1# This file is part of Xpra. 

2# Copyright (C) 2017-2020 Antoine Martin <antoine@xpra.org> 

3# Xpra is released under the terms of the GNU GPL v2, or, at your option, any 

4# later version. See the file COPYING for details. 

5 

6import os 

7 

8from xpra.log import Logger 

9from xpra.os_util import monotonic_time, POSIX 

10from xpra.util import envint 

11 

12DISPLAY_FD_TIMEOUT = envint("XPRA_DISPLAY_FD_TIMEOUT", 20) 

13 

14 

15def write_displayfd(w_pipe, display, timeout=10): 

16 import select #@UnresolvedImport 

17 import errno 

18 buf = ("%s\n" % display).encode("ascii") 

19 limit = monotonic_time()+timeout 

20 log = Logger("util") 

21 log("write_displayfd%s", (w_pipe, display, timeout)) 

22 while buf and monotonic_time()<limit: 

23 try: 

24 timeout = max(0, limit-monotonic_time()) 

25 if POSIX: 

26 w = select.select([], [w_pipe], [], timeout)[1] 

27 log("select.select(..) writeable=%s", w) 

28 else: 

29 w = [w_pipe] 

30 if w_pipe in w: 

31 count = os.write(w_pipe, buf) 

32 buf = buf[count:] 

33 log("wrote %i bytes, remains %s", count, buf) 

34 except (select.error, OSError) as e: 

35 if e.errno!=errno.EINTR: 

36 raise 

37 if not buf: 

38 try: 

39 os.fsync(w_pipe) 

40 except OSError: 

41 log("os.fsync(%i)", w_pipe, exc_info=True) 

42 if w_pipe>2: 

43 try: 

44 os.close(w_pipe) 

45 except OSError: 

46 log("os.close(%i)", w_pipe, exc_info=True) 

47 return len(buf)==0 

48 

49def read_displayfd(r_pipe, timeout=DISPLAY_FD_TIMEOUT, proc=None): 

50 import select #@UnresolvedImport 

51 import errno 

52 # Read the display number from the pipe we gave to Xvfb 

53 # waiting up to 10 seconds for it to show up 

54 limit = monotonic_time()+timeout 

55 buf = b"" 

56 log = Logger("util") 

57 log("read_displayfd%s", (r_pipe, timeout, proc)) 

58 while monotonic_time()<limit and len(buf)<8 and (proc is None or proc.poll() is None): 

59 try: 

60 timeout = max(0, limit-monotonic_time()) 

61 if POSIX: 

62 r = select.select([r_pipe], [], [], timeout)[0] 

63 log("readable=%s", r) 

64 else: 

65 r = [r_pipe] 

66 if r_pipe in r: 

67 v = os.read(r_pipe, 8) 

68 buf += v 

69 log("read=%s", v) 

70 if buf and (buf.endswith(b'\n') or len(buf)>=8): 

71 break 

72 except (select.error, OSError) as e: 

73 if e.errno!=errno.EINTR: 

74 raise 

75 return buf 

76 

77def parse_displayfd(buf, err): 

78 if not buf: 

79 err("did not provide a display number using displayfd") 

80 return None 

81 if not buf.endswith(b"\n"): 

82 err("output not terminated by newline: '%s'" % buf) 

83 return None 

84 buf = buf.rstrip(b"\n\r") 

85 try: 

86 n = int(buf) 

87 except ValueError: 

88 err("display number is not a valid number: %s" % buf) 

89 if n<0 or n>=2**16: 

90 err("provided an invalid display number: %s" % n) 

91 return n