Win32 - forked process doesn't create a Window

Hello Perl gurus,

1. I have a web page where I can push a button (dospawn.html).
2. This button calls a CGI script (spawnboss.cgi)
3. spawnboss.cgi calls a forking perl script (forkme.pl)
4. forkme.pl calls the process creation script (createme.pl)
5. createme.pl creates my notepad.exe process, but no window shows up on my
PC.

The result on my web browser is:
SPAWNBOSS: Running perl forkme.pl C:\Windows\system32 notepad.exe
FORKME: Forking perl createme.pl C:\Windows\system32 notepad.exe
CREATEME: Starting C:\Windows\system32\notepad.exe
CREATEME: process notepad.exe is running

When I kill the notepad.exe from my Task Manager,
I then get on my web browser the final output:
CREATEME: process notepad.exe was ended

The only thing missing is the graphical window for NOTEPAD so I can type
into it.

Thanks for your assistance :)
Rob

Details following...

Have the latest installed version of ActivePerl 5.8.2.
The web page is on my personal Apache web server 2.0.47.
http://localhost/~test/dospawn.html
Configured for CGI with:
=====================================
LoadModule cgi_module modules/mod_cgi.so
ScriptAlias /cgi-bin/ "D:/Apps/Apache2/cgi-bin/"
UserDir "D:\Web\USERS"
<Directory "D:/Web/USERS/test/cgi-bin/">
AllowOverride None
Options ExecCGI
Order allow,deny
Allow from all
</Directory>
AddHandler cgi-script .cgi .pl
=====================================

The files are as follows:
=====================================
DOSPAWN.HTML
<html><body>
<form action="cgi-bin/spawnboss.cgi?action=spawn" method="post"
enctype="multipart/form-data">
<input type=hidden name="action" value="spawn">
<input type="submit" value="Spawn NOTEPAD">
</form>
</body></html>
=====================================
SPAWNBOSS.CGI
#!d:/apps/perl/bin/perl.exe
use CGI qw/:standard :html3/;
&spawn if (param('action') eq 'spawn'); # Spawn a process
exit;
sub spawn {
print "Content-type: text/html\n\n";
print "<HTML><BODY>\n";
$command = "perl forkme.pl C:\\Windows\\system32 notepad.exe";
print "SPAWNBOSS: Running $command<br>\n";
system("$command");
print "</BODY></HTML>\n";
return;
}
=====================================
FORKME.PL
#!d:/apps/perl/bin/perl.exe
$command = "perl createme.pl $ARGV[0] $ARGV[1]";
if ($pid = fork) {
print "FORKME: Forking $command<br>\n";
exec "$command";
die "couldn't exec $command : $!";
}
else {
die "DO_RUNME: fork failed: $!";
}
exit;
=====================================
CREATEME.PL
#!d:/apps/perl/bin/perl.exe
use Win32::Process;
use IO::Handle;
STDOUT->autoflush(1);
STDERR->autoflush(1);
sub ErrorReport{
print Win32::FormatMessage( Win32::GetLastError() );
}
print("CREATEME: Starting $ARGV[0]\\$ARGV[1]<br>\n");
Win32::Process::Create($ProcessObj,
"$ARGV[0]\\$ARGV[1]",
"$ARGV[1]",
1,
NORMAL_PRIORITY_CLASS,
"$ARGV[0]\\")|| die ErrorReport();
print("CREATEME: process $ARGV[1] is running<br>\n");
$ProcessObj->Wait(INFINITE);
print("CREATEME: process $ARGV[1] was ended<br>\n");
exit;
=====================================
The END

Jul 19 '05 #1

Subscribe Post Reply

4961

Jim Gibson

In article <rP******************@news20.bellglobal.com>, RL
<lr*******@hotmail.com> wrote:

Hello Perl gurus,

1. I have a web page where I can push a button (dospawn.html).
2. This button calls a CGI script (spawnboss.cgi)
3. spawnboss.cgi calls a forking perl script (forkme.pl)
4. forkme.pl calls the process creation script (createme.pl)
5. createme.pl creates my notepad.exe process, but no window shows up on my
PC.

The result on my web browser is:
SPAWNBOSS: Running perl forkme.pl C:\Windows\system32 notepad.exe
FORKME: Forking perl createme.pl C:\Windows\system32 notepad.exe
CREATEME: Starting C:\Windows\system32\notepad.exe
CREATEME: process notepad.exe is running

When I kill the notepad.exe from my Task Manager,
I then get on my web browser the final output:
CREATEME: process notepad.exe was ended

The only thing missing is the graphical window for NOTEPAD so I can type
into it.

Thanks for your assistance :)
Rob
Since I don't work on Windows, I am afraid I can't help you too much. I
can, however, point out some oddities in your program.

Details following...

Have the latest installed version of ActivePerl 5.8.2.
The web page is on my personal Apache web server 2.0.47.
http://localhost/~test/dospawn.html
Configured for CGI with:
=====================================
LoadModule cgi_module modules/mod_cgi.so
ScriptAlias /cgi-bin/ "D:/Apps/Apache2/cgi-bin/"
UserDir "D:\Web\USERS"
<Directory "D:/Web/USERS/test/cgi-bin/">
AllowOverride None
Options ExecCGI
Order allow,deny
Allow from all
</Directory>
AddHandler cgi-script .cgi .pl
=====================================

The files are as follows:
=====================================
DOSPAWN.HTML
<html><body>
<form action="cgi-bin/spawnboss.cgi?action=spawn" method="post"
enctype="multipart/form-data">
<input type=hidden name="action" value="spawn">
<input type="submit" value="Spawn NOTEPAD">
</form>
</body></html>
=====================================
SPAWNBOSS.CGI
#!d:/apps/perl/bin/perl.exe
use CGI qw/:standard :html3/;
&spawn if (param('action') eq 'spawn'); # Spawn a process
exit;
sub spawn {
print "Content-type: text/html\n\n";
print "<HTML><BODY>\n";
$command = "perl forkme.pl C:\\Windows\\system32 notepad.exe";
print "SPAWNBOSS: Running $command<br>\n";
system("$command");
print "</BODY></HTML>\n";
return;
}
=====================================
FORKME.PL
#!d:/apps/perl/bin/perl.exe
$command = "perl createme.pl $ARGV[0] $ARGV[1]";
if ($pid = fork) {
print "FORKME: Forking $command<br>\n";
exec "$command";
die "couldn't exec $command : $!";
}
else {
die "DO_RUNME: fork failed: $!";
}
exit;
fork() returns a non-zero pid (that of the child) to the parent and
returns zero to the child. Thus, you are exec'ing from the parent
process and the child just dies with an error message. You can probably
eliminate the fork and this entire script, since you are not using the
child process. Do you want the parent process to return the completed
web page to the browser while notepad.exe runs? Then you should run
notepad.exe from the child.

=====================================
CREATEME.PL
#!d:/apps/perl/bin/perl.exe
use Win32::Process;
use IO::Handle;
STDOUT->autoflush(1);
STDERR->autoflush(1);
sub ErrorReport{
print Win32::FormatMessage( Win32::GetLastError() );
}
print("CREATEME: Starting $ARGV[0]\\$ARGV[1]<br>\n");
Win32::Process::Create($ProcessObj,
"$ARGV[0]\\$ARGV[1]",
"$ARGV[1]",
1,
NORMAL_PRIORITY_CLASS,
"$ARGV[0]\\")|| die ErrorReport();
print("CREATEME: process $ARGV[1] is running<br>\n");
$ProcessObj->Wait(INFINITE);
print("CREATEME: process $ARGV[1] was ended<br>\n");
exit;
=====================================
The END

Another tip: make sure you can run your CGI script from the command
line before you try to execute it from the web server, if you have
command line access to the server.

FYI: this newsgroup is defunct. Try comp.lang.perl.misc in the future
for better response.

Jul 19 '05 #2

Hi Jim,

You are correct, I don't need the fork.

Also, just realized I forgot to add the createme.pl program
=====================================
CREATEME.PL
#!d:/apps/perl/bin/perl.exe
use Win32::Process;
use IO::Handle;
STDOUT->autoflush(1);
STDERR->autoflush(1);
sub ErrorReport{
print Win32::FormatMessage( Win32::GetLastError() );
}
print("CREATEME: Starting $ARGV[0]\\$ARGV[1]<br>\n");
Win32::Process::Create($ProcessObj,
"$ARGV[0]\\$ARGV[1]",
"$ARGV[1]",
1,
NORMAL_PRIORITY_CLASS,
"$ARGV[0]\\")|| die ErrorReport();
print("CREATEME: process $ARGV[1] is running<br>\n");
$ProcessObj->Wait(INFINITE);
print("CREATEME: process $ARGV[1] was ended<br>\n");
exit;
=====================================

"Jim Gibson" <jg*****@mail.arc.nasa.gov> wrote in message
news:050220041717002619%jg*****@mail.arc.nasa.gov. ..

In article <rP******************@news20.bellglobal.com>, RL
<lr*******@hotmail.com> wrote:
Hello Perl gurus,

1. I have a web page where I can push a button (dospawn.html).
2. This button calls a CGI script (spawnboss.cgi)
3. spawnboss.cgi calls a forking perl script (forkme.pl)
4. forkme.pl calls the process creation script (createme.pl)
5. createme.pl creates my notepad.exe process, but no window shows up on my PC.

The result on my web browser is:
SPAWNBOSS: Running perl forkme.pl C:\Windows\system32 notepad.exe
FORKME: Forking perl createme.pl C:\Windows\system32 notepad.exe
CREATEME: Starting C:\Windows\system32\notepad.exe
CREATEME: process notepad.exe is running

When I kill the notepad.exe from my Task Manager,
I then get on my web browser the final output:
CREATEME: process notepad.exe was ended

The only thing missing is the graphical window for NOTEPAD so I can type
into it.

Thanks for your assistance :)
Rob

Since I don't work on Windows, I am afraid I can't help you too much. I
can, however, point out some oddities in your program.

Details following...

Have the latest installed version of ActivePerl 5.8.2.
The web page is on my personal Apache web server 2.0.47.
http://localhost/~test/dospawn.html
Configured for CGI with:
=====================================
LoadModule cgi_module modules/mod_cgi.so
ScriptAlias /cgi-bin/ "D:/Apps/Apache2/cgi-bin/"
UserDir "D:\Web\USERS"
<Directory "D:/Web/USERS/test/cgi-bin/">
AllowOverride None
Options ExecCGI
Order allow,deny
Allow from all
</Directory>
AddHandler cgi-script .cgi .pl
=====================================

The files are as follows:
=====================================
DOSPAWN.HTML
<html><body>
<form action="cgi-bin/spawnboss.cgi?action=spawn" method="post"
enctype="multipart/form-data">
<input type=hidden name="action" value="spawn">
<input type="submit" value="Spawn NOTEPAD">
</form>
</body></html>
=====================================
SPAWNBOSS.CGI
#!d:/apps/perl/bin/perl.exe
use CGI qw/:standard :html3/;
&spawn if (param('action') eq 'spawn'); # Spawn a process
exit;
sub spawn {
print "Content-type: text/html\n\n";
print "<HTML><BODY>\n";
$command = "perl forkme.pl C:\\Windows\\system32 notepad.exe";
print "SPAWNBOSS: Running $command<br>\n";
system("$command");
print "</BODY></HTML>\n";
return;
}
=====================================
FORKME.PL
#!d:/apps/perl/bin/perl.exe
$command = "perl createme.pl $ARGV[0] $ARGV[1]";
if ($pid = fork) {
print "FORKME: Forking $command<br>\n";
exec "$command";
die "couldn't exec $command : $!";
}
else {
die "DO_RUNME: fork failed: $!";
}
exit;

fork() returns a non-zero pid (that of the child) to the parent and
returns zero to the child. Thus, you are exec'ing from the parent
process and the child just dies with an error message. You can probably
eliminate the fork and this entire script, since you are not using the
child process. Do you want the parent process to return the completed
web page to the browser while notepad.exe runs? Then you should run
notepad.exe from the child.

=====================================
CREATEME.PL
#!d:/apps/perl/bin/perl.exe
use Win32::Process;
use IO::Handle;
STDOUT->autoflush(1);
STDERR->autoflush(1);
sub ErrorReport{
print Win32::FormatMessage( Win32::GetLastError() );
}
print("CREATEME: Starting $ARGV[0]\\$ARGV[1]<br>\n");
Win32::Process::Create($ProcessObj,
"$ARGV[0]\\$ARGV[1]",
"$ARGV[1]",
1,
NORMAL_PRIORITY_CLASS,
"$ARGV[0]\\")|| die ErrorReport();
print("CREATEME: process $ARGV[1] is running<br>\n");
$ProcessObj->Wait(INFINITE);
print("CREATEME: process $ARGV[1] was ended<br>\n");
exit;
=====================================
The END

Another tip: make sure you can run your CGI script from the command
line before you try to execute it from the web server, if you have
command line access to the server.

FYI: this newsgroup is defunct. Try comp.lang.perl.misc in the future
for better response.

Jul 19 '05 #3

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