Get amount of free disk space using Go

Question

Basically I want the output of df -h, which includes both the free space and the total size of the volume. The solution needs to work on Windows, Linux, and Mac and be written in Go.

I have looked through the os and syscall Go documentation and haven't found anything. On Windows, even command line utils are either awkward (dir C:\) or need elevated privileges (fsutil volume diskfree C:\). Surely there is a way to do this that I haven't found yet...

UPDATE:
Per nemo's answer and invitation, I have provided a cross-platform Go package that does this.

Answer 1

On POSIX systems you can use sys.unix.Statfs.
Example of printing free space in bytes of current working directory:

import "golang.org/x/sys/unix" import "os"  var stat unix.Statfs_t  wd, err := os.Getwd()  unix.Statfs(wd, &stat)  // Available blocks * size per block = available space in bytes fmt.Println(stat.Bavail * uint64(stat.Bsize)) 

For Windows you need to go the syscall route as well. Example (source, updated to match new sys/windows package):

import "golang.org/x/sys/windows"  h := windows.MustLoadDLL("kernel32.dll") c := h.MustFindProc("GetDiskFreeSpaceExW")  var freeBytes int64  _, _, err := c.Call(uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(wd))),     uintptr(unsafe.Pointer(&freeBytes)), nil, nil) 

Feel free to write a package that provides the functionality cross-platform. On how to implement something cross-platform, see the build tool help page.

Answer 2

Minio has a package (GoDoc) to show disk usage that is cross platform, and seems to be well maintained:

import (
        "github.com/minio/minio/pkg/disk"
        humanize "github.com/dustin/go-humanize"
)

func printUsage(path string) error {
        di, err := disk.GetInfo(path)
        if err != nil {
            return err
        }
        percentage := (float64(di.Total-di.Free)/float64(di.Total))*100
        fmt.Printf("%s of %s disk space used (%0.2f%%)\n", 
            humanize.Bytes(di.Total-di.Free), 
            humanize.Bytes(di.Total), 
            percentage,
        )
}