Mail Archives: cygwin/2004/02/24/10:48:18
--nFreZHaLTZJo0R7j
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I am currently writing an application that uses win32 named pipes to
communicate. The random length records being sent dictated opening
a file handle to the named pipe on the client and then using read()
to access the record. After noticing that libwin32-0.191 had been ported
to cygwin, I tried a perl named pipe server and client that I had written
for debugging the app on ActiveState Perl-5.8.2. I noticed the following:
Win32::Pipe-Connect() is either non-blocking, doesn't get passed the timeout
value when the pipe is created or has a very low timeout value. This could
also be an interpretation problem. The behavior I had expected was that when
no client is connected, the Win32::Pipe-Connect() would wait for a client
to connect until a timeout occurs. The behavior I got was that Win32::Pipe->
Connect() returns immediately with "True" if a client is connected and "False"
if one has not.
Perl open() on the client side doesn't seem to understand using UNC to open
an existing named pipe. For example if I do the following:
open(PIPE, "<", "\\\\.\\pipe\\my named pipe"); I get an error
message: "Mount device busy." After trying to use open() to connect to the
named pipe, No other connections are possible. It would appear that open
is interpreting "\\\\.\\pipe\\my named pipe" as a mount request.
A perl script illustrating the problem is attached. Vital statistics are:
Cygwin DLL version info:
DLL version: 1.5.7
DLL epoch: 19
DLL bad signal mask: 19005
DLL old termios: 5
DLL malloc env: 28
API major: 0
API minor: 109
Shared data: 3
DLL identifier: cygwin1
Mount registry: 2
Cygnus registry name: Cygnus Solutions
Cygwin registry name: Cygwin
Program options name: Program Options
Cygwin mount registry name: mounts v2
Cygdrive flags: cygdrive flags
Cygdrive prefix: cygdrive prefix
Cygdrive default prefix:
Build date: Fri Jan 30 19:32:04 EST 2004
CVS tag: cr-0x9e
Shared id: cygwin1S3
and
perl 5.8.2-1
perl-libwin32 0.191-1
Thanks in advance
--nFreZHaLTZJo0R7j
Content-Type: application/x-perl
Content-Disposition: attachment; filename="pipe_as_read_fh.pl"
Content-Transfer-Encoding: quoted-printable
#!/usr/bin/perl=0D
=0D
use Win32::Pipe;=0D
use Sys::Hostname;=0D
my $PipeName =3D "My Named Pipe";=0D
=0D
$| =3D 1; # Set output buffering to AUTO_FLUSH=0D
=0D
print "Spawning server and client\n" ;=0D
=0D
SPAWN: {=0D
my $pid;=0D
print "Preparing to fork\n" ;=0D
=0D
if($pid=3Dfork()) {=0D
print "Spawning server\n" if defined ($DEBUG);=0D
=0D
np_server() ;=0D
=0D
} elsif (defined($pid)) {=0D
print "Spawning client\n" if defined ($DEBUG);=0D
=0D
np_client() ;=0D
=0D
} elsif ($! =3D~ /No more process/) {=0D
sleep 5;=0D
print "Respawning\n" ;=0D
redo SPAWN;=0D
} else {=0D
die "Can't fork: $!\n";=0D
}=0D
}=0D
=0D
sub np_server {=0D
=0D
my $Pipe_Error ;=0D
my $Client_Disconnected;=0D
my $Pipe_Connect_Status;=0D
my $Test_Done ; =0D
my $In;=0D
=0D
print "NP Server: Creating pipe \"$PipeName\".\n";=0D
=0D
=0D
if( ($Pipe =3D new Win32::Pipe( $PipeName, NMPWAIT_WAIT_FOREVER, PIPE_T=
YPE_BYTE | PIPE_READMODE_BYTE | PIPE_WAIT)) )=0D
{=0D
print "NP Server: Done creating pipe.\n";=0D
=0D
$User =3D getlogin() ;=0D
print "NP Server: Pipe opened by $User.\n";=0D
$Pipe_Error =3D 0;=0D
$Test_Done =3D 0;=0D
while(!$Pipe_Error && !$Test_Done) {=0D
$Client_Disconnected =3D 0;=0D
print "NP Server: Waiting for client to connect\n";=0D
=0D
while(( $Pipe->Connect()) && !$Pipe_Error && !$Client_Disconnected && =
!$Test_Done) {=0D
print "NP Server: Client connected\n";=0D
my $Data =3D "Pipe writen by $User. Time on " . hostname() . " is: " . lo=
caltime() . "\n";=0D
=0D
if (!$Pipe->Write( $Data )) {=0D
print "NP Server: Error writing pipe\n";=0D
$Pipe_Error =3D 1;=0D
next ;=0D
}=0D
if (!($In=3D$Pipe->Read())) {=0D
print "NP Server: Error reading pipe\n";=0D
$Pipe_Error =3D 1;=0D
next ;=0D
}=0D
$Client_Disconnected =3D 1 if ($In eq "DONE") ;=0D
$Test_Done =3D 1 if ($In eq "FINIS") ;=0D
print "NP Server: Test Done\n" if ($In eq "FINIS") ;=0D
=0D
print "NP Server: Disconnecting...\n";=0D
$Pipe->Disconnect();=0D
$Pipe->Close() if ($Test_Done);=0D
=0D
}=0D
=0D
print "NP Server: Client Disconnected\n" if ($Client_Disconnected);; =
print "NP Server: Pipe Error -- $|\n" if ($Pipe_Error);=0D
print "NP Server: Test Done\n" if ($Test_Done);=0D
sleep 1;=0D
}=0D
}=0D
else=0D
{=0D
print "\nNP Server: Could not create pipe Error: " . Win32::Pipe::Error . =
"\n";=0D
}=0D
}=0D
=0D
sub np_client {=0D
=0D
my $FQNPipeName =3D "\\\\.\\pipe\\" . $PipeName;=0D
print "NP Client: Connecting to $FQNPipeName via Win32::Pipe\n";=0D
=0D
if( $Pipe =3D new Win32::Pipe( $FQNPipeName ) )=0D
{=0D
print "NP Client: Pipe has been opened, read data from it...\n";=0D
my $In =3D $Pipe->Read();=0D
print "NP Client: Server sent the client -- $In\n";=0D
print "NP Client: Closing the pipe\n";=0D
$Pipe->Write("DONE");=0D
$Pipe->Close();=0D
}=0D
else=0D
{=0D
print "NP Client: Error connecting: " . $Win32::Pipe::Error . "\n";=0D
}=0D
print "NP Client: Connecting to $FQNPipeName via open()\n";=0D
=0D
sleep 1;=0D
if( open(PIPE, "+<", $FQNPipeName ) )=0D
{=0D
my $In;=0D
print "NP Client: Pipe has been opened, reading data from it...\n";=0D
=0D
read PIPE, $In, 70 ;=0D
print "NP Client: Server sent the client -- $In\n";=0D
print PIPE "DONE", 4;=0D
=0D
close(PIPE);=0D
}=0D
else=0D
{=0D
print "NP Client: Error connecting via open(): $!\n";=0D
}=0D
print "NP Client: Finishing the test\n";=0D
=0D
if( $Pipe =3D new Win32::Pipe( $FQNPipeName ) )=0D
{=0D
print "NP Client: Finishing the test\n";=0D
=0D
$Pipe->Write("FINIS");=0D
$Pipe->Close();=0D
}=0D
else=0D
{=0D
print "NP Client: Error connecting: " . $Win32::Pipe::Error . "\n";=0D
}=0D
print "NP Client: Test Done\n";=0D
=0D
}=0D
--nFreZHaLTZJo0R7j
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