Get amount of free disk space using Go

go diskspace
Rick Smith picture Rick Smith · Nov 20, 2013 · Viewed 16.6k times · Source

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

nemo picture nemo · Nov 21, 2013

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.

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