将 C 结构实例复制到 Swift 后缺少成员

Question

我正在使用 C 的 inotify库，通过 Swift 中的包装器。这个想法是提供一个 Swift Package Manager 库，它在 Linux 中提供基本的文件系统事件支持。

几乎一切正常。除了这里，我似乎无法复制 inotify_event 成员 name:

let bufferLength = Int(MemoryLayout<inotify_event>.size + NAME_MAX + 1)
let buffer = UnsafeMutablePointer<CChar>.allocate(capacity: bufferLength)

var fileSystemEvent : FileSystemEvent?
var currentIndex: Int = 0
let readLength = read(Int32(self.fileDescriptor), buffer, bufferLength)

while currentIndex < readLength {
  var event = withUnsafePointer(to: &buffer[currentIndex]) {
    return $0.withMemoryRebound(to: inotify_event.self, capacity: 1) {
      return $0.pointee
    }
  }
  if event.len > 0 {
     fileSystemEvent = FileSystemEvent(
       watchDescriptor: WatchDescriptor(event.wd),
       name: "", //String(cString: event.name),
       mask: event.mask,
       cookie: event.cookie,
       length: event.len
     )
  }
  currentIndex += MemoryLayout<inotify_event>.stride + Int(event.len)
}

我想做的事:

name: String(cString: event.name)，但是然后编译器抛出一个错误:

           `value of type 'inotify_event' has no member 'name'`

关于为什么会发生这种情况，或者关于如何访问 name 成员，我找不到任何线索。以下是 inotify.h 中的结构声明:

/*
 * struct inotify_event - structure read from the inotify device for each event
 *
 * When you are watching a directory, you will receive the filename for events
 * such as IN_CREATE, IN_DELETE, IN_OPEN, IN_CLOSE, ..., relative to the wd.
 */
struct inotify_event {
    __s32       wd;     /* watch descriptor */
    __u32       mask;       /* watch mask */
    __u32       cookie;     /* cookie to synchronize two events */
    __u32       len;        /* length (including nulls) of name */
    char        name[0];    /* stub for possible name */
};

这是怎么回事？

提前致谢:)

附言:here's my full project ，如果您需要更多信息。

Answer 1

name 字段定义为零长度数组:

char        name[0];    /* stub for possible name */

那些不是 导入到 Swift 中。一个可能的解决方案是计算偏移量 接收缓冲区中名称字符串的开头:

 fileSystemEvent = FileSystemEvent(
   watchDescriptor: WatchDescriptor(event.wd),
   name: String(cString: buffer + currentIndex + MemoryLayout<inotify_event>.size),
   mask: event.mask,
   cookie: event.cookie,
   length: event.len)