a492c0fb0e
Before this change rclone didn't use sparse files on Windows. This means that when you downloaded a file with multithread download it wrote the entire file with zeros first on the first write not at the start of the file. This change makes the file be sparse on Windows. Linux/macOS files were already sparse.
93 lines
2.2 KiB
Go
93 lines
2.2 KiB
Go
//+build windows
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package local
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import (
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"os"
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"syscall"
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"unsafe"
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"github.com/pkg/errors"
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"golang.org/x/sys/windows"
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)
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var (
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ntdll = windows.NewLazySystemDLL("ntdll.dll")
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ntQueryVolumeInformationFile = ntdll.NewProc("NtQueryVolumeInformationFile")
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ntSetInformationFile = ntdll.NewProc("NtSetInformationFile")
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)
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type fileAllocationInformation struct {
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AllocationSize uint64
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}
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type fileFsSizeInformation struct {
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TotalAllocationUnits uint64
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AvailableAllocationUnits uint64
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SectorsPerAllocationUnit uint32
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BytesPerSector uint32
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}
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type ioStatusBlock struct {
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Status, Information uintptr
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}
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// preAllocate the file for performance reasons
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func preAllocate(size int64, out *os.File) error {
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if size <= 0 {
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return nil
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}
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var (
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iosb ioStatusBlock
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fsSizeInfo fileFsSizeInformation
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allocInfo fileAllocationInformation
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)
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// Query info about the block sizes on the file system
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_, _, e1 := ntQueryVolumeInformationFile.Call(
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uintptr(out.Fd()),
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uintptr(unsafe.Pointer(&iosb)),
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uintptr(unsafe.Pointer(&fsSizeInfo)),
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uintptr(unsafe.Sizeof(fsSizeInfo)),
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uintptr(3), // FileFsSizeInformation
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)
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if e1 != nil && e1 != syscall.Errno(0) {
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return errors.Wrap(e1, "preAllocate NtQueryVolumeInformationFile failed")
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}
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// Calculate the allocation size
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clusterSize := uint64(fsSizeInfo.BytesPerSector) * uint64(fsSizeInfo.SectorsPerAllocationUnit)
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if clusterSize <= 0 {
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return errors.Errorf("preAllocate clusterSize %d <= 0", clusterSize)
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}
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allocInfo.AllocationSize = (1 + uint64(size-1)/clusterSize) * clusterSize
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// Ask for the allocation
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_, _, e1 = ntSetInformationFile.Call(
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uintptr(out.Fd()),
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uintptr(unsafe.Pointer(&iosb)),
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uintptr(unsafe.Pointer(&allocInfo)),
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uintptr(unsafe.Sizeof(allocInfo)),
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uintptr(19), // FileAllocationInformation
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)
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if e1 != nil && e1 != syscall.Errno(0) {
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return errors.Wrap(e1, "preAllocate NtSetInformationFile failed")
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}
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return nil
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}
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const (
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FSCTL_SET_SPARSE = 0x000900c4
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)
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// setSparse makes the file be a sparse file
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func setSparse(out *os.File) error {
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err := syscall.DeviceIoControl(syscall.Handle(out.Fd()), FSCTL_SET_SPARSE, nil, 0, nil, 0, nil, nil)
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if err != nil {
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return errors.Wrap(err, "DeviceIoControl FSCTL_SET_SPARSE")
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}
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return nil
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}
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