Question

块角

how does O.S know that writer is still writing. ?... What is workflow of EOF for file(closing file handle like ^D or ^z) ? what happens if EOF is never written ?

如果读者阅读率比作家写作速度快,会怎样? 汇率错配会导致僵局吗?

其他不想要的情况又会是什么?

O. S 读取文件时如何计算 EOF?

- 尼基尔

P. S. : 当前操作系统是窗口, 但我不介意在 unix 上学习同样有趣的功能。

块角

<强度 > 更多编辑和关于问题的更多信息

现在我知道EOF不是字符, 所以它不能写在文件的数据上。 IF O. S. 使用文件大小来决定 EOF, 就像 @saurabh 指点的一样。

( & gt;) 读取 < / 强 > 时 < 强 > EOF (可能根据文件大小确定,文件大小将存储在相应文件系统的驱动器表格中) )

So does process keeps polling File table for file size to determine EOF as there could be cases of not-fixed files size.
To my little knowledge, EOF is encountered when you read beyond the EOF(in our case file-size). Assume a situation where writer is writing intermittently and reader is reading blocks. SO if reader tries to read more than the available chunk would EOF be thrown ? But Writer has not signalled EOF yet ?

Answer 1

直到程序不关闭文件。 OS 假设文件可以读/ 写或两者兼有( 取决于打开文件的模式 ) 。
EOF不算什么,但OS从文件大小中知道。让我们说,您的文件大小为100字节, 您要求从字节 99 中读取, 并要求增加 6 字节, 然后OS知道该文件直到第100字节, 所以它会返回 EOF 。

Answer 2

If you are writing to a file from one process and reading from it from another, you may want to look into using pipes instead. Those are special files designed exactly for your purpose: you can only write at one end, read at the other end and the reader blocks or is notified if there isn t any data to read...
And yes, there is no special EOF marker. If using normal files and you don t like headaches much, just don t mess with them simultaneously from multiple processes.

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