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