damus

nostr ios client
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Root.swift (4449B)

      1 /*
      2  * Copyright 2023 Google Inc. All rights reserved.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #if !os(WASI)
     18 import Foundation
     19 #else
     20 import SwiftOverlayShims
     21 #endif
     22 
     23 /// Takes in a prefixed sized buffer, where the prefixed size would be skipped.
     24 /// And would verify that the buffer passed is a valid `Flatbuffers` Object.
     25 /// - Parameters:
     26 ///   - byteBuffer: Buffer that needs to be checked and read
     27 ///   - options: Verifier options
     28 /// - Throws: FlatbuffersErrors
     29 /// - Returns: Returns a valid, checked Flatbuffers object
     30 ///
     31 /// ``getPrefixedSizeCheckedRoot(byteBuffer:options:)`` would skip the first Bytes in
     32 /// the ``ByteBuffer`` and verifies the buffer by calling ``getCheckedRoot(byteBuffer:options:)``
     33 public func getPrefixedSizeCheckedRoot<T: FlatBufferObject & Verifiable>(
     34   byteBuffer: inout ByteBuffer,
     35   fileId: String? = nil,
     36   options: VerifierOptions = .init()) throws -> T
     37 {
     38   byteBuffer.skipPrefix()
     39   return try getCheckedRoot(
     40     byteBuffer: &byteBuffer,
     41     fileId: fileId,
     42     options: options)
     43 }
     44 
     45 /// Takes in a prefixed sized buffer, where we check if the sized buffer is equal to prefix size.
     46 /// And would verify that the buffer passed is a valid `Flatbuffers` Object.
     47 /// - Parameters:
     48 ///   - byteBuffer: Buffer that needs to be checked and read
     49 ///   - options: Verifier options
     50 /// - Throws: FlatbuffersErrors
     51 /// - Returns: Returns a valid, checked Flatbuffers object
     52 ///
     53 /// ``getPrefixedSizeCheckedRoot(byteBuffer:options:)`` would skip the first Bytes in
     54 /// the ``ByteBuffer`` and verifies the buffer by calling ``getCheckedRoot(byteBuffer:options:)``
     55 public func getCheckedPrefixedSizeRoot<T: FlatBufferObject & Verifiable>(
     56   byteBuffer: inout ByteBuffer,
     57   fileId: String? = nil,
     58   options: VerifierOptions = .init()) throws -> T
     59 {
     60   let prefix = byteBuffer.skipPrefix()
     61   if prefix != byteBuffer.size {
     62     throw FlatbuffersErrors.prefixedSizeNotEqualToBufferSize
     63   }
     64   return try getCheckedRoot(
     65     byteBuffer: &byteBuffer,
     66     fileId: fileId,
     67     options: options)
     68 }
     69 
     70 /// Takes in a prefixed sized buffer, where the prefixed size would be skipped.
     71 /// Returns a `NON-Checked` flatbuffers object
     72 /// - Parameter byteBuffer: Buffer that contains data
     73 /// - Returns: Returns a Flatbuffers object
     74 ///
     75 /// ``getPrefixedSizeCheckedRoot(byteBuffer:options:)`` would skip the first Bytes in
     76 /// the ``ByteBuffer`` and then calls ``getRoot(byteBuffer:)``
     77 public func getPrefixedSizeRoot<T: FlatBufferObject>(byteBuffer: inout ByteBuffer)
     78   -> T
     79 {
     80   byteBuffer.skipPrefix()
     81   return getRoot(byteBuffer: &byteBuffer)
     82 
     83 }
     84 
     85 /// Verifies that the buffer passed is a valid `Flatbuffers` Object.
     86 /// - Parameters:
     87 ///   - byteBuffer: Buffer that needs to be checked and read
     88 ///   - options: Verifier options
     89 /// - Throws: FlatbuffersErrors
     90 /// - Returns: Returns a valid, checked Flatbuffers object
     91 ///
     92 /// ``getCheckedRoot(byteBuffer:options:)`` Takes in a ``ByteBuffer`` and verifies
     93 /// that by creating a ``Verifier`` and checkes if all the `Bytes` and correctly aligned
     94 /// and within the ``ByteBuffer`` range.
     95 public func getCheckedRoot<T: FlatBufferObject & Verifiable>(
     96   byteBuffer: inout ByteBuffer,
     97   fileId: String? = nil,
     98   options: VerifierOptions = .init()) throws -> T
     99 {
    100   var verifier = try Verifier(buffer: &byteBuffer, options: options)
    101   if let fileId = fileId {
    102     try verifier.verify(id: fileId)
    103   }
    104   try ForwardOffset<T>.verify(&verifier, at: 0, of: T.self)
    105   return T.init(
    106     byteBuffer,
    107     o: Int32(byteBuffer.read(def: UOffset.self, position: byteBuffer.reader)) +
    108       Int32(byteBuffer.reader))
    109 }
    110 
    111 /// Returns a `NON-Checked` flatbuffers object
    112 /// - Parameter byteBuffer: Buffer that contains data
    113 /// - Returns: Returns a Flatbuffers object
    114 public func getRoot<T: FlatBufferObject>(byteBuffer: inout ByteBuffer) -> T {
    115   T.init(
    116     byteBuffer,
    117     o: Int32(byteBuffer.read(def: UOffset.self, position: byteBuffer.reader)) +
    118       Int32(byteBuffer.reader))
    119 }