mirror of
https://github.com/dennwc/btrfs
synced 2025-01-10 00:59:23 +00:00
b300237e77
* better code generator * regenerate btrfs_tree.h constants * implement subvolume create, delete and snapshot create commands * exec-based snapshot send and receive
83 lines
1.4 KiB
Go
83 lines
1.4 KiB
Go
package ioctl
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import (
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"fmt"
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"os"
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"reflect"
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"syscall"
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)
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const (
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nrBits = 8
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typeBits = 8
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sizeBits = 14
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dirBits = 2
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)
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const (
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nrMask = ((1 << nrBits) - 1)
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typeMask = ((1 << typeBits) - 1)
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sizeMask = ((1 << sizeBits) - 1)
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dirMask = ((1 << dirBits) - 1)
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)
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const (
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nrShift = 0
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typeShift = (nrShift + nrBits)
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sizeShift = (typeShift + typeBits)
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dirShift = (sizeShift + sizeBits)
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)
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const (
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None = 0
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Write = 1
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Read = 2
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)
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func IOC(dir, typ, nr, size uintptr) uintptr {
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return (dir << dirShift) |
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(typ << typeShift) |
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(nr << nrShift) |
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(size << sizeShift)
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}
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func IO(typ, nr uintptr) uintptr {
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return IOC(None, typ, nr, 0)
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}
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func IOR(typ, nr, size uintptr) uintptr {
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return IOC(Read, typ, nr, size)
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}
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func IOW(typ, nr, size uintptr) uintptr {
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return IOC(Write, typ, nr, size)
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}
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func IOWR(typ, nr, size uintptr) uintptr {
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return IOC(Read|Write, typ, nr, size)
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}
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func Ioctl(f *os.File, ioc uintptr, addr uintptr) error {
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_, _, e := syscall.Syscall(syscall.SYS_IOCTL, f.Fd(), ioc, addr)
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if e != 0 {
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return e
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}
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return nil
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}
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func Do(f *os.File, ioc uintptr, arg interface{}) error {
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var addr uintptr
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if arg != nil {
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v := reflect.ValueOf(arg)
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switch v.Kind() {
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case reflect.Ptr:
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addr = v.Elem().UnsafeAddr()
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case reflect.Slice:
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addr = v.Index(0).UnsafeAddr()
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default:
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return fmt.Errorf("expected ptr or slice, got %T")
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}
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}
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return Ioctl(f, ioc, addr)
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}
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