How to find the mountpoint a file resides on?

Question

For example, I\'ve got a file with the following path:

/media/my_mountpoint/path/to/file.txt

I\'ve got the whole path and want to get:

Answer 1

@larsmans Very good answer, this was very helpfull! I have implemented this in Golang where I needed it.

For people who are interested in the code (this has been tested for OS X and Linux):

package main

import (
    "os"
    "fmt"
    "syscall"
    "path/filepath"
)

func Mountpoint(path string) string {
    pi, err := os.Stat(path)
    if err != nil {
        return ""
    }

    odev := pi.Sys().(*syscall.Stat_t).Dev

    for path != "/" {
        _path := filepath.Dir(path)

        in, err := os.Stat(_path)
        if err != nil {
            return ""
        }

        if odev != in.Sys().(*syscall.Stat_t).Dev {
            break
        }

        path = _path
    }

    return path
}

func main() {
    path, _ := filepath.Abs("./")
    dir := filepath.Dir(path)
    fmt.Println("Path", path)
    fmt.Println("Dir", dir)
    fmt.Println("Mountpoint", Mountpoint(path))
}