package syscallcompat import ( "sync" "syscall" "github.com/rfjakob/gocryptfs/internal/tlog" ) const FALLOC_FL_KEEP_SIZE = 0x01 var preallocWarn sync.Once // EnospcPrealloc preallocates ciphertext space without changing the file // size. This guarantees that we don't run out of space while writing a // ciphertext block (that would corrupt the block). func EnospcPrealloc(fd int, off int64, len int64) (err error) { for { err = syscall.Fallocate(fd, FALLOC_FL_KEEP_SIZE, off, len) if err == syscall.EINTR { // fallocate, like many syscalls, can return EINTR. This is not an // error and just signifies that the operation was interrupted by a // signal and we should try again. continue } if err == syscall.EOPNOTSUPP { // ZFS and ext3 do not support fallocate. Warn but continue anyway. // https://github.com/rfjakob/gocryptfs/issues/22 preallocWarn.Do(func() { tlog.Warn.Printf("Warning: The underlying filesystem " + "does not support fallocate(2). gocryptfs will continue working " + "but is no longer resistant against out-of-space errors.\n") }) return nil } return err } } func Fallocate(fd int, mode uint32, off int64, len int64) (err error) { return syscall.Fallocate(fd, mode, off, len) } func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) { return syscall.Openat(dirfd, path, flags, mode) } func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error) { return syscall.Renameat(olddirfd, oldpath, newdirfd, newpath) }