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aafe56cd6f
* feat(snapshots): support restoring sparse files This commit implements basic support for restoring sparse files from a snapshot. When specifying "--mode=sparse" in a snapshot restore command, Kopia will make a best effort to make sure the underlying filesystem allocates the minimum amount of blocks needed to persist restored files. In other words, enabling this feature will "force" all restored files to be sparse-blocks of zero bytes in the source file should not be allocated. * Address review comments - Separate sparse option into its own bool flag - Implement sparsefile packagewith copySparse method - Truncate once before writing sparse file - Check error from Truncate - Add unit test for copySparse - Invoke GetBlockSize once per file copy - Remove support for Windows and explain why - Add unit test for stat package Co-authored-by: Dave Smith-Uchida <dave@kasten.io>
99 lines
1.5 KiB
Go
99 lines
1.5 KiB
Go
package sparsefile
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import (
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"bytes"
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"os"
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"path/filepath"
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"runtime"
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"testing"
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"github.com/kopia/kopia/internal/stat"
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)
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func TestSparseWrite(t *testing.T) {
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t.Parallel()
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if runtime.GOOS == "windows" {
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t.Skip("sparse files are not supported on windows")
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}
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dir := t.TempDir()
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blk, err := stat.GetBlockSize(dir)
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if err != nil {
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t.Fatal(err)
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}
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type chunk struct {
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slice []byte
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off uint64
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rep uint64
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}
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cases := []struct {
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name string
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size uint64
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data []chunk
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}{
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{
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name: "null",
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size: 0,
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},
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{
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name: "empty",
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size: blk,
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data: []chunk{
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{slice: []byte{0}, off: 0, rep: blk},
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},
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},
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{
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name: "hole",
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size: 2 * blk,
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data: []chunk{
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{slice: []byte{1}, off: blk, rep: blk},
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},
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},
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{
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name: "mix",
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size: 2 * blk,
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data: []chunk{
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{slice: []byte{1}, off: 3, rep: blk - 10},
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{slice: []byte{1}, off: 2*blk - 10, rep: 10},
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},
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},
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}
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for _, c := range cases {
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src := filepath.Join(dir, "src"+c.name)
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dst := filepath.Join(dir, "dst"+c.name)
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fd, err := os.Create(src)
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if err != nil {
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t.Fatal(err)
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}
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for _, d := range c.data {
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fd.WriteAt(bytes.Repeat(d.slice, int(d.rep)), int64(d.off))
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}
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err = Write(dst, fd, int64(c.size))
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if err != nil {
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t.Fatalf("error writing %s: %v", dst, err)
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}
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s, err := os.ReadFile(src)
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if err != nil {
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t.Fatal(err)
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}
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d, err := os.ReadFile(dst)
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if err != nil {
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t.Fatal(err)
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}
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if !bytes.Equal(s, d) {
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t.Fatalf("contents of %s and %s are not identical", src, dst)
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}
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}
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}
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