rclone/lib/file/preallocate_windows.go
Nick Craig-Wood c4110780bf lib/file: fix SetSparse on Windows 7 which fixes downloads of files > 250MB
Before this change we passed both lpOverlapped and lpBytesReturned as NULL.

> If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when
> an operation produces no output data, and lpOutBuffer can be NULL,
> the DeviceIoControl function makes use of the variable pointed to by
> lpBytesReturned. After such an operation, the value of the variable
> is without meaning.

After this change we set lpBytesReturned to a valid pointer.

See: https://forum.rclone.org/t/errors-when-downloading-any-file-over-250mb-from-google-drive-windows-sparse-files/16889
2020-06-06 13:13:15 +01:00

102 lines
2.6 KiB
Go

//+build windows
package file
import (
"os"
"syscall"
"unsafe"
"github.com/pkg/errors"
"golang.org/x/sys/windows"
)
var (
ntdll = windows.NewLazySystemDLL("ntdll.dll")
ntQueryVolumeInformationFile = ntdll.NewProc("NtQueryVolumeInformationFile")
ntSetInformationFile = ntdll.NewProc("NtSetInformationFile")
)
type fileAllocationInformation struct {
AllocationSize uint64
}
type fileFsSizeInformation struct {
TotalAllocationUnits uint64
AvailableAllocationUnits uint64
SectorsPerAllocationUnit uint32
BytesPerSector uint32
}
type ioStatusBlock struct {
Status, Information uintptr
}
// PreallocateImplemented is a constant indicating whether the
// implementation of Preallocate actually does anything.
const PreallocateImplemented = true
// PreAllocate the file for performance reasons
func PreAllocate(size int64, out *os.File) error {
if size <= 0 {
return nil
}
var (
iosb ioStatusBlock
fsSizeInfo fileFsSizeInformation
allocInfo fileAllocationInformation
)
// Query info about the block sizes on the file system
_, _, e1 := ntQueryVolumeInformationFile.Call(
uintptr(out.Fd()),
uintptr(unsafe.Pointer(&iosb)),
uintptr(unsafe.Pointer(&fsSizeInfo)),
uintptr(unsafe.Sizeof(fsSizeInfo)),
uintptr(3), // FileFsSizeInformation
)
if e1 != nil && e1 != syscall.Errno(0) {
return errors.Wrap(e1, "preAllocate NtQueryVolumeInformationFile failed")
}
// Calculate the allocation size
clusterSize := uint64(fsSizeInfo.BytesPerSector) * uint64(fsSizeInfo.SectorsPerAllocationUnit)
if clusterSize <= 0 {
return errors.Errorf("preAllocate clusterSize %d <= 0", clusterSize)
}
allocInfo.AllocationSize = (1 + uint64(size-1)/clusterSize) * clusterSize
// Ask for the allocation
_, _, e1 = ntSetInformationFile.Call(
uintptr(out.Fd()),
uintptr(unsafe.Pointer(&iosb)),
uintptr(unsafe.Pointer(&allocInfo)),
uintptr(unsafe.Sizeof(allocInfo)),
uintptr(19), // FileAllocationInformation
)
if e1 != nil && e1 != syscall.Errno(0) {
return errors.Wrap(e1, "preAllocate NtSetInformationFile failed")
}
return nil
}
const (
FSCTL_SET_SPARSE = 0x000900c4
)
// SetSparseImplemented is a constant indicating whether the
// implementation of SetSparse actually does anything.
const SetSparseImplemented = true
// SetSparse makes the file be a sparse file
func SetSparse(out *os.File) error {
var bytesReturned uint32
err := syscall.DeviceIoControl(syscall.Handle(out.Fd()), FSCTL_SET_SPARSE, nil, 0, nil, 0, &bytesReturned, nil)
if err != nil {
return errors.Wrap(err, "DeviceIoControl FSCTL_SET_SPARSE")
}
return nil
}