| 1 | package rootstate |
| 2 | |
| 3 | import ( |
| 4 | "os" |
| 5 | |
| 6 | "github.com/carlosframework/platform/internal/safefile" |
| 7 | "golang.org/x/sys/unix" |
| 8 | ) |
| 9 | |
| 10 | func (d *directory) liveFile(name string, create bool) (*os.File, error) { |
| 11 | if !component(name) || uint32(os.Geteuid()) != d.owner { |
| 12 | return nil, os.ErrPermission |
| 13 | } |
| 14 | if err := d.check(); err != nil { |
| 15 | return nil, err |
| 16 | } |
| 17 | flags := os.O_RDWR |
| 18 | if create { |
| 19 | flags |= os.O_CREATE |
| 20 | } |
| 21 | f, err := safefile.OpenFileAt(int(d.file.Fd()), name, flags, 0600) |
| 22 | if err != nil { |
| 23 | return nil, err |
| 24 | } |
| 25 | if err := trusted(int(f.Fd()), d.owner, unix.S_IFREG); err != nil { |
| 26 | f.Close() |
| 27 | return nil, err |
| 28 | } |
| 29 | return f, nil |
| 30 | } |
| 31 | |
| 32 | func (d *directory) HoldLive(name string) (func(), error) { |
| 33 | f, err := d.liveFile(name, true) |
| 34 | if err != nil { |
| 35 | return nil, err |
| 36 | } |
| 37 | lock := unix.Flock_t{Type: unix.F_WRLCK, Whence: 0} |
| 38 | if err := unix.FcntlFlock(f.Fd(), unix.F_OFD_SETLK, &lock); err != nil { |
| 39 | f.Close() |
| 40 | return nil, err |
| 41 | } |
| 42 | return func() { _ = f.Close() }, nil |
| 43 | } |
| 44 | |
| 45 | func (d *directory) LiveHeld(name string) (bool, error) { |
| 46 | f, err := d.liveFile(name, false) |
| 47 | if err != nil { |
| 48 | return false, err |
| 49 | } |
| 50 | defer f.Close() |
| 51 | lock := unix.Flock_t{Type: unix.F_RDLCK, Whence: 0} |
| 52 | if err := unix.FcntlFlock(f.Fd(), unix.F_OFD_GETLK, &lock); err != nil { |
| 53 | return false, err |
| 54 | } |
| 55 | return lock.Type == unix.F_WRLCK && lock.Pid == -1, nil |
| 56 | } |
| 57 | |
amadan