorDescription: String? { + switch self { + case .bufferOverflow: return "Reading the requested value would read past the end of the buffer" + case .incompleteData: return "The buffer still has data after lifting its containing value" + case .unexpectedOptionalTag: return "Unexpected optional tag; should be 0 or 1" + case .unexpectedEnumCase: return "Raw enum value doesn't match any cases" + case .unexpectedNullPointer: return "Raw pointer value was null" + case .unexpectedRustCallStatusCode: return "Unexpected RustCallStatus code" + case .unexpectedRustCallError: return "CALL_ERROR but no errorClass specified" + case .unexpectedStaleHandle: return "The object in the handle map has been dropped already" + case let .rustPanic(message): return message + } + } +} + +fileprivate let CALL_SUCCESS: Int8 = 0 +fileprivate let CALL_ERROR: Int8 = 1 +fileprivate let CALL_PANIC: Int8 = 2 +fileprivate let CALL_CANCELLED: Int8 = 3 + +fileprivate extension RustCallStatus { + init() { + self.init( + code: CALL_SUCCESS, + errorBuf: RustBuffer.init( + capacity: 0, + len: 0, + data: nil + ) + ) + } +} + +private func rustCall<T>(_ callback: (UnsafeMutablePointer<RustCallStatus>) -> T) throws -> T { + try makeRustCall(callback, errorHandler: nil) +} + +private func rustCallWithError<T>( + _ errorHandler: @escaping (RustBuffer) throws -> Error, + _ callback: (UnsafeMutablePointer<RustCallStatus>) -> T) throws -> T { + try makeRustCall(callback, errorHandler: errorHandler) +} + +private func makeRustCall<T>( + _ callback: (UnsafeMutablePointer<RustCallStatus>) -> T, + errorHandler: ((RustBuffer) throws -> Error)? +) throws -> T { + uniffiEnsureInitialized() + var callStatus = RustCallStatus.init() + let returnedVal = callback(&callStatus) + try uniffiCheckCallStatus(callStatus: callStatus, errorHandler: errorHandler) + return returnedVal +} + +private func uniffiCheckCallStatus( + callStatus: RustCallStatus, + errorHandler: ((RustBuffer) throws -> Error)? +) throws { + switch callStatus.code { + case CALL_SUCCESS: + return + + case CALL_ERROR: + if let errorHandler = errorHandler { + throw try errorHandler(callStatus.errorBuf) + } else { + callStatus.errorBuf.deallocate() + throw UniffiInternalError.unexpectedRustCallError + } + + case CALL_PANIC: + // When the rust code sees a panic, it tries to construct a RustBuffer + // with the message. But if that code panics, then it just sends back + // an empty buffer. + if callStatus.errorBuf.len > 0 { + throw UniffiInternalError.rustPanic(try {{ Type::String.borrow()|lift_fn }}(callStatus.errorBuf)) + } else { + callStatus.errorBuf.deallocate() + throw UniffiInternalError.rustPanic("Rust panic") + } + + case CALL_CANCELLED: + throw CancellationError() + + default: + throw UniffiInternalError.unexpectedRustCallStatusCode + } +} |