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Re^2: ActivePerl Gtk2::Helper Hangs

by renegadex (Beadle)
on Nov 29, 2013 at 03:03 UTC ( #1064890=note: print w/replies, xml ) Need Help??


in reply to Re: ActivePerl Gtk2::Helper Hangs
in thread ActivePerl Gtk2::Helper Hangs

Hi bulk88,

I've been trying to adopt your codes to mine and I get this error that there was an overflow every time I call sub add_job on run-time by pressing the Button A
*** unhandled exception in callback: *** Win32::API::Call: parameter 5 had a buffer overflow at (eval 18) + line 2. *** ignoring at pipecall.pl line 65.

this is my new code
#!/usr/bin/perl -w use strict; use Gtk2 '-init'; use Gtk2::Helper; use Data::Dumper; use FileHandle; use IPC::Open2; use Win32API::File; use Win32; use Win32::API; { my $api; die "PeekNamedPipe" if ! ($api= Win32::API::More->Import("kernel32", " BOOL PeekNamedPipe( HANDLE hNamedPipe, LPVOID lpBuffer, DWORD nBufferSize, LPDWORD lpBytesRead, LPDWORD lpTotalBytesAvail, LPDWORD lpBytesLeftThisMessage );")); } my $wfh = FileHandle->new(); my $rfh = FileHandle->new(); open2($rfh,$wfh,"C:\\Windows\\System32\\cmd.exe"); my $hnd = Win32API::File::FdGetOsFHandle($rfh->fileno()); #get Win32 k +ernel handle from Perl land if($hnd == Win32API::File::INVALID_HANDLE_VALUE()) { die "bad hnd"; } my $tag = Gtk2::Helper->add_watch($rfh, 'in',\&preview_call); my $window = Gtk2::Window->new(); $window->signal_connect("destroy",sub{Gtk2->main_quit();}); $window->set_size_request(300,300); my $hbox = Gtk2::HBox->new(); $window->add($hbox); my $button = Gtk2::Button->new("A"); $button->signal_connect('clicked'=>sub{ add_job(); }); $hbox->pack_start($button,1,1,0); $button = Gtk2::Button->new("B"); $button->signal_connect('clicked'=>sub{ print "i do nothing\n"; }); $hbox->pack_start($button,1,1,0); $window->show_all(); Gtk2->main(); sub preview_call { my $bRead = 0; my $bLeft = 0; my $bAvail = 0; my $ret = 0; my $buffer; $ret = PeekNamedPipe($hnd,undef,0,undef,$bAvail,undef); if(!$ret) { my $err = Win32::GetLastError(); die "PNP failed $err $^E"; } if($bAvail) { print "Available: $bAvail\n"; sysread($rfh,$buffer,1); print $buffer . "\n"; }else{ } return 1; } sub add_job { print $wfh "dir\n"; }
Mabuhay Civil Engineers! :D

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Re^3: ActivePerl Gtk2::Helper Hangs
by bulk88 (Priest) on Nov 29, 2013 at 04:46 UTC
    I think you hit a bug in Win32::API.
    2013-06-27 Win32::API v0.76_02 bulk88 .......... - Fixed, Win32::API::More::Import created Win32::API objs, not Win32::API::More
    upgrade to 0.76_02 or newer (Win32::API::More objects do automatic packing and unpacking of pointers to numbers, Win32::API objects require you to call pack and unpack yourself to convert the string/buffer filled with C-style binary numbers to Perl numbers)

    or convert the Win32::API::More->Import( to Win32::API->Import(, then pad out $bAvail with $bAvail = "\x00" x 4;, then after PeekNamedPipe, if successful, do unpack('L', $bAvail). Previous sentence is a summary of Win32::API.

    What happened was, because there isn't automatic packing my $bAvail = 0; was stringfied to "0", which is 1 byte long. The C function PeekNamedPipe wrote 4 bytes to $bAvail, even though $bAvail had only 1 byte space. An anti-memory corruption detector in Win32::API caught the mistake.

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