Problems restraining read command to 32 bits -perl Post: 302334516

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Top Forums Shell Programming and Scripting Problems restraining read command to 32 bits -perl Post 302334516 by TeamUSA on Wednesday 15th of July 2009 07:03:35 PM

07-15-2009

Registered User

Problems restraining read command to 32 bits -perl

Hey everybody,

I'm having difficulty using the read command to perform a checksum operation. Whenever I print the final checksum, the result always returns FFFFFFFF, and I know thats not the checksum.

Code:

 #!/usr/bin/perl -w
  
  use strict;
  use FileHandle;
  use warnings;
  my $data = "file.bin";
  my $buffer;
  my $string;
  my $n = 0;
  my $checksum = 0;
  my $num = 0;
  my $str = unpack("B32", pack("N", shift));
  my $bits = 4;
  my $decimal;

open FILE, $data or die $!;
binmode FILE;  
 while (($n = read FILE, $buffer, 4))
 {
 
 $decimal = unpack("N", pack("B32", $buffer));
 
 {$checksum = $checksum + $decimal;
 #$num = $num + $bits;}
 
 #print "1. $num\n";
 print "2. $decimal\n";
 #print "3. $n bytes read\n";
 print "4. $checksum \n";
 }
 
 $checksum = $checksum & 0xFFFFFFFF;

Basically, I'm trying to read a binary file 32 bits at a time by unpacking them into decimal and then adding them. Furthermore, I am trying to use the $checksum & 0xFFFFFFFFF command to restrain the checksum to 32 bits. Also, just ignore the commented out stuff, I was using it for my own testing. Any assistance would be greatly appreciated.

TeamUSA

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LEARN ABOUT DEBIAN

lfc_setfsizeg

LFC_SETFSIZEG(3)					       LFC Library Functions						  LFC_SETFSIZEG(3)

NAME

       lfc_setfsizeg - set filesize for a regular file having the given GUID; set also last modification time to the current time

SYNOPSIS

       #include <sys/types.h>
       #include "lfc_api.h"

       int lfc_setfsizeg (const char *guid, u_signed64 filesize, const char *csumtype, char *csumvalue)

DESCRIPTION

       lfc_setfsizeg  sets  the  filesize for a regular file having the given GUID; set also the last modification time to the current time.  This
       function should only be called by the stager after the last write operation has been performed on the file.  The file is identified by  its
       guid.

       guid   specifies the Grid Unique IDentifier.

       csumtype
	      specifies the type of checksum. Valid types are:

	      CS     standard 32 bits checksum

	      AD     Adler 32 bits checksum

	      MD     MD5 128 bits checksum

RETURN VALUE

       This routine returns 0 if the operation was successful or -1 if the operation failed. In the latter case, serrno is set appropriately.

ERRORS

       EFAULT	    guid is a NULL pointer.

       EINVAL	    The  length  of  the  guid exceeds CA_MAXGUIDLEN or the length of the csumtype exceeds 2 or csumtype is an unknown type or the
		    length of the csumvalue exceeds 32.

       SENOSHOST    Host unknown.

       SENOSSERV    Service unknown.

       SECOMERR     Communication error.

       ENSNACT	    Name server is not running or is being shutdown.

SEE ALSO

       Castor_limits(4), lfc_statg(3)

LFC
							   $Date: 2008/09/19 11:32:26 $ 					  LFC_SETFSIZEG(3)