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1   /*
2    * Copyright 2024 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://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, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.channel.uring;
17  
18  import java.nio.ByteBuffer;
19  
20  /**
21   * <pre>{@code
22   * struct cmsghdr {
23   *     socklen_t cmsg_len;    // data byte count, including header
24   *     int cmsg_level;  //originating protocol
25   *     int cmsg_type;   // protocol-specific type
26   *     // followed by unsigned char cmsg_data[];
27   * };
28   * }</pre>
29   */
30  final class CmsgHdr {
31  
32      private CmsgHdr() { }
33  
34      static void write(ByteBuffer cmsghdr, int cmsgHdrDataOffset,
35                        int cmsgLen, int cmsgLevel, int cmsgType, short segmentSize) {
36          int cmsghdrPosition = cmsghdr.position();
37          if (Native.SIZEOF_SIZE_T == 4) {
38              cmsghdr.putInt(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_LEN, cmsgLen);
39          } else {
40              assert Native.SIZEOF_SIZE_T == 8;
41              cmsghdr.putLong(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_LEN, cmsgLen);
42          }
43          cmsghdr.putInt(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_LEVEL, cmsgLevel);
44          cmsghdr.putInt(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_TYPE, cmsgType);
45          cmsghdr.putShort(cmsghdrPosition + cmsgHdrDataOffset, segmentSize);
46      }
47  
48      static void writeScmRights(ByteBuffer cmsghdr, int cmsgHdrDataOffset, int fd) {
49          int cmsghdrPosition = cmsghdr.position();
50          if (Native.SIZEOF_SIZE_T == 4) {
51              cmsghdr.putInt(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_LEN, Native.CMSG_LEN_FOR_FD);
52          } else {
53              assert Native.SIZEOF_SIZE_T == 8;
54              cmsghdr.putLong(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_LEN, Native.CMSG_LEN_FOR_FD);
55          }
56          cmsghdr.putInt(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_LEVEL, Native.SOL_SOCKET);
57          cmsghdr.putInt(cmsghdrPosition + Native.CMSG_OFFSETOF_CMSG_TYPE, Native.SCM_RIGHTS);
58          cmsghdr.putInt(cmsghdrPosition + cmsgHdrDataOffset, fd);
59      }
60  
61      static int readScmRights(ByteBuffer cmsghdr, int cmsgHdrDataOffset) {
62          return cmsghdr.getInt(cmsghdr.position() + cmsgHdrDataOffset);
63      }
64  }