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rclone/lib/file/preallocate_windows.go

106 lines
2.7 KiB
Go

//go:build windows
package file
import (
"fmt"
"os"
"sync"
"syscall"
"unsafe"
"golang.org/x/sys/windows"
)
var (
ntdll = windows.NewLazySystemDLL("ntdll.dll")
ntQueryVolumeInformationFile = ntdll.NewProc("NtQueryVolumeInformationFile")
ntSetInformationFile = ntdll.NewProc("NtSetInformationFile")
preAllocateMu sync.Mutex
)
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
}
preAllocateMu.Lock()
defer preAllocateMu.Unlock()
var (
iosb ioStatusBlock
fsSizeInfo fileFsSizeInformation
allocInfo fileAllocationInformation
)
// Query info about the block sizes on the file system
_, _, e1 := ntQueryVolumeInformationFile.Call(
out.Fd(),
uintptr(unsafe.Pointer(&iosb)),
uintptr(unsafe.Pointer(&fsSizeInfo)),
unsafe.Sizeof(fsSizeInfo),
uintptr(3), // FileFsSizeInformation
)
if e1 != nil && e1 != syscall.Errno(0) {
return fmt.Errorf("preAllocate NtQueryVolumeInformationFile failed: %w", e1)
}
// Calculate the allocation size
clusterSize := uint64(fsSizeInfo.BytesPerSector) * uint64(fsSizeInfo.SectorsPerAllocationUnit)
if clusterSize <= 0 {
return fmt.Errorf("preAllocate clusterSize %d <= 0", clusterSize)
}
allocInfo.AllocationSize = (1 + uint64(size-1)/clusterSize) * clusterSize
// Ask for the allocation
_, _, e1 = ntSetInformationFile.Call(
out.Fd(),
uintptr(unsafe.Pointer(&iosb)),
uintptr(unsafe.Pointer(&allocInfo)),
unsafe.Sizeof(allocInfo),
uintptr(19), // FileAllocationInformation
)
if e1 != nil && e1 != syscall.Errno(0) {
if e1 == windows.ERROR_DISK_FULL || e1 == windows.ERROR_HANDLE_DISK_FULL {
return ErrDiskFull
}
return fmt.Errorf("preAllocate NtSetInformationFile failed: %w", e1)
}
return nil
}
// 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()), windows.FSCTL_SET_SPARSE, nil, 0, nil, 0, &bytesReturned, nil)
if err != nil {
return fmt.Errorf("DeviceIoControl FSCTL_SET_SPARSE: %w", err)
}
return nil
}