in reply to Re^3: Win32::API Memory Exception with GetCommandLine() (which returns a static string)
in thread Win32::API Memory Exception with GetCommandLine() (which returns a static string)

I still get the same length discrepancy on ActivePerl - ie Inline's 20 vs Win32::API's 21.

I have a vague recollection that somewhere in Win32::API, they have code to extend the length of various strings/buffers passed in and/or out by one to 'allow room for terminating nulls'.

Maybe I'm too tired or mis-remembering, because I cannot find it now? :(

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  • Comment on Re^4: Win32::API Memory Exception with GetCommandLine() (which returns a static string)

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Re^5: Win32::API Memory Exception with GetCommandLine() (which returns a static string)
by syphilis (Archbishop) on Jul 06, 2007 at 07:31 UTC
    I've just noticed that if I take the OP's code out of the batch file, it works ok (no faults) though it still returns the wrong string.

    Also, if I replace the OP's code in the batch file with: 
    use Win32::API;

$function = new Win32::API("kernel32", "GetCommandLine", '', 'P');

$string = $function->Call();

print "string[".length($string)."] = '$string'\n";

    [download]
    then the batch file runs without error and $string no longer contains the additional trailing space - ie Win32::API and Inline are in complete agreement.

    A problem with the Import method perhaps ? ... I've never trusted it.

    Cheers,
    Rob
    Update: As BrowserUk has subsequently demonstrated, it's the pack('Z*', ...) that leads to the extra trailing space - nothing to do with Win32::API->Import() at all.
[reply]
[d/l]
[select]

      The extra trailing space is explainable to the weird use the OP is making of pack: 

      #!/usr/bin/perl -w
use strict;
use Win32::API;
Win32::API->Import("kernel32", "LPTSTR GetCommandLine()");

my $cl = GetCommandLine();
printf "%d : '%s'\n", length( $cl ), $cl;

my $cl2 = pack 'Z*', GetCommandLine();
printf "%d : '%s'\n", length( $cl2 ), $cl2;

__END__
C:\test>junk3
46 : '"c:\perl\bin\perl.exe" -sw "C:\test\junk3.pl" '
47 : '"c:\perl\bin\perl.exe" -sw "C:\test\junk3.pl"  '

      [download]

      I'm lost as to why the combination of pack, mingw built perl and a batch file would cause a segfault?

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
        I'm lost as to why the combination of pack, mingw built perl and a batch file would cause a segfault?

        I'm still at a loss on how to fix this as well. But you've all given me a couple of other avenues to take in order to tackle the issue.

        Thanks.

[reply]

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