117 lines
1.9 KiB
Go
117 lines
1.9 KiB
Go
package controllers
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import (
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"os"
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"syscall"
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"unsafe"
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)
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// See https://github.com/benmcclelland/mtio
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const (
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mtioCpos = 0x80086d03 // Get tape position
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mtioCtop = 0x40086d01 // Do magnetic tape operation
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mtFsf = 1 // Forward space over FileMark, position at first record of next file
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mtOffl = 7 // Rewind and put the drive offline (eject?)
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mtEom = 12 // Goto end of recorded media (for appending files)
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mtSeek = 22 // Seek to block
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BlockSize = 512
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)
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// position is struct for MTIOCPOS
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type position struct {
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blkNo int64 // Current block number
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}
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// operation is struct for MTIOCTOP
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type operation struct {
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op int16 // Operation ID
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pad int16 // Padding to match C structures
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count int32 // Operation count
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}
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func GoToEndOfTape(f *os.File) error {
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if _, _, err := syscall.Syscall(
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syscall.SYS_IOCTL,
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f.Fd(),
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mtioCtop,
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uintptr(unsafe.Pointer(
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&operation{
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op: mtEom,
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},
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)),
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); err != 0 {
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return err
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}
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return nil
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}
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func GoToNextFileOnTape(f *os.File) error {
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if _, _, err := syscall.Syscall(
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syscall.SYS_IOCTL,
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f.Fd(),
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mtioCtop,
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uintptr(unsafe.Pointer(
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&operation{
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op: mtFsf,
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count: 1,
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},
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)),
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); err != 0 {
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return err
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}
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return nil
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}
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func GetCurrentRecordFromTape(f *os.File) (int64, error) {
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pos := &position{}
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if _, _, err := syscall.Syscall(
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syscall.SYS_IOCTL,
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f.Fd(),
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mtioCpos,
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uintptr(unsafe.Pointer(pos)),
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); err != 0 {
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return 0, err
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}
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return pos.blkNo, nil
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}
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func SeekToRecordOnTape(f *os.File, record int32) error {
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if _, _, err := syscall.Syscall(
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syscall.SYS_IOCTL,
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f.Fd(),
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mtioCtop,
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uintptr(unsafe.Pointer(
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&operation{
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op: mtSeek,
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count: record,
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},
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)),
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); err != 0 {
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return err
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}
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return nil
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}
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func EjectTape(f *os.File) error {
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if _, _, err := syscall.Syscall(
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syscall.SYS_IOCTL,
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f.Fd(),
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mtioCtop,
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uintptr(unsafe.Pointer(
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&operation{
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op: mtOffl,
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},
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)),
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); err != 0 {
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return err
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}
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return nil
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}
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