Adds a way to verify/exposes Entities ids (#7221)

src/idl_gen_swift.cpp

@@ -506,12 +506,13 @@ class SwiftGenerator : public BaseGenerator {
     if (!struct_def.fixed) {
       if (parser_.file_identifier_.length()) {
         code_.SetValue("FILENAME", parser_.file_identifier_);
+        code_ += "{{ACCESS_TYPE}} static var id: String { \"{{FILENAME}}\" } ";
         code_ +=
             "{{ACCESS_TYPE}} static func finish(_ fbb: inout "
             "FlatBufferBuilder, end: "
             "Offset, prefix: Bool = false) { fbb.finish(offset: end, "
             "fileId: "
-            "\"{{FILENAME}}\", addPrefix: prefix) }";
+            "{{STRUCTNAME}}.id, addPrefix: prefix) }";
       }
       code_ +=
           "{{ACCESS_TYPE}} static func getRootAs{{SHORT_STRUCTNAME}}(bb: "

swift/Sources/FlatBuffers/ByteBuffer.swift

@@ -400,10 +400,13 @@ public struct ByteBuffer {
   /// SkipPrefix Skips the first 4 bytes in case one of the following
   /// functions are called `getPrefixedSizeCheckedRoot` & `getPrefixedSizeRoot`
   /// which allows us to skip the first 4 bytes instead of recreating the buffer
+  @discardableResult
   @usableFromInline
-  mutating func skipPrefix() {
+  mutating func skipPrefix() -> Int32 {
     _writerSize = _writerSize &- MemoryLayout<Int32>.size
+    return read(def: Int32.self, position: 0)
   }
+
 }
 
 extension ByteBuffer: CustomDebugStringConvertible {

swift/Sources/FlatBuffers/FlatbuffersErrors.swift

@@ -19,6 +19,10 @@ import Foundation
 /// Collection of thrown from the Flatbuffer verifier
 public enum FlatbuffersErrors: Error, Equatable {
 
+  /// Thrown when verifying a file id that doesnt match buffer id
+  case bufferIdDidntMatchPassedId
+  /// Prefixed size doesnt match the current (readable) buffer size
+  case prefixedSizeNotEqualToBufferSize
   /// Thrown when buffer is bigger than the allowed 2GiB
   case exceedsMaxSizeAllowed
   /// Thrown when there is an missaligned pointer at position

swift/Sources/FlatBuffers/Root.swift

@@ -28,10 +28,39 @@ import Foundation
 /// the ``ByteBuffer`` and verifies the buffer by calling ``getCheckedRoot(byteBuffer:options:)``
 public func getPrefixedSizeCheckedRoot<T: FlatBufferObject & Verifiable>(
   byteBuffer: inout ByteBuffer,
+  fileId: String? = nil,
   options: VerifierOptions = .init()) throws -> T
 {
   byteBuffer.skipPrefix()
-  return try getCheckedRoot(byteBuffer: &byteBuffer, options: options)
+  return try getCheckedRoot(
+    byteBuffer: &byteBuffer,
+    fileId: fileId,
+    options: options)
+}
+
+/// Takes in a prefixed sized buffer, where we check if the sized buffer is equal to prefix size.
+/// And would verify that the buffer passed is a valid `Flatbuffers` Object.
+/// - Parameters:
+///   - byteBuffer: Buffer that needs to be checked and read
+///   - options: Verifier options
+/// - Throws: FlatbuffersErrors
+/// - Returns: Returns a valid, checked Flatbuffers object
+///
+/// ``getPrefixedSizeCheckedRoot(byteBuffer:options:)`` would skip the first Bytes in
+/// the ``ByteBuffer`` and verifies the buffer by calling ``getCheckedRoot(byteBuffer:options:)``
+public func getCheckedPrefixedSizeRoot<T: FlatBufferObject & Verifiable>(
+  byteBuffer: inout ByteBuffer,
+  fileId: String? = nil,
+  options: VerifierOptions = .init()) throws -> T
+{
+  let prefix = byteBuffer.skipPrefix()
+  if prefix != byteBuffer.size {
+    throw FlatbuffersErrors.prefixedSizeNotEqualToBufferSize
+  }
+  return try getCheckedRoot(
+    byteBuffer: &byteBuffer,
+    fileId: fileId,
+    options: options)
 }
 
 /// Takes in a prefixed sized buffer, where the prefixed size would be skipped.
@@ -61,9 +90,13 @@ public func getPrefixedSizeRoot<T: FlatBufferObject>(byteBuffer: inout ByteBuffe
 /// and within the ``ByteBuffer`` range.
 public func getCheckedRoot<T: FlatBufferObject & Verifiable>(
   byteBuffer: inout ByteBuffer,
+  fileId: String? = nil,
   options: VerifierOptions = .init()) throws -> T
 {
   var verifier = try Verifier(buffer: &byteBuffer, options: options)
+  if let fileId = fileId {
+    try verifier.verify(id: fileId)
+  }
   try ForwardOffset<T>.verify(&verifier, at: 0, of: T.self)
   return T.init(
     byteBuffer,

swift/Sources/FlatBuffers/Verifier.swift

@@ -200,4 +200,14 @@ public struct Verifier {
   internal mutating func finish() {
     _depth -= 1
   }
+
+  mutating func verify(id: String) throws {
+    let size = MemoryLayout<Int32>.size
+    let str = _buffer.readString(at: size, count: size)
+    if id == str {
+      return
+    }
+    throw FlatbuffersErrors.bufferIdDidntMatchPassedId
+  }
+
 }

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/FlatbuffersVerifierTests.swift

@@ -201,12 +201,34 @@ final class FlatbuffersVerifierTests: XCTestCase {
     XCTAssertNoThrow(try getCheckedRoot(byteBuffer: &byteBuffer) as Movie)
   }
 
+  func testErrorWrongFileId() {
+    // swiftformat:disable all
+    var byteBuffer = ByteBuffer(bytes: [20, 0, 0, 0, 77, 79, 86, 73, 12, 0, 12, 0, 0, 0, 0, 0, 8, 0, 4, 0, 12, 0, 0, 0, 8, 0, 0, 0, 20, 0, 0, 0, 3, 0, 0, 0, 24, 0, 0, 0, 32, 0, 0, 0, 12, 0, 0, 0, 3, 0, 0, 0, 3, 1, 4, 0, 2, 0, 0, 0, 7, 0, 0, 0, 0, 0, 6, 0, 8, 0, 4, 0, 6, 0, 0, 0, 8, 0, 0, 0])
+    // swiftformat:enable all
+    XCTAssertThrowsError(try getCheckedRoot(byteBuffer: &byteBuffer, fileId: "FLEX") as Movie)
+  }
+
+  func testVerifyPrefixedBuffer() {
+    // swiftformat:disable all
+    var byteBuffer = ByteBuffer(bytes: [0, 0, 0, 1, 20, 0, 0, 0, 77, 79, 86, 73, 12, 0, 12, 0, 0, 0, 0, 0, 8, 0, 4, 0, 12, 0, 0, 0, 8, 0, 0, 0, 20, 0, 0, 0, 3, 0, 0, 0, 24, 0, 0, 0, 32, 0, 0, 0, 12, 0, 0, 0, 3, 0, 0, 0, 3, 1, 4, 0, 2, 0, 0, 0, 7, 0, 0, 0, 0, 0, 6, 0, 8, 0, 4, 0, 6, 0, 0, 0, 8, 0, 0, 0])
+    // swiftformat:enable all
+    XCTAssertThrowsError(
+      try getCheckedPrefixedSizeRoot(byteBuffer: &byteBuffer) as Movie)
+  }
+
   func testFullVerifier() {
     XCTAssertNoThrow(
       try getCheckedRoot(
         byteBuffer: &validFlatbuffersObject) as MyGame_Example_Monster)
   }
 
+  func testFullVerifierWithFileId() {
+    XCTAssertNoThrow(
+      try getCheckedRoot(
+        byteBuffer: &validFlatbuffersObject,
+        fileId: MyGame_Example_Monster.id) as MyGame_Example_Monster)
+  }
+
   func testInvalidBuffer() {
     XCTAssertThrowsError(
       try getCheckedRoot(

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/monster_test_generated.swift

@@ -683,7 +683,8 @@ public struct MyGame_InParentNamespace: FlatBufferObject, Verifiable, ObjectAPIP
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  public static var id: String { "MONS" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_InParentNamespace.id, addPrefix: prefix) }
   public static func getRootAsInParentNamespace(bb: ByteBuffer) -> MyGame_InParentNamespace { return MyGame_InParentNamespace(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -736,7 +737,8 @@ public struct MyGame_Example2_Monster: FlatBufferObject, Verifiable, ObjectAPIPa
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  public static var id: String { "MONS" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_Example2_Monster.id, addPrefix: prefix) }
   public static func getRootAsMonster(bb: ByteBuffer) -> MyGame_Example2_Monster { return MyGame_Example2_Monster(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -789,7 +791,8 @@ internal struct MyGame_Example_TestSimpleTableWithEnum: FlatBufferObject, Verifi
   internal var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  internal static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  internal static var id: String { "MONS" } 
+  internal static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_Example_TestSimpleTableWithEnum.id, addPrefix: prefix) }
   internal static func getRootAsTestSimpleTableWithEnum(bb: ByteBuffer) -> MyGame_Example_TestSimpleTableWithEnum { return MyGame_Example_TestSimpleTableWithEnum(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -871,7 +874,8 @@ public struct MyGame_Example_Stat: FlatBufferObject, Verifiable, ObjectAPIPacker
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  public static var id: String { "MONS" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_Example_Stat.id, addPrefix: prefix) }
   public static func getRootAsStat(bb: ByteBuffer) -> MyGame_Example_Stat { return MyGame_Example_Stat(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -1011,7 +1015,8 @@ public struct MyGame_Example_Referrable: FlatBufferObject, Verifiable, ObjectAPI
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  public static var id: String { "MONS" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_Example_Referrable.id, addPrefix: prefix) }
   public static func getRootAsReferrable(bb: ByteBuffer) -> MyGame_Example_Referrable { return MyGame_Example_Referrable(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -1118,7 +1123,8 @@ public struct MyGame_Example_Monster: FlatBufferObject, Verifiable, ObjectAPIPac
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  public static var id: String { "MONS" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_Example_Monster.id, addPrefix: prefix) }
   public static func getRootAsMonster(bb: ByteBuffer) -> MyGame_Example_Monster { return MyGame_Example_Monster(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -2275,7 +2281,8 @@ public struct MyGame_Example_TypeAliases: FlatBufferObject, Verifiable, ObjectAP
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MONS", addPrefix: prefix) }
+  public static var id: String { "MONS" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: MyGame_Example_TypeAliases.id, addPrefix: prefix) }
   public static func getRootAsTypeAliases(bb: ByteBuffer) -> MyGame_Example_TypeAliases { return MyGame_Example_TypeAliases(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/optional_scalars_generated.swift

@@ -33,7 +33,8 @@ public struct optional_scalars_ScalarStuff: FlatBufferObject, Verifiable {
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "NULL", addPrefix: prefix) }
+  public static var id: String { "NULL" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: optional_scalars_ScalarStuff.id, addPrefix: prefix) }
   public static func getRootAsScalarStuff(bb: ByteBuffer) -> optional_scalars_ScalarStuff { return optional_scalars_ScalarStuff(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/union_vector_generated.swift

@@ -328,7 +328,8 @@ public struct Attacker: FlatBufferObject, Verifiable, ObjectAPIPacker {
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MOVI", addPrefix: prefix) }
+  public static var id: String { "MOVI" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: Attacker.id, addPrefix: prefix) }
   public static func getRootAsAttacker(bb: ByteBuffer) -> Attacker { return Attacker(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -410,7 +411,8 @@ public struct HandFan: FlatBufferObject, Verifiable, ObjectAPIPacker {
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MOVI", addPrefix: prefix) }
+  public static var id: String { "MOVI" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: HandFan.id, addPrefix: prefix) }
   public static func getRootAsHandFan(bb: ByteBuffer) -> HandFan { return HandFan(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }
@@ -492,7 +494,8 @@ public struct Movie: FlatBufferObject, Verifiable, ObjectAPIPacker {
   public var __buffer: ByteBuffer! { return _accessor.bb }
   private var _accessor: Table
 
-  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: "MOVI", addPrefix: prefix) }
+  public static var id: String { "MOVI" } 
+  public static func finish(_ fbb: inout FlatBufferBuilder, end: Offset, prefix: Bool = false) { fbb.finish(offset: end, fileId: Movie.id, addPrefix: prefix) }
   public static func getRootAsMovie(bb: ByteBuffer) -> Movie { return Movie(Table(bb: bb, position: Int32(bb.read(def: UOffset.self, position: bb.reader)) + Int32(bb.reader))) }
 
   private init(_ t: Table) { _accessor = t }