Utils: Renaming files across devices

util/io.go

@@ -17,13 +17,37 @@
 package util
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"strings"
+	"syscall"
 )
 
+func MoveFile(src, dst string) error {
+	err := os.Rename(src, dst)
+	var errno syscall.Errno
+	if err != nil && errors.As(err, &errno) && errno == syscall.EXDEV {
+		// os.Rename() failed because src and dst are on different filesystems
+		// Must manually copy and delete the original file
+		return manuallyMoveFile(src, dst)
+	}
+	return err
+}
+
+func manuallyMoveFile(src, dst string) error {
+	tmpDst := dst + ".tmp"
+	if _, err := CopyFile(src, tmpDst); err != nil {
+		return err
+	}
+	if err := os.Rename(tmpDst, dst); err != nil {
+		return err
+	}
+	return os.Remove(src)
+}
+
 // CopyFile uses io.Copy() to copy a file to another location
 // This was copied from https://opensource.com/article/18/6/copying-files-go
 func CopyFile(src, dst string) (int64, error) {

util/io_test.go

@@ -18,16 +18,19 @@ package util
 
 import (
 	"os"
+	"os/exec"
 	"path"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/algorand/go-algorand/test/partitiontest"
 )
 
 func TestIsEmpty(t *testing.T) {
 	partitiontest.PartitionTest(t)
+	t.Parallel()
 
 	testPath := path.Join(os.TempDir(), "this", "is", "a", "long", "path")
 	err := os.MkdirAll(testPath, os.ModePerm)
@@ -39,3 +42,57 @@ func TestIsEmpty(t *testing.T) {
 	assert.NoError(t, err)
 	assert.False(t, IsEmpty(testPath))
 }
+
+func testMoveFile(t *testing.T, src, dst string) {
+	t.Helper()
+
+	require.NoFileExists(t, src)
+	require.NoFileExists(t, dst)
+
+	defer os.Remove(src)
+	defer os.Remove(dst)
+
+	f, err := os.Create(src)
+	require.NoError(t, err)
+
+	_, err = f.WriteString("test file contents")
+	require.NoError(t, err)
+	require.NoError(t, f.Close())
+
+	err = MoveFile(src, dst)
+	require.NoError(t, err)
+
+	require.FileExists(t, dst)
+	require.NoFileExists(t, src)
+
+	dstContents, err := os.ReadFile(dst)
+	require.NoError(t, err)
+	assert.Equal(t, "test file contents", string(dstContents))
+}
+
+func TestMoveFile(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+
+	src := path.Join(os.TempDir(), "src.txt")
+	dst := path.Join(os.TempDir(), "dst.txt")
+	testMoveFile(t, src, dst)
+}
+
+func TestMoveFileAcrossFilesystems(t *testing.T) {
+	partitiontest.PartitionTest(t)
+
+	t.Skip("This is a manual test that must be run on a linux system")
+
+	os.Mkdir("/mnt/tmpfs", os.ModePerm)
+	defer os.Remove("/mnt/tmpfs")
+
+	err := exec.Command("mount", "-t", "tmpfs", "-o", "size=1K", "tmpfs", "/mnt/tmpfs").Run()
+	require.NoError(t, err)
+	defer exec.Command("umount", "/mnt/tmpfs").Run()
+
+	src := path.Join(os.TempDir(), "src.txt")
+	dst := path.Join("/mnt/tmpfs", "dst.txt")
+
+	testMoveFile(t, src, dst)
+}