The stat() function fills a struct stat structure with information about a specific file; if you've got a file descriptor instead of a file name, you can use the fstat() function instead.

stat() 函数会将特定文件的相关信息填入 struct stat 结构中，如果您获得的是文件描述符而不是文件名，那么作为替代，您可以使用 fstat() 函数。

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The iocb argument can usually be treated as an opaque cookie used by the AIO subsystem; if you need the struct file pointer for this file descriptor, however, you can find it as iocb->ki_filp.

通常可以把iocb看作AIO子系统使用的不透明数据结构。 然而，如果需要文件描述符的struct file指针，可以通过iocb->ki_flip获取。

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