contrib/barry_freebsd/ptyexec

   1 #!/bin/sh -- # A comment mentioning perl
   2 eval 'exec perl -S $0 ${1+"$@"}'
   3         if 0;
   4 #
   5 # ptyexec: connect the STDIN and STDOUT of some command to a
   6 # pseudo terminal (e.g. /dev/ptyp2 (master) and /dev/ttyp2 (slave))
   7 #
   8 # based on "ssh-ppp" (ppp over secure shell VPN hack)
   9 #
  10 # Usage: ptyexec <command and args to run ...>
  11 #
  12 # Runs the command in background; writes to output what pseudoterminal
  13 # has been connected to it.
  14 #
  15
  16 @cmd = @ARGV;
  17
  18 die "no command" unless @cmd;
  19
  20 # loop over possible pseudoterminals until we can open one:
  21 foreach $m1 ("p" .. "z") {
  22         foreach $m2 ("0".."9", "a".."f") {
  23                 &try("$m1$m2"); # exit takes place in try() on success
  24         }
  25 }
  26 exit 1;
  27
  28 sub try {
  29         my ($dev) = @_;
  30
  31         my $master = "/dev/pty$dev";
  32         my $slave  = "/dev/tty$dev";
  33
  34         # try to open the pseudoterminal read/write:
  35         if ( open(PTY, "+>$master") ) {
  36                 # now fork off a child in background to exec @cmd:
  37                 my $pid = fork();
  38                 die "cannot fork, $!" if ! defined($pid);
  39
  40                 if ( ! $pid ) {
  41                         # child remaps his stdio to the pseudoterm:
  42                         open(STDIN,  "<&PTY") || die "reopen STDIN,  $!";
  43                         open(STDOUT, ">&PTY") || die "reopen STDOUT, $!";
  44                         close(PTY);
  45
  46                         # and then runs the command:
  47                         exec @cmd;
  48                         # exec failed:
  49                         die "exec: " . join(' ', @cmd) . ": $!";
  50                 } else {
  51                         # parent tells the user what we have set up:
  52                         close(PTY);
  53                         sleep 1;
  54                         print STDOUT "PID:$pid\n";
  55                         if ( ! kill 0, $pid ) {
  56                                 # see if the child is still alive:
  57                                 print STDOUT "WARNING: NO CHILD PID\n";
  58                         }
  59                         print STDOUT "MASTER: $master\n";
  60                         print STDOUT "SLAVE:  $slave\n";
  61                         exit 0;
  62                 }
  63         }
  64 }