[go-nuts] Linux File descriptor question in golang

[Homer Li]

Could I get file path from the file descriptor number ? 

OS : Linux

How to write in golang ?

Thanks.

--

Best Regards
Homer Li

[Konstantin Khomoutov]

On Thu, 21 Jul 2016 18:02:53 +0800
Homer Li <01ja...@gmail.com> wrote:

> Could I get file path from the file descriptor number ?
> OS : Linux
> How to write in golang ?

I'm afraid, you can't.

But as usually in such cases, I have an imminent question: what initial
problem are you trying to solve?

[Alex Bligh]

> On 21 Jul 2016, at 11:02, Homer Li <01ja...@gmail.com> wrote:
>
> Could I get file path from the file descriptor number ?
> OS : Linux
> How to write in golang ?

On Linux (and indeed most if not all POSIX like systems)
one cannot get a file path from the file descriptor number.
This is irrespective of programming language used.

Consider what happens if you open a file, then unlink it.
Or open it then rename it. Or open a file with multiple links
to it. Etc.

--
Alex Bligh

[Peter Waller]

On 21 July 2016 at 12:37, Alex Bligh <al...@alex.org.uk> wrote:

On Linux (and indeed most if not all POSIX like systems)
one cannot get a file path from the file descriptor number.
This is irrespective of programming language used.

While your statement is true generally, it is actually possible so long as the file descriptor refers to an existing file. Consider:

$ fd2path < main.go 

/home/pwaller/.local/src/github.com/pwaller/fd2path/main.go

Code:

package main

import (

"fmt"

"log"

"os"

)

func main() {

fd := os.Stdin.Fd()

fileName, err := os.Readlink(fmt.Sprint("/proc/self/fd/", fd))

if err != nil {

log.Fatal(err)

}

fmt.Println(fileName)

}