diff options
Diffstat (limited to 'lib/open2.pl')
| -rw-r--r-- | lib/open2.pl | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/lib/open2.pl b/lib/open2.pl new file mode 100644 index 0000000000..dcd68a8cd3 --- /dev/null +++ b/lib/open2.pl @@ -0,0 +1,54 @@ +# &open2: tom christiansen, <tchrist@convex.com> +# +# usage: $pid = &open2('rdr', 'wtr', 'some cmd and args'); +# or $pid = &open2('rdr', 'wtr', 'some', 'cmd', 'and', 'args'); +# +# spawn the given $cmd and connect $rdr for +# reading and $wtr for writing. return pid +# of child, or 0 on failure. +# +# WARNING: this is dangerous, as you may block forever +# unless you are very careful. +# +# $wtr is left unbuffered. +# +# abort program if +# rdr or wtr are null +# pipe or fork or exec fails + +package open2; +$fh = 'FHOPEN000'; # package static in case called more than once + +sub main'open2 { + local($kidpid); + local($dad_rdr, $dad_wtr, @cmd) = @_; + + $dad_rdr ne '' || die "open2: rdr should not be null"; + $dad_wtr ne '' || die "open2: wtr should not be null"; + + # force unqualified filehandles into callers' package + local($package) = caller; + $dad_rdr =~ s/^[^']+$/$package'$&/; + $dad_wtr =~ s/^[^']+$/$package'$&/; + + local($kid_rdr) = ++$fh; + local($kid_wtr) = ++$fh; + + pipe($dad_rdr, $kid_wtr) || die "open2: pipe 1 failed: $!"; + pipe($kid_rdr, $dad_wtr) || die "open2: pipe 2 failed: $!"; + + if (($kidpid = fork) < 0) { + die "open2: fork failed: $!"; + } elsif ($kidpid == 0) { + close $dad_rdr; close $dad_wtr; + open(STDIN, "<&$kid_rdr"); + open(STDOUT, ">&$kid_wtr"); + warn "execing @cmd\n" if $debug; + exec @cmd; + die "open2: exec of @cmd failed"; + } + close $kid_rdr; close $kid_wtr; + select((select($dad_wtr), $| = 1)[0]); # unbuffer pipe + $kidpid; +} +1; # so require is happy |