Is possible opening stdin after close(0)?

Question

I have one question,studying standard I/O.

    #include <stdio.h>
    int main(){
    void *mem = malloc(0x80);
    close(0)
     /*
      something code (solution)
   */
    read(0,mem,0x80);
    }

with above code, Is possible opening stdin ? before ask question on stackoverflow, i thought that open('/dev/tty'); . but it not seem to completely open stdin. i hope that do not use dup()

Imagine that `stdin_fileno` is actually the FD of a file on disk, and it's the last such FD. Once you close it, the file may be deleted. So you definitely have no way in principle to restore a closed FD that points to the same file. You could reopen FD 0 to a *new* file of course. — Kerrek SB, Jan 26 '17 at 15:26
@BasileStarynkevitch i want to know actual principle of creating stdin. — 오우진, Jan 26 '17 at 16:09
@오우진: You don't. The FDs come already open. The parent process usually provides them. — Kerrek SB, Jan 26 '17 at 16:59

score 1 · Answer 1 · answered Jan 26 '17 at 15:20

1

In my view, the ideal way to achieve this would be

use dup() to create a backup fd.
close() the stdin.
perform the operations
restore stdin using the dup2() and passing the previous backup fd.

answered Jan 26 '17 at 15:20

Sourav Ghosh

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Isn't there another way? If possible , It would be good to do not use dup() – 오우진 Jan 26 '17 at 15:25

Is possible opening stdin after close(0)?

1 Answers1