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package syscallcompat
import (
"os"
"sync"
"syscall"
)
// prealloc - preallocate space without changing the file size. This prevents
// us from running out of space in the middle of an operation.
func Prealloc(fd int, off int64, len int64) (err error) {
//
// Sorry, fallocate is not available on OSX at all and
// fcntl F_PREALLOCATE is not accessible from Go.
//
// See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
return nil
}
var openatLock sync.Mutex
// Poor man's Openat:
// 1) fchdir to the dirfd
// 2) open the file
// 3) chdir back.
func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
openatLock.Lock()
defer openatLock.Unlock()
oldWd, err := os.Getwd()
if err != nil {
return -1, err
}
err = syscall.Fchdir(dirfd)
if err != nil {
return -1, err
}
defer os.Chdir(oldWd)
return syscall.Open(path, flags, mode)
}
func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
return syscall.EOPNOTSUPP
}
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