9 # &open2: tom christiansen, <tchrist@convex.com>
11 # usage: $pid = open2('rdr', 'wtr', 'some cmd and args');
12 # or $pid = open2('rdr', 'wtr', 'some', 'cmd', 'and', 'args');
14 # spawn the given $cmd and connect $rdr for
15 # reading and $wtr for writing. return pid
16 # of child, or 0 on failure.
18 # WARNING: this is dangerous, as you may block forever
19 # unless you are very careful.
21 # $wtr is left unbuffered.
25 # pipe or fork or exec fails
27 $fh = 'FHOPEN000'; # package static in case called more than once
31 local($dad_rdr, $dad_wtr, @cmd) = @_;
33 $dad_rdr ne '' || croak "open2: rdr should not be null";
34 $dad_wtr ne '' || croak "open2: wtr should not be null";
36 # force unqualified filehandles into callers' package
37 local($package) = caller;
38 $dad_rdr =~ s/^[^']+$/$package'$&/;
39 $dad_wtr =~ s/^[^']+$/$package'$&/;
41 local($kid_rdr) = ++$fh;
42 local($kid_wtr) = ++$fh;
44 pipe($dad_rdr, $kid_wtr) || croak "open2: pipe 1 failed: $!";
45 pipe($kid_rdr, $dad_wtr) || croak "open2: pipe 2 failed: $!";
47 if (($kidpid = fork) < 0) {
48 croak "open2: fork failed: $!";
49 } elsif ($kidpid == 0) {
50 close $dad_rdr; close $dad_wtr;
51 open(STDIN, "<&$kid_rdr");
52 open(STDOUT, ">&$kid_wtr");
53 warn "execing @cmd\n" if $debug;
55 croak "open2: exec of @cmd failed";
57 close $kid_rdr; close $kid_wtr;
58 select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe
61 1; # so require is happy