1 # &open2: tom christiansen, <tchrist@convex.com>
3 # usage: $pid = &open2('rdr', 'wtr', 'some cmd and args');
4 # or $pid = &open2('rdr', 'wtr', 'some', 'cmd', 'and', 'args');
6 # spawn the given $cmd and connect $rdr for
7 # reading and $wtr for writing. return pid
8 # of child, or 0 on failure.
10 # WARNING: this is dangerous, as you may block forever
11 # unless you are very careful.
13 # $wtr is left unbuffered.
17 # pipe or fork or exec fails
20 $fh = 'FHOPEN000'; # package static in case called more than once
24 local($dad_rdr, $dad_wtr, @cmd) = @_;
26 $dad_rdr ne '' || die "open2: rdr should not be null";
27 $dad_wtr ne '' || die "open2: wtr should not be null";
29 # force unqualified filehandles into callers' package
30 local($package) = caller;
31 $dad_rdr =~ s/^([^']+$)/$package'$1/;
32 $dad_wtr =~ s/^([^']+$)/$package'$1/;
34 local($kid_rdr) = ++$fh;
35 local($kid_wtr) = ++$fh;
37 pipe($dad_rdr, $kid_wtr) || die "open2: pipe 1 failed: $!";
38 pipe($kid_rdr, $dad_wtr) || die "open2: pipe 2 failed: $!";
40 if (($kidpid = fork) < 0) {
41 die "open2: fork failed: $!";
42 } elsif ($kidpid == 0) {
43 close $dad_rdr; close $dad_wtr;
44 open(STDIN, "<&$kid_rdr");
45 open(STDOUT, ">&$kid_wtr");
46 warn "execing @cmd\n" if $debug;
48 die "open2: exec of @cmd failed";
50 close $kid_rdr; close $kid_wtr;
51 select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe
54 1; # so require is happy