Get file inode in Go

Question

How can I get a file inode in Go?

I already can print it like this:

file := "/tmp/system.log"
fileinfo, _ := os.Stat(file)
fmt.Println(fileinfo.Sys())
fmt.Println(fileinfo)

Looking at Go implementation it was obvious looking for some stat method, but I still did not manage to find the structure definition for a Unix system.

How can I get the inode value directly?

Which file/s in the source code define the structure of Sys()?

Answer 1

You can use a type assertion to get the underlying syscall.Stat_t from the fileinfo like this

package main

import (
    "fmt"
    "os"
    "syscall"
)

func main() {
    file := "/etc/passwd"
    fileinfo, _ := os.Stat(file)
    fmt.Printf("fileinfo.Sys() = %#v\n", fileinfo.Sys())
    fmt.Printf("fileinfo = %#v\n", fileinfo)
    stat, ok := fileinfo.Sys().(*syscall.Stat_t)
    if !ok {
        fmt.Printf("Not a syscall.Stat_t")
        return
    }
    fmt.Printf("stat = %#v\n", stat)
    fmt.Printf("stat.Ino = %#v\n", stat.Ino)
}

Answer 2

You can do the following:

file := "/tmp/system.log"
var stat syscall.Stat_t
if err := syscall.Stat(file, &stat); err != nil {
    panic(err)
}
fmt.Println(stat.Ino)

Where stat.Ino is the inode you are looking for.