3 from bup import options, helpers
8 This command is run automatically by 'bup on'
10 o = options.Options(optspec)
11 (opt, flags, extra) = o.parse(sys.argv[1:])
13 o.fatal('no arguments expected')
15 # get the subcommand's argv.
16 # Normally we could just pass this on the command line, but since we'll often
17 # be getting called on the other end of an ssh pipe, which tends to mangle
18 # argv (by sending it via the shell), this way is much safer.
19 buf = sys.stdin.read(4)
20 sz = struct.unpack('!I', buf)[0]
23 buf = sys.stdin.read(sz)
24 assert(len(buf) == sz)
25 argv = buf.split('\0')
26 argv = [argv[0], 'mux', '--'] + argv
28 # stdin/stdout are supposedly connected to 'bup server' that the caller
29 # started for us (often on the other end of an ssh tunnel), so we don't want
30 # to misuse them. Move them out of the way, then replace stdout with
31 # a pointer to stderr in case our subcommand wants to do something with it.
33 # It might be nice to do the same with stdin, but my experiments showed that
34 # ssh seems to make its child's stderr a readable-but-never-reads-anything
35 # socket. They really should have used shutdown(SHUT_WR) on the other end
36 # of it, but probably didn't. Anyway, it's too messy, so let's just make sure
37 # anyone reading from stdin is disappointed.
39 # (You can't just leave stdin/stdout "not open" by closing the file
40 # descriptors. Then the next file that opens is automatically assigned 0 or 1,
41 # and people *trying* to read/write stdin/stdout get screwed.)
45 fd = os.open('/dev/null', os.O_RDONLY)
49 os.environ['BUP_SERVER_REVERSE'] = helpers.hostname()
50 os.execvp(argv[0], argv)