The Universe of Disco

A security problem in a CGI program: addenda

Shell-less piping in Perl

Unfortunately, there is no easy way to avoid the shell when running a command that is attached to the parent process via a pipe. Perl provides open "| command arg arg arg...", which is what I used, and which is analogous to [system STRING], involving the shell. But it provides nothing analogous to [system ARGLIST], which avoids the shell. If it did, then I probably would have used it, writing something like this:

        open M, "|", $MAILER, "-fnobody\@plover.com", $addre;

and the whole problem would have been avoided.

        open M, "|-", $MAILER, "-fnobody\@plover.com", $addre;

(Jet lag when travelling with a toddler is worse than normal jet lag, because nobody else can get over the jet lag until the toddler does.)

Jeff Weisberg also pointed out that even prior to 5.8.0, you can write:

        open(F, "|-") || exec("program", "arg", "arg", "arg");

RFC 822

Quite so. Such addresses are extremely rare, and people who use them are expected to figure out how to subscribe by email, rather than using the web form.

qmail

Moreover, since I have previously been paid to give classes at large conferences on how to avoid exactly this sort of problem, I deserve whatever scorn and ridicule comes my way because of this.

Thanks to everyone who wrote in.

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