Re: [PATCH] Convert open("-|") to qx{} calls

From: Randal L. Schwartz <merlyn@stonehenge.com>
Date: Feb 23, 2006, 16:07 UTC
Message-ID: <86hd6qgit5.fsf@blue.stonehenge.com>
In-Reply-To: <81b0412b0602230738s3445bd86h2d1d670e0ef5daed@mail.gmail.com>

>>>>> "Alex" == Alex Riesen <raa.lkml@gmail.com> writes:

Alex> Is $tmpname safe?

>> -       my $sha = <$F>;
>> +       my $sha = qx{git-hash-object -w $name};
>> +       !$? or exit $?;

Alex> Is $name safe?

>> -       while(<$f>) {
>> +       foreach (qx{git-ls-tree -r -z $gitrev $srcpath}) {
>> chomp;

Alex> Is $srcpath safe?

>> -                       while(<$F>) {
>> +                       foreach (qx{git-ls-files -z @o1}) {

Alex> @o1 must contain filenames. Can be dangerous

Convert all of these to use "safe_qx" (perl 5.6 compatible):

    sub safe_qx {
      defined (my $pid = open my $kid, "-|") or die "Cannot fork: $!";
      unless ($pid) { # child does:
        exec @_;
        die "Cannot exec @_: $!";
      }
      my $result = do { local $/; <$kid> };
      close $kid;                   # sets $?
      return $result;
    }

my $result = safe_qx('some shell command'); my $other_result = safe_qx('git-ls-tree', '-r', '-z', $gitrev, $srcpath);

Args are safe, as if being passed to system/exec, so a single arg can be a shell command, multiargs are passed arg-by-arg to a single exec target. $? is set correctly.

-- 
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!