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utils.go
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utils.go
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package tilemap
import (
"errors"
"fmt"
"os"
"syscall"
"unsafe"
)
const (
setFlags = uintptr(0x40086602)
getFlags = uintptr(0x40086601)
NO_COMP uint32 = 0x00000400
COMP uint32 = 0x00000004
NO_COW uint32 = 0x00800000
)
var (
sipkey1 uint64 = 0xDEADBEEFFEEDFEBE
sipkey2 uint64 = 0x0123456789ABCDEF
)
type es struct{}
type controlFunc func(fd uintptr) error
func rawFdCall(fio *os.File, cf controlFunc) error {
if fio == nil || cf == nil {
return errors.New("invalid parameters")
}
rc, err := fio.SyscallConn()
if err != nil {
return err
}
rc.Control(func(fd uintptr) {
err = cf(fd)
})
return err
}
func safeFallocate(fio *os.File, oldsz, newsz int64) (err error) {
//attempt to use syscall.Fallocate
err = rawFdCall(fio, func(fd uintptr) (lerr error) {
if errno := syscall.Fallocate(int(fd), 0, oldsz, newsz); errno != nil {
if errno == syscall.ENOTSUP || errno == syscall.EOPNOTSUPP {
lerr = slowFileAllocate(fio, oldsz, newsz)
} else {
lerr = fmt.Errorf("Failed to perform fallocate: %v", errno)
}
}
return
})
return
}
func slowFileAllocate(fio *os.File, oldsz, newsz int64) error {
if newsz <= oldsz {
return nil
}
buffsize := 64 * 1024
toWrite := newsz - oldsz
buff := make([]byte, buffsize)
ptr := oldsz
for toWrite > 0 {
if toWrite < int64(len(buff)) {
buff = buff[0:toWrite]
}
n, err := fio.WriteAt(buff, ptr)
if err != nil {
return err
}
ptr += int64(n)
toWrite -= int64(n)
}
return nil
}
func setAttr(f *os.File, attr uint32) (err error) {
err = rawFdCall(f, func(fd uintptr) error {
if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, fd, setFlags, uintptr(unsafe.Pointer(&attr))); errno != 0 {
return os.NewSyscallError("IOCTL", errno)
}
return nil
})
return
}
func getAttr(f *os.File) (attr uint32, err error) {
err = rawFdCall(f, func(fd uintptr) error {
if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, fd, getFlags, uintptr(unsafe.Pointer(&attr))); errno != 0 {
return os.NewSyscallError("IOCTL", errno)
}
return nil
})
return
}