Add lib/diskusage to measure used/free on disks

lib/diskusage/diskusage.go

@@ -0,0 +1,15 @@
+// Package diskusage provides a cross platform version of the statfs
+// system call to read disk space usage.
+package diskusage
+
+import "errors"
+
+// Info is returned from New showing details about the disk.
+type Info struct {
+	Free      uint64 // total free bytes
+	Available uint64 // free bytes available to the current user
+	Total     uint64 // total bytes on disk
+}
+
+// ErrUnsupported is returned if this platform doesn't support disk usage.
+var ErrUnsupported = errors.New("disk usage unsupported on this platform")

lib/diskusage/diskusage_netbsd.go

@@ -0,0 +1,27 @@
+//go:build netbsd
+
+package diskusage
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// New returns the disk status for dir.
+//
+// May return Unsupported error if it doesn't work on this platform.
+func New(dir string) (info Info, err error) {
+	var statfs unix.Statvfs_t
+	err = unix.Statvfs(dir, &statfs)
+	if err != nil {
+		return info, err
+	}
+	// Note that these can be different sizes on different OSes so
+	// we upcast them all to uint64
+	//nolint:unconvert
+	info.Free = uint64(statfs.Bfree) * uint64(statfs.Bsize)
+	//nolint:unconvert
+	info.Available = uint64(statfs.Bavail) * uint64(statfs.Bsize)
+	//nolint:unconvert
+	info.Total = uint64(statfs.Blocks) * uint64(statfs.Bsize)
+	return info, nil
+}

lib/diskusage/diskusage_openbsd.go

@@ -0,0 +1,27 @@
+//go:build openbsd
+
+package diskusage
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// New returns the disk status for dir.
+//
+// May return Unsupported error if it doesn't work on this platform.
+func New(dir string) (info Info, err error) {
+	var statfs unix.Statfs_t
+	err = unix.Statfs(dir, &statfs)
+	if err != nil {
+		return info, err
+	}
+	// Note that these can be different sizes on different OSes so
+	// we upcast them all to uint64
+	//nolint:unconvert
+	info.Free = uint64(statfs.F_bfree) * uint64(statfs.F_bsize)
+	//nolint:unconvert
+	info.Available = uint64(statfs.F_bavail) * uint64(statfs.F_bsize)
+	//nolint:unconvert
+	info.Total = uint64(statfs.F_blocks) * uint64(statfs.F_bsize)
+	return info, nil
+}

lib/diskusage/diskusage_test.go

@@ -0,0 +1,23 @@
+package diskusage
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNew(t *testing.T) {
+	info, err := New(".")
+	if err == ErrUnsupported {
+		t.Skip(err)
+	}
+	require.NoError(t, err)
+	t.Logf("Free      %16d", info.Free)
+	t.Logf("Available %16d", info.Available)
+	t.Logf("Total     %16d", info.Total)
+	assert.True(t, info.Total != 0)
+	assert.True(t, info.Total > info.Free)
+	assert.True(t, info.Total > info.Available)
+	assert.True(t, info.Free >= info.Available)
+}

lib/diskusage/diskusage_unix.go

@@ -0,0 +1,27 @@
+//go:build aix || android || darwin || dragonfly || freebsd || ios || linux
+
+package diskusage
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// New returns the disk status for dir.
+//
+// May return Unsupported error if it doesn't work on this platform.
+func New(dir string) (info Info, err error) {
+	var statfs unix.Statfs_t
+	err = unix.Statfs(dir, &statfs)
+	if err != nil {
+		return info, err
+	}
+	// Note that these can be different sizes on different OSes so
+	// we upcast them all to uint64
+	//nolint:unconvert
+	info.Free = uint64(statfs.Bfree) * uint64(statfs.Bsize)
+	//nolint:unconvert
+	info.Available = uint64(statfs.Bavail) * uint64(statfs.Bsize)
+	//nolint:unconvert
+	info.Total = uint64(statfs.Blocks) * uint64(statfs.Bsize)
+	return info, nil
+}

lib/diskusage/diskusage_unsupported.go

@@ -0,0 +1,10 @@
+//go:build illumos || js || plan9 || solaris
+
+package diskusage
+
+// New returns the disk status for dir.
+//
+// May return Unsupported error if it doesn't work on this platform.
+func New(dir string) (info Info, err error) {
+	return info, ErrUnsupported
+}

lib/diskusage/diskusage_windows.go

@@ -0,0 +1,16 @@
+//go:build windows
+
+package diskusage
+
+import (
+	"golang.org/x/sys/windows"
+)
+
+// New returns the disk status for dir.
+//
+// May return Unsupported error if it doesn't work on this platform.
+func New(dir string) (info Info, err error) {
+	dir16 := windows.StringToUTF16Ptr(dir)
+	err = windows.GetDiskFreeSpaceEx(dir16, &info.Available, &info.Total, &info.Free)
+	return info, err
+}